Expanding on the general overview presented in the previous posting, with some (important) revisions, here are the conditions expected for today (July 11th) for the greater Montreal area.

Temperature/Humidity

Narrowly outside of the greatest warmth in the warm sector of this low pressure system (i.e. the remnants of Hurricane Beryl), a more reserved maximum temperature of 22-23 C is favorable. This is due to more persistent low-cloud coverage limiting solar heating as a result of a slight NE shift in this system’s path, which is an important revision with respect to the previous post. Borderline high to very high humidity would correspondingly induce a maximum Humidex of 29 C. Another important revision would be that the humidity would decrease into high standards (as opposed to staying very high as suggested above) for the evening. Considering this and persistent cloud cover limiting cooling, a display temperature of 21-22 C is likely, with a Humidex of 28 C.

Precipitation

Lift within the warm sector of the remnants of Hurricane Beryl will be mostly important during the morning to early-afternoon period. At that time, scattered convective rainfall (40% probability for rainfall) would develop North of the system’s warm front. However, since the trajectory would follow slightly more of a NE pattern, breaks in the low-cloud deck would be much more limited, as mentioned in the previous section. The lack of solar heating would, thus, keep the thunderstorm risk minimal. Beyond the early-afternoon, skies remain mostly cloudy (low stratiform cloud deck) through to the end of the evening. Convective rainfall would also become sparse for the afternoon, and with even more restricted coverage into the evening (20-30% probability for rainfall).

Wind

The most important update would be to wind speed and direction. Contingent with faster movement of the remnants of Hurricane Beryl, a wind direction in the form of a light NNW tendency (7-9 km/h) would be favored at all altitudes during the mid- to late-evening (following NE to NNE patterns during the morning to afternoon). This would allow the accumulating smoke, at all altitudes, to drift slowly to the left of the La Ronde and towards those on adjacent sections of the bridge. Though the humidity would be somewhat lower from what was described in the post above, it would remain under high standards for the evening, allowing for periods of large smoke accumulation. This would be notably the case along low- to mid-altitudes of the display at La Ronde’s left, and deeper in the show. That said, the wind direction (and marginally-decent speeds) would help La Ronde viewers, and this would be the first time this year where the on-site audience avoids smoke interception. *For those on the bridge closest to the park, however, please try to avoid those sections.

*If necessary, another update would follow by this mid- to late-afternoon (July 11th) for wind speed and/or direction.

Trav.

As a continued well warmer than normal pattern overspreads this region, very warm to hot and highly humid conditions would persevere for the Mexican display day (July 14th). This would include a maximum temperature of 29-30 C for the greater Montreal area. Borderline high to very high humidity would further send the Humidex to a maximum of 36 C. For the evening, limited cooling in light of high to very high humidity would result in a display time temperature of 26-27 C, along with a Humidex of 34 C.

Despite sufficient atmospheric instability in the area, lift would be fairly limited. As such, convective rainfall would remain quite sparse (20% probability of rainfall) during the afternoon, with the sky being occupied with patches of high-altitude cirrus and some defined cumulus clusters. Beyond sunset, the cumulus clusters reduce in number and definition, leaving behind mostly clear skies with patches of cirrus. However, this would be followed by an increase in cloud coverage by late-evening due to a shortwave trough advancing East and causing some light rainfall overnight/predawn.

Winds are mostly in the form of SSW but occasionally SW and breezier during the mid-afternoon. Speeds during the late-evening would be 12-15 km/h. As such, the smoke would be displacing at a reasonable pace, and clear to the right of the La Ronde audience (clear to the left for those on Notre-Dame Street). Smoke at the highest altitudes would be guided a little more closely to the right of the La Ronde audience. Although the smoke would be accumulating fairly quickly deeper into the display along principally low- to mid-altitudes, these accumulations would often be clearing sufficiently quickly, and the correct wind direction makes viewing suitable for all spectators.

Another update will appear here during early-predawn tomorrow (July 14th).

Edit: A massive 79.2 mm of rainfall were registered at YUL on July 10th. 59.2 mm at the McTavish station farther East, in downtown, where flooding was more prominent.

Trav.

Weather conditions described in the above posting remain applicable. As such, described below are the dominant conditions expected for July 14th for the greater Montreal area.

Temperature/Humidity

A maximum temperature of 30-31 C is likely, along with a maximum Humidex of 37 C due to continued high to very high humidity. Very humidity would be in place into the evening period, prompting limited nocturnal cooling. A display-time temperature of 26-27 C is, therefore, favored, along with a corresponding Humidex of 34 C.

