*A near-average Summer is possible for much of eastern Canada in terms of temperature and precipitation this year (more details below under the Summer outlook section).

Summer is, once again, fast approaching, but after a fairly dreary Spring 2011 across much of the country, many Canadians are wondering what could be awaiting for Summer 2011. As stated in my personal Spring-Summer 2011 outlook (in the reference link provided below) at the beginning of April, and previously on several occasions, I outlined that Spring 2011 could follow an average to below average temperature regime, while precipitation could be average to above average. As it turned out, Spring 2011 was, indeed, quite the contrast from what we had seen last year in 2010 (2010 being an exceptional year for warm weather in its entirety). For this Spring, we had undoubtedly seen well above average precipitation, with March, April and May exhibiting total amounts that easily exceeded 100 mm for each individual month - in fact, May 2011 was the third wettest May in recorded history (covers a timespan of about 70 years), with a final cumulative amount of over 140 mm, just trailing behind 1945 (175.3 mm), and fairly recently in 2006 (173.4 mm). Non-severe thunderstorms also contributed to some of the rainfall that we received, especially towards the end of April into May. The copious rainfall was particularly conducive to the ongoing flooding event that had been taking place just southeast of Montreal, in St-Jean-sur-Richelieu. In the context of monthly daytime highs, temperatures have been about average to slightly above average for March and April, respectively. Conversely, May 2011 had largely directed below average temperatures, which is to be expected, given the very little sunlight received for the month. Winter 2011 had also demonstrated a sharp contrast, as compared to Winter 2010. For a comparative examination of Winter 2010 vs. Winter 2011, please see the following link and refer to the tabulated statistics at the bottom of the final post (note that January’s normal snowfall should read as 52.5 cm, and the actual snowfall for January 2010 was 44.8 cm). My Spring-Summer 2011 outlook can also be found in the same post:

http://www.montreal-fireworks.com/forum/index.php?action=vthread& forum=5&topic=996&page=2

South of the border, I had predicted a fairly active tornado season in the U.S midwest and southeast - however, I never anticipated that it would be as severe and as deadly as it was in April and May. The enduring and violent nature of many of the tornado outbreaks in the U.S this past Spring was primarily attributed to persistent cool air descending into the western U.S and Great Plains from northwest Canada - this, in turn, serves to keep the jet stream farther South into the U.S than is usual. The persistence of the cool airmass itself out West was possibly due to the lingering effects of La Nina. It was largely these episodes of cool air that frequently fueled the development of strong areas of low pressure in the U.S, eventually leading to severe outbreaks of thunderstorms and tornadoes, especially at the end of April in the southeast U.S and more recently in the midwest (namely in Joplin, Missouri). To put things into perspective, the preliminary estimates from the National Weather Service for the total number of tornadoes so far this year is 1,314, and the yearly average over the last decade is about 1,274. Incredibly, a record 875 tornadoes have been reported in April 2011 alone, and the average number for the month of April over the last decade is actually closer to 160. Tragically, 512 fatalities have been reported in association with tornadoes so far this year in the U.S, a death toll figure that has not been observed since 1953. This past tornado season has been a monster.

As far as hurricane activity is concerned, the Atlantic could be facing an average to slightly above average number of total named storms, but if an El Nino develops by end-Summer into the Fall, I suspect that this would reduce activity for the latter part of the hurricane season.

La Nina continues to weaken in the equatorial Pacific, and in doing so we can expect average weather pattterns to eventually respond into the Summer as La Nina completely dissipates, though it is possible that La Nina may continue to have some influence (a lagging-effect in weather patterns adjusting accordingly) for the early part of Summer 2011 in spite of the dissipation. Much of the information that I had presented previously for my personal Spring-Summer 2011 outlook remains mostly unchanged, so I will just briefly re-state what was said beforehand in terms of potential temperature and precipitation trends.

Summer 2011 outlook

Temperature

I am still expecting a near-average temperature pattern to govern much of eastern Canada this Summer in terms of monthly daytime highs - that is, we could see a reasonable Summer, but this suggests fewer heat waves (in the technical sense), and, therefore, a reduction in days reaching 30 C or more, as compared to Summer 2010 (in short, I don't believe that it will be a blazing hot Summer, as was seen last year). It is possible to see a particularly warm August, but this depends on if an El Nino builds towards the end of the season. If an El Nino does develop, even if weak in nature, this may have positive implications for the end-Fall to Winter period, and so we could see a more forgiving Winter in that respect. We'll continue to monitor the progress of the sea-surface temperature anomalies in the equatorial Pacific in the coming months.

Precipitation

As always, precipitation forecasting is challenging, especially on a seasonal scale, and when transitions are taking place in the equatorial Pacific. That said, I believe that Summer 2011 precipitation could be average to above average, much like the Spring, although there is a better chance of Summer 2011 being closer to average. The principal reason behind this potential trend is because the average configuration of the sub-tropical jet stream during a transition from La Nina to near-neutral conditions tends to lie near the Canadian-American border across much of the country. Consequently, the jet stream allows for a storm track that traces closely along much of the southern periphery of Canada. At the same time, as mentioned previously, this may also invite an accompanied slight increase in severe weather this Summer for southern Ontario, southern Quebec and the U.S northeast, especially towards the end of June spanning towards mid August - the jet stream's influence enhances vertical wind shear (speed shear, in this case) at the upper levels of the atmosphere, permitting a better likelihood for storms to become more organized, most notably those storms that form along cold frontal waves. Enhanced precipitation may also be partly favored, again, by the already saturated soil surface, which would increase the amount of water vapor, or moisture, released to the atmosphere. Depending on the number of thunderstorms received, total precipitation may vary greatly at a local scale, simply because of the stochastic nature of thunderstorms.
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Concerning the fireworks displays of 2011, weather updates will be prepared and posted on this thread just before each of the displays, starting with a (usual) preliminary review about two days in advance. Again, I will try to keep the forecasts condensed and brief for the sake of simplicity, but a little more detail would be required if or when the atmosphere shows indications of instability, particularly in the event of thunderstorms or severe thunderstorms. As always, you are more than welcome and encouraged to post weather updates as well, but always be sure to pay particular attention to wind speed/direction, moisture (humidity), and the potential for unsettled conditions, if it exists. I sincerely hope that all of the 2011 entrants will be blessed with ideal Summer weather, especially in terms of wind (wind-related problems seem to be trending in recent years)!

Here's to a successful season!

Trav.

I just had wanted to share some footage (two parts) of the severe weather that affected the Montreal area on the late afternoon of June 8th:

http://www.youtube.com/watch?v=xMlOqlkpBuk&feature=related

http://www.youtube.com/watch?v=oM44G_GGlqI&feature=related

^^^
There is a nice anvil crawler capture at the end of the second part. Also note that this storm had a history of rotation.

Trav.

