Since it is now the glorious month of June, I thought that it would be appropriate to post this thread.

As always, I will provide forecasts just before or on each fireworks display date, with preliminaries given about two days prior to each show. Forecasts will include information based on temperature, humidity, cloud coverage, wind speed/direction, and the risk for precipitation, if necessary. If or when precipitation development becomes favorable, especially in the case of deep convection (i.e. thunderstorms), more updates will be provided. You are also more than welcome and encouraged to share updates, so please feel free to do so!

I continue to be active on Facebook in posting analyses when severe/extreme weather becomes possible. My profile is located here:

https://www.facebook.com/travis.moore.5074?ref=tn_tnmn

For those interested, my personal Spring-Summer 2014 outlook can be found using the following link, along with a review of this past late-Fall and Winter (this outlook was originally posted on March 16th, 2014):

https://www.facebook.com/notes/travis-moore/winter-2013-2014-and-a-loo k-ahead-to-spring-summer-2014/10152272641796346

To be brief, like 2013, I am anticipating a generally humid and stormy late-Spring to Summer period for 2014 across Ontario and Quebec, with an increase in thunderstorm/severe thunderstorm days (we have already seen numerous thunderstorm days so far this year in Eastern Ontario to Southern Quebec, with the first occurrence on April 13th). I do not believe that this will be a “spectacularly” hot late-Spring and Summer, so we should generally observe fewer days reaching 30 C or more, relative to 2010, 2011, and 2012, and about similar to 2013. Thus, a temperature distribution somewhat similar to 2013's. Rainfall should be above normal, especially where thunderstorms/convective rains are most dominant. Finally, as I suspected since January, El Nino (potentially at moderate strength) has continued to show stronger indications of emerging later this Summer into the early-Fall. This would imply an improved likelihood of seeing a warmer late-Fall and Winter 2014-2015, as well as fewer Atlantic storms this Summer and Fall, should an El Nino successfully occur (more updates on that as the Summer progresses).

I am hoping for the 30th edition of Montreal fireworks to be free of unsettled/unstable weather!

Trav.

Trav, I am looking forward to read your detailed forecast during the season. At this stage, it seems that we may have very good weather conditions next Saturday. That would be a welcome difference with last year rainy opening night!

Fred

Indeed, Fred, weather conditions are expected to be very inviting over the next several days and are quite the contrast from those that set the stage for 2013's opening. Past and recent short- and long-term model projections continue to favor a typical enduring Summer-like pattern emerging in time for this weekend (June 27th-28th, 2014), and stretching as far as July 2nd, with possible severe weather developing on both July 1st (Canada Day) and July 2nd. A strong Bermuda High will eventually migrate over the Atlantic, and with the aid of a series of low pressure systems far to the SW and West, very warm/hot and moist air will likely circulate from the Gulf of Mexico into much of central and E. North America within this warming period. Technical heat wave status is also possible for many areas. Note that the UV index will also be high during most of this period, so be sure to adequately protect exposed skin if heading out for prolonged periods during the day.

With this atmospheric configuration, for our first display of the 30th edition of the Montreal Fireworks Competition on June 28th, we can expect very warm and moist air to be in place. Maximum temperatures are currently estimated to be as high as 29-30 C across much of extreme S./SW Quebec, along with high humidity that will make it feel closer to 35-37C. Late-evening temperatures should be closer to 23-24 C (25-26 C in the metropolitan area, and feeling like 32-33C). Precipitation chances should be minimal near and beyond sunset for this weekend, but a few extremely sparse convective/air mass showers in the region may occur due to some mild instability. Winds are generally expected to be light throughout the day, with speeds of 9-13 km/h. However, something to still monitor is the generally lighter projected wind speeds in time for the evening, which are currently shown to be 6-8 km/h. Because of the high humidity, this could lead to periods of smoke build up when the display becomes more active, especially at low- to mid-levels. Some disagreement as to overall wind direction, but it is generally shown to be SW, and so the smoke should be moving gently to the right of the audience at La Ronde (left for those on De Lorimier/Notre-Dame) but could also sometimes affect spectators on the far right of the grandstands.

Another update will be provided by tomorrow, or early-Saturday for wind speeds and direction.
----------------------------------------
Paul, I will also soon provide a finalized forecast for your display on Sunday (the 29th), although there does not appear to be much in terms of changes to the original forecast. Winds are just expected to be light at about 5-8 km/h during the evening (similar to Saturday evening in Montreal) and continuing to transition to SSW status by that time.

