In true Southern Manitoba fashion, one that historically sees many use May Long Weekend as the unofficial kick-off to Summer activities, the refrain of, "Hey, at least it's not raining on May Long," may be the positive spin we need to take looking at the forecast for Thursday and Friday.
"Cold and wet May Long Weekends are not unfamiliar to us, but considering the well above average precipitation and below average temperatures we've had the last four to five weeks, seeing sunny but cool Friday through Sunday is a bonus," said CMOS Accredited Weathercaster Chris Sumner. "Before we get to that, another round of substantial rainfall is in the cards Thursday afternoon through to Friday morning."
According to Sumner, a low pressure system crossing the Southern Prairies, and a low moving northward out of the Dakotas, will combine to tap into a moisture rich air from the Gulf of Mexico. That will set the stage for significant precipitation throughout a good portion of the province.
"Early estimates are placing rainfall totals in the 15 to 30mm range for the Red River Valley and Southeastern Manitoba," noted Sumner. "Based on current model runs, the southwestern corner of the province may see a little less, topping out in the 10 to 20mm range. I want to stress, similar to the last several systems that have impacted the region, those totals will be storm-track dependent, and could fluctuate significantly depending on how this all plays out."
Rain isn't the only form of precipitation we'll be seeing from this system. Sumner added, as the low pulls eastward, northerly winds will develop, gusting between 50 and 60km/h.
"Those winds will pull down much cooler air from northern Canada, and that cooler airmass mixing with the moisture laden low will produce a snow-rain mix Friday," he said. "We're expecting that unwelcome combination to end by around noon, with a cloudy afternoon set to kick off May Long Weekend, but again, at least there's no rain in the forecast Saturday through Monday."
Temperatures will be well below average for this time of year today through Victoria Day. Daytime highs Thursday we'll be in the 13 to 15 range, cooler Friday because of that cold air-mass sinking southward, topping out around 6 to 8 degrees. For the weekend, as sunshine returns, and high pressure settles over the Prairies, temperatures will inch upward over the three day stretch starting in the low double digits Saturday, and landing around 15 to 17 on Monday. Sunny conditions are expected Saturday through Monday, at this point.
"And for those who have already planted their flower beds and vegetable gardens, that 'getting it done' early season risk taking may mean covering things up a couple of nights," said Sumner. "Thursday, Friday and Saturday nights are expected to be quite chilly, with overnight temperatures forecast to get very close to freezing. Keep an eye on those lows, and have your blankets ready."