Precipitation

While instability exists, minimal lift in the area would be able to take advantage of it. As such, mostly clear skies, consisting of patches of high-altitude cirrus and clusters of semi-defined cumulus would be present. Beyond sunset, skies would be mostly clear consisting of residual cirrus patches. The previously-mentioned increased (cirrus) cloud coverage for late-evening would also begin to overspread the area as a cold front and attendant shortwave trough become in closer proximity to the region.

Wind

Wind direction would follow a SW tendency for the day and would gradually adopt a SSW pattern beyond sunset. Wind Speeds for the day would be 19-23 km/h, decreasing to 12-15 km/h post-sunset. This SSW wind flow would ideally direct the smoke clear to the right of the La Ronde audience (for those on Notre-Dame Street, clear to their left). Smoke at the highest altitudes of the display would be moving more closely to the right of the La Ronde audience (overhead), as mentioned in the previous posting. It should be noted that rapidly-building smoke accumulations at mostly low- to mid-altitudes would unfold at the far right-hand side of the display (La Ronde’s right) during more active sections (and during times of particularly smoke-rich products). However, these accumulations would often be clearing sufficiently quickly, and the favorable wind direction would make for excellent viewing conditions for all spectators located at all principal vantage points (the first time this year).

If necessary, another update will be provided here by mid- to late-afternoon today (July 14th).

Trav.

Weather conditions for July 20th would be guided by a strong SW flow while a sharp cold front drifts quickly to the SSE later in the day. Such conditions would favor a maximum temperature of 28 C, along with a Humidex of 32 C. By display time, a temperature of 20-21 C would be favored at saturation, prompting a Humidex of 27 C. A healthy SW to WSW wind field would allow sustained speeds of 29-33 km/h (gusts occasionally reaching 47-51 km/h).

Ascent ahead of the cold front itself would be sufficient for fairly ubiquitous rainfall after sunset (70% probability of rainfall), along with an isolated non-severe thunderstorm risk embedded within this rainfall (30% probability) due to some instability accumulated from early-day solar heating and a brief transition to high humidity. If this cold front stalls long enough to the North, however, this would correspondingly delay the onset of rainfall/saturated air during the evening, and so it needs to be monitored. Within the pre-frontal environment would be mostly sunny conditions, featuring also patches of cirrus and fair-weather cumulus. By mid-afternoon, a more significant increase in this cloud coverage would appear, including with more defined cumulus with gradually lower cloud bases. This would leave the evening cloudy.

Meanwhile, as the aforementioned cold front advances farther South, winds quickly shift into a NW tendency by just prior to sunset and going forward. That said, speeds do diminish substantially, to 11-14 km/h while adopting a WNW flow during late-evening. As such, at all altitudes, smoke accumulations would be advancing at a reasonable pace towards left-hand and adjacent central sections of the La Ronde audience (more swift displacement at the highest levels of the display). However, the damper, saturated air at high humidity induced by the light to moderate rainfall during the evening would favor periods of rapidly-developing smoke accumulation deeper into the display along low- to mid-levels. This is also notably true when smoke-rich materials are used at those levels of the display and would further cause the display to more often appear hazy if viewing from La Ronde.

Another update to follow by late this evening (July 19th) into early-predawn (July 20th).

Trav.

Conditions mentioned in the above posting continue to be mostly applicable for the situation today (July 20th). Here are, then, the overall patterns most favorable for the day for the greater Montreal area.

Temperature/Humidity

A strong SW/WSW flow would sustain a very warm and moderately humid air for much of the day. As such, a maximum temperature of 27-28 C is favored, along with a Humidex of 32 C. Over the course of the evening, the temperature does decrease quickly in response to the evaporative cooling induced by the scattered convective rainfall advancing into the area (see next section) and sending humidity levels into high standards. As such, a display-time temperature of 21 C is likely, with a corresponding Humidex of 27 C.

Precipitation

As mentioned in the previous posting, a sharp cold front will advance South and SSE later today, affecting this region in time for the evening, and going forward into early-predawn (July 21st). Lift ahead of this feature, though now weaker, would be sufficient to support scattered and light convective rainfall (60% probability of rainfall later in the evening, and 40% during the early-evening), and with a few isolated non-severe thunderstorms accompanying these (30% probability for thunderstorms specifically). There would, nevertheless, still be some opportunity for the display to narrowly miss the more moderate rainfall during late-evening. Prior to the cold front affecting the region, most of the day would be rather dry and pleasant, despite gusty SW/WSW wind fields. Patches of cirrus and fair-weather cumulus would overspread the region for the late-morning to mid-afternoon period, followed by an increase in cloud coverage thereafter (and lowering cloud bases/ceilings for the evening). As such, the evening would remain cloudy under largely low-based and defined cumulus.

