Regional Impacts
Today
NB: Potential for severe thunderstorms giving strong wind gusts, small hail, locally heavy rainfall and slight risk of a tornado.
NS/PEI/LAB: Chance of isolated thundershowers giving local heavy rainfall.
NL: None.
Tonight
NB/PEI/NS/LAB: Isolated thunderstorms giving locally heavy rainfall.
NL: None
Tomorrow
NL/LAB: Scattered thunderstorms giving brief strong wind gusts, small hail and locally heavy downpours.
NS/PEI : Isolated thundershowers.
NB: None
Convective Discussion
A stationary upper low sits over Hudson Bay, with a cold front that will progress eastward today across Maine and into New Brunswick by late this afternoon. Ahead of the front this morning, showers and embedded isolated thundershowers have persisted across northeastern New Brunswick, with some clearing expected early this afternoon prior to the cold front. This should allow for enough daytime heating for MLCAPE values to reach of exceed 1250 J/kg across central and western New Brunswick. With stronger southwesterly winds increasing with the approaching front, effective shear may reach 40 kt, with some indications of moderate low-level shear and storm relative helicity, storms that develop may either organize into lines or possible supercells with the risk of a tornado ahead or along the front. There is also an increasing 250mb jet moving into the Maritimes, and in an ideal left exit region, allowing for divergence aloft and the maintenance of storms. The main hazards will be strong wind gusts of 90 km/h, hail of 1-2cm and heavy downpours with rainfall rates of 30-40 mm/h possible. The front extends also into southwestern and southcentral Labrador with possible isolated embedded thunderstorms.
A short-wave trough is also moving across the southern Maritimes marine district and some interaction with this system, possible clearing skies in the western Nova Scotia and the cold front may help with potential storm development also along the Bay of Fundy extending northeastward into Prince Edward Island late this afternoon and evening. Heavy downpours are the likely main threat with these given the orientation of storm development and possible training storms.
With an increasing 250mb jet spreading into the Maritimes tonight, storms may persist overnight across southeastern New Brunswick, Prince Edward Island and central Labrador giving heavy downpours.
For tomorrow, the cold front continues into eastern Labrador and Newfoundland while the shortwave moves across the eastern Maritimes marine waters and across southeastern Newfoundland with convection. There will be the risk of brief strong wind gusts, small hail and locally heavy downpours.
Thunderstorm Outlook for Today
Thunderstorm Outlook for Tonight
Thunderstorm Outlook for Tomorrow
Forecaster: McArthur