The same potent upper trough that was responsible for yesterdays severe convective weather in Manitoba is once again the focus for today in northwestern Ontario. Latest water vapor imagery shows strong vorticity center just south of Saskatchewan along the U.S. border in Montana. This will provide large scale ascent within the warm sector of the low.

The low is currently located near Charron Lake, MB just west of the elbow of Ontario. From here a warm front extends across northern Ontario currently in Pickle Lake and across to Kapuskasing and Timmins. The cold front is currently sitting right along the MB/ON borders from Charron Lake and extends down into MN along the ND and SD borders. As the low and wave progress ENE through today, the cold front as well as regions near the low centre will see thunderstorms develop throughout today and into the evening. The NAM/WRF surface forecast here shows the wave does not progress much during the day but does begin to surge ENE through the overnight period. Therefore there is a dual wave that develops overnight with the primary wave in ON and a secondary cold front in southern MB. With MLCAPES forecast to be between 2000 - 2500 J/KG in northwestern ON and between 400-600 J/KG in central MB there will be two primary areas for thunderstorms development. 1. The Interlake region in MB where heavy downpours and large hail are the main threat. 2. In northwestern ON where regions along the the cold front (from Fort Frances across to Thunder Bay and up to Big Trout Lake) where weakly veered hodographs and shear vectors parallel to the cold front will make for fast moving splitting cells with some supercells in the area. Also regions along the warm front will see some convection as well where hail and heavy downpours are the main threat. As the 850 mb low level jet strengthens this evening expect storms to increase in intensity and thus bringing in the threat of a few isolated tornadoes. The largest threat for tornadoes looks the be in the region outlined by Sandy Lake, south to Goose Lake, then east to Pipestone River Provincial Park. The peak tornado threat will be between 8 pm and 2 am local time. Storms that do initiate will progress NE at about 30 to 50 knots and continue through the overnight period, but gradually decrease in strength as they push NE.