Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today: Embedded convection along a trundling trof line from Avalon down to slope waters. No severe hazards forecast. Rain and scattered lightning expected.

Tonight: No thunderstorms forecast.

Tomorrow: Risk of thunderstorms in southern and western Labrador. Additional risk of organized convection across NB. These storms could bring gusty winds and heavy downpours.

Convective Discussion

Conditions are fairly stable behind dominant cold frontal forcing today/tonight. Ahead of the front (and near the triple point near Stephenville, NL)  activity continues. Rainfall is the biggest hazard under organized clusters. Significant mid-level smoke is entering into the Maritimes from the NW under the building ridge. This may act as enhanced CIN to the TS forecast for Sunday. But, if it doesn’t – multicell thunderstorms are possible in NB in the afternoon and evening. Effective shear is over 30 kts and bases will be decently high, giving a wind gust risk.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Saturday Night

Thunderstorm Outlook for Sunday

Forecaster: TIRONE

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today:

NB/PEI/NS: Risk of severe thunderstorms with torrential downpours and strong wind gusts.

NL: Risk of thunderstorms with locally heavy downpours and strong wind gusts.

LAB: Risk of an isolated thundershower.

Tonight:

NS/PEI/NL: Isolated embedded thunderstorms giving locally heavy downpours.

Tomorrow:

NL/LAB: Risk of isolated thunderstorms giving locally heavy downpours.

Martimes: None

Convective Discussion

This morning, a trough is moving through northern New Brunswick giving some heavy downpours (15-25mm/h rates), while a trailing cold front will sweep through the Maritimes and Newfoundland this afternoon and overnight. The main area of interest exists across central to southern New Brunswick, Prince Edward Island and northern Nova Scotia, where clearing of cloud is more likely along with adequate daytime heating ahead of the cold front and allow MLCAPE values to exceed 1000 J/kg. With effective shear increasing to 45 knots ahead of the front and advection of precipitable water above 50 mm, there could be an isolated supercells early in the afternoon but mainly expecting cells to organize into line segments by late afternoon over southern New Brunswick and Prince Edward Island and continue southeastward in the evening before they lose surface instability. With these ingredients, the main threats with these storm will be very strong wind gusts and torrential downpours. Isolated thunderstorms are also possible in the trough over Labrador this afternoon with brief wind gusts.

For tomorrow the cold front continues eastward across the Maritimes waters into Newfoundland while a low pressure system develops over Newfoundland into the trough in the morning and tracks into the Labrador Seas by Sunday. Isolated thunderstorms are possible along the front and in the troughing behind the low as colder air moves in aloft and behind the low over eastern Labrador and central Newfoundland.

 

Thunderstorm Outlook for TODAY

Thunderstorm Outlook for TONIGHT

Thunderstorm Outlook for TOMORROW

Roberta McArthur

 

 

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today: Isolated risk of a thunderstorm in extreme northwestern New Brunswick late this evening. Heavy downpours are the main risk.

Tonight: Some isolated thunderstorms possible over northern and central New Brunswick tonight. Heavy downpours are the main risk.

Tomorrow: Scattered strong thunderstorms expected across southern New Brunswick tomorrow afternoon. Strong wind gusts and torrential downpours are the main risk.

Convective Discussion…

A quiet day is in store for the Maritimes today as a ridge of high pressure sits off the Atlantic coast. Late this evening, a trough expected to bring widespread severe weather to Ontario today will slowly make its way into New Brunswick. With much of the region largely capped (evident on the 12Z Caribou and Maniwaki soundings), only extreme northwestern New Brunswick will see the potential for any thunderstorm activity late this evening. By this time, daytime heating will have dropped off, so storms are not expected to be severe as they cross northern New Brunswick tonight. Weak lapse rates out ahead of the trough will also diminish the severe potential here tonight, so the main hazard will be heavy downpours.

Tomorrow looks to be more interesting, as an intense cold front will sweep across New Brunswick during the day, which will likely trigger some marginally severe thunderstorms. The main area of interest exists across the southern half of New Brunswick, where adequate daytime heating ahead of the cold front could help increase MLCAPE values upwards of 1000 J/kg. Dynamics look really good as well out ahead of the front, but once again lapse rates remain fairly weak so hail is not likely. A few discrete cells might fire early in the afternoon ahead of the cold front, but things are expected to line out fairly quickly as upwards of 60 knots of bulk shear crosses the region late in the afternoon with the passage of the cold front. An abundance of moisture will also be fed into this system, with PWATs expected to rise above 50 mm over southern New Brunswick tomorrow, increasing the potential for torrential downpours. As such, the main threats with these storm will be very strong wind gusts, and torrential downpours.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Forecaster: Copp

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today: Nil sig weather.

Tonight: No thunderstorms expected.

Tomorrow: Trof starts to enter NW NB and western Lab late in the evening, may lead to a lightning strike or 2 in embedded showers.

Convective Discussion

Weather today and Thursday is dominated by a building ridge of high pressure. No thunderstorm activity is expected, until a late day trof starts to sweep thru central and northern Quebec late in the day on Thursday. High heat and humidity may set the stage for a thundershower or 2. Nil sig weather forecast at this time in the Atlantic AOR.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Forecaster: Jimmy.

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today: Scattered embedded thundershower activity within the boundary that’s in the vicinity of the Grand Banks. No severe hazards forecast.

Tonight: No thunderstorms expected.

Tomorrow: No convection forecast. Strong cap.

Convective Discussion

Upper trof is departing Nfld this morning. Convection is possible out ahead of the trof, but would be non-severe and embedded. The risk would only be 5-10mm of rain. Stability increases tonight from a Ridge building in from the west. Building heights are preventing any deep convection on Wednesday. The next trof approaches late in the day on Thursday, and may bring a lightning strike or 2 before midnight over extreme western Lab and NWrn NB.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Thunderstorm Outlook for Thursday

Forecaster: Tirone.