Convective Outlook Valid for Today and Tomorrow

Regional Impacts

NB, NS, and PEI: Scattered thunderstorms today and tomorrow, some of the stronger storms could produce heavy downpours 10 to 20 mm, and possibly higher.

NL: None, deeper instability limited to the west of a line from Fermont/Lab City to Lake Eon to Chevery.

 

Convective Discussion…

A surface and upper low over Maine will move east today, reaching the Gulf of St. Lawrence tonight. The upper low will then weaken and open up over Labrador. Moisture associated with these features will continue to produce widespread showers with embedded thundershowers with forecast guidance suggesting CAPE of 250 J/kg or less, however as the day progresses, insolation from breaks in the cloud cover and the cold temperatures aloft will increase the depth of the instability with surface-based CAPE values expected to reach 500 J/kg. Under these conditions this deeper convection will produce locally heavier showers 10-20 mm, some small hail < 1cm, and wind gusts to around 60 km/h. Generally the shear is weak, except over NS where current soundings indicate 0-6km values above 20 kt which might produce weakly organised convective cells.

 

A series of weak low pressure systems will extend from NY state to Atlantic Canada on Friday. Low level moisture/fog will give way to isolated thunderstorms during the day.

 

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

 

Thunderstorm Outlook for Friday

 

 

Convective Outlook Valid for Today, Tonight, and Tomorrow

Regional Impacts

NB, NS, and PEI: Scattered thunderstorms today and tomorrow, with locally heavy downpours up to 25 mm, possibly higher.

NL: Isolated thundershowers possible over western Labrador, locally heavy downpours up to 15 mm.

 

Convective Discussion…

An upper trough is moving through the Maritimes today, bringing the risk for some elevated convection. 0 to 6 km wind shear of 30 to 40 kts, in combination with the aforementioned trough are providing ample lift and instability today for some organized convection. Thunderstorms are expected to stay elevated, as a thermal ridge at 850 mb should prevent anything from becoming surface based, however heavy downpours up to 25 mm and potentially higher are possible. An upper low will then approach the Maritimes from the west tonight, bringing the risk for some elevated convection for parts of western New Brunswick and southwestern Nova Scotia into tomorrow morning. This upper low will continue to slowly move east tomorrow afternoon, bringing upper and mid level cooling across the Maritimes. This will allow for convection to be more surface based, with locally heavy downpours of up to 25 mm the main risk.

 

Some isolated thundershowers are possible in parts of western and central Labrador today with an upper low moving through northern Quebec. Locally heavy downpours of up to 15 mm are possible with these thundershowers.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Tomorrow

 

Copp

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

NB: Scattered thunderstorms tonight and Wednesday, with locally heavy downpours possible, 15-30 mm.

NS: Scattered thunderstorms tonight and Wednesday, with locally heavy downpours possible, 15-30 mm.

PEI: Scattered thunderstorms on Wednesday afternoon, with locally heavy downpours possible, 15-30 mm.

NL: Isolated thundershowers possible over central Labrador on Wednesday afternoon.

 

Convective Discussion…

As a ridge of high pressure continues to dominate Atlantic Canada today, an approaching trough from the west will provide ample instability and wind shear for some elevated convection overnight tonight over the southwestern Maritimes. This trough will continue to push east on Wednesday, spreading the risk for elevated convection across most of the Maritime provinces. A thermal ridge at 850 mb will prevent any convection from becoming surface based, as such the main risk for these storms will be locally heavy rainfall, with 15-30 mm possible.

 

For Labrador, some isolated thundershowers are possible on Wednesday afternoon as a shortwave currently over Hudson’s Bay slowly approaches from the west. Locally heavy rainfall near 15 mm is possible with these thundershowers.

 

Thunderstorm Outlook for Today

 

 

Thunderstorm Outlook for Tonight

 

 

Thunderstorm Outlook for Wednesday

 

 

Copp

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

Central/Eastern NB, Western PEI, and Western NS: Isolated thundershowers, with locally heavy downpours of 10-15 mm possible.

NL: None.

 

Convective Discussion: A ridge of high pressure dominates the Maritimes today and tomorrow. Mixed layer CAPE values of 250 to 500 J/kg in central and eastern NB, extending into western NS, will aid in developing some weak thundershowers along terrain, with locally heavy downpours the main risk. Storms are not expected to be long lived due to a lack of wind shear and upper level support.

 

Thunderstorm Outlook for Day 1

 

 

Thunderstorm Outlook for Day 2

 

 

-Copp

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

Western Labrador… low likelihood of isolated thundershower. Locally heavier downpours possible 10-15mm.

 

Convective Discussion… For the most part today will be relatively quiet with a few isolated thunderstorms developing over western Labrador. The dynamics are not particularly favourable with very little wind shear, and no upper support for long lived thunderstorms. Activity will likely be driven by daytime heating and terrain, with mixed layer CAPE is likely less than 500 J/kg. It is possible that there will be some locally heavier rain and small hail. No Severe weather is expected.

 

 

Thunderstorm Outlook for Day 1

 

 

Thunderstorm Outlook for Day 2

 

 

Lemmon