Chilly Mid-Week, Gradual Return to Above-Normal Temperatures

Today will be off to a chilly start as rain showers or flurries move through the Red River Valley alongside near-freezing temperatures and a gusty northwesterly wind. Fortunately, this brief outbreak of colder weather will be short-lived as above-normal temperatures gradually build back into the region for the weekend.

Cool & Soggy Wednesday

It will be cool and soggy today for Winnipeg & the Red River Valley as a brisk west to northwesterly wind carries flurries & showers through the region. Much of today’s precipitation will fall as rain, however for several hours this morning snow will be possible. No significant accumulations are expected since temperatures (and the ground) will be above zero, but it could be enough to dust grassy areas and cars.

Temperatures will be below-normal today with the high temperature topping out at just 6°C.

RDPS 12hr QPF valid for 00Z Wednesday October 28, 2015
RDPS 12hr precipitation totals valid for 00Z Wednesday October 28, 2015

The wind will be out of the north to northwest for much of the day at around 30km/h with some gustiness on top of that, however as an inverted trough passes through late in the afternoon & the pressure gradient straightens out, winds will increase to 40–50km/h this evening for several hours before tapering off as a ridge of high pressure pushes in overnight. Temperatures will drop to around 2°C overnight.

Warming Trend for Second Half of the Week

Thursday and Friday will be slightly more pleasant days with temperatures gradually returning to seasonal values. Both days will see a fair amount of cloud through the Red River Valley, although Thursday has the potential for a few more sunny breaks than Friday does. Daytime highs will be just above the seasonal value of 6°C on both days with a high of 7°C expected on Thursday and a high of 9°C on Friday. No precipitation is expected on either day and overnight lows will sit near the freezing mark both Thursday & Friday nights.

Well Above-Normal Temperatures Return for the Weekend

Snow suits will be absent for Halloween this year as temperatures some 6°C above normal will result in a relatively mild end to October.

CPC 6-10 Day Temperature Outlook
The Climate Prediction Center’s 6-10 day outlook is predicting a fair chance for above-normal temperatures early next week.

Daytime highs in the low teens are expected this weekend and into the beginning of next week thanks to a broad zonal flow that will develop aloft, keeping the colder Arctic air in the north and spreading milder Pacific air across the southern Prairies.

There’s a bit of uncertainty as to precipitation; most models show a dry weekend ahead, however the GFS wants to push a disturbance through midday Saturday bringing a shot of rain to the Red River Valley. We’ll keep an eye out as that situation develops and be sure to have a complete Halloween evening forecast in our Friday forecast. Other than that, it does look like we’ll head into a more unsettled pattern next week, with potentially the first “real” snowfall of the season, so enjoy the coming mild weather while you can!

Warmer Weather Gradually Returns

The Red River Valley had an abrupt cool-down Monday evening as a dry, but quite potent, cold front pushed across the Red River Valley, dropping some of the warmest temperatures in the country by 10°C in a matter of an hour and returning the region to far more seasonal temperatures. The foray into fall will be brief, however, as warmer weather is already set to build back into the region over the coming days.

Today will be a bit of a mixed day; skies will be cloudier than not, but fortunately things should remain fairly dry with a high temperature near 17°C. The wind will be noticeable, though, as it builds out of the east through the morning to around 30–40km/h with some gustiness on top of it. The cloud will stick around through the night with an increasing chance of showers overnight.

4km NAM Forecast Sounding for Winnipeg valid early Thursday morning.
This forecast sounding for Winnipeg from the 4km NAM shows tremendous vertical velocities on Wednesday morning.

There’s uncertainty to how intense the shower activity will be and whether or not there will be any thunderstorms over the Red River Valley. At this point, the weather model most in favour of thunderstorm development has been the NAM model from the NWS. It’s difficult, though, to fully believe its output given some of the parameters it has been outputting.

Shown above is a forecast sounding from the 4km NAM model for early Wednesday morning. It reveals a high likelihood of thunderstorms, however what’s more important is the omega values it’s producing. Omega (Ω) is a measure of how fast air is moving up or down in the atmosphere, and often has values in the range of ±5–10µb/s. In strong summer-time convective situations, Ω can have values in excess of –60µb/s. The 4km NAM is producing values in excess of –160µb/s, which seems a bit physically implausible. The NAM follows similar ideas, which gives me hesitation to jumping on board the thunderstorm train.

