I just wanted to provide an update concerning wind direction for this evening. Because the current area of low pressure is retrograding somewhat more quickly, the wind direction should undergo a transition by early this evening. Previous model runs were showing more SW/SSW wind tendencies beyond midnight, but this is now illustrated to occur a little earlier. As such, winds should change from the current NE/NNE patterns to SSW to SW patterns by a little past dinner time (6:00 p.m.) and should remain for the duration of the evening - this should now push smoke to the right of the audience at La Ronde (left for those on Notre-Dame), though possibly occasionally affecting extreme right-hand sections if becoming more Southwesterly. Wind speeds remain identical, however, but are slightly less at 10-13 km/h. Some periods for smoke accumulation are possible (mostly at low-/mid-level), though not to the same extent as what was seen with Australia's display. Also, evening temperatures should remain steady at 14-15 C. All other conditions remain constant, and, as mentioned previously, rainfall should largely come to a close into the mid-afternoon, leaving mostly cloudy conditions, and a few possible lingering isolated showers until the late-afternoon/early-evening.
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Paul, weather conditions remain similar to what was previously posted for your display tomorrow in Knowlton. The only difference is that forcing for convection is more associated with a surface warm front, and the current upper level low, for the afternoon. Isolated severe thunderstorms are more possible to your East/NE. Also, wind direction is more SW/SSW for the evening, and temperatures for the afternoon are closer 22-23 C. At approximately what time is your show expected to begin? 10:00 p.m.?

Trav.

Thanks for the update Trav! Yes, showtime for me is 10:00pm. We start the setup at 1pm so hopefully it will be mainly dry. There's no danger of setting any trees or grass on fire this year! What wind velocities can we expect? The past two years had completely calm conditions, which is not good for a fireworks display.

Paul.

Scattered convective showers and isolated thunderstorms are most likely during the afternoon hours ahead of a cold front (not warm front, as I erroneously mentioned in the previous post) before it transitions to more stationary status to your East later in the day. Convection should gradually dissipate near, and a little after dinner time tomorrow.

As for the wind patterns, you may dealing with a third year in a row where winds are very light (though not quite calm)! Wind speeds are expected to be light at 4-7 km/h, and from the SW/SSW around the time when your show begins, as well as the surrounding hours.

No problem for the update.

Trav.

Canada Day forecast:

Temperature/Humidity

Afternoon temperatures will likely reach 23-24 C for the afternoon tomorrow for most of S. Quebec, with moderate humidity. Evening temperatures should remain steady at 20-21 C (except 18-19 C for the late-evening), along with continued moderate humidity levels.

Precipitation

Precipitation is generally not expected – however, cloud cover will gradually increase as the day progresses, especially into the early-afternoon and onwards.

Wind

Winds will generally be slightly breezy throughout the day at 12-16 km/h from the NE (occasionally NNE) and will increase steadily in speed near midnight and onwards.

Trav.

Weather conditions for Hong Kong/China's display on Friday, July 5th, are expected to be the polar opposite of what had been observed for England's performance. After a cool and very wet June 2013, temperatures are projected to be consistently above-seasonal for at least the next several days, beginning today (July 3rd), courtesy of a Bermuda High that recently developed in the Atlantic. As such, for the first time this year, a fireworks day/night will very likely experience more Summer-like weather.

There is some divergence in the latest model guidance concerning overall cloud coverage for Friday, thus leading to two somewhat different maximum temperature scenarios. At this point, daytime highs for Friday are shown to reach as high as 30-31 C, but if extensive cloud cover develops into the afternoon, then highs will be closer to 26-27 C. In either case, however, very high humidity will be present, making temperatures feel like the mid to upper 30s C. By the late-evening, values should remain closer to 23-24 C, with continued very high humidity, causing it to feel more like 29-30 C. Skies should be partly cloudy for the evening.

Because of the increasingly buoyant atmosphere over the next few days, a few isolated convective showers and non-severe thunderstorms could develop during the afternoon hours. No lifting mechanisms are associated with convection, suggesting that it is largely dynamically-driven (through daytime heating) and should, thus, be fairly sparse and dissipate into the late-afternoon to early-evening periods. A few isolated organized lines of thunderstorms, however, could develop during the afternoon on Friday in E. Ontario to S. Quebec.

Wind direction should be largely in the form of Southwesterlies, pushing smoke towards right-hand sections of the audience at La Ronde. Wind speeds, though, are expected to become breezy (and occasionally gusty) into the late-afternoon to evening hours, but it is still a question as to how windy.

