Conditions specified above largely remain applicable for the fourth originally scheduled display day for 2020. As such, here the expected conditions for the greater Montreal area, for Saturday, July 11th:

Temperature/Humidity

Temperatures should remain very warm (maximum of 28-29 C), together with very high humidity. Due to excessive time spent in cloud during the morning hours, achieving 30.0 C, while possible, would be difficult to achieve. As such, the current heat wave is likely to come to a close tomorrow. Breaks in the cloud deck continue to be favorable by early-afternoon, and so this appears sufficient to allow the maximum temperature to reach fairly close to 30.0 C. Due to a return of excess cloud cover by evening, as well as very high humidity, late-evening temperatures of 26-27 C are likely (humidex of 36 C). If rainfall occurs, the temperature would decline to 23 C (humidex of 32 C).

Precipitation

Due to the influence of the remnants of tropical cyclone/storm Fay, periods of (needed) rainfall are likely across S. Quebec. However, because these remnants will be moving fairly quickly off to the North, a fair portion of the rainfall would be focused to the morning to early-afternoon period. Thereafter, as mentioned, the cloud deck should eventually exhibit discontinuities, although this appears to be more favorable by mid-afternoon to allow for some periods for solar heating to initiate for a few hours. As temperatures begin to rise fairly quickly in response to this, scattered thunderstorms and/or convective rainfall will also become increasingly possible. As such, the probability of precipitation should be 40% during the late-afternoon to evening. However, by late-evening and beyond, convective coverage should increase in response to enhanced lift, and atmospheric instability will remain relatively high. For this reason, thunderstorm and convective rainfall development will favorably ensue during this time (60% probability). Although mostly non-severe, a few strong thunderstorms would also be possible in this environment, including during the late-evening to mostly early-overnight. This is notably true for areas where earlier solar heating was maximized. All thunderstorms would be capable of torrential rains as their primary hazard and would increase the risk for localized flooding where they affect.

Wind

Without the influence of thunderstorms in the area, winds should generally be in the form of light Southerlies (9-13 km/h) for the late-evening (as opposed to the SW/WSW mentioned in the above post). This suggests that the rapidly accumulating smoke would be pushing narrowly fast enough clear to the right of the La Ronde audience. The display would have likely appeared hazy at right-hand sections of the display, especially along low- to mid-level, and deeper into it. This is principally due to the very high humidity and near-saturated lower atmosphere.

If necessary, another update will follow to address wind speed/direction and/or rainfall development tomorrow mid-afternoon (July 11th).

Trav.

Conditions presented above are still largely applicable, except that wind direction would be more in the form of the originally specified SW/WSW tendency. This would allow the (thick) smoke to drift reasonably quickly, at all altitudes, towards principally right-hand (partially central) sections of the La Ronde audience (if there were to be a display).

All other details remain constant.

Trav.

From what I saw on the radar, we would have experienced rainy weather conditions at the time of the display.

Fred

Hi Fred,

Yes, this display would have met with a more persistent rainfall (light to occasionally moderate intensity). Thunderstorms were lighting up the skies some distance to the East and SE, as well, at the time. Winds were also likely from the SSE to South during display time, so it seems likely that the the smoke would have been moving clear to the right of the La Ronde audience at a decent pace.

Near-saturated, damp and very humid conditions for this display night!

Trav.

On the cusp of the potential next (official) heat wave over the July 17th-July 21st period, the fifth display day scheduled for 2020 (July 15th) would likely meet with largely pleasant weather conditions. Temperatures should reach a maximum of 26-27 C (humidex of 29-30 C) under a mix of sun and cloudy periods occupying the skies throughout the day in this region. Humidity would be moderate for the day, at best, and so the disparity between the base temperature and humidex should be small. For the late-evening, the temperature should decline to 24-25 C in the greater Montreal area, but with a mild humidex of 27 C. By evening, skies should become increasingly cloudy (mid- to high-level cloud) in response to a weak North-South oriented cold front ejecting East late-day. Some isolated light rain is possible by late-evening, but due to the dry nature of the air near and at the surface, any light rain would largely evaporate before reaching the ground successfully.

Winds should be in the form of light (9-12 km/h) ENE to straight easterlies. Therefore, accumulating smoke would, at all altitudes, be moving directly and fairly gently away from the La Ronde audience, and towards those on Notre-Dame-De Lorimier streets, most likely causing the display to appear hazy from there.

Another update to follow by late this evening into the early-predawn (July 14th-July 15th).

Trav.

Conditions specified in the above posting remain valid for this originally scheduled 5th display day (first Wednesday display) of 2020. As such, presented here are the expected conditions for today (July 15th) for the greater Montreal area:

Temperature/Humidity

The maximum temperature for the day would be approximately 27 C, under borderline moderate-high humidity. This will induce a maximum humidex of 31 C. By late-evening, the temperature will not drop significantly because of sufficiently high humidity and increased cloud cover, and so 26 C is favorable (humidex of 30 C as borderline moderate-high humidity continues).

