Regional Impacts
Today:
NB: Scattered thunderstorms possible this evening over southern regions giving lightning, locally heavy downpours of 10-20 mm.
NS: Scattered thunderstorms possible this evening for western regions giving lightning, locally heavy downpours of 25-50 mm, small hail and 70-90 km/h wind gusts .
NL and LAB: Scattered thunderstorms possible through Labrador and parts of central NFLD today giving lightning, 1-2 cm hail, 70km/h wind gusts, and locally heavy downpours of 20-30 mm.
Tonight:
NB/PEI/NS: Scattered thunderstorms possible tonight giving locally heavy downpours of 20-30 mm.
LAB: Isolated thunderstorms for eastern area giving locally heavy downpours.
Friday:
NB: Scattered thunderstorms giving lightning, locally heavy downpours, small hail, and strong wind gusts.
LAB: Isolated thunderstorms giving lightning, locally heavy downpours, small hail, and strong wind gusts.
Convective Discussion
There are a couple of different features to track of interest today. An intense short wave trough that affected southern Ontario yesterday is moving over New England today and eastward towards the Maritimes tonight. Ahead of this trough, afternoon instability will increase along with moisture over southern New Brunswick and Nova Scotia. Although the main threat of severe weather remains west over New England given the dynamics and the timing of this feature, convection could persist into the overnight hours. An approaching 30KT 850mb jet, moderate 0-6km shear, and cloud top cooling will also aid in continued risk of convection overnight, giving the risk of lightning and heavy downpours into Friday morning as the trough axis exits east of Cape Breton.
An upper low over northern Quebec will shift southeastward across Labrador today and out over the Labrador Sea tonight with a trough extending southward into Newfoundland. Convection occurring this morning east of the low centre will persist into this afternoon. An area of concern lies in central to southeastern Labrador (left exit of a 250mb jet, an approaching 500mb cold trough, increasing moderate shear and MLCAPE values above 1500 J/kg) such that convection that develops this afternoon with daytime heating could organize into multicell lines. Freezing levels are also lower which could increases the hail potential as well. There is also the possibility of embedded convection over Newfoundland from an area of moisture moving in from the Gulf of St. Lawrence this morning.
For Friday, the short wave trough exiting Cape Breton will affect portions of the marine waters south of Newfoundland. Meanwhile, the next short wave over central Quebec will be quickly tracking eastward towards New Brunswick and the Gulf of St. Lawrence by Friday night. Ahead of this trough in the afternoon, scattered thunderstorms are possible over northern New Brunswick and southwestern Labrador.
Thunderstorm Outlook for Today
Thunderstorm Outlook for Tonight
Thunderstorm Outlook for Friday
