Everything mentioned in the above posting still applies for this evening, except that I would boost the late-evening temperature to 24-25 C.

Trav.

As previously mentioned in the postings above, near-heat wave status is favorable for extreme Southern/SW Quebec over the July 19th-July 21st period. July 20th, which features the Canadian display, will, therefore, be a part of this warming event.

For the greater Montreal area on July 20th, a strong circulation of hot and very/near-extremely humid air will allow the maximum temperature to achieve 32-33 C by mid-afternoon (already near 30 C during the mid- to late-morning period). With moisture-rich air, this would allow a maximum humidex of 42-43 C. By late-evening, temperatures will decrease by very little, still remaining at 29-30 C (if there is rainfall, then 26 C), with a humidex of 37-38 C (36 C if there is rainfall).

In response to the hot and humid air mass, isolated non-severe thunderstorms could also develop by the mid-afternoon period at maximum heating. Although thunderstorm coverage is rather sparse during the afternoon (i.e. 30% probability), a weak cold front and shortwave trough will enhance lift later in the day. These lifting mechanisms become more important by late-afternoon (i.e. by traditional dinner time to sunset and onward), so a risk for scattered convective showers and thunderstorms will be possible (40% probability) by this time, which would include display time. Some of the thunderstorms could further briefly attain strong standards. In this environment, the most organized convection will be capable of locally torrential rains and intense lightning. This will continue to be monitored.

Due to the strong circulation of hot and humid air, wind speeds could be rather strong, from the SW to even WSW for most of the day. Although some uncertainty exists for the evening period, this directional tendency could continue during this time. Sustained speeds of 24-28 km/h are favorable for the afternoon, but gusts may occasionally reach 38-43 km/h. Should this continue into the evening period, this would allow the rapidly accumulating smoke, at all altitudes, to move quickly towards right-hand sections (partially central sections, at times) of the La Ronde audience, causing the display to appear murky from there.

Another update will follow by either late tomorrow evening (July 19th) or pre-dawn July 20th, mostly to address thunderstorm potential and wind velocity.

Trav.

Weather details presented in the above posting are still mostly valid for the Canadian display day. Therefore, I present here the expected conditions for the greater Montreal area for Saturday, July 20th:

Temperature/Humidity

As a hot and very/near-extremely humid air mass continues to affect Southern Ontario to Southern Quebec until July 21st, temperatures will ubiquitously reach and surpass 30 C by mid-afternoon (already close to that by mid-morning). For the greater Montreal area, a maximum temperature of 31-32 C is likely by the mid-afternoon period (provided minimal interference from rainfall). With very high humidity, a maximum humidex of 43 C is favorable. As very high humidity continues into the evening period, temperatures will not be liable to drop significantly, remaining at 28-29 C by late-evening (humidex of 38-39 C), including display time (if rainfall occurs persistently, then 25-26 C – humidex of 35-36 C). This will continue into much of July 21st.

Precipitation

As mentioned previously, a shortwave trough and weak cold front will be affecting this area by the early-afternoon period. These lifting features will be the focus for scattered thunderstorm coverage during the afternoon (40% probability). Due to the dynamics present in conjunction with the hot and very humid air mass, there is reason to believe that some thunderstorms will be capable of becoming better organized during the afternoon period, and so there is potential for stronger thunderstorms during this time. This may encourage a severe thunderstorm watch. That said, while instability further increases into the evening, convective coverage appears to decrease slightly to isolated (i.e. 30% probability), including during display time. Thus, while the thunderstorm risk will remain, the thunderstorms/convective rainfall should be sparsely distributed, although a few of these may still be strong during the evening and overnight period in this environment. Otherwise, skies should be partly cloudy for the evening, mostly consisting of clusters of vertically defined cumulus. Distant lightning is also possible during the evening.

Wind

Winds are still expected to be breezy (occasionally gusty) for the day, from the SW. Speeds of 24-28 km/h are likely, with occasional gusts of 38-43 km/h. By late-evening, wind speeds do diminish slightly but are still somewhat breezy (which would provide a little comfort for those who are not a fan of high heat and humidity). Speeds of 13-17 km/h (occasional gusts of 27-31 km/h) are favorable for the evening, including display time. This would allow the smoke to displace reasonably quickly, but also towards right-hand sections of the La Ronde audience, causing the display to appear hazy from there. This is especially true because of the very high humidity encouraging rapidly expanding smoke, despite the smoke clearing fairly quickly. High-altitude smoke, however, should be moving towards the La Ronde audience somewhat more directly (right-hand and partially central sections) and at a slightly faster pace. *Should thunderstorms occur, then the smoke would be moving towards the La Ronde audience more directly.

