Southerly winds will pick up tomorrow to between 20 and 30 km/h and remain strong throughout Monday night and Tuesday ahead of a strong low pressure system in the northern Prairies. This will usher in much warmer weather. Highs will be in the 21 to 22°C range on Monday and 25 to 27°C range on Tuesday with lots of sunshine.
Things get interesting on Wednesday as a Montana Low moves into southern Manitoba. Weather models have been hinting at this system since last week. A strong southerly flow in the low levels of the atmosphere will usher in plentiful moisture so it will feel a bit humid. Thunderstorms are likely with the associated fronts with this system Wednesday night. Exact location of these storms is difficult to predict this far out but all of southern Manitoba will have the opportunity for these storms.
The following is a surface temperature map with approximate front locations for 4 pm Wednesday... from the NAM weather model.
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| Keep in mind this a weather model forecast... therefore things wont actually look exactly like this in reality |
Much cooler weather will likely make a brief return behind the system.
Official lows from this morning (the ones I had this morning were unofficial):
ReplyDeleteFisher Branch -2.4°C
Berens River -2.3°C
Wasagaming -1.4°C
Roblin -0.8°C
Swan River -0.2°C
Brandon -0.1°C
Winnipeg airport 0.5°C
Data courtesy of ogimet.com SYNOP reports
Just calculated the 1981-2010 normal for first freeze of the season for anyone interested...
ReplyDeleteNormal first freeze (first day to dip below zero) = September 24 (Sep 23 on a leap year)
Normal first hard freeze (first day to reach -2.0°C or lower) = October 1 (Sep 30 on a leap year)
Thankfully Winnipeg escaped frost overnight. Coldest temperatures were confined mainly to the outskirts:
ReplyDeleteNorth Kildonan 1.0°C
St Vital 1.3°C
South St Vital (me) 1.5°C
Southdale 2.4°C
Charleswood 2.8°C
Airport 3.3°C
Whyte Ridge 3.7°C
uofw (downtown) 6.4°C
There was frost on roofs here at my place, but that's it. Anyone else see frost?
Other lows across southern Manitoba:
Sprague -1.9°C
Wasagaming -1.7°C
Brandon -0.3°C
Also -1°C in Dugald and -3°C in Woodlands according to Manitoba Agriculture.
Wednesday's severe weather threat sure does look interesting at this point. Could be the best severe weather setup of the year here. Go figure, in Mid September
ReplyDeleteYes, looking at some models makes me think I'm looking at a summer setup, not something we normally see a couple weeks before October! I might issue some slight severe risks tomorrow for parts of southern Manitoba if things continue to look good.
DeleteI have a feeling temperature forecasts for today will be way busted....
ReplyDeleteArea of low cloud associated with a very moist air mass moing up from the Dakotas this afternoon will likely keep things much cooler than it could have been today.
Today was the true definition of being robbed of a good day. The sun just wasn't enough to thin out that low cloud shield today. Only reached about 19-20°C in the city today when it could have been in the mid 20's.
DeleteNot really liking the thunderstorm potential for us here Winnipeg tomorrow. Looks like best storm threat will be over Southwest MB with little chance for severe weather here as storms will weaken by the time they get here which is usuallly the case.
ReplyDeleteI'm cautiously optimistic about tomorrow evening's potential in Winnipeg. Right now I don't see why storms would dissipate or completely weaken to nothing by the time they reach the RRV tomorrow later in the evening. Dynamics and instability are only expected to increase in the evening.
DeleteBut yes, it is Winnipeg... which is why I'm ''cautiously'' optimistic.
There is one worry about southwestern Manitoba tomorrow, which is capping. Unfortunately it is expected to be fairly strong. If nothing forms during the day, then we'll have to hope we can get some nocturnal action late evening... which I should note can still be severe.
I don't know about you guys, but I just want a good light show. Nothing like a good lightning display to end the season.
On another note, long range models still indicate high probabilities of above normal temperature trends to end September. Good news if you're not quite ready for an extended period of fall weather. (note this does not mean it will be above normal every single day).
ReplyDeleteWe just have to get through the big cool down for this coming Thursday and Friday.
Unfortunately it's a wait and see game today. Cloud cover is extremely abundant around southern Manitoba this morning. Right now I'd say best chance for storms today is in southwestern/western Manitoba and the Interlake afternoon and evening. There will also be a small window this evening for storms in the RRV. Any storms today can be severe despite all the cloud cover.
ReplyDeleteThings have shifted south in the latest nam... But it,s not over yet.
DeleteThings not looking that good for storms here in Winnipeg/RRV for today and tonight. Too much cloud cover limiting the needed daytime heating and latest model guidance has shifted west and south. It looks like if any storms develop it will be in Western Manitoba and the interlake with a very slight chance for Winnipeg and the RRV. So once again it appears like we will mostly likely miss out on the action for the most part here in Winnipeg. With the way things have gone in 2013 I wouldn't be suprised if a split forms around Winnipeg.
ReplyDeleteI feel doubtful as well.. Theres still the potential for activity tonight, but i,m not feeling optimistic.
DeleteHeard a few rumbles of thunder earlier with that small line of showers that passed through. As for tonight looking more and more unlikely that we'll see severe weather tonight. Just not enough daytime heating today to destabalize things further. Not so sure we'll even see non-severe thunderstorms tonight but we'll see.
ReplyDeleteWeather models have really poorly handled the last couple days. Temperature forecasts yesterday were overestimated by over 5 degrees in some cases.. and then today... let's just call it a dismal end to a dismal thunderstorm season. I'm leaving it at that .
