Atlantic Canada Weather Blog: Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

NFLD… today eastern Labrador and northern NFLD, isolated thunderstorms with some stronger wind gusts. Rainfall likely less than 15mm, unless back build storms develop. Tomorrow western Labrador, isolated thunderstorms possible.

PEI and NS… no thunderstorms expected

NB… Thunderstorms tomorrow could bring some gusty winds and locally heavy downpours.

Convective Discussion

A ridge of high pressure currently across the region will dominate the weather in the short term as it slowly slides eastward over the next couple of days. The upper jet is not in a favourable position, with most of the Atlantic region on the left exit side of the departing jet streak.

A weak trough will approach the region overnight, and by tomorrow afternoon, it is expected to extend from Labrador through the Saint Lawrence River Valley. Surface moisture is relatively limited today, with dew point temperatures around 10–15°C, but values are expected to increase somewhat tomorrow ahead of the approaching surface trough — possibly exceeding 16°C in northern New Brunswick and reaching over 14°C in western Labrador.

Over eastern Labrador and the Northern Peninsula of Newfoundland, surface CAPE values could exceed 1000 J/kg today. As a result, scattered thunderstorms are expected to continue. Although updrafts are expected to remain weak, some locally heavier downpours are possible. Quasi-stationary or back-building thunderstorms may also develop and should be monitored.

With improving dynamics tomorrow, there will still be a limited amount of potential energy, with surface CAPE values possibly reaching 1500 J/kg. While updrafts are not expected to be particularly strong overall, small changes in surface dew points could significantly impact updraft strength. Nonetheless, the environment will remain marginally supportive of isolated wind gusts and locally heavy downpours.

Thunderstorm Outlook for Today