If necessary, another update will follow by this mid-afternoon (July 20th) to address convective potential, as well as wind speed/direction.

Trav.

The details above are still very much applicable.

That said, unless thunderstorms are present, the smoke should be moving a little more distinctly to the right of the La Ronde audience (at the same speeds) but still sometimes reaching far right-hand sections of the audience, causing the display to appear hazy from there (mostly to La Ronde's right). High-altitude smoke should still be moving more towards right-hand sections, however.

The thunderstorm risk continues, as well. However, lift ahead of the aforementioned cold front is shown to be more enhanced into the evening period, including around display time. Therefore, strong to severe thunderstorms, as mentioned above, will still be possible into evening, except that coverage will be more scattered than isolated (i.e. 60% probability mid to late this afternoon to 40% by mid-evening). Note that thunderstorms, especially the stronger thunderstorms, will be capable of torrential rains, gusty downdrafts and intense lightning.

For all other information, please refer to the above posting.

Trav.

Your reports and updates are very appreciated, especially when radar is as colorful as it is now.

Fred

No problem, Fred. Luckily, that line of severe thunderstorms to the West dissipated before reaching this general area, but others formed over Laval and the East end, and some spectacular lightning was observed over the West Island. Severe thunderstorm warnings were also released for Mirabel-St-Jerome. The thunderstorm risk will continue into the evening, but coverage will likely diminish slightly (so, a 40% probability, as opposed to 60% this mid- to late-afternoon).

We'll keep the winds in the form of breezy Southwesterlies for the evening, and so rapidly accumulating smoke should favorably move reasonably quickly towards right-hand sections of the La Ronde audience (occasionally partially central sections). All other information presented above remains valid.

Trav.

High pressure is expected to govern the day tomorrow (July 24th) across Southern Ontario to Southern Quebec. Under this system, it would allow for stabilized atmospheric conditions throughout July 24th, including during the Australian display, restricting rainfall and cloud development. This is unlike the situation featured by July 20th into early-July 21st. Some lift during the afternoon period would allow for a few isolated distant cirrus, but skies should remain largely clear, including into the evening.

The maximum temperature is likely to attain 23-24 C in the greater Montreal area. By late-evening, the temperature should decline to 20-21 C. As the humidity will be low, the humidex will correspondingly be negligible.

With an area of high pressure in the area, winds should be light (7-11 km/h) and in the form of WSW. This is likely to endure into the evening period. While particularly extensive smoke accumulation is not expected, the smoke, at all altitudes, would be fairly gently drifting towards central and right-hand sections of the La Ronde audience, causing the display to frequently appear hazy from these sections. It is possible, however, for more of a light SW flow to be present by late-evening, but this will have to be monitored.

Another update to follow by either late this evening (July 23rd), or the early pre-dawn of July 24th.

Trav.

Adhering closely to the above posting, here are the expected conditions for the greater Montreal area for Wednesday, July 24th.

Temperature/Humidity

The maximum temperature is likely to reach 24 C by mid-afternoon, with a decline to 21-22 C by late-evening. Due to high pressure advancing into the area, humidity will be low, and so a humidex is not favorable.

Precipitation

No rainfall is expected. The aforementioned area of high pressure will keep lift very limited throughout the day, although sufficient for a few isolated fair-weather cumulus and distant cirrus during the afternoon. With further restrictive lift during the evening period, clear skies are favored.

Wind

Due to high pressure, winds will be generally light throughout the day, at 7-11 km/h, with a westerly component during the afternoon. By evening, however, wind speeds should weaken slightly, to 5-8 km/h, and with a transition to a SW tendency. This would allow the smoke to very gently move towards right-hand sections (partly central sections) of the La Ronde audience, causing the display to appear murky from there. Higher altitude smoke should be moving somewhat faster but a little more directly towards right-hand/central sections of the La Ronde audience. Periods of smoke accumulation are expected deeper into the display (notably following more active segments), but particularly extensive accumulations are not favored due to low humidity.

If necessary, another update will follow by this mid-afternoon (July 24th) for wind speed/direction.

