Saturday, July 16, 2022

Extreme Heat and Humidity for the weekend, Storms also possible.

 Hello everyone, I know I’m a bit late on your weekend forecast I apologize for that. I volunteered at the fringe festival yesterday so I had no time to create a weather outlook. I’ll be back volunteering during the week. Anyways let’s get to the weekend outlook, as you know a heat warning is in place for all of Manitoba except eastern portions of Manitoba, an upper level ridge continues to sit over the northern portions of the plains and over southern Manitoba. This heat dome will be situated just enough south that low pressure systems will be able to ride over top of that dome, that could impact southern sections of Manitoba. Find out what to expect weather wise , and how long this heat will last below.


Saturday: Sunny skies are expected into the later half of the day today. Today and Sunday will be the hottest days of the weekend, temperatures by this evening will have soared into the high 20’s to low 30’s on top of that the humidex will make it feel like the low to mid 30’s. In some locations the humidex could feel like the high 30’s.  The hottest of the weather is expected in the southwest part of Manitoba.  

Saturday Night: Not much in the way of relief for the heat is expected for tonight as a strong southerly flow remains in place bringing in very humid conditions. There will be a chance that an area of thunderstorms from Saskatchewan overnight could drift in and affect primarily the interlakes and the central parts of Manitoba. The severe weather risk would be primarily over lake Winnipeg, with isolated severe thunderstorms possible overnight as a warm front moves through. Overnight lows will be quite mild with most models agreeing on overnight lows tonight in the high teens to the low to mid 20’s. 




Top: NAM 12Z Energy Helicity Index, brighter yellow and orange indicate areas of potential supercell development. Middle: NAM12Z CAPE shows extreme instability in place by mid afternoon, with 5,000J/Kg possible in some areas. Bottom: SKEW T Graph detailing severe potential for areas north of and around Winnipeg on Sunday afternoon. 

Sunday: This is when the heat really kicks in and causes not only higher humidex readings but the dewpoints will jump significantly making it feel like Mexico over our area. Temperatures are expected to soar into the low to mid 30’s over southern portions all the way into the parklands and the interlakes region, dewpoints will rise into the low 20’s in the southwest early in the day before dropping to the mid to high teens. There is a chance that humidity could stay further west during the day according to the RAP but it’s not picking up on the trough that will move in during the afternoon that will divert the humidity eastwards. Areas further east however in the red river valley and eastern Manitoba may see those higher dewpoints in the low to mid 20’s which will not only amp up the humidex to the low to mid 40’s but it will also fuel severe weather potential heading into the evening. T Why? A trough will be moving into the red river valley and eastern Manitoba during the latter half of the day, and with the combined humidity and CAPE levels from 2,500 to 5,000J/Kg or 6,000J/Kg. Shear looks strong enough to support severe thunderstorm organization and supercell thunderstorms as a possibility and capping looks nonexistent surprisingly. This threat is conditional however, as other models hint at storms happening in the interlakes only so will have to watch for any alerts that get issued. The consensus for main areas of concern for severe thunderstorms tomorrow is from Portage La Prairie south to the American border north into the Lake Manitoba area east into Gimli and east/southeast into the Whiteshell regions including all of the red river valley and eastern Manitoba. Storms that form could become severe quite quickly, with toonie to golf ball to baseball size hail possible. Tornadoes cannot be ruled out. Monitor for severe weather alerts that get posted tomorrow. 



(Above: Thunderstorms look to possibly impact western Manitoba into the red river valley overnight into Monday, will watch for any changes to this). 

Sunday night: Thunderstorms look to clear the region by the evening the trough should be in Ontario by the time overnight comes. However a cold front will move into that hot and humid airmass overnight, IF thunderstorms don’t develop during the day time there will be plentiful instability left overnight with around 2,000 to 4,000J/Kg of CAPE. Computer models are agreeing on a area of thunderstorms forming in eastern Saskatchewan moving east southeast overnight. These thunderstorms may have a potential to have all modes of severe weather. Right now areas in western Manitoba through the parklands and interlakes into the red river valley and southeastern Manitoba are at risk mostly. If nothing happens expect cloudy to partly cloudy skies and mild conditions as the front passes. We will know more during the day on Sunday. Overnight low temperatures will drop into the high teens to low 20’s, with initial temperatures near midnight in the low to mid 20’s before the cold front moves through. 

Early Next Week: Another low pressure system will move in knocking down our temperatures into the mid to high 20’s and high teens for overnight lows with an increasingly unsettled pattern possible. Showers and thunderstorms will likely start off the week, there’s some consensus there could be significant rainfall that occurs with this. Will watch as this could lead to flash flooding potential. Will monitor this for you all. Cooler weather looks like for Tuesday and Wednesday back down to near or slightly below average temperatures. 

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