Cool, humid and damp weather has settled into much of eastern Canada since about two days, as an area of low pressure had pushed in from the West and brought with it mostly cloudy conditions, periods of heavy rains, and embedded thundershowers/thunderstorms. The computer models have been showing that this system would remain nearly stationary due to a blocking area of high pressure situated just North of Newfoundland, so this surface low is expected to provide a fair deal more rain throughout at least the next 24-36 hours, especially if we see multiple thunderstorms.

As far as the first fireworks display of 2011 is concerned, it is a possibility that the periods of rain/showers could lighten by the evening hours tomorrow (Saturday), but the current projections do not indicate a gradual clearing until roughly noon on Sunday, June 26th. Embedded thundershowers are also possible to develop both today and Saturday, partly because of the available energy present. I will continue to monitor the movement of this system in the newer model outputs. On another note, I would, additionally, like to keep an eye on both wind speed and direction - because of the position of the center of the low through Saturday, winds may be unfavorable in both direction and speed, but more so in terms of speed. Temperatures are expected to be suppressed (daytime highs in the high teens/very low 20s Celsius) through Saturday because of our position relative to the low at the time, and because of the cloud cover and periodic rainfall, so you will likely need to bring a light jacket for the evening.

In spite of the wet conditions that were experienced yesterday, the 23rd, and possibly still through the next 48-60 hours, there are signs of a nice warming trend into the start of the final week of June, with the slight possibility of a potential first heat wave by the very end of the month into the start of July. For June itself, temperatures have, so far, generally been above average (in terms of average daytime highs and overnight lows), along with near-average rainfall. So far this year, two days have exceeded 30 C.

I will post an update later today to determine Saturday’s final weather conditions. In the meantime, if you are planning to head to any existing fireworks displays for St-Jean Baptiste tonight, be sure to have an umbrella and light jacket handy, as periods of heavy rain and thunderstorms are a possibility.

Trav.

I apologize for the delay with this, as I just wanted to continue to track the speed of the system, as well as the associated wind tendencies.

After revising the newer model runs, most of what was stated in the above post still applies to the weather for today (June 25th), but there are some additional details that I would like mention. As such, here are the forecast details in terms of temperature, precipitation and wind for today.

Temperature/Humidity

Because this current system continues to move at a very slow pace, temperatures are expected to continue to exhibit below seasonal values. Daytime highs could be reaching a maximum of 21-22 Celsius (if there are at least some pockets of sunshine - if not, then closer to 18-19C), and evening values steady around 17-18 C (perhaps 19 C in the greater Montreal area). Humidity levels, however, should be moderate to high, so this will make the air temperature feel warmer than it actually is.

Precipitation

The air will remain near saturated at low to mid levels of the atmosphere because of the lingering effects of this system, so skies will stay mostly cloudy (some pockets of sun, again, are possible), along with periods of rain/showers. The models are still showing signs that the amount of available convective energy is still fairly abundant (likely because of the moderate to high humidity), particularly for the afternoon-early evening period, so the possibility for thunderstorms (largely non-severe) is still there. I also would not rule out isolated severe thunderstorm cells for the mid-afternoon to early evening period, given the history of this system over the last few days, although the chance is less today due to this system weakening. Note that the nature of the precipitation is widely scattered in association with this system, so I would accompany a 70-80% probability through the day (40% for thunderstorms/embedded thundershowers), and slightly lower chances for the evening at 60% (most thunderstorms and thundershowers should cease by the later evening period) - otherwise, mostly cloudy skies. The scattered nature of the showers also indicate that it should not rain for the entire day - rather, just on and off periods of rain/showers, with the risk for thunderstorms or embedded thundershowers. I would recommend having an umbrella and light jacket handy (or at least a hooded jacket), just in case of anything this evening.

Wind

Winds are a little tricky, but I no longer believe that wind direction will be much of a problem for the majority of spectators. The models are currently indicating that the winds are blowing from the South to South-southeast (SSE), but the speeds are quite light in nature during the evening period at roughly 4-7 km/h (possibly closer to 11 km/h by the later evening) - speeds are higher during the afternoon at 14-17 km/h. Winds may tilt slightly from the South-southwest by the later evening. As such, smoke should be gently blowing mostly to the right of the audience at La Ronde. There may be periods of smoke buildup, however, because of the moderate-high humidity and overall light winds, particularly when the display becomes more active at low to high level.

That’s the way the weather should typically behave for today. In summary, we should see mostly cloudy conditions accompanied by periods of ubiquitous rain/showers. Thunderstorms and embedded thundershowers are also possible. Winds should be very light from the South to, occasionally, the SSE. A shift to SSW tendencies is possible later in the evening as the system pushes slowly eastward. Temperatures are likely cool during the evening, so you may want to either have a light jacket or sweater equipped. The humidity is moderate to high, so it will feel a touch sticky. With some luck, the wet weather will hold off just before and during China’s display, and we will just, instead, be faced with overcast conditions. Again, expect Summer-like weather to gracefully return for most of the work week. Severe weather is possible later Tuesday, however.

Trav.

Summer-like weather is expected to resume in much of eastern Canada to bring in the month of July, as a defined ridge in the jet stream (as well as an associated surface low pressure system) that recently formed over western Canada is now on its way East. Consequently, seasonal to above seasonal temperatures are expected, with high to potentially very high humidity for this coming weekend. This warming trend was the prospective “heat wave” that I had mentioned last week, but although it is no longer a formal heat wave in nature, it is still a nice warming trend, nonetheless.

Under these conditions, Saturday’s fireworks display (by the Czech Republic) is forecasted to have typical July weather, with plenty of sunshine, high to very high humidity, and a few defined clusters of cumulus clouds, due to some atmospheric instability. I do not anticipate precipitation for the day, but thunderstorms could be moving in by the overnight hours and through the day Sunday. Winds seem to be more cooperative this week than what was seen last week in terms of speed (I will continue to monitor this in the future model runs, however), and the direction is likely South-southwesterlies (SSW), so the smoke should be moving relatively quickly to the right of the audience at La Ronde (to the left of those stationed on Notre-Dame). The breezy winds should also compensate for possible rapid smoke build up attributed to the high humidity. The warmer weather is also beginning to build in for Canada’s 144th birthday (more details for Canada Day’s forecast below).

I will post a final update later today to confirm these conditions, but I still would like to keep an eye on wind tendency towards the late afternoon-evening hours for Saturday.

Welcome to July, the warmest month of the year (my personal favorite month, as well). Enjoy the upcoming weather for the long weekend.
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Your Canada Day forecast:

As an area of high pressure slowly migrates eastward, this gloomy, unsettled weather pattern will gradually break by early tomorrow morning, and more Summer-like conditions will return, slowly building into a very nice warming trend for the long weekend. Here are the forecast details for the Canada Day festivities, including for the fireworks displays that may be taking place this evening.

