Thursday, September 25, 2014

Record blast of late season heat over southwest Manitoba

4 pm temperatures across RRV and SW MB - Sep 25 2014
Temperatures soared into the 30s over SW MB
A sprawling upper ridge of high pressure over central North America together with a southerly flow of unseasonably warm air from the southwestern United States resulted in a late season blast of summer like temperatures over southern MB today, especially over southwestern parts of the province. Temperatures soared into the upper 20s over the Red River valley, and into the low to mid 30s over southwest Manitoba. These temperatures were some 13 to 18C above normal for late September, and resulted in some impressive late season heat records. In Brandon for example, the high of 34.0C at YBR airport was not only a record for the day (prev record 31.1C in 1950), but was also the latest the city has hit a temperature over 33C (previous latest was on Sept 22 1938 with a high of 33.9C)   It was even warmer southeast of Brandon with a high of 35C in Wawanesa from the Manitoba Ag weather network.  South of the border, WiIlliston ND hit an incredible 36.1C (97F), easily a record for the day and the latest the city has ever been that hot.

Record highs across the central Prairies Sep 25 2014
(Graphic from The Weather Network)
In Winnipeg, temperatures weren't quite as high as areas further west, but it did manage to reach a high of 27.7C at Winnipeg airport.. the warmest day of the month so far and about 13C above normal. The day was accompanied by brisk southerly winds and abnormally high dewpoints for late September.. with a dewpoint reading of 18C by the afternoon and evening. This was the highest dewpoint ever recorded for Sept 25th and is one of the latest days in the year for dewpoints of 18C or more (latest is Oct 11 1997 with a dewpoint of 18.1C)

Friday should be a repeat day over southern MB, with temperatures in the upper 20s and low 30s once again along with sunny skies and humid conditions (dewpoints again in the upper teens) Southerly winds however will be stronger Friday in Winnipeg and up the RRV, with gusts to 60 km/h or more. Temperatures should climb to a high of 28-29C in Winnipeg, just shy of the record high for Sept 26th of 31.7C set in 1952. Saturday will see one more warm day over the Red River valley with highs in the mid 20s, before a cold front pushes through by afternoon.  This front will usher in much cooler air by Sunday with highs only in the low teens along with periods of rain. So enjoy these last couple of summer like days before reality kicks back in!

UPDATE: Fri Sept 26:  It was another unseasonably warm day across southern Manitoba with temperatures climbing to the 30C mark or higher in most areas.  Winnipeg hit a high of 30.2C, some 15C above normal for Sep 26th, and just 1.5C shy of the record high for the day. In addition, humidity values were unusually high for late September with dewpoints of 18C through midday, resulting in a peak humidex reading of 36C by late afternoon, the latest in the season that Winnipeg has hit a 35C+ humidex since humidex records began in 1953 (previous latest on record was a 38C humidex on Sep 19 2004). The hot spot in the province and country today was Swan River at a sizzling 35.1C.

16 comments:

  1. Already up to 26.2C at the airport as of noon, 26.7C at my place.. so we're running a good 4-5C warmer than yesterday at this time. Looks like 30C is a good possibility for us today! Not only that, dewpoints are a sultry 18C.. so humidex values will be near 35 this afternoon. Truly tropical!

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    1. I'm really enjoying this afternoon, soaking up all the heat and humidity. It's looks much cooler next week ( near normal ) and then next weekend looks quite chilly!!

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  2. A high of 30.2C at Winnipeg airport today, a whopping 15C above normal and just 1.5C off the record high for today. Humidity was also a factor, with a 36C humidex today marking the latest 35C+ humidex at Winnipeg airport since humidex records began in 1953.

    Tonight will be another balmy night.. with southerly winds keeping temps up all night, and an overnight low of only 18C.. One more warm day tomorrow with highs near 25C before cold front comes through in the afternoon.. snapping us back to reality Saturday night into Sunday. Sure was nice while it lasted!

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  3. Williston was only 3 degrees cooler than Baghdad yesterday! That sure puts it in perspective.