Trav.

Conditions specified in the above post remain generally constant, and there is now more of a consensus with wind patterns for tomorrow evening. As such, here are the weather conditions for Saturday, June 28th for the Montreal area.

Temperature/Humidity

Maximum temperatures are still forecasted to be at about 29-30 C by the mid-afternoon hours, with late-evening temperatures of generally 22-23 C (25-26 C in the metropolitan area). Newest projections generally favor the highest humidity levels arriving into June 29th and onwards, but humidity for today should be more moderate, with a slight boost to borderline moderate-high levels into the evening hours, making it feel like 30-31 C in the metropolitan area (33-34 C during the afternoon).

Precipitation

The risk for precipitation will be minimal this weekend due to the ongoing influence of the upper-level ridge in place. That said, there could be some very localized brief afternoon air mass showers associated with some weak instability, but the air will generally maintain stability. Skies will remain with a mix of sun and high-level cirrus clouds, with isolated clusters of cumulus clouds developing during the afternoon hours. Sky conditions should stay mostly clear this evening, with some high-level clouds lingering.

Wind

Winds continue to be light throughout the day at 9-13 km/h, and generally from the SW. Winds are expected to weaken to very light standards (6-8 km/h) by the evening, along with directional tendencies more from the SSW to eventually South by late-evening. As such, winds should be generally blowing the smoke gently clear to the right of the audience at La Ronde (left for those on Notre-Dame/De Lorimier). However, periods of smoke build up are favorable at low- to mid-levels whenever the display becomes more active because of the combination of very light winds and somewhat high humidity.

In summary, a typical Summer evening is forecasted, with temperatures in the mid-20s C (generally in the metropolitan area), and humidex values into the very low 30s C. Skies should be mostly clear (some remaining high-level clouds), and winds should be very light, and generally from the SSW to South by the late-evening hours.

*Other than that, still something to watch, but we are carefully monitoring the situation on July 1st across S. Ontario to S. Quebec (as highlighted briefly in the above posting), as a severe weather outbreak is possible ahead of a passing cold front later in the day.
-----------------------------------------------------------
Paul, weather conditions continue to look good for your display late Sunday evening (June 29th). Temperatures remain very warm/hot during the afternoon, with highs of 29-30 C, along with high humidity, generating a humidex of 36-38 C. Weak instability will likely lead to scattered cumulus cloud clusters, along with possible sparse convective showers/air mass thunderstorms during the afternoon. Late-evening temperatures should be closer to 22-23 C with continued high humidity (humidex of 29-30 C). Winds continue to be very light from the SSW by late-evening at 6-8 km/h. Skies will remain mostly clear for the evening hours.

Trav.

Weather conditions for Saturday, July 5th are characterized by a gradually advancing broad area of surface high pressure migrating from the West and passing closely to the South relative to S. Quebec. This system, with the aid of the upper-level longwave trough in the jet stream, will assist in steering the later Tropical Storm Arthur farther East/NE towards the Maritimes as it travels North. The combination of these systems will likely produce mostly clear skies, a few isolated fair weather cumulus clouds, and warm temperature distributions into the mid-20s C (24-25 C), along with late-evening temperatures of 21-22 C across extreme S. Quebec. Humidity levels should generally be low to borderline low-moderate, and precipitation development will likely be kept at a minimum.

All that said, wind speed and direction need to be carefully monitored. Because of the potential increasing pressure gradient forming between the area of high pressure and Tropical Storm Arthur, wind speeds may become gusty into Saturday through to Sunday (July 6th). Present and recent simulations suggest sustained wind speeds and top gusts of 24-31 km/h and 44-48 km/h, respectively, during the afternoon hours, which may then continue into the evening time frame throughout extreme S. Quebec. General directional tendencies are Westerly during the day but then transition to more WSW by the late-afternoon and remaining in that manner thereafter. This would imply that smoke should be blowing very quickly towards the audience at La Ronde, though largely towards right-hand/central sections of the grandstands. In any case, some of the models are comparatively less robust in terms of the interaction occurring between both the high pressure system and Tropical Storm Arthur, which would signify somewhat less significant winds, so we will continue to monitor the situation, and so an update will be provided, either later today, or early July 5th.

Trav.

