If any of you happen to live in the greater Montreal area or even in Laval, chances are that you have encountered some very wild weather on Canada Day around dinner time. Flash flooding rains, marble sized hail, gusty winds and frequent loud crackles of thunder were the story from a severe thunderstorm that rolled through many parts of these areas. This gentleman posted a video on YouTube of what the storm was like in his vicinity:

http://www.youtube.com/watch?v=979FGW7nTVw

Though I was not so much expecting severe weather to erupt, in general, on Canada Day, I didn't rule out the possibility of it occurring altogether. I was actually tracking many of the cells displaying high reflectivity on radar coming in from New York, including the one that affected Montreal. It wasn't long after that Environment Canada issued the watch, and eventually a public warning.

Thunderstorms have died down now due to, as mentioned, the loss of daytime heating, though they will fire up again today in the same scattered fashion and pushing up from the South- Southeast. Some of these storms can, again, reach severe standards, especially if the sun is able to remain out for prolonged periods, much like earlier yesterday. All of this unsettled/active weather is, once more, due to a persistent upper level disturbance. This brings me into Saturday's weather.

At this point in time, I think this disturbance will still be plaguing extreme Eastern Ontario, Quebec and the Maritimes for a fair portion of this weekend before finally clearing. Being on the back end of the low at that point, cooler air will flood into much of Eastern Canada (highs barely reaching the low 20s), and unsettled conditions may remain for much of Saturday, although t-showers/t-storms should come to an end. Winds could be another problem, though not in the same context as last Saturday. Rather, the directional tendency is likely Westerly to Northwesterly, which could be affecting folks on the bridge just behind and adjacent to La Ronde as well as possibly those in the park itself - I'll keep an eye on that. Winds look to be light in nature, but should have much higher speeds than what was seen the last time. Temperatures are likely cool, so I think you'll need your jackets. All that said, I hope the showers and thunderstorms aren't interferring with Foti's setup too much.

I'll have a final update later on tomorrow (Friday) or early Saturday. I leave you with a video I took of a full rainbow arc seen in the distance when the sun came out from behind and projected its light towards the storm cloud at the Southeast (the one that dumped all that rainfall and hail). If you look carefully, you'll also see the much fainter secondary bow, who's color order is the reverse of that of the primary.

http://www.youtube.com/watch?v=XtF0xKldne4&feature=channel_page

Edit: I also caught this photo when the storm was in development:

http://i18.photobucket.com/albums/b132/Rain12/CIMG1544.jpg

These are called "Mammatus" clouds and sometimes form beneath the anvil of a thunderstorm. Though they are amongst the most beautiful, striking and captivating cloud formations for photographers and weather watchers alike, they commonly warn of a vigorous storm, so take precaution if you ever encounter them.

Rachel, sorry for the technicalities - just have a habit of being as specific as possible, I suppose. I'll try to condense/simplify things, however, for future reports, but at least you have some idea for wind direction this coming Saturday. I'd still like to keep an eye on overall patterns, though.

Trav.

Hi guys,

Everything that was mentioned in my post above regarding Saturday's weather (the 4th of July) still holds true, though I'd like to add a couple of things as I make my summary.

Firstly, though still unsettled, I think most of the rains should conclude by late tonight into the morning hours tomorrow, leaving us with cloudy to partly cloudy skies for ending Saturday into the evening-overnight. The chance for lingering showers still exists, but precipitation development should taper off by later in the day altogether. If you recall what I mentioned above, as we will be clearly on the back end of the low for tomorrow, cooler air will invade much of Eastern Canada (it's already in the process of doing so), and so temperatures will be quite unseasonably cool for tomorrow (again, struggling to strike the 20 C mark), particularly into the evening-overnight period (hovering around 16-18 C), so you'll find yourselves needing to equip either a light sweater or light jacket (yes, in July, I know ). Humidity levels will also drop off gradually later on tomorrow.

Winds are more of something to keep an eye on. Because of the cooler air descending from the North, winds have been picking up recently and will continue into the afternoon tomorrow, reaching a peak of up about 35 km/h (gusting to 45 km/h) in parts of the island by around 2:00-3:00 p.m. As the afternoon progresses, winds should still stay at moderate speeds, but I'm expecting them to diminish by the evening down to light standards. Wind tendency is still a little difficult to predict during the evening, but right now I'm still detecting W to WSW. Winds overall are light, nevertheless, at that time, but unlike last Saturday, they should be at much higher speeds at anywhere between 9-16 km/h.

