Mostly Sunny

Models indicate that there is a chance of showers late overnight and into tomorrow morning, and then we should return back to mostly sunny skies before cooler air pushes in for the weekend.

The GEM-REG model is currently the most aggressive in pushing rain through southern Manitoba tomorrow morning, as shown above in the 12H precipitation accumulation map valid 12Z Wednesday morning.

Sunny skies this evening should cloud up overnight as a cold front passes through southern Manitoba.  Most models lean towards just a slight chance of showers for the RRV, with a majority of the precipitation occurring in Northwestern Ontario.  The GEM-REG model, however, fires up a fair line of showers along the front as it passes through overnight, giving up to 5mm of rain to the RRV.  This solution currently looks to be an outlier, however so far this cold front has had a good history of precipitation along it.

Either way, it’s fairly certain that any accumulations that do develop should stick to the 5mm range, and will certainly be less than 10mm.   After the front passes through, we should see another mostly sunny day with a few clouds scattered around.

By Friday, as an upper ridge builds in the western Prairies, we should see a brisk northerly flow develop as a cold front slumps down through the province.  Expect cloudier skies than the forecast currently suggests in the afternoon.  The good news is that despite the chill in the air, precipitation is looking like it should stay north of Winnipeg.  Saturday looks to be a chilly day with 850 temperatures struggling to get above 0 for most of the RRV, and then we begin to transition back to warmer weather for the beginning of next week as the upper ridge moves east.

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.