Convective Outlook for Atlantic Canada Valid for Today

Regional Impacts

 

NB: Chance of a thundershower this afternoon/evening in the northeast.

NFLD: Scattered thundershowers this afternoon and evening with the potential for small hail and gusty winds.

Labrador: Chance of a thundershower this afternoon in the southeast.

 

Convective Discussion

 

Just a chance of thundershowers in northeast New Brunswick and southeast Labrador today.  In Newfoundland, dry mid layers will allow possible wind gusts and low freezing levels of 8,000 feet may allow small hail. The ML cape is generally low (300-500 J/kg) and the shear is 35 kts so any storms that develop will be mostly pulse in variety. Precipitable water values are 20 mm or less, so rainfall is not so much of a concern.

 

Thunderstorm Outlook for Day 1

 

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Today

 

Regional Impacts:

 

Isolated thunderstorms are possible over Northwestern NB late in the day. Some of these individual storms could give a very brief shower and gusts around 60 km/h.

 

Convective Discussion:

An upper trough will approach from the west late in the day and will be the focus for any convective development. Lightning flashes are currently detected on CLDN between Lac Saint-Jean and Chibougamau. This feature will act as a potential trigger over northwestern NB late this afternoon and into this evening. At this time, the airmass over NB is relatively dry in the low and mid levels, however forecast maximum temperature of 22 combined with dewpoint values of 10 or 11 should be enough to kick start convection. The Upstream soundings from this morning indicate surface-based CAPE values between 300-500 J/kg which would be enough to push the CB tops to 7-8 km. Storm motion would be towards the southeast at about 30 km/h.

 

 

 

Thunderstorm Outlook for Day 2

 

For Wednesday, no thunderstorms expected during daylight hours.

 

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Today

 

Convective Discussion

Brief heavy downpours are likely today throughout the Maritimes. There is a slight risk of a thundershower over western sections this evening.

 

 

 

Convective Discussion

Brief heavy downpours are likely today throughout the Maritimes. There is a slight risk of a thundershower over western sections this evening.

 

Thunderstorm Outlook for Tuesday

 

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Day 1

No impacts except for southern Maritimes marine waters.

 

Regional Impacts

 

Newfoundland and Labrador and the Maritimes: none for today and Sunday.

Nova Scotia Marine:  reasonable chance for thunderstorms over slope waters, diminishing to a chance south of coastal waters.

 

Convective Discussion

A combination of low moisture, negligible instability and high shear for the Maritimes will prevent any significant convection. For Labrador a ridge building in from the west, combined with low moisture and instability and cooling will prevent anything significant.

 

For the slope water near the North Wall of the Gulf Stream, surface temperatures and precipitable water levels of 30-40 mm and light to moderate shear support scattered air mass thunderstorms along the North Wall of the Gulf Stream, with decreasing likelihood going farther north. This should continue today, tonight and tomorrow.

 

Thunderstorm Outlook for Day 2

 

 

 

Convective Outlook Valid for Today and Tomorrow

New Brunswick.. Severe thunderstorms are possible with strong wind gusts and brief heavy downpours during the late afternoon and early evening.

 

Prince Edward Island.. There is a risk of thunderstorms in western areas this evening.

 

Nova Scotia.. There is also a risk of thunderstorms over western and northern parts of the province this evening.

 

Western Labrador.. Risk of a thunderstorm this afternoon.

 

Convective Discussion

 

Based on this morning’s upper air soundings, there is a potential for destabilization but only later in the afternoon or early this evening. The main supporting features are analyzed just east of the Great Lakes this morning and it will take some time before they reach our region. Parts of New Brunswick have a greater potential for thunderstorm initiation, though the limitations appear to be more significant in the north and therefore the threat is reduced.