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  4. Warmest daily minimum was set for September 26 at 17.4 C, smashing the previous record by 3 C. Could Winnipeg set another record minimum for the 27th?

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  5. Hi rob, random question. What is the latest first freeze the city has seen? Second week of Oct?

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    1. Latest first freeze was during the amazing fall of 1963.. first freeze at the airport wasn't until October 30th (-4.4C) if you can believe that. October 1963 was our warmest October on record with an average temperature of 12.8C, normal for September.

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  6. Looks like September will end up with no official freeze at the airport (min <= 0.0C) for the first time since Sept 2005. The lowest temp so far this month has been +1.1C on Sept 12th. Average first date of 0.0C or lower at Winnipeg airport is Sep 22nd, with at least 2-3 days during the month on average seeing a low of 0.0C or lower. Only 10 Septembers in the past 75 years have escaped without a freeze at the airport, so on average you can expect this to happen every 7-8 years or so (although it's highly variable). I see the forecast is calling for a low of -1C on Saturday Oct 4th which would mark the end of the growing season here if that verifies.

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  7. Quite the cold push coming in Friday behind a sharp cold front associated with an upper trof digging across the eastern Prairies. Single digit temperatures likely Friday with some cold rain or drizzle.. possibly mixed with some wet snow over higher terrain and at night. As an aside, the heat records we challenged this past Thursday and Friday were from 1950 and 1952 when we had some late September 30+C heat. Both those years saw measurable snow in the first few days of October (12.7 cm on Oct 2 1950, and 8.6 cm on Oct 4 1952) Also, the last time we had a frost free September (2005), was followed by a massive early season snowstorm on Oct 5th over SW MB that dropped up to 45 cm of snow in Pilot Mound and about 5 cm in Winnipeg. Not saying it will happen again this year.. but it does show how quickly things can change around here at this time of year.

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  8. Re: the cold front on Friday.... any estimation as to the speed and duration of the winds behind the front?

    My eyebrows were raised a bit late this afternoon when I looked at the marine forecast... sustained northwest winds of 45 knots forecast on Lake Manitoba Friday morning, and north 40 knots forecast for Lake Winnipeg's south basin. Both lakes are far higher than desirable at this time of year (Lake Manitoba still slightly over its flood stage of 814 feet for only the 2nd out of the past 60 autumns, and Lake Winnipeg sitting at 716 feet, a foot over its desirable 711-715 foot range). If those winds do materialize, and last for any amount of time, there will be a sizeable seiche, and likely some damage to areas that do not have flood protection. Hopefully the forecast is a bit aggressive, but this is the time of year when we occasionally see such winds (I recall one event in 1999, and the October "weather bomb" of 2010 that hit the Grand Beach boardwalk when the lake was also higher than normal).

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    1. I think those 40-45 knot winds will be gusts rather than sustained.. but 30-35 knots sustained quite possible Friday. As you say, this will present problems on the south end of Lakes Winnipeg and Manitoba given the high water levels. Wind speeds drop off a bit Saturday (still from the NW though) but then increase from the NW again Sunday into Monday as deep low bombs over northern Ontario. This will mean a long duration event of NW winds over the lakes, quite strong at times, which will not be good news for lake shore areas.

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    2. Surprised that the province has not issued a wind warning yet for the lakes.. would expect to see one issued some time today.

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    3. Gale warnings from EC for 35-45 knot winds overnight and into the morning. The province will probably be issuing a warning about the wind set-ups along the south and east shores later today.

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    4. Province has finally issued severe wind alerts for Lake Winnipeg and Manitoba. Lake levels could rise up to 5 feet with significant wave action on the shorelines, especially southern and eastern shores.

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  9. Any chance of a few snowflakes mixing in with the rain on Friday for Winnipeg ??

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    1. Probably just rain in Winnipeg Friday, but a cold rain with strong NW winds and temps only near +7C. There is a slight chance of some wet flakes mixing in Friday night but any snow flurries more likely over western MB Friday especially over higher terrain.

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