DeleteThundercast will be closed for the season tomorrow... I will only be updating it when a decent chance of thunderstorms exists.
ReplyDeleteLet's just say, it's probably more that of very poor interpretation of the models rather the models themselves. I for one never even considered the idea of severe weather for today/tonight would come through. It hasn't happened in 2013, it sure ain't gonna start now 2 weeks away from October. With that said it is very true that the models have been all over the place lately. I think it's time to close the door on severe thunderstorm forecasting for the season that hasn't even seen many to begin with. I think the term thunderstorms is used too much in the forecast for an area that sees little to none of it. Well hopefully 2014 will be different in that aspect but the way things have gone in the last couple of years it makes you wonder.
ReplyDeleteWe may see nocturnal non-severe thunderstorms tonight but I wouldn't bet on it.
Thunderstorms are inherently unpredictable and one of the biggest factors in thunderstorm development, moisture, is one of the most poorly handled model parameters. Therefore, model error can be significant in severe weather forecasting. That is not to mention the fact that storms are inherently unpredictable in the first place...we don't know where they'll form...we just know there's a chance they'll form.
DeleteThis particular event was handled very poorly by the models outside of today (even including today in some cases). There remains a risk of severe storms along the border tonight, and indeed a severe cell is currently ongoing along the border at the moment.
I've noticed that there are some big thunderstorm in western North Dakota and SE SSK that appears to be moving towards Manitoba. Whether or not this becomes something over Southern Manitoba remains to be seen.
ReplyDeleteThe number of near misses, splits and busts around here has been astonishing this year... just when we thought it couldn't get any worse.. it did.
ReplyDeleteAs you mention there is some decent storms in NW North Dakota which do look interesting. Looks like there will indeed be a chance for a storm here overnight and morning tomorrow.
Speaking of which, I've only had 6.6 mm of rain here so far this month... and just a measly 34.9 mm since July 26... the third year in a row of very dry summer conditions.
ReplyDeleteAs if we didn't miss out enough, those storms near the SK border last night did in fact merge to form a line which raced into southwestern Manitoba and was headed in a direction that would have taken it right through the RRV and Winnipeg... but then the predictable occurred and it completely dissipated as soon as it reached the RRV.. Winnipeg not even getting a drop of rain. The story of 2013.
ReplyDeleteNow that I'm closing the thundercast for the season (will be updated if there's a significant storm chance), here's a summary of severe weather forecasts this year for DAY 1 forecasts:
Number of slight risks issued: 16 (2 were busts on July 29 and Sept 18)
Number of moderate risks issued: 5 (1 was a bust on July 11)
Number of high risks issued: 0
Good job on your thunderstorm outlooks this year. It takes a lot of commitment to put out imagery everyday, so I commend you for that.
DeleteOut of curiosity, what do you consider slight and moderate risks for verification purposes? Do they require a certain number of severe reports, or a certain intensity of severe weather?
Thank you for the kind words Scott :)
DeleteSorry for the slow response to your question, I was busy the entire day (literally).
Unfortunately, how I defined slight versus moderate versus high this year is very vague. This year I simply defined the risk based on how widespread the severe weather is expected to be and yes also the severity of the storms. Essentially, slight risks were issued for ordinary severe weather events that we see quite often during the year... moderate risk is for the biggest severe weather events of the year and high risks are issued for the biggest severe events which don't necessarily occur every year, or even every couple years.
Honestly, I have thought many times about implementing actual numerical values similar to what the SPC does.... but honestly I just have not figured out how I would be able to do it.. both in the forecasting position and also in the verification position after the event occured.
That is the big downfall with my thundercasts... No CLEAR criteria. This was only my second year doing these forecasts and there is definitely still room for improvement with this.
don't like new EC radar, the white background looks bad and only having 2 main colours I don't like ether. It might just be because I used the old one daly and got used to it.
ReplyDeleteYou can still view the original radar version by clicking on the ''14 colours'' button under the ''intensity scale'' section.. If this does not bring it back to normal right away, try refreshing the page and hopefully that fixes it.
DeleteYou can also use A Weather Moment's radar viewer which seems unaffected by the changes and still shows the original layout.
Thank's so much JJC.
DeleteLake effect streamers are coming off Lake Manitoba today... a sign of Fall!
ReplyDeleteYeah your right, today has a real fall feeling to it, the north west wind, lake affect streamers and mainly the cold temps.
DeleteGrowing season officially ends at the airport today, dropping below zero as of 7 am. Puts this year's growing season at 131 days long.. will try to calculate the 1981-2010 later today if I have time.
ReplyDeleteWarmer in the central and south ends with a low of 1.5°C at my place and 5°C at The Forks.
JJ, does that system for Monday look pretty intense in terms of heavy rainfall and/or thunderstorms for us?
ReplyDeleteThanks, Anon
Looks like a slow moving frontal boundary to move across the province tomorrow night through to Monday night. Very strong low-level flow will drag in moderate amounts of moisture from the south.
DeleteThat being said, looks like a good chance for rain on Monday. It wont be an all-day rain here in Winnipeg but will perhaps come in one or two waves instead. There is also the possibilty that the bulk of the rain stays to our west.. as it does look like another close call for Winnipeg.
A thunderstorm cannot be ruled out early on Monday as there does appear to be a bit of instability in place.
General rainfall totals of 5-15 mm are possible with areas that receive the most rain. If Winnipeg ends up missing out again we may only get 2-5 mm. Of course, due to the convective nature of the rains locally higher and lower amounts may occur.
Will have to see how things trend in tomorrow's updates.
I didn't get any frost at my place in eastern river heights with a low of 3.7 at 6:40,.
ReplyDelete