Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Atlantic Canada: No thunderstorms forecast.

Convective Discussion

Dewpoints across NB are near 10 this morning, and Nova Scotia/PEI are drying out as well. Morning soundings at Caribou and YQI are very dry 850mb to the trop. Smoke and Haze blanket the southern Maritimes. And a very stable ridge of high pressure is anchored over the region for much of this week. No convection is forecast or progged over land at this time. TS Dexter brings an embedded lightning risk but remains well offshore, simply skirting the southern-most marine district. See FQCN20 and Tropical Cyclone Information Statement for detailed information about that system.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Forecaster: Tirone.

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

Newfoundland and Labrador… low risk of isolated thunderstorms over central Newfoundland, heavier downpour potential in thunderstorms.

New Brunswick… a chance of thunderstorms with locally heavy downpours.

PEI and Nova Scotia… low risk of isolated thunderstorms, heavier downpour potential in thunderstorms.

Convective Discussion

A weak surface trough could potentially trigger thunderstorms over New Brunswick and possibly Newfoundland. Dew point temperatures above 16°C will support convective development; however, overall updraft strength is expected to remain modest, with deep but relatively thin CAPE.

Similar to yesterday, smoke aloft may negatively impact solar insolation, potentially delaying or even suppressing convection altogether. If thunderstorms do develop, there is some potential for locally heavy downpours, with rainfall rates possibly exceeding 30 mm/h. There is also a low chance that storms could back-build if they become established.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tomorrow (No thunderstorms expected)

Mel Lemmon

 

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

Newfoundland and Labrador… slight risk of isolated thunderstorm over western Labrador

New Brunswick… low risk of severe thunderstorms over northwestern areas early this evening. Gusty winds and heavy downpours possible.

PEI and NS… No thunderstorms expected.

Convective Discussion

Although the synoptic ingredients are not fully aligned for severe thunderstorms, there is a risk that lingering severe storms could move in from Quebec into northern New Brunswick early this evening. A drier-than-normal airmass will persist today, with surface dew point temperatures reaching the mid-teens over New Brunswick and slightly lower across Labrador, where thunderstorms are also possible.

The surface trough expected to trigger thunderstorm activity will cross Labrador today but is forecast to move only slowly toward New Brunswick. The upper-level jet may play a limited role, with its axis extending from central Labrador toward the Saint Lawrence River by this evening.

Surface-based CAPE values exceeding 1000 J/kg, combined with moderate wind shear over eastern Quebec and into northern New Brunswick, could support the development of a mesoscale convective system (MCS) along the trough through the day. If organized thunderstorms do develop, there will be an elevated risk of strong wind gusts and heavier downpours.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

 

Mel Lemmon

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

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

 

Mel Lemmon

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today: Risk of some non-severe pop up thundershowers in parts of Labrador this afternoon.

Tonight: No thunderstorms forecast.

Tomorrow: Risk of some non-severe pop up thundershowers in southeastern Labrador and the Northern Peninsula tomorrow afternoon.

Convective Discussion…

A quiet day is in store for most of Atlantic Canada today as a ridge of high pressure settles into the central Maritimes. Over Labrador, a weakly unstable environment may be enough to trigger some non-severe pop up thundershowers today. The 12Z Goose Bay sounding this morning showed some relatively weak lapse rates, though a cool airmass aloft will only require convective temperatures of around 16 or 17 degrees. However a lack of moisture (PWATs <15 mm) and effective shear (10 to 20 knots) will limit the intensity and lifespan of any storms that do fire today.

Tomorrow a similar environment is expected over southeastern Labrador, where the risk once again exists for some non-severe pop up thundershowers.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Forecaster: Copp