Another update to follow by later tomorrow/early-Friday.

Trav.

Conditions specified in the above post remain largely constant. As such, here are the most likely weather patterns for today, as well as this evening (July 5th):

Temperature/Humidity

The persistence of the Bermuda High will circulate very warm and humid-rich air into much of the Eastern North American continent. For S. Quebec, temperatures will likely reach 29-30 C during the afternoon hours, along with very high humidity, making it feel as hot as 36-38 C. By the late-evening, temperatures should remain at 24-25 C in the Montreal metropolitan area, but the continued very high humidity will make it feel closer to 32-33 C (though somewhat regulated by the breezy SW winds – see wind section).

Precipitation

Convection is expected to become enhanced into the afternoon hours in association with a moderately unstable atmosphere. Due to atmospheric dynamics, convective showers and thunderstorms should be sparse in coverage, but enhanced wind shear fields could support a few organized clusters of thunderstorms, and isolated severe thunderstorms, in the afternoon. Like yesterday (the 4th), convection should be most active throughout the afternoon and slowly subside by late-afternoon into the early-evening. Skies should remain partly cloudy with some mid-level cloud clusters for the evening.

Wind

Like previous runs, latest model guidance projects gusty winds developing into the afternoon hours, where sustained speeds and top gusts could reach 21-25 km/h and 34-38 km/h, respectively. By evening, wind speeds should diminish slightly to 16-19 km/h, with gusts closer to 31-34 km/h (marginally close to the 40 km/h threshold). Wind direction remains Southwesterly, pushing smoke quickly towards the right of the audience at La Ronde, but also towards (extreme) right-hand sections of the audience there. Winds will also provide some relief for those who cannot tolerate the very high humidity.

That’s the way the weather should work. In summary, a breezy evening, with very high humidity, warm evening temperatures, and partly cloudy skies.

*I will provide another update concerning wind speed for the evening hours early today.

Trav.

Winds continue to be breezy throughout this afternoon. However, sustained wind speeds for this evening should be a little less than what had been previously shown, with a more suitable range of 12-15 km/h (from the SW). Speeds should begin to slowly diminish by around dinner time.

With respect to convection, recent model runs have favored continued isolated convection until early this evening (more gradual scattered coverage for this afternoon, especially into upstate New York), owing to a high shearing and unstable environment to promote some development. Thus isolated showers and non-severe thunderstorms remain possible until early this evening, followed by partly cloudy skies for the late-evening.

On another note, today is the 14th anniversary of S. Quebec's violent electrical storm, called a derecho (a fast propagating and elongated cluster of powerful thunderstorms capable of producing widespread damaging straight-line winds over a span of hundreds of kilometers). This system caused large-scale damage in association with the winds and produced continuous lightning that was enough to mimic daylight. Top sustained wind speeds rivaled those of a near-category 2 hurricane. The July 5th, 1999 thunderstorm is certainly the most powerful thunderstorm that I have ever witnessed to this day.

Trav.

Following the passage of yesterday evening's (July 10th) cold front, a broad area of high pressure is slowly following behind from the NW. This area of high pressure will be the weather maker until the end of the weekend and, as such, will influence tomorrow's (Friday, the 12th) patterns.

Friday's weather is expected to be fair, with plenty of sunshine, light to moderate NNE winds, borderline low-moderate humidity, and stable air. As a result, no precipitation is expected for the Spanish display, and we should instead have pleasant evening conditions.

Late-evening temperatures should be around 20-21 C in the metropolitan area, along with borderline low-moderate humidity (so no significant humidex). Winds should be light (8-11 km/h) from the NNE, so the smoke will be generally blowing gently clear to the left of the audience at La Ronde and headed to adjacent sections of the bridge (sections near the park and over the river). For those at the Old Port, smoke could periodically affect viewing.

Another update will be provided later today/early-Friday.

Trav.

For once, the weather should be fully cooperative. That is great!

Fred

Hi Fred,

Yes, weather conditions should be mostly good for the Spanish display. However, the only aspect that concerns me for the evening is the lack of wind - above, I had mentioned light winds of 8-11 km/h, but newer projections have consistently indicated near-calm conditions.

In any case, I'll have another update prepared later on to address this.

Trav.

