Heat and Humidity to Spark Severe Weather, Calmer more seasonal weather midweek.

Significant severe weather is expected to occur, over the coming hours as a warm front drives north out of North Dakota. A trough is also expected to stall over the interlakes region overnight, that will enhance thunderstorm probability from the inter lakes south into areas along and south of the international border.

A moderate risk of severe weather is on tap for all of southern Manitoba over the coming hours, as a frontal wave moves into a warm and unstable airmass, thunderstorms have already started to occur over portions of southwestern Manitoba, with a few storm cells ongoing in the Red River Valley. 

 The ingredients we have for severe Weather tonight (MIST Principle from A Weather Moment)
Moisture- With Dewpoints in the 70's (mid twenties) significant moisture of is available for storms to develop, and drop significant amounts of rainfall over a short period of time when training thunderstorms occur.,
Instability: Instability is there for explosive storm development with CAPES in excess of 2,000 to 3,000 J/Kg, lifted indicies of -6 to -10 , along with Sweat indicies between 300 to 400 will contribute to severe thunderstorm development throughout the night in much of southern Manitoba.
Shear: Shear is lacking a cross a large portion of the province, Storm Relative Helicity is on the order of 200 to 500 m2s2 possibly may contribute to storm organization but shear and significant tornado parameters are too low for tornadoes for the night ahead.
Trigger: Warm front along with a associated trough will provide for a large area of lift throughout the southern part of Manitoba, main area of focus will be along and south of the trans Canada highway including areas of the Inter lakes. 

As a result we expect thunderstorms to continue to form west to east along a warm front, potential for more potent storms to develop, once that occurs later this evening the possibility of a squall line or something down the lines of a multicell convective complex. Large hail up to golf ball size hail, winds in excess of 100 km/h, rainfall amounts of 50mm are possible, along with Frequent Dangerous lightning. Storm threat expected to ease into the overnight period.