Precipitation

Unlike the previous display day, no rainfall is generally expected. This is owing to dry near-surface air and limited lift in the region, as the aforementioned cold front will stall farther West. Still, sufficient lift will encourage some cloudy periods (at mid- to high-level) by mid-afternoon and onward.

Wind

Winds continue to be in the form of ENE to occasionally NE. Speeds of 9-12 km/h are favored. This suggests that accumulating smoke, at all altitudes, would drift reasonably quickly directly away from the La Ronde audience and towards those on Notre-Dame/De Lorimier street, especially those sections closest to the bridge there; this would, therefore have likely caused the display to appear hazy from those vantage points (had there been a display).

If necessary, another update will follow by tomorrow mid-afternoon (July 15th).

Trav.

An official heat wave (or near-official heat wave) continues to be favorable for S./SW Quebec for the July 17th-July 20th period. Therefore, the originally scheduled sixth display day (July 18th) will be a part of this event. Temperatures should be hot for July 18th, with a maximum of 30-31 C by mid-afternoon, and then dropping to 27-28 C in the greater Montreal area by late-evening. Combined with hot temperatures, humidity will be borderline high to very high, and so this would generate a maximum humidex of 37 C by mid-afternoon, and 35-36 C by late-evening.

While the rainfall risk would be minimal, sparsely-distributed and briefly-sustained convective rainfall and non-severe thunderstorms will be possible in this general area during the afternoon period. Due to relying largely on solar heating, however, all of these will quickly subside not long after sunset. Late-evening skies should largely remain clear, but some modest lift in the area will favor some clusters of cirrus cloud. Winds, from the WSW, would also be somewhat breezy during the day but do become lighter by evening. WSW tendencies are also expected to shift SSW by late-evening, at 8-11 km/h, so the smoke would be drifting fairly slowly to the right of the La Ronde audience (though high-altitude smoke would be passing more so over far right-hand sections of the audience, and at a slightly quicker pace).

Another update will follow this posting by later this evening into the early-overnight (July 17th-July 18th).

Trav.

The above-mentioned weather details remain valid for this originally scheduled sixth display day (July 18th). Here are the expected conditions for the greater Montreal area for July 18th:

Temperature/Humidity

The maximum temperature is expected to be 30-31 C, with a slight decline to 28-29 C by late-evening. Because of borderline high to very high humidity, the maximum humidex should be 37 C by mid-afternoon, and then 35 C for late-evening.

Precipitation

Convection will be sparsely-distributed and largely driven by solar heating and moistening. Therefore, the probability of precipitation would effectively remain at 20-30% for the afternoon but subsiding not long after sunset. Still, some lift in the area would favor clusters of high-level cloud (cirrus) for post-sunset, but large clear breaks between them are favorable.

Wind

Winds will largely be in the form of WSW to SW for the majority of the day. Winds will be breezy (17-21 km/h) through principally the afternoon, but they will become lighter for the evening (9-13 km/h) and transition to SSW tendencies. This would allow the often rapidly accumulating smoke to drift fairly quickly to the right of the La Ronde audience, though high-altitude smoke would move over far right-hand sections of the audience.

Another update will follow by tomorrow mid-afternoon (July 18th), if necessary.

Trav.

An area of low pressure will advance NE Wednesday (July 22nd). As it does, its warm front will eventually become in close proximity to this region and will, thus, be the focus for rainfall during primarily the afternoon-evening period. Embedded non-severe thunderstorms also appear possible, but their development will likely be significantly limited. As such, it is with greater possibility for the 7th originally scheduled display day to encounter periods of (convective) rainfall, although the extent to which the rainfall will persist will be more carefully reviewed in the following update(s).

For the greater Montreal area, following some morning sunlight, the day itself should involve extensive cloud coverage as this system migrates farther NE, limiting substantial warming. The maximum temperature should reach 24-25 C (humidex of 30 C) by early-afternoon before cooling to 20-21 C once the air reaches (near-) saturation from the rainfall. This 20 to 21 C would persist for the late-evening (humidex of 29 C). North of the warm front, winds should largely be in the form of ESE, persisting into the evening. Winds are additionally light through to the evening (to 8-11 km/h). This would allow the rapidly accumulating smoke (due to high humidity and (near-) saturated air)) to slowly drift directly away from the on-site audience and towards Notre-Dame Street going North. However, there is a chance for Northeasterlies to develop for the evening, depending on the trajectory of this low pressure system. This would instead cause the smoke to slowly drift to the left of and away from the on-site audience but would displace towards portions of the bridge nearest to Notre-Dame Street and the river. This will also be closely monitored.

Another update will follow later this evening or early-predawn (July 21st-July 22nd).

Trav.

As the details presented in the above posting largely remain valid, here are the expected conditions for today (July 22nd) for the greater Montreal area for this 7th originally scheduled display day of 2020:

Temperature/Humidity

Due to a slightly more northward migration of the coming area of low pressure, the maximum temperature is likely to be 27 C (maximum humidex of 32 by mid-afternoon due to high humidity re-developing). Extensive cloud cover will continue to limit substantial warming. By late-evening, the temperature should drop only slightly, to 25 C (humidex of 31 C), though the temperature should eventually drop further, to 21 C (humidex of 27 C) as periods of rainfall gradually moisten and saturate the air.

