Monday, August 09, 2010

Humidex advisory issued for southern MB.. temperatures of 32-35C today with humidex readings of 40-43C

A humidex advisory has been issued for much of southern MB today including Winnipeg as a hot and humid airmass spreads over the eastern Prairies. Temperatures today are expected to climb into the 32-35C range this afternoon over southern MB, with dewpoints around the 20c mark. This will result in widespread humidex values of 40-43C this afternoon, with local readings of 45C possible. Winnipeg should hit 33C this afternoon, with a chance of reaching the 35C mark. This should make today the hottest day in the city in 3 years since a 35.3C reading on July 29 2007, and the hottest August temperature in 7 years (35.9C on Aug 19 2003) Today will mark the peak of the heat spell, as unsettled conditions with cooler weather is expected beginning tomorrow.

29 comments:

  1. Well, the poll concensus for today's high in Winnipeg is 33.5C.. which I think is a very good prediction. 12Z upper air analysis shows a good surge of 20-23C air at 850 mb to our southwest, which is forecast to move over us by this afternoon. We should be able to hit 33C easily today, with a chance of 35C if we get full sun and a bit of a southwest surface flow. (For the record, I chose 35C in the poll)

    As hot as it will be today, the record high for today's date is 36.7C in 1929, so I don't think today will be a record breaker, at least in Winnipeg.

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  2. I see WDAZ Grand Forks is predicting 98 F today!

    Scott could be right in that someone could very well hit 100 F in the international border area!

    Maybe Emerson?????

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  3. Looks to be some cloud cover arriving from the west!

    Could that put a damper on our high temperatures????

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  4. Temps struggling at YWG.. only at 30 C. Problem is subtle boundary which lies along int'l border. To the north there is a SSE flow which is not allowing for efficient mixing ... SW flow at GFK allowing for 35 C. Our flow does not turn SW until around 6 PM according to RUC which may be too late.

    The tropical dewpoints (24-27 C)remain locked up behind yet another boundary in Iowa and S Dakota and will not reach us today.

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  5. Looks like some severe storms have developed in North Dakota and are heading northeast!

    Could be an active evening for some parts of southern Manitoba!

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  6. Looks like the 35C mark has evaded Steinbach yet again! Last two years have seen maximum high temperatures of 34.2C and 34.3C respectively. This year the high so far is +33.8C, with the surface temperature making a last ditch rally as of 5:15pm this evening. For the record, I was predicting a high of 35C in Steinbach and 34C in Winnipeg (So yes, I picked 34C in the poll).

    NAM blows up a good storm complex over south-western and south-central MB over the next few hours. With favourable dynamics (somewhat backed surface flow, 40 to 45kts of mid-level flow and 80 to 90kts of upper flow), we could see some decent storms when combined with the 2000 to 3000J/kg of CAPE. Could be an interesting evening.

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  7. Looks like Winnipeg broke a record today!

    The Winnipeg AIRPORT that is!!!

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  8. Winnipeg airport hit a high of 32.9C today.. kudos to those who picked 33C in the poll! It was also the most popular guess with 42% of respondents picking it proving once again, the poll ensemble does a great job predicting the weather! The 32.9C was not a record for the date though if you included St John's college data back to 1872 which is part of Winnipeg's official records. Temperatures of 32-34C were common across the RRV today, with the Forks claiming national hot spot honours at 34.8C.

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  9. Another steamy day out there.. not as hot as yesterday but dew points are higher which makes it feel as uncomfortable. As a result, humidex advisory has been re-issued for Winnipeg and the RRV with values near 40C this afternoon. Further west, nice north-south line of thunderstorms along the MB/SK border marks the leading edge of cooler air to our west. Training cells will give locally heavy rain with amounts of 30-50 mm possible. Models show that area of storms moving through the RRV this evening, with the potential for some heavy thunderstorms, especially with this oppressive heat and humidity over us. Stay tuned..

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  10. Interesting situation unfolding... large area of thunderstorms developing on nose LLJ and downwind of moisture transport maxima. This feature lifts north and convection will be able to interact with 4000 J/kg of surface based CAPE locally thanks to clearing and t/td's of 32/22 or thereabouts at YWG.

    Best dynamics lift north by around 5 PM and with precipitable waters reaching 50 mm.. we are in store for an interesting evening...

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  11. Interesting indeed.. 45 mm of rain past hour at Boissevain with a gust to 72 km/h according to the ag-wx site there. These storms will be heavy rain producers as they come through southern MB this afternoon and evening. You can just feel the atmosphere is wanting to unload a lot of moisture out there!

