Author: Brad

Brad lives in Winnipeg with his wife and two children and is the founder of A Weather Moment. He has loved weather from a very young age and has followed that passion through his life so far. He received a B.Sc. in Earth Sciences with Specialization in Atmospheric Sciences and is currently employed in the field of meteorology. You can find the author as WeatherInThePeg on Mastodon.

Thunderstorm Risk Returns

Brad Leave a comment

The risk for thunderstorms returns to the Red River Valley today as a cold front with a history of producing severe weather pushes into the region.

850mb Analysis from the GFS

850mb Analysis from the GFS model for mid-morning today.

We’ll see some clouds/light showers clearing out early this morning across the Red River Valley, leaving us in sunshine for the latter half of the morning and early afternoon. By early afternoon, a cold front will be draped N-S over the western RRV. With temperatures climbing into mid-to-high 20’s by mid-afternoon, there should be enough heat and moisture to get storms going along the cold front. It’s likely, but not certain, that some thunderstorms will deveop on a north south line from near Winnipeg south towards the International Border. These storms will track eastwards across the RRV through the mid-to-late afternoon.

They will certainly have the potential to be severe. This cold front has a history of producing storms capable of damaging winds, large hail, and isolated tornadoes. For us, conditions don’t look quite as favorable as they did yesterday in SK or the day before in AB. We’ll be looking at:

  • 1000-2000 J/kg of CAPE
  • LI values near -7
  • Bulk shear values of only 20-35kt
  • 0-3km EHI values only 1-1.5

Wind shear will be the biggest limiter to storm development today. Storms may struggle to develop a distinguished structure, which could result in a relatively tame outcome. There’s just enough support to not be able to rule a severe storm out, however, and I expect we’ll likely see some watches issued for the RRV midday. The main threats for these storms will be heavy downpours with rapid rainfall accumulation and large hail. There’s a secondary threat of strong winds and, while tornadoes cannot be ruled out, the threat for the RRV is nowhere near the threat yesterday in Saskatchewan. Ultimately, though, the chance for seeing storms depends highly on the speed of the cold front; we’ll have to wait and see how quickly it moves into the RRV today to refine the thunderstorm forecast.

Things should clear out in the evening before a chance for showers returns late overnight and Thursday morning as the main upper low tracks over the RRV. We’ll see a mix of sun and cloud on Thursday with a high near 25°C. Friday heading into the weekend looks fairly nice. Sunshine should dominate and temperatures will climb back into the high 20’s or low 30’s. We’re certainly shaping up for another above-average month for temperatures. If July’s mean temperature is above normal, it will be the 13th consecutive month with above-normal temperatures in Winnipeg.

Dog Days of Summer

Brad Leave a comment

The weather has been very warm so far this July and there is no sign of this pattern changing any time soon. The dog days of summer are in full swing.

A surface high pressure system will help keep the weather warm and calm through Monday and Tuesday

A surface high pressure system will help keep the weather warm and calm through Monday and Tuesday

Temperatures on Monday will remain warm, but will be fairly comfortable. High temperatures in Southern Manitoba will generally be in the upper twenties with low humidity. Tuesday should be a bit warmer than Monday, with highs near thirty degrees, but once again humidity levels will remain relatively low. By Wednesday the humidity will rise ahead of an approaching trough of low pressure. At this time it appears that there may be a risk of severe storms on Wednesday afternoon and evening in the Red River Valley and South-Eastern Manitoba as this trough runs into a hot and humid airmass. However, the timing of the front is still a bit uncertain, and the speed at which is moves will determine which areas are at risk for storms on Wedensday.

At this point you can probably predict what next weekend has in store…yes you guessed it, more hot weather. It looks like we may be lucky enough to get one cooler day on Thursday, with high temperatures close to normal (i.e. in the mid twenties) before we heat up again for the last weekend of July.

Warm Weather Continues; Little Rain in Sight

Brad Leave a comment

Upper-level flow for this evening

Upper-level flow forecast for this evening over Central North America from the GEM-GLB. Of note is the shortwave pushing out of Alberta. This feature will flatten the upper ridge over Southern Manitoba and bring some unsettled weather to SW MB on Sunday.