Temperature/Humidity

Temperatures are on the rise, and values should reach a maximum of 25 C for Friday by the mid-late afternoon. Humidity levels are similarly on the rise and could reach borderline moderate to high standards by day’s end. With the moisture levels, temperatures should stay steady at 22-23 C for the later evening hours. Humidity levels themselves will rise further into Saturday as that area of low pressure moves in.

Precipitation

As this area of high pressure advances, the clouds should begin to increasingly break as the morning hours progress, and more so into the afternoon, but some lingering showers are a possibility for the very early morning hours, as we still be under the wrap-around influence of this current area of low pressure. The atmosphere becomes increasingly stable through the day (still a few cloud clusters lingering), so the chances for wet weather are negligible for the evening hours. As such, expect mainly clear skies for the evening.

Wind

Winds are expected to be very light, but directional tendencies are shifting through the day, as the area of low pressure moves in from the West. As such, expect winds to firstly be coming out lightly and variably between the North-northwest (NNW) to North-northeast, and then shifting to South-southeasterlies (SSE) by the late evening hours. Winds, again, are light, regardless of the direction, and they will likely be anywhere from 7-11 km/h for the morning hours to the early afternoon, and then becoming, overall, lighter at 3-6 km/h by the mid afternoon and onwards. Periods of calm conditions are also possible later in the day.

That’s the way the weather should behave for Canada Day. In summary, temperatures are likely at 25 to possibly 26 C for daytime highs and evening values that are in the low 20s C at 22-23 C. Humidity is building through the day and could reach high standards towards the evening. Unsettled weather is not expected, except possibly for very early in the day, so expect a fair amount of sunshine. Winds are generally very light to occasionally calm, especially for the afternoon. In short, a pleasant Canada Day on the way, but be sure to protect yourself accordingly from the sun (if you plan to be out for extended periods), as the UV level is very high for this afternoon.

Trav.

Most of what was mentioned in the first section of the above post still adheres to today's dominant weather conditions, but there are a couple of additional things that I would like to point out in terms of wind speed, after revising the latest model runs. Here are the details for Saturday, July 2nd.

Temperature/Humidity

Temperatures are expected to rise into the very high 20s C to as much as 31 C by the mid afternoon period. Late-evening temperatures should remain steady between 23-24 C (possibly as much as 25 C in the metropolitan area). Humidity levels are currently high and will remain so through the day today. Values could reach very high standards through the overnight hours.

Precipitation

Not too much to report here, but you will notice some scattered cumulus clouds as the day progresses due to increasing atmospheric instability. There could also be an increase in cloud cover towards the late afternoon into the evening hours because of an approaching cold front - this front may set off some convective showers and possible thunderstorms (mostly non-severe, if any) overnight into the early morning of Sunday. The chance for severe thunderstorms increases slightly for the late-morning into the afternoon on Sunday, but this is dependent on how quickly the low pressure system tracks eastward.

Wind

Wind tendencies are largely from the southwest for the day, and I suspect that they will gradually shift from the South-southwest (SSW) by the early evening period in accordance with the eastward migrating speed of this system. Ideally, the smoke should be mostly blowing slowly to the right of the audience of La Ronde (to the left of those spectators on Notre-Dame). Speeds are breezy through the day at 15-19 km/h but diminish to 8-12 km/h for the evening period. Lighter winds during the evening may cause periods of smoke build up (with the high humidity) when the display becomes more active, but, overall, the smoke should mostly be clearing quickly enough.

That's the way the weather should behave for today. To summarize, mainly sunny skies coupled with a few cumulus cloudsas the day progresses. There will likely be an increase in cloud cover towards the end of the day, but unsettled conditions are more possible for the overnight hours into Sunday. Temperatures are very warm, possibly attaining slightly above 30 C. Humidity levels are high, and the winds are expected to be firstly breezy during the day before becoming lighter by evening.

I hope that everyone had a fantastic Canada Day!

Trav.

Thank you for your updates, Trav. While I don't often post on this topic, I read carefully your forecast before each display. It is very useful!

Fred

Weather patterns are expected to continue to exhibit Summer-like conditions for the coming weekend. An area of high pressure is slowly moving in from the West and is expected to provide rather pleasant weather for both Saturday and Sunday. At the same time, a rapidly developing low pressure area is also going to be moving up the eastern seaboard, but this high pressure system will act to keep it well to the East, as it is serving as a blocking mechanism.

With the atmospheric setup in place for England’s display, this favors mainly sunny conditions with some scattered overhead cirrus clouds and a few cumulus cloud clusters. UV levels are expected to be high to very high during the day, though. Humidity levels are likely moderate, and the temperature readings should be hovering around seasonal (about 25-26 C), along with evening values into the lower 20s C (likely 22 C). With this area of high pressure, as well as the area of low pressure tracking northward in the Atlantic, winds are likely to display North-northwest (NNW) to straight northerly tendencies at 15-19 km/h. Speeds will then then diminish slightly by the evening to 11-14 km/h. Winds may, however, shift from the West-northwest (WNW) to even possibly westerly by evening, which could potentially mean that the smoke may be blowing towards the audience of La Ronde this time around. I will continue to monitor this, as the shift in wind direction ultimately depends on the track of the system in the Atlantic.

I will post a final update either later today or early Saturday to confirm these conditions, particularly for wind speed and directional tendencies for the evening hours.

And it is absolutely no problem for posting the weather forecasts, Fred, as it is always a pleasure - I am just delighted to know that they are useful.

Trav.

After revising the latest model projections, conditions are still mostly in agreement with what was stated in the above post. Here are the details for Saturday, July 9th.

Temperature/Humidity

Temperatures are expected to climb to a seasonal 25-26 C (locally 27-28 C) for daytime highs, and late evening temperatures should, again, decline to roughly 22 C (as much as 23 C in the metropolitan area). Moisture levels should be borderline low-moderate, so humidex values are negligible, although expect humidity to rise to high standards for tomorrow (Sunday).

Precipitation

As an area of high pressure is governing much of this weekend, there is, naturally, not much to report in this section. There will, however, be a few scattered cirrus clouds (those whispy high-level clouds) and some isolated cumulus clouds. Expect mainly sunny conditions for the day (with a high to very high UV level), and mainly clear skies for the evening.