Precipitation

As the area of low pressure’s warm front drifts North/NE, larger amounts of continuous high- to mid-level cloud will overspread this region by the early-afternoon (following more of a sun-cloud mix during the morning). However, despite this cloud cover, conditions should remain largely dry until at and following sunset, when lift becomes most magnified ahead of/along the front. Scattered convective coverage is favorable, and so a 60% probability of precipitation is appropriate for the evening. Continued limited instability should keep thunderstorm risks minimal.

Wind

Directional tendencies are mostly light ESE (8-11 km/h) for the day, but they do become more Easterly to ENE for the late-evening period (9-13 km/h). This suggests that the rapidly building smoke, at all altitudes, would move at a reasonable pace directly away from the La Ronde audience and towards those sections of Notre-Dame Street closest to the bridge. From those sections of Notre-Dame Street, the display might have appeared very murky under the high humidity and (near-) saturated air, notably deeper into the display.

If necessary, another update will follow by this mid-afternoon (July 22nd) to address wind direction and rainfall persistence/coverage for the evening.

Trav.

I am glad that smoke would have moved away from the audience at La Ronde... ;-)

I will definitely monitor the weather tonight, as there is some possibility that we could have experienced a show under precipitation.

Thank you for this forecast, Trav.

Fred

Hi Fred,

I think this display would have remained largely dry, despite consistent rainfall passing uncomfortably close to the North/NW during the 10:00-10:30 p.m. period. I think that perhaps a very light rain (or drizzle), though, might have been occurring at the firing site during the last 4-5 minutes of display time - a near-similar situation to the second display day (June 27th).

Winds also appeared to be NE to later NNE (13-16 km/h), so the smoke would have likely been moving directly away from and clear to the left of the La Ronde audience. This meant that the smoke would have likely displaced towards those on Notre-Dame Street nearest to the bridge, although going farther South of where most people would normally watch the fireworks on that street. Also, those on that section of the bridge over the river and Notre-Dame Street would have likely been receiving the smoke.

Trav.

A mid- to upper-level low will circulate over these regions for July 29th, and, thus, for the final display day originally scheduled for 2020. This trough will yield instability suitable for scattered (deep) convection, including generally non-severe thunderstorms, for the afternoon-evening period (40% probability of precipitation), though more isolated coverage for the late-evening (30% probability). The maximum temperature for the day should be 28-29 C with high (not very high) humidity, generating a maximum humidex of 33-34 C. The temperature would then drop to 25-26 C by late-evening under the same humidity concentration (humidex of 30-31 C).

Winds should be largely in the form of breezy SW to occasionally SSW. Speeds of 18-22 km/h are favorable for the afternoon, but this declines slightly for the evening, to 13-16 km/h. This would allow the smoke to drift fairly quickly to the right of the La Ronde audience, though would have likely sometimes been reaching far right-hand sections (especially the more quickly displacing high-altitude smoke). Smoke accumulation would likely not have been too excessive in this situation,

An update to follow late this evening into the predawn tomorrow (July 28th-July 29th).

Trav.

Forecast details presented in the above posting remain largely applicable, and so presented here are the weather conditions expected for the greater Montreal area for this originally scheduled final display day (8th display) of 2020 (July 29th):

Temperature/Humidity

Despite an increased density in cumulus clouds into the afternoon period, substantial solar heating within this very warm fairly humid air mass should generate a maximum temperature of 28-29 C. Borderline moderate-high humidity would allow for a maximum humidex of 33-34 C by mid-afternoon. By late-evening, the temperature should drop to 24-25 C, with a corresponding humidex of 30-31 C due to the high humidity.

Precipitation

A broad mid- to upper-level trough will be circulating over this region over the next two days. Within this feature would be a moderately unstable environment suitable for sparsely-distributed (deep) convection, including isolated thunderstorms. While generally non-severe, some thunderstorms will be capable of attaining strong to even severe standards for the afternoon period, and so intensity/coverage would more aggressively diminish during the late-evening (i.e. near midnight). Thus, a 40% probability for precipitation is favorable for the afternoon to just after sunset, but more so 30% by closer to midnight. Skies should be partly cloudy (composed of large cumulus clusters) for the evening.

Wind

Winds should largely be in the form of SSW for the day (occasionally SW). Speeds of 18-22 km/h should be present during the afternoon (occasional gusts of 29-34 km/h). Somewhat lighter speeds would then develop for the evening period, with speeds of 12-16 km/h. Therefore, fairly rapidly accumulating smoke would have likely been displacing clear to the right of the La Ronde audience, though high-altitude smoke would occasionally drift very quickly over far right-hand sections. If thunderstorms are in the area, however, then the winds would suddenly turn westerly and blow more directly towards the on-site area. Extensive smoke accumulation would have likely not been favored due to sufficiently strong speeds.

Another update, if necessary, will follow by this mid-afternoon (July 29th) to address wind direction and rainfall/thunderstorm persistence/coverage for the evening.

Trav.

The weather forecast and the radar behavior would be very stressing for tonight award ceremony and closing display!

Fred