Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Today

 

Regional Impacts

No thunderstorm expected.

 

Convective Discussion

500 mb ridge over the Maritimes at 12z this morning will be east of NF Monday. Mid and High cloud spilling over the ridge today with shower activity west of the region spilling into the forecast districts tonight, precipitable water increases to 30+mm and steady rain spreads over parts of the Maritimes. There is a slight risk of an elevated thunderstorm after midnight over NW NB as the airmass moisture increases, and cloud top cooling enhances embedded TCU/ACC’s.  

 

 

Thunderstorm Outlook for Monday

Showers will linger Monday morning with perhaps the risk of a thunderstorm early in the morning. Surface-based convection will develop over Maine during the afternoon but the airmass will likely remain capped over NB, with the expected of westernmost areas which could destabilize late in the day. The approach of a vigorous shortwave from the Great Lakes, a surface cold front, and daytime heating will all contribute to this next bout of convection. Upper Jet, MLCAPE 500+ J/kg, strong shear, lower freezing levels – all point to enhanced convective conditions late on Labour Day.  

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

Slight risk of a non-severe thunderstorm over the Gulf of St. Lawrence and southwest NF.

 

Convective Discussion

500 mb cold low east of Gaspe will slowly move northeast today. Under mainly cloudy conditions widespread showers are expected, and later today there may be just enough instability to produce a weak thunderstorm under the cold pool.

High pressure system will build over the Atlantic provinces Sunday.

 

Thunderstorm Outlook for today

 

Thunderstorm Outlook for Sunday

 

No thunderstorms expected

 

 

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

Nova Scotia/New Brunswick/PEI/Newfoundland:  A risk of embedded thundershowers from the tropical moisture left over from Ida. Heavy downpours giving 30 mm in an hour are possible today and tonight.

Labrador: Nil.

 

Convective Discussion

 

A risk of embedded thundershowers as the remnants of Ida move across the region. PWAT values are near 50 mm so rainfall is a concern but we have rainfall warnings out for a broad area of Atlantic Canada. Heavy downpours giving 30 mm in an hour are possible today.

 

Thunderstorm Outlook for Day 1

 

 

Thunderstorm Outlook for Day 2

 

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

Newfoundland:  Isolated thundershowers this afternoon and evening.  Potential severe thundershowers giving downpours, gusty winds and hail in the southwest early this afternoon.

Nova Scotia: Slight risk over Cape Breton

New Brunswick/PEI/Labrador: Nil.

 

Convective Discussion

 

A weak low pressure system will approach western Newfoundland this afternoon. ML cape values near 500 J/kg are expected and wind shear near 25 kts.  This morning, convection developed over the Gulf of St. Lawrence near the Magdalen Island and then advected eastward. The earlier convection was mainly driven by upper level dynamics which weaken somewhat this afternoon as the jet slips south of Newfoundland.  Dry mid layers will allow for gusty conditions. PWAT values will be near 25 mm so rainfall is a concern. Just a risk of embedded non-severe thunderstorms over the Maritimes on Thursday.

 

Thunderstorm Outlook for Day 1

 

 

Thunderstorm Outlook for Day 2

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

For Labrador today… Isolated thunderstorms giving 15-20mm locally.

NB, PEI and NS today… Low probability of near severe thunderstorms.

 

Convective Discussion

 

There is a low probability that severe or near severe thunderstorms could develop today over the gulf waters and Northumberland Straight. The dynamics are good with plenty of deep shear and weak convergence along a surface trough. It may be a struggle to break through a stable layer above 700mb until later today when it weakens however daytime heating will also be weakening. For now no severe thunderstorm alerts are expected however should longer lived cells develop they may be issued. The warmer waters this time of year may also help to feed the thunderstorms and should they develop could pose a risk to marine waters.

 

 

Thunderstorm Outlook for Day 1

 

 

Thunderstorm Outlook for Day 2

 

 

Mel Lemmon