That's the way the weather should operate for the most part. In summary, we're looking at a cool, mostly cloudy/slowly clearing evening with fairly light winds (with some occasional breezes). It's going to be an overall dismal greyish kind of day, but at least providing pretty much ideal conditions for the fireworks.

*I'd like to keep an eye on wind direction still simply because it still may concern folks at La Ronde, so I'd like to see how things play out before I state anything. If things come into more of an agreement, I'll let you know in advance.

Trav.

Thanks, Trav. I met dark clouds and heavy rain this afternoon as I was on the Aut. 20 between Quebec and Montreal. We are very lucky because it looks that once again, tomorrow, we will avoid rain for the fireworks and the waiting time just before it. I look forward to wear just shorts and t-shirts, but the most important is to not have a rainy night. Some wind would be welcomed also, especially with the massive display I expect from Foti, with all these nautical shells.

It is nice to have our in-house meteorologist. Do you study in that field?

Fred

Hello everyone,

I have prepared a short analysis of the winds tonight in what we could possibly expect. The models are still reading wind tendency coming out from anywhere between the Northwest to West (not so much the occasional SSW any longer). The average direction, I believe, will be in the form of North-Northwesterlies (NNW), so smoke may be, at times, blowing towards folks at La Ronde (moreso towards the left end of the seating area) and even towards the bridge thanks to the occasional Northwest tilt. It sounds like the display will be rather active, so smoke could sometimes become more of a problem in that respect. Note that winds have been Westerly all day. Winds should, again, diminish to lower speeds from what they currently are this afternoon (9-16 km/h). Humidity levels have dropped off to moderate.

Though there is some clearing this evening, there's still the slight chance for some lingering rain showers during this time (nothing enduring, if any), much like what has been seen in parts of the island this afternoon with some brief isolated showers along with the partly cloudy conditions. There are still some bands of showers to the Northwest (clouds moving to the Southeast). Nevertheless, expect overall partly cloudy conditions this evening. Temperatures are quite cool and I think they will be closer to the 16 C mark than 18 C this evening.

For everything else, please refer to my post above.
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Hi Fred,

I was actually tracking the cells in Eastern and Southern Quebec yesterday, and I spotted the huge cluster of steady rains on Aut. 20 and the 40 between the two cities, so I'd imagine that you would encounter such an event there at the time.

Though the winds should be ideal in terms of speed, the direction may, at times, be inconvenient to some of those seated at La Ronde and the adjacent bridge, especially since this display is likely going to be so active at many points. For the most part, I think we should be ok in terms of rain, but there's still the slight risk for some isolated showers in the evening. If there are showers, however, I don't anticipate them to be enduring. Overall, though, partly cloudy conditions should dominate the evening skies.

Don't worry. You'll likely get the chance to get out your shorts and t-shirts this coming work week as temperatures gradually rise back up to more July-like.

And, indeed, I'm working to become a professional forecaster. I've been studying meteorology for many years now, and the fascination first triggered since I was about 3-4 years of age.

EDIT: Enjoy the show, guys, and KEEP WARM!

Trav.

Hi Trav,

Following Paul's exciting interview with Pyromagic crew, I think that we are due for a weather update. I hope that the display will not be impacted by poor weather conditions and that the Ferris Wheel will run in the evening, allowing me to take some pictures of this particular setup. However, I'm afraid: MétéoMédia projects showers and thunderstorms for Saturday, 80%, with about 20mm of precipitations. It doesn't look good.

Fred

MétéoMédia projects showers and thunderstorms for Saturday, 80%, with about 20mm of precipitations. It doesn't look good.

I noticed the same thing this morning Fred. If the weather is that bad I would not be opposed to postponing the display until Sunday where MétéoMédia is calling for nice weather and strong enough winds. I won't worry to much until Travis tells me to.

Tyler

MétéoMédia is notoriously pessimistic this summer- in fact, apart from Trav, all the mainstream forecasts have been way off base and the weather has been nowhere near as bad as they have predicted. Only Pascal Yiacouvakis on RDI/CBC Daybreak tells it like it is!

Paul.

p.s. as far as I understand, the only reason a display will be postponed is excessive wind, not rain - let's hope this isn't put to the test

For the past weeks, MeteoMedia was pretty accurate on the hour the rain would stop. They predict 20h for this coming saturday... but still let's keep our finger crossed all !