Ultimately, any precipitation over our region is part of a secondary area of lift enhanced by confluence near a deformation zone of a larger system passing to our southeast. Because of that, it seems quite likely that we’ll see some shower activity this evening or overnight with a slight chance of an isolated thunderstorm or two. The more extreme solutions being presented by the NAM seem misplaced given the large-scale dynamics present. There’s always an off chance that the model that seems way out to lunch is correct, but I wouldn’t bet the farm on it at this point.

Thursday will be a bit of a damp day with cloud and scattered showers sticking around for at least the first half of it. Any remaining precipitation will taper off through the afternoon, but the cloud looks like it will stick around through the overnight, sustained by another approaching area of lift. Expect a high in the upper teens on Thursday with an overnight low in the low teens. Fortunately, the winds will be fairly light.

Warming Trend Begins on Friday

Friday will see the heat return to Winnipeg & the Red River Valley as a warmer air continues to push its way into Southern Manitoba. Winds will gradually pick up out of the south to around 30km/h in the afternoon as the temperature climbs into the low 20’s, some 5–8°C above seasonal highs for this time of year. The cloud will gradually push out of the region through the day, likely leaving us with more sun than cloud in the afternoon, making for pleasant fall conditions.

Overnight lows will fall just to the mid-teens on Friday night.

Beautiful Weekend Ahead

This weekend looks positively beautiful for late September. Saturday looks to be a fairly sunny day with highs climbing into the mid- to upper–20’s with winds gradually tapering off. It looks like there will be a chance for some rain or thunderstorms over lake Winnipeg (mainly the South Basin & the Narrows) and areas east through the overnight period as a cold front pushes into the region.

Forecasted 850mb temperatures from the GDPS weather model
The GDPS is forecasting a surge of warm air pushing into Manitoba on Saturday, shown by this 850mb – about 1.5km off the ground – temperature forecast.

Sunday looks cooler than Saturday with a slight chance of morning showers, but all in all it should still be a pretty nice day. Mixed skies will accompany a high in the low–20’s, still some 5–10°C above normal. Winds don’t look to be too much of an issue either. All in all, for this late in the year, the weather this weekend looks fantastic.

Next week has the potential to be more unsettled, as many models are showing a train of disturbances pushing across the Northern Plains of the U.S. These systems can often bring rainy weather to Southern Manitoba, but at this point it’s far too early to say one way or another how things will go. For now, enjoy the rest of the week and the coming warmth!

Slowly Warming Up

Conditions will slowly warm this week as the weekend’s potent weather system departs our region. Temperatures should return to seasonal values by midweek.

Monday

Today will remain on the cool side, with high temperatures in the upper teens. Winds will remain gusty as well, as we continue to deal with the stiff north-west flow behind the weekend’s low pressure system. Skies will finally become sunny however, which is a welcome change from the grey and rainy conditions of the weekend.

Tuesday

Tuesday will see temperatures warm further, with highs reaching the low twenties. Skies will remain mainly sunny and winds will be light making for a nice day.

Wednesday

Wednesday should see temperatures climb back toward seasonal, or even above-seasonal values. High temperatures will be in the mid to upper twenties as we return to a mild southerly flow. Skies may be somewhat variable due to the passage of an upper-level disturbance.

Gradually Warming Up

Temperatures will gradually warm this week as we move back into more spring-like conditions.

Monday will remain cool as a strong high pressure sits just off to our north
Monday will remain cool as a strong high pressure sits just off to our north

Monday

Monday
1°C / -4°C
Mainly Sunny

Today will remain on the cool side as a surface high remains parked off to our north. This high will keep arctic-ish air over southern Manitoba, suppressing high temperatures to near the freezing mark. Winds will be light however, making for a pleasant, but slightly chilly day.

Tuesday

Tuesday
4°C / -1°C
Mix of sun and cloud

Tuesday will see a slight uptick in temperatures over Monday, with values climbing a few degrees above zero. Skies will be a mixture of sun and cloud and winds will be breezy from the east. There may be a bit of snow on Tuesday night as a strong upper-impulse moves through, but accumulations will be small.

Wednesday

Wednesday
7°C / 0°C
Mainly Sunny

Wednesday will see temperatures increase further, with highs in the mid to upper single digits in southern Manitoba. Skies should remain mainly sunny with light winds, making for a nice day!

Long Range

The long range forecast shows increasingly warm temperatures toward the end of the week. Models suggest that above-normal weather will last into mid-April at least. This means highs frequently into the teens and very long range models even show our first 20C readings of the year!