Updated: Jul 11, 2019
Here we go again. Some severe thunderstorms could be possible on Thursday as a warm front (depicted in red above) advects northward into central Manitoba. A trough of low pressure (in orange) and cold front will provide the focus for thunderstorm development in south-central to southeastern Manitoba on Thursday late-afternoon.
Threat Level: MODERATE
Confidence level (based on model trends): MODERATE
Impacted areas: NE North Dakota, SE Manitoba and Interlakes
Timing: late-afternoon to overnight
Main hazards: STRONG WINDS // SMALL to LARGE HAIL // POSSIBLE TORNADOES
Cities to watch: Peguis, Morden, Winkler, Gimli, Fort Alexander, Arborg, Winnipeg
*Cities to watch are color-coded, purple being highest likeliness of seeing significant severe weather and light-blue being low likeliness of seeing significant severe weather.
Why are we mentioning tornadoes?
You may be wondering why we included "possible tornadoes" in our main hazards. July is the climatological peak of tornado season for the Prairie Provinces. Considering this, the 850MB wind shear and the amount of MLCAPE, we included the potential for tornadoes. While the potential isn't as big as it was on Monday for Manitoba, we certainly could see some rotating storms on this day.
Above is a forecast sounding depicting what the atmosphere might look like before storms develop in the Interlakes Region of Manitoba. This profile shows veering winds with height (turning in the atmosphere), high storm-relative helicity (SRH), moderate instability and a great looking hodograph. Basically, all of this means that storms that enter this area could begin to rotate, become supercells and drop tornadoes.
So the ultimate question is will storms occur? The NAM 3km model today has been trending towards yes, with the latest 00z NAM being an outlier, showing storms in the late-evening. If storms develop in the late-evening, the severe threat will be much lower, so we will keep an eye on this. If storms develop in the Interlakes region in the late-afternoon and move into the aforementioned environment then supercells are possible with all severe weather hazards.
Timing: Thursday afternoon and evening.
Threats: 3-5 cm hail, wind gusts to 110 km/h
Thunderstorms will form in southern Manitoba ahead of a surface trough. Thunderstorms will likely be scattered along the trough late in the afternoon, congealing into a solid line around dark.