Mylene.

Mylene Salvas is right. It won't last all day. The latest is that the thunderstorm will end by early evening and so by 10pm, the sky will be partly cloudy, but this could change, of course! At the moment, it looks like it's some crazy thunderstorm that will passby during the day. Travis would know!

Why not postpone it until Sunday. Already the attendance at La Ronde has been very low due to the poor weather, like last year, and Saturdays haven't been so great! What a bad luck!

Hi everyone,

It would seem that we have some concerns here, but I can certainly understand the feeling with respect to the forecast you're all seeing. Let me make sense as to what we could be dealing with.

As a general overview, this is a vigorous surface low pressure system that has been affecting much of the Western portion of the country over the last 3 days, and is expected to move through parts of Eastern Canada in the same manner. The associated cold front will be responsible for the unsettled weather for Saturday (as I briefly mentioned before in Rachel's Australia thread) over Ontario and Quebec as it clashes with this warmer and mildly moist air mass. Once this front passes through, temperatures will drop off by about 5 C from what they will be tomorrow for daytime highs by Sunday and Monday through to Tuesday.

With the front's average speed and nature shown in the computer models, I'm predicting that isolated cells and lines of cell clusters along the front won't be (at this point in time) affecting Southern Quebec until about lunch time and thereafter, especially as daytime heating begins to reach its peak (assuming we get enough sun). Convective showers and thunderstorms are possible in the late afternoon to the evening period, and possibly won't completely clear out until the early overnight hours. This cold front also has a history of producing severe thunderstorms, so I wouldn't be surprised if some of the storms manage to reach severe limits. However, I'm still a little doubtful about severe t-storms forming in the region, simply because there isn't a great deal of moisture to work with. Because this is a cold front, many thunderstorms won't really die or fizzle out rapidly, even with the onset of the evening-overnight, and so showers and thundershowers/t-storms are still possible until the front finally passes through late evening-overnight. Just to be clear, again, "unsettled" generally signifies that conditions are favorable to the development of showers and thunderstorms, and therefore holds that there is a greater portion of cloud cover (due to instability) with the "risk" for stormy weather - the entire day wouldn't be a washout and it doesn't necessarily mean that everywhere in the forecasted region will in fact see showers and storms - that is where the current forecasts are a little misleading. We should encounter some sun during the day, although this drives storms to develop. I would establish the risk at 40-60%, particularly since we're dealing with thunderstorms.

The winds are behaving a little different than the previous weeks. For Saturday, as expected, wind tendency is typically out from the South (slight SSE tilt) and later coming out from the SW. They may become quite gusty passed lunch time (gusting up to possibly *50 km/h), but slowly dropping in speed by the evening. It will remain fairly windy at moderate speeds of close to 25 km/h and coming out from the SW during the evening. There is also some indication of a Westerly shift in the late evening, like last week, which suggests that the front may completely come through by that time, though this isn't ideal for La Ronde viewers due to wind direction. I'll keep tabs on this.

As for a show being canceled, as Paul stated, it is likely that enduring strong winds would cause this course of action (which is what almost happened for England in 2003). However, a severe thunderstorm in the area, much like the case for England 2007, could also call for a delayed show until conditions improve. It was disclosed to me on this forum that, as a safety measure, a display cannot be fired safely unless winds are constantly below the 40 km/h threshold, or even 35 km/h. Though it is likely moderately windy Saturday evening, I don't think we can expect winds reaching that level.

All that was mentioned here should serve as a fair idea in what we can expect for this Saturday, but I'd really like to keep an eye on things before providing confirmation of these conditions, especially with an atmospheric setup such as this. As new model runs come in, I'll have a better idea in what's likely in store for the evening.

I'll have a report by later tomorrow or early Saturday to finalize things.

EDIT: Temperatures will be more comfortable compared to last week.

Trav.

Good evening,

All that was stated in my previous post still stands firmly, though I'd like to make some small adjustments with respect to a number of variables.

