Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Day 1

Strong winds, especially multicells with organising features giving strong winds, are possible for south New Brunswick and parts of Nova Scotia.

 

Regional Impacts

New Brunswick and Nova Scotia: high winds and heavy downpours, possibly severe for both.

Newfoundland and Labrador: nothing significant.

Prince Edward Island: Gusty winds and local heavy rain, probably less than severe.

 

Convective Discussion

A tropical ridge south of the district and a deep trough extending southwest of Hudson Bay slanting east as you near ground level. A weak thermal ridge near NB with weak cold advection and good moisture trapped under an inversion. When the inversion breaks we expect multicells and linear features. PWATs are near 50 mm, dewpoints below the 850 layer are in the low to mid 20s, shear is about 40 kts for the threat region shown, and the winds are mainly straight line. With possible organising due to convergence and some weak troughing my cause things to persist tonight

 

 

 

Thunderstorm Outlook for Day 2

A broad weak low over the southern Maritimes and local convergence, including sea breeze fronts, may give some isolated thundershowers. Moisture is okay, and there is some moderate shear, so it may give near severe conditions in the afternoon.

 

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Day 1

 

Regional Impacts

Non-severe thunderstorms for Labrador. Non–severe for part of the Maritimes, with a higher threat to western Nova Scotia and New Brunswick.

 

Convective Discussion

For the Maritimes there is plenty of moisture at least up to 850 mb, with PWATs up to 50+ mm and dewpoints above 20 C,  and a LLJ advectiing more from New England. Shear a bit on the high side over northern NB but in the 25-40 kt range for the rest of the Maritimes.  There is some PVA and upper jet support, and the upper trough farther west slanting down to the east. New Brunswick and Western Nova Scotia and PEI are mostly clear, but with Cu and TCu starting.

 

For Labrador there is a deep trough to the west and moving east, partially clearing skies in the west for good insolation, and healthy shear near 45 kts, but PWATs less than 20 mm and marginal instability. Isolated to scattered thundershowers with local heavy showers, followed by some wind gusts, and a chance of small hail with FZLVLs near 10,000 feet.

 

 

 

Thunderstorm Outlook for Day 2

Non–severe for part of the Maritimes, with a threat of severe thunderstorms for western Nova Scotia and New Brunswick. The highest threat is for heavy rainfall, followed by strong wind gusts to near warning levels.

 

 

ATL Thunderstorm Outlook for Today and Tomorrow

Thunderstorm Outlook for Day 1 – JUNE 28

 

Regional Impacts 

Severe thunderstorms possible over central and southern NB ahead of a trough line in a very hot and humid airmass. Non-severe isolated storms are also possible inland in NS along sea-breeze convergence lines. 

Convective Discussion 

With 35-40kts of 0-6k shear, sfc based CAPE of 800-1200J/kg and Pwats of 45-55mm, the hazards in NB is heavy rainfall, small hail, and gusty winds. If a few storms can bubble up ahead of the approaching front, then discrete supercells are possible on Monday afternoon. Watches and warnings may be required. This is being monitored closely from the Atlantic Storm Prediction Centre. 

Thunderstorm Outlook for Day 2 – JUNE 29

 

Regional Impacts 

Non-severe airmass driven thundershowers are possible over many areas of the Maritimes, and Labrador. The best organized convection will be in eastern NB. 

Convective Discussion 

Less daytime heating energy is available to work with than on Day 1 but still enough to get 500J/kg in pockets. Single cell storms are expected, with rain and gusty winds. 

Thunderstorm Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Day 1 – JUNE 27th 

 

Regional Impacts 

Isolated thunderstorms are expected this afternoon and evening across central and parts of northern New Brunswick. In central NB, a cell or two could approach severe limits today for heavy rainfall of 25-40mm. A few lightning strikes are also possible along an elongated boundary in Labrador. 

 

Convective Discussion 

Today's thunderstorm risk is highly dependent on synoptic cloud location. The moisture is certainly available with >20 degree dew points. The limiting factor could be the daytime heating needed to overcome a weak cap at 700mb. If highs near 30 can be achieved, then heavy rainfall is the main hazard. Low-mid level shear values are more favourable for severe weather on Day 2 (dynamics advecting in from west). 

 

 

 

Thunderstorm Outlook for Day 2 

 

Regional Impacts 

Severe thunderstorms are possible in southern and central New Brunswick. Isolated, non-severe thunderstorms are also possible near the Cobequid pass in Nova Scotia. Hot daytime highs, and dew points remaining near 20 will facilitate this. 

 

Convective Discussion 

800-1200J/kg of sfc based CAPE can be realized, with ample sfc-midlevel moisture, 16-18 degree T diffs from 500-700mb, and 35-40kts of 0-6k shear. Pwats near 50mm make heavy rain, small hail – FL at 11,000ft – and gusty winds the main hazards. Low level helicity does not appear elevated at this time. Check back tomorrow for an updated OUTLOOK. 

 

 

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Today

Regional Impacts

Isolated thunderstorms over western Labrador this afternoon and into the evening. the main threat will be brief heavy downpours and high wind gusts.

Convective Discussion

A weak surface cold front extending through northern Quebec will advance towards Labrador this afternoon. Colder air aloft will destabilize the airmass between Shefferville and Wabush, and then around Churchill Falls late in the day. The La Grande sounding was modified with a Ts,Td combination of 23,14 which was enough to generate CAPE values of 250+ J/kg  and Lifted index of -1. The hodograph is showing unidirectional winds through the unstable column and a westerly shear / Jet of 50kt - which would be enough to sustain these isolated pulse thunderstorms a little longer, which could in turn could produce surface gusts of 35kt or more.

   

Thunderstorm Outlook for Sunday