Convective Discussion
Isolated thundershowers are occurring over northern Quebec this morning. Smaller cumulus clouds are widespread across Labrador. Also, Radar is currently detecting an area of rain over southeastern Newfoundland.
Technical Discussion
A surface low and its associated frontal wave east of Hudson Bay will advance over northern Quebec today. A 20 knot southwesterly low-level jet is supplying ample moisture and instability to support thunderstorms southeast of the low. Temperatures in the 20-24 degree range and dewpoints approaching 15 should be enough to fuel isolated thundershowers with CAPE values in excess of 500 J/kg west of Labrador this afternoon. Some of these storms could propagate over Western Lab with some help from a 40-50 knot westerly upper jet.
A frontal band continues to maintain a very moist air mass over southeastern Newfoundland. The sounding from St John’s West indicates a moist profile from the surface up to 850mb and again from 500mb and up, with precipitable water of 47mm! A series of vorticity centres will support isolated thundershowers along the frontal band throughout the day.
Regional Impacts
New Brunswick, Prince Edward Island and Nova Scotia
Nil.
For Newfoundland
Heavy downpours for the southeast.
For Labrador
Lightning and possible gusts for western Labrador.
Jean-Marc Couturier