Weather Cooperation (or not) for Summer 2020.

Hi Fred,

You’re very welcome! Despite the lack of fireworks, it was still fun to prepare these forecasts and pretend that the competition was still occurring.

This year’s edition of Montreal fireworks would have been a part of an interesting mix of weather conditions during display times. Particularly noteworthy is that this edition would have taken place during potentially the hottest Summer in recorded history. This is notably true for July for the island, where July 2020 will be, as envisioned, the hottest July on record for its overall temperature (i.e. all daily maximum and minimum temperatures averaged), which is astounding because this title was achieved just two years, in July 2018! The 2020 edition would have further opened appropriately on the first official day of Summer (June 20th), which would have coincidentally been likely tied (with July 17th) for the warmest fireworks evening of all originally scheduled fireworks evenings. Although difficult to verify actual on-site conditions, it is likely that temperatures would have been 28-29 C in time for the opening display, as well as for July 17th. Additionally, the first fireworks day would have been part of a significant and historical June heat wave (the longest June heat wave ever observed here: June 17th-June 23rd). Conversely, the coolest fireworks evening would have likely been a tie between July 22nd and July 29th. The most humid fireworks evening was on July 11th, when the remnants of tropical cyclone Fay yielded some rainfall early in the day that day. The least humid fireworks evening would have likely been that of July 4th, but the July 4th fireworks day would have also been a part of an official heat wave.

There was also an unusually high frequency of rainfall this year during display time. Indeed, some form of rainfall likely occurred during the 10:00-10:30 p.m. period for 50% of the fireworks days (June 27th, July 11th, July 22nd, and July 29th). It was also possible that a few drops were in the area during the July 4th display, making this potentially a fifth display time to observe some kind of rainfall at some point, though it was likely that these drops were evaporating before reaching the surface that evening. Thus, it is reasonable to assume that the July 4th display time would have remained completely dry. However, two of the rainfall events during display time were relatively light and occurring during the final 4-10 minutes of those displays (June 27th and July 22nd). More persistent and higher intensity rainfall would have been observed for both July 11th and July 29th. Thunderstorms were in the general area twice this year, as well, during fireworks evenings, where, on June 27th, lightning could be seen flickering occasionally in the distance, in the Saint-Jerome-Mirabel corridor, just within 30 minutes prior to display time. More notably, the (strong) thunderstorm that was in the area (or, at the very least, passing very closely to the fireworks site) in time for the closing show led to more substantial rainfall during fireworks time, but it might have also induced delays in the commencing of the closing show, and/or the awards ceremony prior to that. Conditions were largely dry for setup for the first three displays, but more regular rainfall from thunderstorms would have seemingly negatively affected setup at some point for the remaining shows. Quite astoundingly, only one fireworks evening (the opening) had skies that were mostly clear – all others faced substantial cloud coverage.

More consistently, wind speeds were likely never an issue this year, for speeds were suitably strong enough to displace the smoke. No display time this year met with dangerously strong or overly weak wind speeds, and so the range of speeds across display times was quite narrow and hovering around light values. This was particularly important due to the frequently (very) humid conditions characteristic of this late-Spring and Summer so far. Thus, no display times would have likely suffered from substantially obscured viewing from often rapidly accumulating smoke, or from near-stationary (thickened) smoke. That said, the largest smoke concentration would have been favorable for the evening of July 11th, when near-saturated and very humid air were present (negatively affecting color richness of the fireworks). For the same reasons, similar conditions would have been present for the closing show. This is especially true if these displays were generally active and featured many smoke-rich products.

Interestingly, it appeared likely that all major vantage points intercepted smoke at some point this year because of variable wind direction. For example, the La Ronde audience would have likely intercepted smoke during two of the fireworks evenings (July 4th – largely left hand sections, and July 29th – largely central to right-hand sections, most likely, though it is unclear the degree to which the thunderstorm altered the wind fields around the firing site at the time). On July 22nd, the smoke would have been drifting to those on the bridge nearest to the park and over the river, while on July 15th, those on Notre-Dame Street would have received the smoke. For the other four fireworks days, the smoke would have more favorably been moving clear to the right of the La Ronde audience (clear to the left for those on Notre-Dame/de Lorimier streets) and, thus, not impacting viewing for any major vantage point.

There was definitely quite a mixture of situations this year!

Trav.

Montreal Fireworks Forum

Weather Cooperation (or not) for Summer 2020.

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	Weather Cooperation (or not) for Summer 2020.
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	Smoke Member	#31 \| Posted: 29 Jul 2020 18:34
		Hi Fred, Yes, no real changes to the forecast details to this evening (July 29th), although persistent rainfall in the area this did prevent reaching the maximum of 28-29 C (though it did reach about 26 C before dropping). One other detail is I believe the overall wind direction, outside of thunderstorms, will be more SW than SSW for this evening (same speeds). Thus, while the smoke would have likely still been moving to the right of the on-site audience, it would have also most likely been moving, at all altitudes, towards far right-hand sections. Due to the instability that would linger this evening, I see it also necessary to extend the 40% probability for convective rainfall/thunderstorms mentioned for this afternoon to early-evening to the late-evening. The risk for strong to severe thunderstorms should still gradually diminish deeper into the evening. Humidity would still be high for the evening, as well, under a temperature of about 24 C (21 C under persistent rainfall). Trav.