Wind

This is where it becomes a little tricky. With this area of high pressure, as well as the positioning of that area of low pressure in the Atlantic, a small pressure gradient will slowly build, creating breezy conditions for today (Saturday). Winds are still expected to be firstly coming out primarily from the North-northwest (NNW) to, occasionally, straight northerlies for the morning-early afternoon hours before transitioning to more northwesterlies by mid-afternoon. Winds are quite breezy at 19-23 km/h for the morning hours before weakening slightly to 16-19 km/h for the afternoon. By the very late afternoon through to the evening hours, I am still detecting a directional shift to West-northwesterlies (WNW) to potentially, on occasion, straight westerlies, simply because of this area of high pressure moving South, along with the relative positioning of the area of low pressure to the East. Winds, then, could be frequently pushing the smoke towards the audience of La Ronde - otherwise, the smoke would be moving steadily to the left of the audience (if NW tendencies are maintained), though possibly affecting left sections of the seating area. Speeds themselves should diminish slightly to 11-15 km/h by evening. There shouldn’t be too much in the way of smoke build up because of the humidity levels. Winds will eventually change to southwesterlies by the overnight hours.

That’s the way the weather should mostly behave for the day. In summary, we should see a pleasant Saturday (morning to evening), with mainly sunny conditions, coupled with borderline low-moderate humidity. Winds are breezy for most of the day but diminish slightly by the evening. If you are planning on staying outdoors for extended periods during the day, be sure to protect yourself accordingly from the high to very high UV. Humidity levels gradually rise into Sunday, but severe weather is possible for Monday as a cold front moves through from the West.

If I notice any changes with the wind behavior in the newer model runs, I will post an additional update covering this - otherwise, what is mentioned here still holds true.

Trav.

Weather conditions are expected to gradually cool to near-seasonal values following the end of today (Tuesday), as a large area of high pressure will slowly advance from the West, bringing with it fair weather by Wednesday up to early Saturday, potentially assisting to give rise to the start of our first official heat wave by this weekend in both southern Ontario and southern Quebec as it pushes east - we’ll continue to monitor the progress of that setup over the next few days.

It is actually quite something that the atmospheric pattern in place for tomorrow is somewhat identical to what we had seen this past Saturday. However, we may be receiving the wrap-around effect of the recent low that brought us some rainfall, which may bring some early isolated showers - the chance for wet weather early in the day may diminish depending on how fast the area of high pressure advances, so I will monitor this. As such, I am expecting largely fair weather conditions to govern much of Wednesday, July 13th, and, as a result, relatively small probabilities for precipitation, mostly as the day progresses. There will likely be a some lingering clusters of cumulus clouds, however, creating, at times, partly cloudy skies, but things should increasingly clear through the day. Temperatures are going to be a touch cooler for the late-evening period into the high teens Celsius (as much as 20-21 C in the metropolitan area), and humidity levels are, again, borderline low-moderate.

Wind tendencies are still a little uncertain at this point (common with high pressure systems), especially for the late-afternoon to evening period, but with the current positioning of the area of high pressure to the West, I believe the winds should be firstly coming out from the West-northwest (WNW) for the morning hours, and then gradually shifting to northwesterlies for the afternoon to eventually North-northwesterlies (NNW) to even straight northerlies by evening. The alternative is that winds maintain NW to WNW status through the evening, because, like this past Saturday, high level winds are similarly pushing this area of high pressure a little to the South, and the area of low pressure that recently brought us wet weather, as well as some severe thunderstorms across parts of southern Quebec, is eventually settling just South of Nova Scotia. With the potential wind behavior by evening, this would suggest that the smoke from the display should be moving steadily to the left of the audience at La Ronde, but it still remains a question of how much to the left. Speeds themselves are breezy through the day between 18-21 km/h but diminish to roughly 10-13 km/h by evening.

I will continue to keep an eye on future model runs and post a final update later today, or early Wednesday, to confirm the specified conditions and note any changes, if necessary, particularly with respect to wind behavior and how quickly this upcoming area of high pressure settles in.

Trav.

I understand from the above post that we shouldn't experience precipitations tomorrow night, am I right? That is a good news since I just saw a risk of some sort of precipitations estimated at 60% on the Weather Channel. It doesn't specify what time of the day these showers/thunderstorms are expected.

Fred

Hi Fred,

Yes, that is correct. I am still holding the belief that instability should subside by dusk tomorrow. The chance for precipitation itself is for the reason I stated previously - that is, we are eventually being influenced by the "wrap-around" effect of the recent low pressure system that had delivered some rainfall and isolated severe thunderstorms in parts of southern Quebec yesterday evening (one storm being just East of Montreal, near Saint-Hyacinthe). More specifically, the reason as to why you are seeing the chance for precipitation for tomorrow is because of a developing upper level short wave trough associated with the departing low. A "short wave trough" occurs when there is a relatively small pocket of cool air settling, or advecting, from the North/northeast/northwest (in this case, the northeast) at high levels of the atmosphere over a given region, as indicated by a valley-like formation on an upper level synoptic weather chart. Coupled with daytime heating at the surface, cool air aloft commonly enhances instability, merely because the air is unstable at mid to high levels of the atmosphere.

Precipitation associated with troughs is usually isolated to scattered in nature, so I would accompany a 30-40% probability of precipitation for mostly the late-morning to afternoon hours, which shifts my initial forecast for precipitation (in the above post) a little forward, but instability should still dwindle towards dusk. I also agree with the risk for isolated thunderstorms (30% probability), given the available convective energy readings for the afternoon.

I will post a final update to confirm these conditions by this evening, or early tomorrow morning, especially for wind tendencies, and the movement of the area of low pressure to the East.

Trav.

After a Summer-like week, a brief cooling will take place in Ontario and Quebec through today (July 13th). Southern Quebec and eastern Ontario are under the influence of an upper level disturbance (a short wave trough), providing some unsettled weather prior to a large area of high pressure that will eventually move in later today. This trough is associated with the departed low that affected southern Quebec Monday evening, bringing with it periods of rain and isolated severe thunderstorms. With the atmospheric setup, here are the weather details for Wednesday, July 13th.

Temperature/Humidity

Temperatures are still expected to be about seasonal to just a little below seasonal for daytime highs tomorrow, with maximum values of 24-25 C, while late-evening readings are roughly at 19 C in the suburbs (potentially as much as 21-22 C in the metropolitan area). Humidity levels are similar to this past Saturday, with borderline low-moderate values through the day and into the evening.

Precipitation

The trough in place will increase atmospheric instability, particularly from the late-morning throughout the afternoon period. Consequently, isolated to scattered showers will develop across the region (30-40% probability) during this time frame. Isolated non-severe thunderstorms (30% probability) are also possible during the afternoon period, as the available convective energy is sufficient. Instability should begin to subside towards sunset, and there should be a few lingering clusters of cumulus clouds thereafter until skies clear completely overnight with the approaching area of high pressure to the West.

