Regional Impacts
Today:
NB: Risk of severe thunderstorms with heavy downpours, strong wind gusts and a non-zero threat of a tornado over Madawaska and western Restigouche county.
NL: Risk of thunderstorms with locally heavy downpours and strong wind gusts.
LAB/PEI/NS: None
Tonight:
Isolated embedded thunderstorms giving locally heavy downpours.
Tomorrow:
NS/NL/LAB: Risk of thunderstorms giving locally heavy downpours.
Convective Discussion
For today, the threat of severe convection increases for northwestern New Brunswick as a low pressure system tracks northeastward over southeastern Quebec and toward Labrador by Friday. Convection has been ongoing this morning along the St. Lawrence towards northern Newfoundland while an MCV materialized ahead of the low centre over the Great Lakes. Looking at the 12Z Caribou sounding and clear skies over much of central and northern Maine and New Brunswick, should convective temperatures be reached (>31C), there is the potential for MLCAPE values of 1000-1500 J/kg, deep 45kt layer shear and further advection of high precipitable water (50 mm) from the Gulf Stream. There may a slight warming in the 500mb temperature leading to a limit in destabilization. However, lift from the approaching cold front as well as the other ingredients will aid in the potential for multicell lines or potential supercells this afternoon and evening across northern Maine and into New Brunswick. Heavy rain and strong wind gusts will be the main threats with convection that develops but there is also a slight threat of a tornado over Madawaska and western Restigouche counties where the SRH values exceed 100.
Troughing over northern Newfoundland continues eastward where some embedded thundershowers may continue into the afternoon where heavy downpours will be the main threat along with brief strong wind gusts.
For tonight into Friday, the cold front associated with the low pressure system will track across the Maritimes tonight and across Newfoundland on Friday giving embedded thunderstorms. As well, moderate to heavy rainfall is likely ahead of the low centre for central and eastern Labrador overnight and throughout Friday.
Thunderstorm Outlook for TODAY
Thunderstorm Outlook for TONIGHT
Thunderstorm Outlook for TOMORROW
Roberta McArthur