Firstly, with respect to wind tendency, as stated yesterday, it will be mainly in the form of Southerlies for the majority of the day, but you will notice the SW shift by late afternoon-early evening. Wind speeds will maintain their moderate status throughout the day, and will likely reach a peak of about 30-35 km/h (gusting, at times, up to 45 km/h) not long following noon, particularly in the East End - the strongest of winds will be concentrated in the Eastern Townships. With some gradual weakening in the late afternoon to early evening, we should see speeds of closer to 22-25 km/h (again from the SW by that time) and then closer to 20 km/h by late evening. The wind direction seems to be behaving in a SSW to SW manner during the evening hours, so for folks at La Ronde, you will notice the smoke typically moving off to your right this time. However, with the possible Southwesterlies in between, I'm thinking that this will, at times, blow the smoke to the extreme right end (not sure of the section name) of the seating area at La Ronde, so avoid that part for viewing if you can.

Now, for the thunderstorms and rainfall. Most of the models are still projecting strong instability into the evening hours. This is not to say that it will rain all evening, but rather that the conditions are still favorable to the development of showers and storms. Once more, I'm thinking that the greatest likelihood for unsettled weather will be just around lunch time and onwards with mostly cloudy skies in between. I was checking in with Ottawa and SW towards Morrisburg, and it would seem that there will be improving conditions by around 8:00 p.m. in both areas. Given the average speed of the cold front and the distance from here to Ottawa, I don't think we'll be completely out of the risk until sometime around 11:30 p.m. here in Montreal. Looking at the big picture, I personally think that things should somewhat improve, in general, by the time we hit 9:00 p.m., but the chance for lingering precipitation will still be with us for the next couple of hours or so. As a precaution, I would recommend having an umbrella handy. It's difficult to say what exactly will happen at 10:00-10:30 p.m., or for any specific narrow time window, but I can safely tell you that the risk for showers and even t-storms exists (40%).

*Also take note, again, that some storms out there could reach severe standards tomorrow afternoon - a good amount of convective potential energy is present. Moisture levels are also decent and the air is unstable. The likelihood for severe thunderstorms would increase depending on how much sun we receive through the day. Before the front moves through, though, a trough will also trigger scattered non-severe thunderstorms. The cold front is responsible for the severe weather, though that will come later in the afternoon.

That's the way the atmosphere should generally behave. In summary, we're looking at a fairly breezy evening along with temperatures holding steady at about 18-20 C (much more comfortable than last week in that respect) and moderate humidity. Showers and thundershowers/t-storms are also possible (I think 40% by 10:00 p.m.). Once that cold front clears out, you guys will notice the cool, windy and dry weather on Sunday into the next few following days.

EDIT: I'll be keeping a track of radar and satellite imagery throughout tomorrow.
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Fred and Tyler,

The main reason as to why you're seeing large measurable rainfall in the forecast(s) is simply because precipitation is mainly associated with thunderstorms, and t-storms, particularly heavy to severe t-storms, can bring locally massive amounts of rain in a very small amount of time. The storm on Canada Day is a good example of that.

Enkil,

I don't think it will rain all day either, but as I mentioned, it will remain mostly cloudy for most of the day, particularly following lunch time. The greatest chance for severe weather is in the latter part of the afternoon.

Trav.

Thank you, Trav, for all these details. I now prefer to take a look on your posts than MétéoMédia, since we have some personalized info for our needs! It looks that the wind will push the smoke toward the VIP section, as it happens most of the time. Not too bad: most (or all) these people don't personnally pay and I suppose that they are often more interested by the free adult beverage and by the opportunity to chat together than by the display! Hopefully, this wind will not detract the anticipated letter effects.

I will leave Quebec City in mid-afternoon. I suppose that the bus may travel through some thunderstorms. I would prefer to see there by the windows along the 20 highway than tonight at La Ronde.

Fred

SEVERE THUNDERSTORM WARNING for the MONTREAL METROPOLITAIN AREA AND TORNADO WARNING FOR LAVAL AT 8:43 p.m (no confirmed touchdown as of yet). Please take precaution out there! Tornado warning has just been ended for Laval.

Trav.

Hi Fred,

Your comment is much appreciated on my part. Though I find most of the main forecasts to be reasonably accurate in giving you a basic idea of how the weather will most likely turn out on a given day, I personally feel that the key to giving a good forecast is to be as open-minded as possible, and that means to consider all meteorological parameters efficiently. A good method that I employ is simply running individual model simulations of, say, wind, cyclonic tendency, and temperature, and then coming out with my own forecast while simply using my own intuition regarding certain things. I then compare my own predictions and findings with those established by the major Canadian (and American) meteorological organizations, such as Environment Canada, and then make an assessment. Following that point, if I happen to be reasonably close in my analysis, I will produce my predictions with a good level of confidence and later make any adjustments if necessary (models aren't perfect since they assume ideal atmospheric conditions). Making a localized weather prediction is where it gets tricky, for micro scale weather patterns can deviate from those of the macro scale due to geographical disturbances, but I have ways of working around that. In essence, I simply try to put the pieces together and then later share my predictions with you guys.