Wind

The models seem to be more in agreement with respect to wind direction and speed in relation to the positioning of the advancing area of high pressure to the West, and the low to the East. The latest runs indicate that winds should firstly be coming out from the northwest (NW) by the very early morning hours, maintaining these tendencies through to the early afternoon. As the area of high pressure pushes a little more eastward, northwesterlies should transition to North-northwesterlies (NNW) to, on occasion, straight northerlies by the mid-afternoon through to the evening and overnight. As such, winds should be pushing the smoke gently to the left of the audience at La Ronde, avoiding all seating areas there. Wind speeds are light for the early morning at 7-11 km/h, but they become breezy for most of the afternoon at 18-21 km/h, with occasional gusts of up to 32 km/h. Speeds are still expected to diminish by evening to 10-13 km/h. Smoke build up should not be too extensive, as the humidity levels are borderline low-moderate, and the winds should be at decent speeds. *It should be noted that for those viewing the fireworks on the bridge just adjacent to the firing site likely will experience smoke slowly advancing towards them, so, if possible, avoid those sections. The smoke may also, at times, hamper viewing conditions for those stationed at the Old Port (especially with the display possibly being active at many points).

That’s the way the weather should generally behave for today. In summary, isolated to scattered showers (30-40% probability) are possible for mostly the afternoon due to an upper level trough. Isolated non-severe thunderstorms are also possible (30% probability). Instability should subside by evening. Winds are breezy during the day but diminishing slightly by the evening. Temperatures are pleasant for the day (and evening), and humidity levels are borderline low-moderate. Following this brief cooling, July-like weather will likely resume by the end of the work week into the weekend.

Trav.

As stated previously, typical Summer conditions are expected to engage eastern Canada by the end of the work week, and that heat wave that I introduced about three days ago is still a possibility for both southern Ontario and southern Quebec for this weekend into Monday.

The atmospheric setup for Saturday, July 16th, and the weekend, in general, is such that this current area of high pressure will eventually move southeast towards the Atlantic, while a rather vigorous low is slowly traveling West to East across northern Canada. The positioning of these two systems will draw moisture from the Gulf of Mexico, and a developing area of low pressure churning in the western U.S will additionally facilitate this circulation process. Consequently, much of central and eastern portions of Canada and the U.S will experience very warm to hot and humid conditions for the weekend. In the case of southern Quebec, the humidity slowly builds in for Saturday and approaches near oppressive levels for Sunday before potentially severe thunderstorms move through late Sunday through Monday.

I am not expecting precipitation for Saturday (again, this is more for later Sunday and onwards), but there will be some scattered cumulus clouds later in the day, as well as some cirrus, which are, again, those wispy-looking clouds at high level. Temperatures could be as warm as 25-26 C in the metropolitan area for later Saturday evening, and high humidity levels could make it feel into the low 30s C. Winds should generally be light in nature (7-11 km/h at this point) and are likely out from the South-southwest (SSW) to possibly southwest (SW) - as a result, winds should be blowing smoke mostly to the right of the audience at La Ronde this time, although the extreme right end of the seating area has a chance to encounter smoke, if SW tendencies dominate. I’ll keep an eye on this over the next little while.

I will post a final update later today, or early Saturday, to confirm these conditions, especially in terms of wind behavior (speed and direction). Shaping up to be a nice July day, regardless.

Trav.

Virtually everything that was described in the above post still applies to today’s overall weather conditions, so, in summary, here are the details for Saturday, July 16th:

Temperature/Humidity

As compared to the last two fireworks days, temperatures are expected to climb to more July-like standards to as much as 31 C during the day and possibly 24-25 C by the late evening hours (potentially 26 C in the metropolitan area by late evening). Humidity levels are likely to be high today, so maximum humidex values by afternoon could be approaching 36 C, while during the evening, readings should be closer to 32 C, especially in the metropolitan area.

Precipitation

No precipitation is expected for the day. There will, again, be some scattered clusters of cumulus clouds, which may provide a few localized cloudy periods. Some scattered cirrus clouds will also occasionally be present. Convective rains, thunderstorms and possibly severe thunderstorms gradually become a threat into Sunday night through to most of Monday, partly due to an approaching cold front and high available convective energy.

Wind

The models seem to be largely in agreement about the overall wind speed and directional tendencies for the day. The atmospheric setup described in my previous post certainly favors southwesterly (SW) winds for the Ontario and Quebec this weekend. For Montreal, the same wind direction pattern is true, but I am expecting a West-southwesterly (WSW) shift for the afternoon hours before gradually returning to southwesterlies to potentially South-southwesterlies (SSW) by evening, and then South-southwesterlies to straight southerlies by the overnight hours. Wind speeds should predominantly be light for most of the day at 7-11 km/h, including for the evening. As such, the winds should be gently blowing the smoke to the right of the audience of La Ronde. There may be periods of smoke accumulation due to the light winds and high humidity.

That’s the way the weather should generally unfold for today. To summarize, very warm to hot conditions are likely across many areas of eastern and central Canada, along with high humidity levels, making it feel into the mid 30s C for the afternoon and lower 30s C by evening, including here in Montreal. Precipitation is not expected until later Sunday, with the risk for severe thunderstorms that night into Monday. Winds are light and coming out mostly from the SW for the day. The UV is expected to be high to very high today, so be sure to protect yourself accordingly against the sun if you plan to be outdoors for extended periods. I still would, however, like to verify the later model runs to see if SW winds would be maintained by evening, as this would, at times, affect the extreme right end of the seating area at La Ronde. If I detect this, I will post a final brief update, but if not, then whatever is stated here still holds true.

A typical July weekend on the way, with the potential of attaining heat wave standards, providing that both today and Monday surpass 30 C.

Trav.

July 2011 has been stunning, as far as temperature is concerned, across many regions of North America, including with the U.S currently facing one of its most severe heat waves in recorded history. Much of central and eastern Canada, too, has experienced well above seasonal temperatures so far this month, which, with the potential of an upcoming defined heat wave, could lead to final average monthly daytime highs that are above seasonal, perhaps on par with values seen in July 2010, which was one of the warmest Julys on record.

In any event, although still remaining very warm for today, we will be seeing a break in the high to very high humidity due to an area of high pressure moving into Ontario and Quebec, providing mainly sunny and dry conditions. However, through the day Wednesday (July 20th), I am expecting a returning flow from the SW to SSW (because of a series of low pressure systems - one coming in from the West, while the other stationed to the North), which will, once again, boost temperature and humidity values back up to values similar to what they previously were before today. As such, expect temperatures to reach near or at 30 C later Wednesday (locally as much as 32 C), with high humidity levels, making it feel in the mid 30s C (very high 20s C by late evening). Temperatures on July 21st in Montreal could reach a very hot value of 35 C, with humidity values well exceeding 40 C (this will likely prompt high heat and humidity advisories across Ontario and Quebec).

I am still keeping an eye on the potential development for precipitation later in the day Wednesday, in accordance with the advancing low to the West, though I believe that instability is more prevalent on July 21st, when more oppressive heat and humidity will endure. Severe weather is possible by the late evening to overnight period of July 21st.

