Severe Weather Threat Returns to Southern Manitoba.

 Hello everyone. An active period of weather is likely to impact southern sections of Manitoba this weekend. I am actually quite surprised at the latest data and it seems like conditions will be similar to the weather we had earlier this week. Overall a humid, hot and potentially unstable pattern is on the way to southern Manitoba this weekend as a batch of tropical air will be moving up from the united states gulf of Mexico. Find out how bad the weather will get and where and when in this weekends latest blog.

(Above: First summer batch of humidity arrives for southern Manitoba with dewpoint values between 15 and 20C - Muggy).

Tonight much of Southern Manitoba will be under threat for another round of thunderstorms especially areas from the Saskatchewan border as far east as Winnipeg could see scattered showers and thunderstorms with small hill mainly. During the later overnight hours most of these should weaken as sunrise nears. Severe weather is not anticipated for this. 

The attention then turns to Saturday when a southwesterly flow will be present with many low pressure systems the last couple of weeks moving east along a zonal flow however given the fact that there will be much high level moisture available tapping from the Gulf of Mexico severe weather is possible later in the day. Temperatures during the afternoon according to the high resolution models including the Canadian High Resolution Model will rise into the mid to upper 20 degrees Celsius range across the south. Current model guidance shows that dew point temperatures will rise into the mid to high teens as a result we are expecting general thunderstorm energy to rise. I don't really get into much atmospheric dynamics however there is broad troughing over the Western United States that is resulting in multiple areas of low pressure to develop over the Canadian Prairie provinces. As a result of this low pressure system there will be an increased threat for severe thunderstorms over southwestern Manitoba into the Red River Valley. Towards the afternoon there is a smaller risk in eastern Manitoba as some high resolution models are hinting at scattered severe thunderstorms popping up during the afternoon in the southern Red River Valley which may impact Winnipeg in the afternoon however this confidence is a lot lower given that the threats will be highest in the western part of Manitoba during the afternoon and evening. So let's get into the details.

(Above: Possible severe storms in the red river valley during the afternoon hours. Based on the RDPS model).

 Scenario #1 Starting in the afternoon a warm front will be sitting over the Canadian border moving into southern Manitoba by the afternoon bringing strong dew points and instability north of the border which will also move into areas of southwestern Manitoba. There is conditional instability present in the Red River valley which may contribute to an area of severe thunderstorms developing in the afternoon and early evening which may impact the Winnipeg and eastern portions of Manitoba, this will only be possible if there is no early morning convection or showers. If storms form later in the day and develop in the southwest as well with these storms they could be some powerful thunderstorms especially in the Red River Valley regions. There is a possibility that some of these may be super cells however there is not a lot of model information on the HRDPS i'm just mentioning that there is a possibility that the Red River valley could also see storms in the late afternoon and early evening. If there is morning showers or storms this risk for this potential thunderstorm threat would be lower. 

(Above: Radar Images on the severe weather forecast to impact southern Manitoba during the evening in the SW.):

The higher levels of concerns for severe thunderstorms will be present in western Manitoba I spoke with Justin and he said that there will be a risk for supercell development in southeastern Saskatchewan and southwestern Manitoba with MUCAPE values between 2000 and 4000 joules per kilogram with plenty of shear. But we are then looking at is the development of possible super cell thunderstorms with the ability to produce hail up to the size of golf balls or baseballs given the fact that we have that experienced that earlier this week, there is also a risk that an area from Melita to Brandon N to Neepawa W to Portage la Prairie will be at risk for tornadoes to develop along with flooding rains, most areas will get between 10 to 70mm+ of rain depending on thunderstorm activity). Based on what Justin had mentioned to me there is a possibility of potentially dangerous situation tornadoes in the southwest part of Manitoba, EHI values which basically tell the severity of storms ahead of time sometimes we can tell how bad it might be. The values are right now forecast to be between one and 4 which show significant severe risk. If conditions allow these thunderstorms will merge into a thunderstorm complex which will then travel east across the southwest part of the province into the Red River valley by overnight which may weaken into rain and possible thunderstorms. Some of the other high res models are also showing that thunderstorm complex dying out with more thunderstorms developing over Northern Lake Winnipeg which is an odd location for thunderstorms given that instability will not be significant in that area will have to monitor to see if there's any changes in future runs.

Thunderstorms are expected to persist during the late evening into the overnight hours there is a possibility they may completely weaken as they reach the Red River valley as instability values drop significantly. However if they do sustain themselves there is a possibility for wind gusts up to 90 kilometers an hour or more with small to moderate hail and frequent lightning. ****(Unrelated note: For those of you who want to see thunderstorms in the Red River valley we still have the entire summer to go and all it takes is for one low pressure system to encounter heat humidity and boom we get storms that could be quite powerful. And the Red River valley is also known for some pretty powerful thunderstorms over the last 50 years or so, I'm not gonna go in a tangent but St Claude had a major tornado in 1984, there was a major wedge tornado by Brunkild in 2000 and you also have Elie in 2007, Gull Lake in 2006 on August 5th and you also have that tornado which struck South Winnipeg on July 6 of 1987. So storm season is not over yet it's just beginning unfortunately for those of you don't like thunderstorms you have to wait until September comes.)***   Temperatures are forecast to drop only into the upper teens overnight. 

During the morning hours on Sunday there may be some remaining instability of CAPE as the front moves east in areas of the Red River Valley East, with a possibility of new thunderstorms developing over the central Red River valley and areas east into the white shell into the morning hours these storms will not be significantly severe. Looking at the possibility at some heavy downpours and hail. However if storms from the overnight are persistent it may not allow for these thunderstorms to develop during the morning and general clearing would be expected. Sunday will be one of those calmer weather days with temperatures behind the cold front sitting in the lower 20s to mid 20s, with areas to the W in the province there will be temperatures in the upper teens for daytime highs.

The week ahead: Unsettled weather will persist On Monday and Tuesday as a southwesterly flow sits over our region with temperatures slightly below average there will be a couple chances for showers and thunderstorms especially on Monday and Tuesday. Your weather is not likely however there is a possibility for some isolated severe cells depending on how much instability builds in. Be happy however I just heard in Montana that there is a possibility of a winter storm headed their way this week so could always be worse in Manitoba. Calmer weather is likely throughout the rest of the week