Weather conditions described in the above posting remain constant across extreme S. Quebec, and there is now more agreement as to overall wind velocity (see wind section below). As such, here are the weather conditions for the Montreal area for Saturday, July 5th:

Temperature/Humidity

Temperatures are expected to reach a maximum of 25 C to locally 26 C, with mostly low humidity levels. By the late-evening hours, values should be closer to 21 C (including the metropolitan area), along with continued low humidity, making humidex readings negligible. Gusty winds could also produce a slight chill in the air.

Precipitation

No precipitation development is expected, courtesy of the aforementioned area of high pressure migrating from the West. Skies should remain mostly clear, with a few isolated clusters of fair weather cumulus/high-level cirrus developing during the afternoon hours.

Wind

As per my posting above, wind speeds and direction continue to remain a concern. Models generally agree as to the strengthening interaction between the advancing area of high pressure and Tropical Storm Arthur. Consequently, wind speeds will very likely become quite gusty during the day. Sustained wind speeds and top gusts during the afternoon are expected to be 31-34 km/h and 48-52 km/h, respectively. By the evening, sustained wind speeds are shown to diminish slightly to 23-27 km/h, but with continued occasional top gusts as high as 44-48 km/h. This situation may cause delays (potentially significant should gusts persistently reach or exceed 40 km/h). Furthermore, wind direction is favored to be Westerly (except NW to WNW during the morning to early-afternoon) to occasional periods of WSW. As such, winds (and smoke) are expected to be blowing towards the audience at La Ronde directly. Winds become even gustier into Sunday, July 6th, from the SW.

In summary, a warm evening is forecasted, with temperatures in the very low 20s C, low humidity, largely clear skies, but with gusty conditions.

***Should any (significant) changes in wind speed and/or direction become apparent, I will post an update by early this afternoon (July 5th).

Trav.

Thank you, Trav, for this important update. It seems that velocity and wind direction may be a major issue tonight. I cross my fingers that Pirotecnica Morsani will be allowed to present its show as scheduled. We stay tuned!

No problem, Fred.

There is no change in the forecast information stated above concerning wind speed and direction and so still remains effective. Hopefully, during show time, we will have suitable enough wind speeds to fire the show safely, but conditions generally continue to be gusty into this evening and into tomorrow (July 6th).

Trav.

How likely are the ""occasional top gusts" > 30 km/h? Should it be nothing more than one gust somewhere in the area, during the evening, or may it be more frequent and spread throughout the area?

Hi Fred,

Gusts above 30 km/h this evening across the island (and throughout extreme S. Quebec) are likely and may be frequent. Gusts around 44-48 km/h are also favorable, and winds are generally sustained between 24-27 km/h. As always, it is difficult to say precisely where and when we will observe the highest gusts, but gusty Westerly (sometimes WSW) winds continue to be favored across the region throughout this evening.

Trav.

Thanks. Definitely not a good time to wear white clothes in the grandstands tonight! Whether we are lucky, the show will be fired at 10pm, as scheduled. And we may experience as much smoke and dust than during the Macedo's Pirotecnnia show in 2010!

Fred

Some local weak convection has also recently developed near the Montreal area and is generally driven by solar heating. This could produce some brief passing isolated showers this afternoon. Convection should diminish near dusk and onwards.

Trav.

A vigorous, broad area of low pressure advancing from the West is expected to influence S. Ontario to S. Quebec this weekend (July 11th-13th), and into the early part of the work week next week. This will promote a return to more July-like weather this weekend but will also enhance the risk for severe thunderstorms into Monday (July 14th), and possibly Tuesday (July 15th), just before a sharp cooling into Wednesday (July 16th) in time for Canada’s display. The anticipated cooling is associated with a large and unusually steep upper-longwave trough and accompanying surface high that will likely eventually eject quickly to the SE from the Arctic. For the Canadian display, sweaters may be required. By contrast, the cooler weather may be followed by a possible heat wave emerging by around July 20th, as suggested by some long-range models, but that will have to be monitored over the coming week.

