The old saying goes April showers bring May flowers, and based on the current rainfall projections for this weekend, that should mean we're up to our ears in flowers by the time next month rolls around. Environment Canada has issued a Rainfall Warning for the Red River Valley and Southeastern Manitoba, including the Morden, Winkler, Carman, Altona, Emerson, Morris, Vita and Steinbach regions. A Winter Storm Watch and Freezing Rain Warning continues for all of Southwestern Manitoba including the Melita, Boissvevain, Killarney, Pilot Mound and Manitou regions.
"Without a doubt this moisture packed system will bring a wet weekend to the province," said CMOS Accredited Weathercaster Chris Sumner Friday morning. "We are in for a significant amount of precipitation, and that's for all regions south of the Trans Canada highway. This Colorado Low's storm track continues to evolve, and like I've mentioned throughout the week, that will impact where mostly snow falls versus mostly rain, but at this point it's still looking like the Red River Valley and Southeastern areas will see more rain than snow, with the bulk of the rainfall coming Saturday."
According to Environment Canada, snow and freezing rain will quickly changeover to rain Friday morning, which will persist through Saturday with some areas receiving more rain Saturday night and Sunday. Total rainfall amounts of 30 to 60mm ware expected.
"We are also keeping an eye on the possibility of the first thunderstorms of the season," noted Sumner. "The warm, moist and unstable air being pulled up from the Gulf of Mexico into this system will lend itself to the development of thunderstorms, so don't be surprised if you hear a clap of thunder of two Saturday. That possibility is highest along the U.S. border in the Red River Valley and Southeastern corner of the province."
Southwestern Manitoba is bracing for a significant snowfall event, in addition to seeing rainfall, as this system tracks through the Dakotas over the weekend. That wintry mix will see light snow transition to rain persisting until Saturday afternoon. The transition back to heavy, wet snow is expected to occur from west to east through Saturday afternoon and evening. Storm-total snowfall accumulations of 20 to 50 cm are still expected by Monday afternoon for areas currently under the Winter Storm Watch.
"We are in for a lot of moisture over the next 48 to 72 hours, and with the frost still in the ground, and many areas still saturated with the Spring melt, overland flooding is something to keep an eye on in the coming days," explained Sumner. "The province has issued an Overland Flood Warning, noting the factors I've mentioned, in addition to ditches and drains still filled with snow and ice may lead to some overland flooding over the weekend. If you are in an area prone to that, it's certainly something to keep an eye on."
The weekend will start rainy, but will end snowy across much of Southern Manitoba as the Colorado low pulls eastward toward Ontario and colder air is brought into the low by northerly winds.
"As that cold air arrives, and temperatures drop as we get to Sunday, rain will turn to snow and last much of the day," he said. "Gusty conditions will also develop as we see that wind shift to northeasterly winds, up to 60 km/h on Saturday, and potentially between 70 and 80km/h Sunday. Those strong winds, combined with the expected falling snow, will more than likely bring blowing snow and reduced visibility into the conversation Sunday. Travel conditions will deteriorate throughout the day across much of the region, so keep a close eye on the forecast and road conditions."
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The low will move our area by Monday, with lingering flurries expected to start the week, as well as well below average temperatures for this time of year.
"An area of Arctic high pressure will slide southward to start the week, and that will allow very cold air for late April to flood into the region," Sumner added. "Sunday and Tuesday could be 15 to 20 degrees below average for this time of year, as temperatures sink to the zero to -5 range. We're expecting temperatures to start warming up mid-week as daytime highs push toward the 7 to 10 degree range, but lets keep in mind normals right now are around 14 during the day and +1 overnight."