Wind

Winds would be in the form of a (very) gusty SW/WSW flow (29-33 km/h) by late-morning, with occasional gusts reaching a maximum of 51-54 km/h during the early- to mid-afternoon. Speeds decrease considerably (9-12 km/h) during frontal passage over the course of the evening, and begin adopting a WNW pattern. Therefore, at all altitudes of the display, accumulating smoke would be advancing at a reasonable pace towards left-hand and partially adjacent central sections of the La Ronde audience, causing the display to often appear hazy at notably La Ronde’s left. During times of smoke-rich material at notably low- to mid-altitude, combined with damp and nearly saturated air, smoke accumulation could be most extensive in the depths of the display, and when active moments appear.

Other updates, as necessary, will appear here during the afternoon today (July 20th) to address wind direction and rainfall consistency.

Trav.

To follow up on the previous two postings, conditions very largely remain constant. To that end, the environment is suitable for scattered convective rainfall and isolated non-severe thunderstorms this late-afternoon to evening under the same probabilities (except 80% for late-afternoon to early-evening). There would further be some potential for moderate to even locally heavy rainfall briefly earlier in the evening (especially with the continued risk for thunderstorms in the area) due to faster Southward movement exhibited by the cold front. The more moderate to heavy rainfall would also be accompanied by briefly strong downbursts of wind locally. Faster frontal movement does also improve the chance that display time would be mostly dry, as suggested above (with some on-off light rain/drizzle at the time). However, the environment would be damp and nearly saturated from the potential late-afternoon to mid-evening rainfall, as described in more detail in the last two posts.

Trav.

As a second (late) update, winds should be more at lighter speeds (4-7 km/h), further causing periods of potentially extensive smoke accumulation at more centralized sections of the on-site audience at times.

Trav.

As a broad area of high pressure further ejects East/SE into this region, largely fair conditions would persevere into the day Saturday (July 27th). As such, for the greater Montreal area, dry conditions are expected, with limited lift supporting mostly patches of fair-weather cumulus and clusters of overhead cirrus. Limited lift for the evening period would continue to support patches of cirrus under what would be a mostly clear sky. A maximum temperature of 28-29 C is further favored under borderline moderate-high humidity, prompting a Humidex of 33 C during mid-afternoon. By display-time, 26 C would be likely, with a corresponding Humidex of 30 C.

A mostly light SW to WSW flow would be favored for the day under this atmospheric configuration, though with a more SW tendency during and around display time (8-11 km/h). However, there exists some chance for a WSW pattern to be withheld for the late evening, so this would have to be monitored. A somewhat breezier flow (13-17 km/h) would be present during the afternoon period before re-adopting lighter speeds for the evening. As such, accumulating smoke (sometimes large due to reasonably high evening humidity) would be moving gently towards right-hand sections of the La Ronde audience (La Ronde’s right), causing the display to appear hazy at mostly La Ronde’s right deeper in the show at principally low- to mid-altitudes, and outside laser sections. Higher-altitude smoke would also be moving overhead more swiftly in the same direction, but also partially towards adjacent central sections of the on-site audience.

Another update will follow by this coming late-evening (July 26th) to pre-dawn (July 27th).

Trav.

Conditions presented in the above post remain applicable. As such, the following would be expected for the greater Montreal area today (July 27th).

Temperature/Humidity

A maximum temperature of 28-29 C is likely, with a Humidex of 33 C guided by borderline moderate-high humidity by mid-afternoon. For display-time, 26 C remains favorable, along with a Humidex of 30 C under borderline moderate-high humidity.

Precipitation

No rainfall is expected. This would be due to suppressed convection under the aforementioned high pressure zone, promoting fair and sunny conditions. The Limited lift would encourage mostly patches of fair-weather cumulus and clusters of overhead cirrus during the afternoon, followed by residual isolated cirrus for the evening.

Wind

Winds remain under mostly a light SW to WSW tendency for the day (8-11 km/h, except occasionally 13-17 km/h for the afternoon). During the evening, including display time, wind speeds of 8-11 km/h are likely under a SW to gradually SSW directional tendency. As such, accumulating smoke would be often moving sufficiently towards far right-hand sections of the La Ronde audience. Smoke at the highest altitudes would be displacing more quickly overhead towards right-hand sections of the on-site audience more directly. At times, right-hand portions of the display (i.e. La Ronde’s right) would appear hazy at low- to mid-altitudes outside of laser segments and deeper in the show. However, particularly extensive smoke accumulation would not be favored due to somewhat more limited humidity.