As the system approaches, humidity levels are expected to gradually increase through the day Saturday (July 12th), along with a shift to SW to SSW and Southerly winds as the day progresses. Consequently, maximum temperatures should return to the very high 20s C (locally 30 C). The associated warm front will gradually increase cloud coverage (mid- to high-level clouds) later in the day Saturday, but the day itself should be mostly sunny. Rainfall associated with the warm front should occur until after midnight. Latest sounding data suggests maximum temperatures of 29-30 C for the island of Montreal, and by the evening hours, temperatures could remain as high as 25-26 C, especially in the metropolitan area. Humidity levels should also increase to high standards by the evening hours, making it feel like 29-30 C. Humidity should be moderate earlier in the day. There is still some disagreement as to when the shift to SSW to Southerly winds will occur, but there is a consensus for the evening hours. Speeds should also be fairly light at 9-12 km/h. As such, at this point, winds should be blowing the smoke clear to the right of the audience at La Ronde (left for those viewing on Notre-Dame). The UV is also expected to be high to very high, so be sure to protect exposed skin if heading out for prolonged periods.

Another update will follow by either the end of tomorrow (July 11th) or early-day Saturday (July 12th).

Trav.

Overall weather conditions specified in the above post are still generally constant across extreme S. Quebec, including the Montreal area. There are some minor modifications to the forecast, though, that needed to be made, which are provided below. As such, here are the dominant conditions for the Montreal area for Saturday, July 12th.

Temperature/Humidity

Temperatures are expected to reach as much as 29 C to locally 30 C by the mid-afternoon hours, along with moderate humidity, making it feel slightly warmer at 32-33 C. By the late-evening, temperatures should drop to about 25-26 C in the metropolitan area, but humidity levels are expected to rise to high standards for the evening, which could make it feel closer to 31-32 C. Again, because of the high/very high UV, be sure to adequately protect exposed skin if planning to remain out for prolonged periods during the day.

Precipitation

Precipitation is not generally expected. However, due to some mild instability projected in extreme S. Quebec, some very isolated convective showers may develop during the mid-afternoon in response to solar heating. Other than that, an increase in mid-level cloud coverage (and some isolated low-level cumulus clusters) should take place by the afternoon and onwards into the evening, largely due to the approaching warm front. Skies should remain mostly sunny. In terms of the aforementioned severe weather potential, I will keep the greatest risk for Sunday afternoon (July 13th), although thunderstorms should remain relatively sparse in coverage because of projected extensive cloud coverage restricting more widespread large instability.

Wind

There is now better agreement that winds should be largely out from the SSW during the evening hours (more SW for the afternoon). Wind speeds will likely become lighter in time for the evening, with speeds of 9-12 km/h and occasional slight gusts of 17-20 km/h. Wind speeds are generally breezier during the afternoon at 13-17 km/h, with occasional gusts of 23-26 km/h. As such, smoke from the fireworks should be blowing at a reasonable pace mostly clear to the right of the audience at La Ronde (left for those on Notre-Dame).

In summary, a very warm evening for the Spanish display, with temperatures in the mid-20s C, high humidity, partly cloudy skies, and light winds from the SSW.

Trav.

A secondary area of low pressure and upper-level longwave trough are expected to continue influencing much of the province of Quebec into the day on Wednesday (July 16th). The low’s associated cold front will likely bring periods of rain and embedded thunderstorms to S. Quebec today (July 15th) and into the pre-dawn hours of the 16th. As the upper trough advances, afternoon isolated showers will still be possible into the 16th, although instability should weaken across the region near dusk and onwards. Temperatures, as mentioned previously, are forecasted to be cooler for the day Wednesday, with maximum values of 23-24 C, but by late-evening, values are projected to drop to 19-20 C in the metropolitan area of Montreal (17-18 C outside the city, especially after midnight). Humidity should be borderline low-moderate, so the humidex is negligible.

Winds need to be closely monitored in the coming model runs, more so with respect to wind speed on the 16th. Because of a developing sharp temperature gradient, winds are expected to become gusty throughout the day, although there is agreement as to some weakening by the evening hours. Afternoon sustained wind speeds are shown to be 23-26 km/h across much of extreme S./SW Quebec, with gusts of 37-41 km/h. By the evening, speeds are predicted to subside somewhat to 16-19 km/h, but with continued gusts as high as 33-36 km/h. Winds should maintain SW tendencies throughout the day, and so the smoke from the fireworks should be blowing quickly towards right-hand sections of the La Ronde audience during the Canadian display. Also note that continued breezy winds following dusk will likely provide that extra chill in the air, so, depending on your tolerance level, a light sweater may be needed.

Another update to follow, either later today (July 15th), or early-Wednesday (July 16th).

Trav.