As for the winds on Wednesday evening, they seem to be cooperative in both direction in speed - however, I am still monitoring speeds, as the models are indicating breezy conditions, likely because of a steepening pressure gradient. The winds themselves are sustained between 21-25 km/h for the day and associated gusts could, on occasion, reach 34 km/h. Wind speeds should diminish slightly by evening but are still remaining breezy (they will quickly pick up again on July 21st). Smoke from the display, then, will likely push the smoke quickly to the right of the audience at La Ronde.

I will post a final update later today or early tomorrow to confirm these conditions after evaluating wind tendencies and precipitation in the newer model runs.

Trav.

The weather forecast for today (July 20th) still follows closely along the lines of the above post. As such, here is a summary of the details in what to expect for the day:

Temperature/Humidity

Two low pressure systems, one situated to the North (heading northeast), and the other approaching from the West, are responsible for the returning circulation of a hot and, at times, oppressively humid airmass. Moreover, a third area of low pressure, in association with the low from the West, will form by early Thursday (July 21st), enhancing the circulation. As this defined heat wave is governing much of central and eastern North America, temperatures are expected to be reaching hot standards, causing the mercury to rise to roughly 32-33 Celsius for maximum daytime highs today, here in Montreal. In such cases, evening to late-evening temperatures are, naturally, expected to remain very warm at 27-28 C (possibly 29 C in the metropolitan area). Humidity is forecasted to be high across southern Quebec today, so assuming that daytime highs reach 31-33 C, humidex readings should be attaining 38 to as much as 40 C (late evening values at 34-35 C, including in the metropolitan area). Note that humidex values on July 21st are not far from 50 C, with actual maximum temperatures at 35-36 C. High heat and humidity, as well as smog advisories are likely.

Precipitation

With this hot and humid airmass, the air is becoming quite unstable, especially as we approach the overnight hours into Thursday, July 21st, where thunderstorms and potentially severe thunderstorms are possible, mostly late in the day, as the cold front from the system out West advances in this direction. Available convective energy is also quite high to support their development. For today, because the air is also unstable, some defined clusters of cumulus clouds will develop, especially for the afternoon period - later in the day, you will notice an increase in cloud cover due to the combined effect of a cold front to our North and the warm front associated with the system approaching from the West. However, I am, again, not anticipating precipitation until the later overnight hours and onwards, but, that being said, I still would not rule out the chance for isolated storms during the late evening (30% probability), given the available convective energy present at the time - otherwise, expect partly cloudy skies.

Wind

Wind speeds are still something to keep an eye on. The newer models are currently indicating winds to firstly be light during the early morning hours but then gradually increasing by late morning. Speeds will likely be at their highest during the mid-afternoon period, being sustained between 31-34 km/h and accompanied by gusts occasionally attaining 43-45 km/h. By evening, I am still detecting a weakening, where speeds are settling more within the range of 21-24 km/h, with gusts, at times, closer to 34-36 km/h. I understand from the past that the cut-off point for safe firing is approximately 40 km/h (regardless of direction), but sustained speeds, and occasional gusts, should be hovering below this level for the evening hours. Nevertheless, as we are dealing with values not too far away from this threshold, I would still like to review the newer model runs through today to get an even better sense of the dominant speeds for the evening. Regardless, though, it will be a breezy evening. Directional tendencies themselves begin as southerlies for the morning hours, but they do shift to more southwesterlies to South-southwesterlies (SSW) by the afternoon and evening, so the smoke, again, should be moving quickly to the right of the audience at La Ronde (to the left of those on Notre-Dame), although there may be points where the smoke could be blowing towards the extreme right end of the seating area. For those who are not comfortable with the combination of a very warm and humid atmosphere, the breezy winds will provide you with some relief for both today and tomorrow.

That’s the way the weather should behave for today. To summarize, the day will be a hot and humid one, setting the stage for a heat wave. Humidity levels are high, so temperatures will feel much warmer (near 40 C during the day and 34-35 C by late evening, especially in the metropolitan area). There is a slight risk for isolated thunderstorms by late evening (30%), but the risk is more prevalent for the overnight hours into Thursday, July 21st. Severe weather is possible late Thursday. I would still like to revise the newer model outputs for wind speed, but the day will largely be breezy, especially for the mid-afternoon. Winds first come out from the South, and then progressively from the southwest by afternoon-evening. It is very important to stay well hydrated during this kind of weather, and please protect yourselves accordingly from the high to very high UV, if you plan to be outdoors for whatever reason.

***If I detect higher wind speeds in the model data today, I will post an additional update covering only this - if not, then what is stated in the wind section still holds true.

Trav.

I suspect that the winds will be a relief tonight, with such warm and humid air. But I am concern with the speed of them. Hopefully, they are not going to exceed the 40 km/h limit. Is your model accurate enough to estimate when the winds should reach their highest speed?

I remember the Hong Kong display in 2009, which started at 9:55pm to avoid more powerful winds expected at 10:30pm. The pyro crew got these information at 9:45 and decision was made to begin the show five minutes early, to minimize the risk to stop the show just before the finale. It was incredible how accurate this information was, since the wind speed actually increased at 10:30!

Fred

Hi Fred,

The newer model simulations, like the previous runs, continue to predict that the highest sustained winds and associated gusts will occur during the mid-afternoon hours today, which has been the case, so far. The top gust that I had previously been estimating for the day was no more than 45 km/h, and that was the highest hourly speed recorded just before 4:00 p.m. today, with a sustained speed of 35 km/h. The last hourly gust was measured at 41 km/h, with a sustained speed between 30-32 km/h.

I am still expecting the winds to weaken slightly by this evening, likely just beyond 9:00 p.m. The wind range for the early evening is mostly between 23-27 km/h, with occasional gusts reaching 36-38 km/h. From 9:00-9:30 p.m, we should see a further decrease to a range of 20-23 km/h, with associated gusts, at times, between 30-34 km/h, which would be suffucient but still a little marginal. Directional tendencies still remain the same, as mentioned above, so the smoke should be, again, moving quickly to the right of the audience at La Ronde, although, at some points, it could be pushing towards the extreme right end of the seating area because of possible changes to southwesterly winds in between.

I do, indeed, recall the precision of that provided information - it is usually quite rare to predict a distinctive change in any meteorological paramater (wind, temperature, moisture, precipitation, etc.) right on a given target time, but sometimes the atmosphere just behaves that way. We do, however, strive to do that more consistently for the future.

Trav.

This heat wave continues to remain in effect for southern Ontario, as well as western and southern Quebec into today, July 22nd, as hot and humid temperatures still dominate these regions, prompting high heat and humidity advisories. The humidity was so high in southern Ontario that the original humidex advisory had become a weather warning. Here in Montreal, the dewpoint reached an impressive maximum of 25 C, generating humidex readings into the high 40s C. For those who are unfamiliar with the "dewpoint" concept, it is simply a measure of atmospheric moisture, as well as indicating at what approximate altitude saturation is taking place. Dewpoints are usually expressed as a temperature (usually Celsius or Fahrenheit), but the larger they are in value, the higher the moisture/humidity - during the mid-late Spring/Summer, dewpoints at roughly 16-19 C are regarded as high, while a dewpoint of 20 C or more is deemed very high. I want to emphasize that dewpoints of 25 C or more are exceedingly rare in southern Quebec, and such values are categorized as extreme.