Trav.

No real change to the above-mentioned details, but just to outline that WSW directional tendencies are more likely to endure for the evening. This would allow the smoke to move (gently), at all altitudes, towards right-hand and central sections of the La Ronde audience more directly, although higher altitude smoke would be moving a little faster, as mentioned above. This would cause the display to appear frequently hazy from those sections, as well as periods of smoke accumulation deeper into the display. However, again, particularly excessive smoke accumulations are not expected due to low humidity.

For all other information, please refer to the above posting.

Trav.

Very warm/hot and humid air is expected to return for Southern Ontario to Southern Quebec over the next week. It is this air mass that could induce (near-) heatwave status for especially extreme Southern Quebec over the July 26th-July 30th period, near-similar to the heatwave achieved during July 19th-July 21st. Consequently, the closing display, on July 27th, will be a part of this event. A maximum temperature of 32 C is likely by mid-afternoon for the greater Montreal area, with a decline to 26-27 C by late-evening, including display time. With high humidity throughout the day, a maximum humidex of 37 C is favorable, while a humidex of 32-33 C is likely by late-evening, including display time.

Conditions are expected to be largely dry for the day in this general area. That said, in response to robust solar heating and high humidity, some sparsely-distributed convective showers and non-severe thunderstorms are possible during the mid- to late-afternoon period (20% probability). By evening, including display time, this risk should subside, but sufficient lift in this region would allow for partly cloudy skies, consisting of clusters of defined cumulus and high-level cirrus (with large clear breaks between these).

With a persistent circulation of very warm and moist air, winds will principally be in the form of South-Southwesterlies (SSW). Speeds of 9-12 km/h are favorable throughout the day (except 15-19 km/h during the afternoon). This would allow the smoke to move reasonably quickly, at all altitudes, clear to the right of the La Ronde audience (clear to the left for those on Notre-Dame Street). Some periods of smoke accumulation are possible deeper into the display, mostly following more active segments along low- to mid-level, but this will be most prevalent to La Ronde’s right.

Another update will follow by later this evening (July 26th) into early-pre-dawn July 27th.

Trav.

Weather details presented in the above posting continue to be applicable for this final display day of 2019. As such, here the conditions expected for Saturday/today, July 27th for the greater Montreal area.

Temperature/Humidity

We are now within the aforementioned hot and humid air mass that may eventually become an official heatwave by Sunday, July 28th. As a result, a maximum temperature of 32 C is favorable by mid-afternoon July 27th, decreasing to 26-27 C by late-evening, including display time. With high humidity (not very high) persisting into the evening, a maximum humidex of 37 C is likely, along with a humidex of 32 C by late-evening.

Precipitation

Conditions should remain generally dry for most areas in this general area throughout the day. However, as mentioned above, moderate instability developing by the early-afternoon period, in response to copious amounts of solar heating and high humidity, would allow for sparsely-distributed convective rain showers and isolated non-severe thunderstorms for principally the mid- to late-afternoon period (i.e. up to about sunset), when lift is at its highest. In this environment, the convection would be slow-moving, and so it will develop and dissipate almost equally quickly. Because of the isolated nature of convection, the probability for any given area within this region to receive convective rainfall will be held at 30% for the mid- to late-afternoon period (20% for thunderstorms, specifically). By late-evening, some clusters of defined cumulus and high-level cirrus will be present, but with large clear breaks between them.

Wind

Winds will likely be in the form of light Southerlies for the evening (more SSW for the afternoon). Evening speeds should be 9-12 km/h, but breezier at 17-21 km/h for the afternoon. This would allow the smoke to blow clear to the right of the La Ronde audience (clear to the left for those on Notre-Dame Street) reasonably quickly, especially at high altitudes. High-altitude smoke would be moving closer to (far) right-hand sections of the La Ronde audience, but very narrowly. Some periods of smoke accumulation will be possible later in the display, especially following active segments, but this would be most predominant to La Ronde’s right, and along low- to mid-level. That said, the smoke should be drifting away to the right quickly enough for the majority of the display.

If necessary, another update will follow by this mid-afternoon (July 27th). If not, this would conclude the weather reports for 2019!

Cheers,

Trav.

I would like to just share here some of my footage from yesterday afternoon's (July 27th's) isolated thunderstorm cluster:

https://www.youtube.com/watch?v=ohmfkyqeNBY

Trav.