Regional Impacts
Today:
NS&PEI: Scattered heavy downpours. Strong wind gusts are also possible for western NB in the evening.
NB: Isolated heavy downpours and strong wind gusts for western NB in the evening.
NL&LAB: None
Tonight:
NS&PEI: Scattered thundershowers giving locally heavy downpours.
NB: None
NL&LAB: Isolated heavy downpours for southwestern Newfoundland.
Sunday:
NS: Isolated heavy downpours over eastern areas.
NL&LAB: Isolated heavy downpours for southern Newfoundland.
Convective Discussion
A trough of low pressure extends over the Maritimes northeastward into central Labrador giving heavy downpours at times. The trough will slow down today as it gets blocked against a ridge of high pressure east of Newfoundland and a building ridge over central Quebec. This will increase the threat of training showers or thunderstorms this afternoon and overnight, enhanced by a 40KT LLJ which will be slowly tracking along the Atlantic coast of NS. Rainfall rates of 25 to 50 mm per hour are possible as precipitable water increases over the Maritimes but there is uncertainty in the amount of lightning expected versus just tropical downpours, which will make rainfall amounts highly variable. Areas of southern New Brunswick, aided by topographic enhancement in strong southerly winds, have already seen total rainfall amounts of 50 to 90 mm overnight and this morning. Meanwhile, a trough over southern Quebec will shift southeastward into Maine and western New Brunswick this afternoon and evening. Although there is increasingly favourable dynamics in that area under the left exit of the 250mb jet and effective shear near 30KT, CAPE remains fairly weak. The strength of any thunderstorms that do develop will be conditional on if cloudiness and showers from this morning clear. At this time, thunderstorms that do develop may not maintain for long, but there is still a small risk of organization into lines where strong wind gusts are possible.
For Sunday, the trough weakens as it slowly pulls eastward. Heavy downpours are possible for much of Newfoundland and southeastern Labrador. Where clouds clear out in the afternoon in Nova Scotia, convection may develop along the spine and drift southeastward.
Thunderstorm Outlook for Today
Thunderstorm Outlook for Tonight
Thunderstorm Outlook for Sunday
Forecaster: McArthur