For those of you who are finding it difficult to cope with this weather, relief is on the way for the weekend, particularly on Sunday, as an area of high pressure slowly migrates from the northwest. This system will also be partly responsible for the weather conditions for the Canadian display for tomorrow.

With this high pressure system advancing, we can expect mainly clear skies for the entire day (some scattered cumulus and cirrus clouds, especially for the late-morning to afternoon period), along with daytime highs at roughly 29 C (late-evening temperatures roughly at 24 C), although the humidity will be much less oppressive as it will be today, and especially yesterday (July 21st). Winds are, again, something to watch in terms of speed, as they may be generally around the same range as what we had seen during the day this past Saturday - the difference, however, is that the model simulations are detecting speeds to be rapidly diminishing by evening, but, of course, I would still like to monitor this. Directional tendencies are currently in the form of northwesterlies to North-northwesterlies, so smoke could be blowing to the left of the audience at La Ronde, but heading to those on the bridge, just adjacent to the firing site.

As always, I will provide a final report later today or early tomorrow to confirm these conditions.
---------------------------------------------------------------------- ---------
As I had anticipated, severe weather did erupt across many parts of southern Quebec on the evening of July 21st, including here in Montreal. Doppler radar did a fantastic job in picking up the thunderstorms during the late afternoon-evening period - some rotation was even detected within some of these storms, indicating potential active mesocyclones - no confirmed tornado touchdowns, however. The reason as to why these storms fired up was partly because of the oppressively high humidity, which contributed to massive amounts of available convective energy at the surface (in excess of 3000 Joules/kg) and mid levels of the atmosphere. When I was evaluating the potential for severe weather through the day, doppler radar also revealed good windshear at various depths above the surface. Adiabatic lapse rates (the rate at which the temperature of a given air parcel decreases with increasing altitude relative to the temperature of the ambient air with height) was also high, especially at mid level. The breezy conditions during the day also facilitated the mixing of air between low and high level, destabilizing the atmosphere, and, of course, there was plenty of daytime heating. There were other supportive factors as well, but it was the moderately strong cold front which descended from the northwest that acted as the necessary catalyst. A few of these storms were quite powerful and were particularly recognized for their strong straight-line winds and frequent to continuous lightning. Here are some of the videos that I'd like to share of the late-afternoon and evening storms on July 21st:

Late-afternoon:

http://www.youtube.com/watch?v=Q5CVn5jOoAk

Evening:

http://www.youtube.com/watch?v=x48MWNXGS3U

http://www.youtube.com/watch?v=_ggLuYdzgNE

Trav.

Lightning were spectacular last night. I thought that we would have experienced a situation similar to the Hong Kong in 2009 whether a fireworks was scheduled, with many lightning in the background at the time of the display.

Fred

Virtually everything that was mentioned previously still stands firmly, but I will add some details to the wind section. Also note that the "Saturday" mentioned in the previous post was meant to be "Wednesday".

Temperature/Humidity

I am going to raise the maximum temperature for the day to 31 C, along with late evening temperatures at roughly 26-27 C (metropolitan area included). Notice that humidity levels have dropped to "high" standards yesterday from the extreme levels witnessed on July 21st - this decrease was related to the passage of the cold front on the evening of July 21st. Expect borderline moderate-high humidity for the day today into this evening, so humidex values should read at, assuming a temperature range of 29-31 C, 34-36 C (evening to late-evening values at 29 C to 30 C).

Precipitation

No precipitation is forecasted for the day, as an area of high pressure is slowly advancing from the West. Some scattered fair-weather cirrus and cumulus clouds may be present during the day, however, but it will be mainly clear.

Wind

Winds, once again, are expected to be, at times, gusty, with the highest sustained speeds and associated gusts likely to occur during the mid-afternoon hours, roughly at 27-31 km/h (gusts at 39-42 km/h). Wind speeds should diminish slightly by evening but remain breezy at 19-22 km/h (occasional gusts between 30-33 km/h). Directional tendencies are firstly from the SW early in the day but then gradually shift to the WSW to even straight westerlies by the afternoon. However, I am still detecting a shift to the WNW to NW by the mid-evening hours. As such, smoke should be blowing to the left of the audience at La Ronde, although possibly affecting, at times, the left extremities of the seating area there, as well as those on the bridge viewing near the castle structure. The reason behind this overall wind pattern is simply because we are going to be situated between the advancing area of high pressure to the West, as the well the departing area of low pressure stationed over the Maritimes, and the winds are breezy because of the pressure gradient building between these systems.

That's the way the weather should behave for today. In summary, continuing very warm to hot conditions, but with lower humidity at borderline moderate-high levels, so the day should be mostly comfortable, especially near dusk and onwards. No precipitation is expected, but there may be some scattered cirrus and cumulus cloud clusters present, especially for the afternoon period. Winds are breezy, but, at times, gusty for the mid-afternoon hours. Speeds should decrease somewhat by the evening but still remaining breezy, and wind direction should be coming from the NW by the mid-evening. *I would like to, however, continue to monitor the winds through today and analyze the latest model runs for directional tendencies - I will post a brief update today covering this, regardless if there aren't any significant changes.

I thought that we would have experienced a situation similar to the Hong Kong in 2009 whether a fireworks was scheduled, with many lightning in the background at the time of the display.

That crossed my mind at the time as well, Fred! The lightning was certainly stunning that evening, especially because of its continuous nature.

Trav.

For the wind update, I am still detecting that directional shift to the WNW to eventually NW later this evening, and there are indications that this change is taking place just after 8:00 p.m. EDT in the models, which remains unchanged from the previous prognostics. Speeds are still the same for this afternoon (as expected, the winds are, at times, quite gusty and are WSW to westerly), but, again, they should be diminishing late this afternoon and into the evening. I'm just going to reduce the occasional gust values for the evening from the above post from 30-33 km/h to 25-28 km/h km/h, and the sustained winds between 16-19 km/h (from the 19-22 km/h specified above). With potentially straight northwesterlies in place, as mentioned above, the smoke will likely be moving mostly to the left of the audience at La Ronde, although, again, there may be times where it affects the left end of the seating area there (especially if WNW tendencies take place in between), as well as for those on the bridge overlooking the firing site at sections near the castle structure.

For everything else, please refer to the above post, as it still holds true. As expected, humidity values have been very slowly decreasing through the day and are now at borderline moderate-high humidity, which recently prompted the cancellation of the high heat and humidity advisory that had been in place since July 20th through Quebec.