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  12. whats the main threats for winnipeg this evening? is winnipeg going to ses violent storms this evening?, and is there a threat of tornados? thanks

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  13. Anonymous,

    The biggest threats are likely extremely heavy downpours. Large hail (lets say quarter-sized or bigger) and damaging wind gusts are a lesser, but still existent, threat.

    Given the huge amount of energy available due to our high dewpoints, and the fact that the winds in Winnipeg are still South-Southeast, one cannot rule out the off chance of a tornado. While I don't think the current setup is explicitly favorable for the development of tornadoes (I'd like to see a straight SE wind and a more pronounced surface boundary somewhere in the RRV), one can never rule out the off chance of one developing.

    My personal opinion is that the risk for one is rather low in S.MB today.

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  14. Agree with Buffalo 7's assessment. Even hail may be a lesser threat given the high freezing levels and very warm low to mid level temps. So very heavy rain will be the main threat along with locally strong wind gusts. Note that Grand Forks has picked up almost 2.5 inches of rain (65 mm) over the past hour and a half.. Rainfall rates of 30-50 mm/hour are possible with these storms which can cause local flooding problems.

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  15. A little more complete summary of my thoughts (just copied from my blog):


    Environment Canada has issued a severe thunderstorm watch for most of southern Manitoba for this evening. A few thoughts on the coming hours…

    For Southwestern MB:

    The main threat for severe storms should end this evening. High temperatures and dewpoints combined with daytime heating have contributed to a favourable environment for severe thunderstorms. These ones should primarily be driven by the sun, so once the sun starts going down, so too should the intensity of the storms.

    For the Red River Valley:

    The main threat for severe storms will continue through the evening as an 850mb jet pushes up out of North Dakota into the RRV. The main threat with these storms will primarily be rain. The storms are developing on the nose of the 850mb jet, just downwind of an area of moisture convergence, so as the evening continues, the storms will have more and more moisture to work with. This, combined with the fact that storms will most likely be training (multiple storms moving in rapid succession over the same area), will result in some areas in the RRV getting large quantities of rain. My initial estimate would be that some areas will receive total amounts of 70-90mm locally, however it could potentially be higher than that. Most areas will probably receive on average 15-25mm of rain.

    Other threats from these storms will primarily exist during the evening hours when they still could be surface based. If any storms can develop by themselves this evening, there's a slight chance they could become supercells given the SSE flow through much of the RRV. If that is able to happen, then there would be a chance of large hail (my estimates would be quarter to loonie sized) and strong winds (90+ km/h). Give the backed surface flow, there would also be a very slight chance of a supercell becoming tornadic, but the overall setup doesn't look to favourable for that; you never know what storms will do when working with 3000+ joules of CAPE, though.

    This MCS will stick around for a good portion of the night, resulting in a widespread wet and noisy evening for many residents in Southern Manitoba.

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  17. Very strong winds affected S Winnipeg as gust front from convection off to our south pushed thru stirring up lots of dust and obscuring visiblity.

    Returns appear to be weakening significantly as they approach the city (unless there is an issue with woodlands radar)as a strong line affects western RRV...

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  19. Did anyone get a maximum wind gust from the airport as these strong winds went through earlier????

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  20. Rob!

    Take a look at that massive storm that might set up in northern Manitoba this upcoming weekend!!!

    Looks like weather could swing dramatically this weekend for Southern Manitoba!!!

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  21. Hi everyone....

    Been busy with severe weather and taking some vacation time. But what a summer so far with the severe weather down here in nd/mn. So far 4 EF4 tornadoes in NWS Grand Forks county warning area. There have been 12 EF4 tornadoes nationwide so far...so over 25 pct of the U.S. EF4 tornadoes have been in eastern ND and northwest MN. Crazy. 103 tornadoes unofficially in the state of Minnesota for the U.S. top spot.

    But on too cooler weather which I for one am glad. Couple of 95 degree days enough for me. I see accu-weather is calling for a very cold winter and so is our local resident climate person. we will see about that...

    stay well friends to our north...

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  22. Nice to hear from you again Dan.. amazing how much of the severe weather is just south of the border this year. Most of the storms have been weakening by the time they reach us.. (yesterday was another example) I guess you've had just enough better dynamics south of the border to generate the more intense cells. We've had some good storms, mostly wind and hail, with 5 reported tornadoes so far in southern MB (none serious)

    Enjoy the cooler weather next week!

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  23. Hi Dan Do these stats include the EF4 last Saturday in Richland ND to Wilkin Minn. ?

    Did this actually cross the RRV or was it too far south of Whapeton/Breckenridge?

    Richland , Wilkin counties tornado confirmed to be EF4

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  24. Daniel P About wind speeds.. CWBs Weather analysis reported Maximum gusts of 100K at Elie yesterday and several from 70 to 75 nearby.

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