As mentioned in the previous update, high pressure will be the dominant weather factor for the day today (July 12th) across S. Ontario through to S. Quebec. As such, the patterns stated previously are still largely constant. Here are the dominant conditions for the Montreal area:

Temperature/Humidity

Maximum temperatures for today should reach 25 C, with low humidity, though humidity levels will rise slightly by the end of the day. By late-evening, temperatures will likely drop to 20-21 C for the metropolitan area (a little cooler outside the city), along with borderline low-moderate humidity. As a result, no significant humidex is forecasted. A formal heat wave may occur for both S. Ontario to S. Quebec, beginning Sunday, July 14th, with warming/moistening beginning tomorrow (the 13th).

Precipitation

No precipitation expected. Skies should remain mainly clear, including for the evening.

Wind

This is where it becomes tricky. Winds will be light throughout the day from the NNE at 9-12 km/h. Latest and recent model guidance have suggested very light to calm wind speeds by the evening to late-evening hours, consistent with the center of high pressure in close proximity to our location. Maximum speeds are 2-4 km/h. Under such conditions, smoke build-up is likely, especially during the more active segments of the display, and along low- to mid-levels. Directional tendencies are NE (occasionally ENE) for the evening, so the smoke should occasionally be moving very slowly towards those on the bridge nearest to the river, as well as for those on Notre-Dame street near the bridge. Folks at the Old Port could also have viewing inhibited by smoke. At times, smoke could be near-stagnant. For those at La Ronde, the overall wind direction could sometimes be of assistance, as smoke would be moving very slowly to your left and away, with build-up mostly in those directions. Fortunately, however, the humidity will not be high to contribute to additional accumulations.

In summary, a pleasant evening, with tolerable temperatures, borderline low-moderate humidity, and very light NE winds.

If necessary, I will provide an additional update concerning wind behavior (speed and direction) early this afternoon.

Trav.

The most recent model data shows a "slight" increase in wind speeds for this evening, with maximum speeds around 4-7 km/h. This should very gently push the smoke to the left of those at La Ronde and head towards the bridge, and towards sections of Notre-Dame street just South of the bridge. Periods of smoke build-up are still likely, mostly near the bridge.

I will also increase the late-evening temperature in the metropolitan area slightly to 21-22 C.

Everything else mentioned previously still remains.

Trav.

Just a note for Trav - yesterday was the hottest day in Montreal (9.6 cooling degree days - average temp for 24 hours was 27.6) since July 14th last year, when we had 9.8 cooling degree days (average temp was 27.8) - though yesterday's high temperature was just a bit higher than July 14th 2012.

Paul.

Hi Paul,

Thank you for sharing this! Indeed, the absolute maximum temperature for the Montreal area for yesterday (July 15th) slightly exceeded that of July 14th, 2012. Outside the city, towards the airport, however, last year's maximum on July 14th remains slightly higher than yesterday's, where the absolute maximum was recorded at 33.3 C on July 14th, 2012 (yesterday, it was 33.1 C), along with a daily mean (daily maximum and minimum averaged) of 28.1 C (so, 10.1 cooling degree-days). In either case, though, both today's, and especially tomorrow's (July 17th) maximum temperature may be enough to be the hottest since July 14th, 2012, and possibly beyond that.

Other than that, the highest daily means remain with August 1st, 1975 and July 21st, 2011, where the means were 30.3 C and 30.0 C (12.3 and 12.0 cooling degree-days), respectively, at the airport. The absolute maximum temperature, at the airport, on August 1st, 1975 was observed at 37.6 C, and on July 21st, 2011, it was 35.6 C (tied with July 22nd, 1955 for the warmest temperature to occur in the month of July). On both days, humidex values were close to 50 C. July 1955 was the warmest July in recorded history and included a monthly maximum average of virtually 30 C (17 of the 31 days reached 30 C or more)!

And it appears that we have now officially attained heat wave status for the Montreal area, as it recently surpassed 30 C today, and, thus, making it three consecutive days where daytime highs reached 30 C or more. Powerful thunderstorms, however, may occur later tomorrow afternoon/evening across E. Ontario to S. Quebec, and again late-day Friday (July 19th) in S. Ontario to S. Quebec, just before a cooling into the weekend.

Trav.

Trav,

where do you get the figures for downtown from? McTavish station reported 32.3max and 27.6 mean for July 15th, at least in the daily figures: http://www.climate.weatheroffice.gc.ca/climateData/dailydata_e.html?ti meframe=2&Prov=QUE&StationID=10761&dlyRange=1994-07-26|2011-10-17&Mont h=7&Year=2013&cmdB1=Go

Just curious,

Paul.