Edit as of 5:41 p.m. EDT: NNW winds are also possible by 10:00 p.m - if such is the case, then the smoke should be heading mostly clear to the left of the audience at La Ronde and towards those on the bridge adjacent to the firing site (near the river). This also means that those at the Old Port may also, at times, be obscured by smoke

Trav.

The radar is showing a very small area of precipitations, moving from north to south. It's currently on the north shore of Montreal and should hit La Ronde between 7:00pm and 8:00pm. Hopefully, it is the one and only episode of rain for tonight!

Fred

Hi Fred,

The isolated pockets of precipitation moving from the NW to SE in southern Ontario and Quebec are associated with a weak passing cold front (hence the drop in humidity through today). I apologize for neglecting to mention this instability earlier, but the atmosphere should stabilize in these regions beyond 8:00 p.m tonight.

Edit: Also, that band of precipitation that you were detecting is weakening rapidly as it heads SE (indicating that the air is progressively stabilizing), so it should dissipate by the time it arrives.

Trav.

As we advance into a short term, unsettled weather pattern for both today and tomorrow, another area of high pressure is expected to follow and slowly make its way eastward by this Wednesday (July 27th), eventually providing Ontario and Quebec with largely fair weather while assisting to gradually heat the air back up to very warm temperature values and eventually boosting temperatures even further by the end of the week as it moves East, with the aid of a low pressure area moving in from the West. Conditions should also be dry, along with borderline low-moderate humidity. Temperatures by late-evening should be around a comfortable 24-25 Celsius (especially in the metropolitan area). Breezy/gusty winds are not an issue for the French display - in fact, wind speeds may be more at the opposite end of the extreme, with very light to, occasionally, near-calm speeds - such is the case when in close proximity to high pressure centers.

I will provide a final update later tomorrow to confirm these conditions, but as far as I can tell, the overall light nature of the winds is the factor for consideration. Additionally, current model simulations are showing WNW to westerly winds, so this is also something to watch, as, in this situation, the smoke would gently head towards the audience at La Ronde. Although the day should remain largely dry, I would still like to keep an eye on the aforementioned low pressure system advancing from the West, as a couple of weather progs are indicating it to be traveling faster eastward than others, and so arriving earlier - I do not believe that such will be the case, but it is good to continue to monitor this and see if the newer simulations become more in agreement amongst the models.

In the meantime, isolated thunderstorms and convective rains are possible through tomorrow (July 26th) due to an upper level trough, especially during the afternoon. A few of the thunderstorms may reach severe criteria.

Trav.

Most of what was stated in the above post still holds true, but there are some additional details that I'd like to add. Here is the forecast for Wednesday, July 27th.

Temperature/Humidity

Temperatures are expected to climb into the mid 20s C for today at roughly 26-27 C, with late-evening temperatures around 24-25 C (especially in the metropolitan area). I'm going to shift humidity levels from borderline low-moderate to moderate-high, so it will feel near 30-31 C for the afternoon.

Precipitation

The newest model runs are more in agreement, and so they are showing that low pressure system to the West arriving more for Thursday into Friday. Consequently, we should see mostly sunny conditions for today, but there will be an increase in cloud cover by the evening hours and into the overnight, so partly cloudy skies for this evening. Convective showers and thunderstorms (some potentially severe) are possible for Thursday into Friday. Temperatures also return to very warm to hot standards for Thursday into Friday, along with a boost in humidity.

Wind

This is where it becomes a little tricky. With an area of high pressure in place, most of today is expected to experience generally light winds. Winds should be coming mostly out from the NW to NNW through the afternoon, with speeds between 11-14 km/h, although slightly breezier during the mid-afternoon at 15-18 km/h. However, the models are still showing speeds to rapidly diminish by the evening hours to as little as 4-7 km/h interspersed with calm conditions. The directional tendencies are usually difficult to predict when winds are this light, but they appear to be withholding NNW tendencies for the early evening, but then later shift to southerlies - if southerlies dominate, smoke would VERY slowly be moving to the right of the audience at La Ronde - if from the NNW, then to the left. Directional variability is also possible during the evening, but with the light nature of the winds, smoke buildup may be problematic for most spectators. I will continue to monitor this and post an update, if necessary.

That's the way the weather should behave for the day. In summary, pleasant temperatures coupled with borderline moderate-high humidity. An increase in cloud cover takes place towards the end of the day. Winds are slightly breezy during the day (especially for the mid-afternoon) but become very light to, occasionally, calm by the evening. Severe weather is possible later Thursday into Friday.

Trav.

Just a quick update about the winds. The newer models from this morning are showing signs of winds taking a WSW to SW tendency by this evening, so the smoke may be, at times, blowing slowly towards the audience at La Ronde, most notably for right sections to extreme right sections of the seating area. Speeds are still within the same range, although, at times, slightly higher at 7-10 km/h. If SSW winds dominate, then the smoke will move clear to the right of the audience. Those are the possibilities by 10:00 p.m.

Also, there will also be a few scattered cloudy periods this afternoon, as the system from the West advances, but increasing cloud cover is more prominent for the evening and onwards. UV is high today.

Trav.

Well, I suppose that these are the last set of weather reports for the season!

Conditions are looking mostly good for the closing display tomorrow night. Following this upcoming area of low pressure from the West, which will further boost humidity levels today to boderline high-very high standards, as well as progressively de-stabilize the atmosphere, an area of high pressure will slowly descend from the NNW, gradually clearing skies out for Saturday. I do not anticipate precipitation for Saturday evening, but a secondary cold front coming from the NNW may provide some lingering scattered showers for the morning hours into lunch time. There will still be a few clusters of cumulus clouds for the afternoon and evening period, but, again, I am expecting precipitation development should subside. Temperatures should be around similar values to what we had seen during the French display (23-25 C, mostly applicable to the metropolitan area) for the late-evening, and humidity should be reduced to moderate levels.

I am still keeping an eye on wind tendencies. Current models are showing breezy conditions for the majority of Saturday, but the speeds diminish quickly by evening. Wind direction should be in the form of northwesterlies for most of the day, but there are indications of a shift to WNW patterns by evening, which would push the smoke to left sections of the audience at La Ronde. I will continue to monitor this.

As mentioned in the second to last above post, we may see a little of nature's fireworks for today due to this upcoming low pressure system, and some storms may be reaching severe criteria, especially for the late-afternoon to early evening period. Things should gradually improve beyond the evening hours.

I will provide an update later today to confirm these conditions, but it is mostly the wind direction that is still in question for the evening Saturday.

Trav.

It looks that we will enjoy perfect weather conditions for the ultimate show of the year. On the weather side, it was a great fireworks season since no display has been disturbed by Mother Nature (no rain, thunderstorm, lack of winds, etc.).

Fred