I also sometimes make use of the "steady state" method in predicting weather events, especially with respect to fronts. In this way, I was able to successfully predict the timing of the first line of storms on Saturday at lunch time and to similarly anticipate the estimated time when the storms would completely exit the area Saturday night, which was just past 11:30 p.m. All that said, a forecast isn't perfect, but it should attempt to try to explain the weather as accurately as possible for the general public.

This coming Saturday's forecast is a little tricky, but I'm certainly not expecting a similar atmospheric setup as what we had seen on July 11th, although we may see storms developing on late Wednesday into Thursday as higher levels of moisture flows into the region. More details later on this week.
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In other weather related news, if any of you happen to remember my Summer prediction this past June, I stated that an El Nino should develop during this Summer and persist likely into next year. As it turns out, I was correct in making this statement as scientists have recently confirmed the presence of an El Nino just three days ago. They are also expecting it to gradually strengthen. Should that be the case and assuming it holds strong during the Winter, it may signal, as I mentioned before, that this coming Winter will be milder than those of the last two years. Depending how warm temperatures get, it will prevent large amounts of snow as well. If a strong El Nino persists into Summer 2010, I feel that it will be a very hot one as we had similarly seen in 1999 and 2005. This also likely means a decrease in the number of hurricanes or tropical storms forming in the Atlantic this Summer-Fall.

Though I was successful in predicting El Nino, temperatures this Summer were clearly not normal or above normal as I had initially stated (no sign of the usual Bermuda High in the Atlantic). Thunderstorm frequency has been fair so far, though, and rainfall above normal. If an El Nino is present, it may have more positive implications for the end of this month into August, as well as granting us an Indian Summer. Thunderstorm frequency would pick up if that's the case, especially in August.

Let's just say that El Nino has a tendency to make North American weather much more exciting.

Trav.

Good day,

With regards to Saturday's (July 18th) weather for Argentina's display, it's a little complex to explain the setup, but I'll do my best to simplify things. Unlike last week Saturday's wild weather, this time it's a fairly strong, blocked upper level low that we'll have to contend with following today's (Friday) fair weather. This disturbance aloft is showing signs of strengthening as it pushes Eastward, and so it will bring about mostly unsettled weather until at least the first half of Sunday. Now, there are also two surface lows converging, which is, in part, why there is so much moisture associated with the entire merged system. Given the speed of the low and the jet stream configuration, I suspect that the bulk of the rain will fall overnight Friday up until close to lunch time Saturday. Following that point, rains will give way to on and off periods of showers into the afternoon and evening (still want to keep an eye on the evening hours, though). The air at upper levels is close to saturation throughout the day and into the evening as well. Before the system comes in, though, we could see some thunderstorms fire up into very late afternoon and early evening hours (For Friday) before the relatively steadier rains arrive overnight. Chance of showers in the evening would be anywhere from 40-60% P.O.P on Saturday.

I'm also watching the winds. You will notice their overall directional pattern to be quite variable duirng the first half of the day Saturday, while being light in nature. I am expecting them to pick up in speed rapidly during the afternoon, however, and could become rather breezy at times. Latest and recent model runs project winds to be mainly in the form of Southwesterlies to SSW in the evening while holding speeds of about 20-25 km/h (higher in the extreme West end of the West Island at this point). This wind tendency would mean that smoke should be moving rapidly to the right for those stationed at La Ronde, though, again, it's best to avoid the extreme right end of the seating area due to Southwesterlies.

Maximum temperature values during Saturday evening is 20 Celsius, though I think it will be hovering around 17-18 C by 10 p.m. Humidity levels will remain close to high standards, but temperatures are unseasonably cool this weekend. As mentioned in my last post, I'm expecting that pattern to break in the closing week of this month into August due to, in part, El Nino.

I'll have a final update either later this evening or early Saturday to confirm these conditions, but this should serve as a basic guideline.

Trav.

P.S. Hope you all liked the storm this evening - it mainly came through the West Island and Southern Laval before dying once it reached downtown. A separate storm hit the South Shore as well. This is what I meant when I said we could see some good storm activity last night!