A Couple Unsettled Days, Then Warmer Weather Returns

As we quickly approach the beginning of fall, Winnipeggers can be happy to know that after the next couple days, the mitts can go back into the closet.

So what’s on tap?  For this evening, most of the RRV should see heavy drizzle or light rain as a trough line moves through that connects two low pressure systems: one in central Saskatchewan and one in South Dakota.  The precipitation will move out overnight and tomorrow will bring mainly cloudy conditions with scattered drizzle and moderate northwest winds.  Showers or drizzle may make an appearance downwind of the lakes, but nothing widespread is expected.

On Wednesday afternoon into the overnight period, areas close to the International border may see some showers spread north from a system moving through the Dakotas, however it seems to me that the models are underestimating the effect of the ridge that will be positioned across the central Prairies.  It’s likely that the dry outflow from the ridge will keep things cloudy instead of rainy over southern areas of the RRV.

The rest of the week looks quite nice with sunny skies through much of the RRV and temperatures climbing into the high teens.  There’s definitely a chance that Winnipeg will see temperatures over 20°C, however I’d currently bet on just high teens as the models tend to over-amplify upper ridges in 60+ hour forecasts.  A string of disturbances will trek across the Dakotas, and there is a slight chance that some precipitation will nudge into areas near the international border, but for the most part, expect the second half of the week to be warm and dry.

As one other note, it looks that from here out, overnight lows look to be in the 5-10°C range, which is good news for farmers in the RRV, many of whom were able to escape the frost which affected Winnipeg and areas north and west on Saturday night.  Drier, frost-free conditions are sure to be good news for many of the province’s farmers.

Afternoon Showers & Cool Weather (and Frost!)

Afternoon showers in the RRV with the slight chance of an isolated thunderstorm or two will mark the arrival of a much cooler arctic airmass in Southern Manitoba.

Under cloudy skies most of the day, the RRV will see increasing southerly winds today as a low pressure system approaches from Southern Saskatchewan.  As the low passes by this afternoon into the early evening, the RRV will see widespread showers with the slight chance of a thunderstorm.

Friday 21Z 3hr QPF w/MSLP Panel from GEM-REG 00Z Run

Current indications are that most of the RRV will see 5-10mm of rain.  There may be accumulations up to 15mm in a few isolated localities due to enhanced convection.  The rain will end by midnight with only a slight chance of a few hang-back showers in the cooler air.

The main story after that is that Winnipeg will be under a much cooler airmass.

Sat 00Z 850mb Temperature Panel from GEM-REG 00Z Run

With current 850mb temperatures hovering around 6°C, expect a chill in the air in the mornings over the weekend as the 850mb temperatures get down to the -2°C range.  This should translate to overnight lows of -3 to 0 through much of southern Manitoba over the weekend. 

Pick your tomatoes if you haven’t!  This weekend certainly holds the potential for widespread frost with the cooler air moving in over the Province. The areas most likely to see frost would be areas west of the RRV, and locales in the RRV north of Winnipeg, with patchy frost possible to the south and southeast of Winnipeg.

Showers With A Chance of Thunderstorms Tonight & Friday

Showers and isolated thunderstorms will push into the Red River Valley tonight, signalling the start of the next major low pressure system to move across the prairies.

A low moving NE out of Eastern Montana has spread rain into much of Southern Saskatchewan through the day today, and is posed to bring more rain into Southern Manitoba.  Thunderstorms have initiated along a warm front draped W-E across North Dakota and will move northwards, supported by a 40-50kt southerly 850 jet and large scale ascent with a strong southerly flow aloft overriding the warm front.

Winnipeg should see rain beginning late this evening into the overnight period and through much of the day tomorrow as the precipitation will continue to blossom coming out of the United States.  All in all, most of the Red River valley should see 20-30mm of rain by the time the rain lets up on Friday evening, with local amounts possibly reaching 50mm underneath a few of those isolated thunderstorms, should they manage to develop.

This is, unfortunately, not good news to many of the Farmers in the RRV, who have had to battle saturated grounds through much of the latter half of the summer.  This is also bad news for the RRV in general, as we continue to have the soil re-saturated as we approach the winter freeze.  Should a long stretch of dry weather not occur, this wet fall could lead right back into a wet spring due to overland flooding.

It’d Be A Shame to Let the Puddles Dry Up

Don’t put your umbrella away yet; our wet start to September isn’t going to be going away any time soon…

I wish I had better news to share, especially for our farmers outside The Perimiter©, but more wet weather is in store as the cool and unsettled weather continues.  At least the mosquitoes won’t be much of a problem, right?

The first thing to note is the incoming surface ridge that will be moving across Southern Manitoba tonight and tomorrow.  Cool air combined with clear skies will drop our overnight lows down to 3-4°C in the city, with temperatures a degree or two colder outside the city.

Cool daytime highs trying to reach 20°C should persist through the weekend.  To begin next week, it appears as if another low pressure system will track through North Dakota, with a warm front draped across the state close to the international border.  I have decided to go with the NAEFS (North American Ensemble Forecast System) solution, as individual models have been varying their solutions a bit for this system:

This shows the probability of 10mm of precipitation or more through 00Z Sept 6 to 00Z Sept 8.  Current indications are that areas close to the border should expect rain through this period, with NAEFS indicating a 70-80% chance of >10mm of rain.  The probability decreases as you head north, but even for Winnipeg the probability of more than 10mm is still > 50%.  This solution will likely change, however I’m fairly confident in saying that people in the RRV can expect a gloomy, rainy Monday into Tuesday.

Things settle down for a couple days with highs near 20°C until the next system rolls through the Dakotas at the end of the week.

This system is currently forecast to be a bit further south, but the NAEFS still plasters the RRV with a 50-70% chance of > 5mm of precipitation from 00Z Sept 9 to 00Z Sept 11.

All in all, likely a rainy start to our week and rainy end to our week after a rainy middle of this week.  And to make things “worse,” there doesn’t look like there will be too much of a chance of thunder making an appearance, except for (most likely) the US side of the border with the first system.

I’ll go get my rubber boots and put them by the door.