Several rounds of severe thunderstorms have left parts of the Central Plains, Pembina and Red River Valleys drenched this morning. Not one, not two, but three waves of severe thunderstorms rolled through the region, with warnings issued for several areas south of Portage including Morden, Winkler and Altona. The warnings came between late afternoon Monday and early this morning.
A tornado warning for southeastern Manitoba triggered the emergency broadcast system on CFRY/Mix 96/Country 93 around 4:30 p.m. on Monday as well. Despite heavy rains nearby, the city of Portage la Prairie received minimal amounts around 1mm.
"The first round of storms developed mid-afternoon Monday, and that was followed by a second round early in the evening between 6 and 8 p.m., with the final round rumbling through the region between 1:30 a.m. and 3:30 a.m.," noted CMOS Accredited Weathercaster Chris Sumner. "The storms developed along a warm front that was pushing northward into Southern Manitoba from North Dakota, and then they were essentially riding along that front in a generally easterly to northeasterly track. Because the front was moving northward relatively slowly, many points within those warning areas saw three rounds of significant rainfall, which is reflected in our Rainwatcher readings this morning."
Sumner noted it is unusual to have see Severe Thunderstorm Warnings issued in mid to late September, because typically the atmospheric conditions necessary to produce that kind of weather is usually not present.
"Severe weather potential is dictated by moisture availability, instability and shear in the atmosphere as well as a trigger to get things started," he said. "Usually, by this point in September, instability and atmospheric moisture are not within the range to kick start things. That wasn't the case yesterday as warm, moist air being pumped into the region by an upper southwesterly flow made things possible, along with the trigger of that warm front."
The first round of severe thunderstorms also prompted Tornado Warnings for the R.M.s of Hanover (including Steinbach), La Broquerie, Ste. Anne and Reynolds. Environment Canada issued the Warnings based off Doppler RADAR imagery which indicated rotation in one particular thunderstorm cell.
The following rainfall totals are for Monday, September 16th through 6am Tuesday, September 17th and are courtesy of the Manitoba Ag Weather Network:
Winkler - 132.6mm
Morris - 92.0mm
St. Pierre - 87.5mm
Steinbach - 74.1mm
Altona - 56.2mm
Cartwright - 21.2mm
Carman - 14.0mm
Starbuck - 12.6mm
Elm Creek - 8.4mm
St. Claude - 7.1mm
25mm = 1 inch
A warm and humid day is in store for Tuesday, with highs around 23 and things feeling like 29, with a mix of sun and cloud expected after the rain tapers off in the morning. According to Sumner, similar conditions are expected for Wednesday, with southerly surface winds continuing to move warmer air into the region.
"Starting Wednesday night, we are looking at multiple chances for showers through the end of the week and into the weekend," he noted. "A couple of upper level lows will bring those chances, but there are a number of factors that will play into whether we see additional severe thunderstorm activity, with the next potential possibility Wednesday afternoon and evening. Generally speaking, temperatures are expected to start trending downward Thursday and into the weekend, with seasonal, to slightly below, conditions forecast for the start of next week."
Average daytime highs for now are 17 degrees daytime and 5 degrees overnight.