Rainfall will continue to be spotty and elusive over the Red River Valley as warm temperatures persist and and upper-level ridging maintains it’s hold over the Eastern Prairies. While numerous systems trek through Alberta and Saskatchewan into Northern Manitoba over the next few days, mainly sunny skies are in store for us as we head into the weekend with daytime highs generally around 28°C across much of the Red River Valley. Humidity levels will be lower today and through the weekend than they were on Thursday, however overnight lows will still remain relatively warm in the high teens.

On Sunday, a low pressure system will move eastwards out of Saskatchewan through the Interlake region. Models are suggesting that a band of nocturnal thunderstorms will push into Southern Manitoba on Saturday night and push eastwards before dying around mid-morning. It’s far too early to know where these storms will actually occur, so we’ll be sure to provide updates in the comments. After that band of thunderstorms falls apart, the rest of Sunday actually looks quite nice with clearing skies in the RRV and a high near 30°C.

Next week looks to start off quite pleasant with little chance of precipitation in the RRV until mid-week.

Hot to Really Hot Weather on the Way

Brad Leave a comment

Southern Manitoba will quickly heat up to be extremely hot for the later half of this week, while any rain/thunderstorms will remain fairly elusive through the Red River Valley.

You might need one of these on Thursday...

You might need one of these on Thursday.

A strong thermal ridge will start pushing it’s way into Manitoba toady with 850mb temperatures of 22-24°C. This will really crank up the heat over the Red River Valley. Today will be our coolest day over the next few days, with temperatures “only” climbing to 27°C with light winds from the north. There will be some clouds around today and a very slight chance of a shower or two late this afternoon as the warm front starts pushing into Southern Manitoba. Winds will shift to the south overnight tonight, with a low around 18°C.

The southerly wind should help clear the air of any haze and smoke that’s remaining in the Red River Valley, which will allow the full power of the sun to help cook the atmosphere on Thursday. 850mb temperatures will climb towards the mid-20’s, which will help surface temperatures easily climb into the mid-30’s. Two uncertainties exist to the daytime high:

  1. Moisture. The higher the dewpoint is, the more energy it takes to heat it up. That makes it harder to reach really high temperatures when the dewpoints are high than when the air is dryer. For Thursday, the NAM currently predicts dewpoints to be right around 20°C, the GFS pumps dewpoints up to nearly 25°C, and the GEM has them right around 22°C.
  2. Wind direction. Winds will be southerly to start the day, however a weak trough pushing across the RRV should start to shift the winds to southwesterly. When a southwesterly wind is in place over the RRV, it helps to increase daytime highs by a few degress as the wind downslopes over the western escarpment and heats up a little bit. The air often drys out a bit in this process as well, which aids in helping the temperatures increase a bit.

Should the moisture end up being on the lower side and we do get a southwest wind in place over the the RRV, temperatures could potentially shatter our previous hottest day of the year. Models indicate temperatures of 37-40°C are possible over the southern RRV, while temperatures of 34-37°C can be expected over the northern RRV. I’d be very hesitant to say we’re going to hit 40°C in Manitoba on Thursday, especially with dewpoints in the 20’s. It will certainly be an extremely hot day, and when the temperature and the dewpoint are taken into consideration, widespread humidex values of 40-45 will be seen across Southern Manitoba with the potential for isolated spots to see even higher values. Either way, it’s almost certain we’ll see temperatures at least in the low-to-mid 30’s over the RRV, with humidity making it feel much closer to the low 40’s.

Things will cool off a bit on Friday as some less-warm air filters in aloft. 850mb temperatures are expected to drop to a more modest 15-20*deg;C, which will cap daytime highs to “only” 30 or 31°C. Dewpoints should also be a good 3-5°C lower, making it a slightly more comfortable day.

There’s a slight chance of a shower or thundershower on Thursday evening over the more northern portions of the Red River Valley, although any activity will likely stay in the Interlake region. Our chances for showery weather increase into the weekend as cooler air beings to inflitrate it’s way in aloft while down here at the surface we remain near the nose of a thermal ridge. Highs will remain in the high 20’s through the weekend.