	Smoke Member	#32 \| Posted: 29 Jul 2020 22:42
		A strong isolated thunderstorm cluster would have been present during this final display. Thunderstorm coverage diminished significantly into the evening, but this organized thunderstorm affected the island and was in the area during display time. Because of this, winds also would have turned towards the audience (becoming WSW during display time). What a way it would have been to close the 2020 edition! Trav.

	fredbastien Member	#33 \| Posted: 30 Jul 2020 20:28
		Yes, it would have been an eventful night! Thank you Trav for keeping the spirit of the competition beat alive this year! Fred

	Smoke Member	#34 \| Posted: 31 Jul 2020 12:26
		Hi Fred, You’re very welcome! Despite the lack of fireworks, it was still fun to prepare these forecasts and pretend that the competition was still occurring. This year’s edition of Montreal fireworks would have been a part of an interesting mix of weather conditions during display times. Particularly noteworthy is that this edition would have taken place during potentially the hottest Summer in recorded history. This is notably true for July for the island, where July 2020 will be, as envisioned, the hottest July on record for its overall temperature (i.e. all daily maximum and minimum temperatures averaged), which is astounding because this title was achieved just two years, in July 2018! The 2020 edition would have further opened appropriately on the first official day of Summer (June 20th), which would have coincidentally been likely tied (with July 17th) for the warmest fireworks evening of all originally scheduled fireworks evenings. Although difficult to verify actual on-site conditions, it is likely that temperatures would have been 28-29 C in time for the opening display, as well as for July 17th. Additionally, the first fireworks day would have been part of a significant and historical June heat wave (the longest June heat wave ever observed here: June 17th-June 23rd). Conversely, the coolest fireworks evening would have likely been a tie between July 22nd and July 29th. The most humid fireworks evening was on July 11th, when the remnants of tropical cyclone Fay yielded some rainfall early in the day that day. The least humid fireworks evening would have likely been that of July 4th, but the July 4th fireworks day would have also been a part of an official heat wave. There was also an unusually high frequency of rainfall this year during display time. Indeed, some form of rainfall likely occurred during the 10:00-10:30 p.m. period for 50% of the fireworks days (June 27th, July 11th, July 22nd, and July 29th). It was also possible that a few drops were in the area during the July 4th display, making this potentially a fifth display time to observe some kind of rainfall at some point, though it was likely that these drops were evaporating before reaching the surface that evening. Thus, it is reasonable to assume that the July 4th display time would have remained completely dry. However, two of the rainfall events during display time were relatively light and occurring during the final 4-10 minutes of those displays (June 27th and July 22nd). More persistent and higher intensity rainfall would have been observed for both July 11th and July 29th. Thunderstorms were in the general area twice this year, as well, during fireworks evenings, where, on June 27th, lightning could be seen flickering occasionally in the distance, in the Saint-Jerome-Mirabel corridor, just within 30 minutes prior to display time. More notably, the (strong) thunderstorm that was in the area (or, at the very least, passing very closely to the fireworks site) in time for the closing show led to more substantial rainfall during fireworks time, but it might have also induced delays in the commencing of the closing show, and/or the awards ceremony prior to that. Conditions were largely dry for setup for the first three displays, but more regular rainfall from thunderstorms would have seemingly negatively affected setup at some point for the remaining shows. Quite astoundingly, only one fireworks evening (the opening) had skies that were mostly clear – all others faced substantial cloud coverage. More consistently, wind speeds were likely never an issue this year, for speeds were suitably strong enough to displace the smoke. No display time this year met with dangerously strong or overly weak wind speeds, and so the range of speeds across display times was quite narrow and hovering around light values. This was particularly important due to the frequently (very) humid conditions characteristic of this late-Spring and Summer so far. Thus, no display times would have likely suffered from substantially obscured viewing from often rapidly accumulating smoke, or from near-stationary (thickened) smoke. That said, the largest smoke concentration would have been favorable for the evening of July 11th, when near-saturated and very humid air were present (negatively affecting color richness of the fireworks). For the same reasons, similar conditions would have been present for the closing show. This is especially true if these displays were generally active and featured many smoke-rich products. Interestingly, it appeared likely that all major vantage points intercepted smoke at some point this year because of variable wind direction. For example, the La Ronde audience would have likely intercepted smoke during two of the fireworks evenings (July 4th – largely left hand sections, and July 29th – largely central to right-hand sections, most likely, though it is unclear the degree to which the thunderstorm altered the wind fields around the firing site at the time). On July 22nd, the smoke would have been drifting to those on the bridge nearest to the park and over the river, while on July 15th, those on Notre-Dame Street would have received the smoke. For the other four fireworks days, the smoke would have more favorably been moving clear to the right of the La Ronde audience (clear to the left for those on Notre-Dame/de Lorimier streets) and, thus, not impacting viewing for any major vantage point. There was definitely quite a mixture of situations this year! Trav.