*If necessary, another update will appear here by mid- to late-afternoon to address wind speed/direction.

Trav.

The closing display (August 1st) will be affected by the continuation of a very warm to hot and highly humid pattern. For the greater Montreal area, a maximum of 30-31 C is favorable, along with a corresponding maximum Humidex of 38-39 C. By display time, the air cools very little, sustaining a potentially impressive 27-28 C (Humidex of 35 C) to create the warmest fireworks evening/day this year.

While the air would further be moderately unstable during the day, very poor use would be made of it in light of limited lift. This is especially true following the morning. As such, the meager ascent would support mostly patches of cirrus and clusters of defined cumulus in the area, including the evening to create partly cloudy conditions with large clear breaks.

Wind direction may be more of an important element during this display for the on-site audience, especially considering the very high humidity characteristic of the day. Most of the day would, as such, favor WNW to WSW (and straight Westerlies at times) during the day and extending into the evening. As such, rapidly accumulating smoke would be largely advancing towards the La Ronde audience mostly directly at all altitudes, with thicker smoke accumulation outside of the laser segments. Deeper into the show at mostly low- to mid-altitudes would be where smoke accumulation is most prevalent to often create a hazy appearance. Wind speeds would be light in the evening (8-11 km/h) but at least marginally-sufficient to allow the smoke to displace, rather than remaining almost stationary. Breezier/gustier tendencies would be more favorable during the afternoon (occasional gusts of 28-32 km/h). Note that there is also some chance for a shift towards SW by evening, which would be much more beneficial, and so this will have to be monitored.

*Another update will follow during this late-evening (July 31st) to predawn tomorrow (August 1st), with a focus on wind direction.

Trav.

Weather conditions specified in the above post for this final display day of 2024 largely remain valid. As such, here is the expected pattern for today (August 1st) for the greater Montreal area:

Temperature/Humidity

The continued very warm to hot and highly humid air mass will affect this closing display. Therefore, a maximum of 31 C is favorable, along with a corresponding maximum Humidex of 40 C. By display time, very limited cooling would occur, sustaining a potentially impressive 29-30 C (Humidex of 38 C), easily making this warmest/hottest fireworks evening/day this year.

Precipitation

As mentioned previously, a moderately unstable environment would persist during the day. However, since lift remains meager, limited use would be of this available energy for convective rainfall. That being said, the intense solar heating by itself would be sufficient for very sparsely-distributed mid- to late-afternoon convective rainfall when convective temperatures are reached (20% probability for rainfall). This would further be sufficient to support patches of cirrus and clusters of defined cumulus in the area, including through to the early-evening to create partly cloudy conditions with large clear breaks. By and a little before display time, this decreases more to leave behind mostly clear skies.

Wind

Most of the day would be guided by a WNW to eventually WSW (and straight Westerlies at times) during the day to evening. By late-evening, including display time, directional tendencies hold a light WSW flow (8-11 km/h). In light of this, rapidly accumulating smoke would be displacing fairly slowly towards central and notably right-hand sections of the La Ronde audience at low- to mid-altitudes. Higher-altitude smoke would be moving a little faster but more directly towards the on-site audience overhead. Thicker smoke accumulation would sometimes develop deeper in the display and outside of the laser segments due to the very high humidity, creating often a hazy appearance at low-/mid-altitudes from La Ronde’s vantage point (principally if the display is often active, and if extensive smoke-rich products are present). Breezier/gustier wind speeds remain favorable during the afternoon, with occasional gusts of 28-32 km/h.

*If necessary, another update will appear here during this mid- to late-afternoon (August 1st) to address wind direction.

Trav.

Expanding on the precipitation section in the above posting(s), there exists a very subtle convergent boundary centered in and closely around the island of Montreal this mid- to late-afternoon (August 1st). This feature could support the sparsely-distributed convective rainfall mentioned previously (and a briefly-sustained isolated non-severe thunderstorm with this locally enhanced ascent) more favorably in this area, as compared with the rest of the broader Montreal region.

Wind speed and direction remain the same for today.

Trav.

Travis, I like to acknowledge you once again for your regular, precise, and reliable weather forecasts. That contribution in this forum is definitely a must for all those who attend the displays and are looking for more specific weather forecasts than those provided by other sources.

Fred

Hi Fred,

You're more than welcome, and it was a pleasure to again make sense of weather conditions for each fireworks day/evening this year. I am also glad that the synopses presented have been useful!

Trav.