Convective Outlook Valid for Today

Regional Impacts

 

New Brunswick:  Isolated to scattered thundershowers this afternoon and evening.  Potential severe thundershowers giving downpours, gusty winds and hail.

NS/PEI: A risk of thundershowers this afternoon and evening.

NFLD/Labrador: Nil.

 

Convective Discussion

 

A cold front will cross New Brunswick afternoon and Nova Scotia this evening. ML cape values of 1000-1500 J/kg are expected and straight line wind shear near 30 kts.  Freezing levels are high but decent cape exists in the hail growth zone. Dry mid layers will allow for gusty conditions this afternoon. Precipitable water values will be near 40 mm so rainfall is a concern. The upper support/dynamics are not strong so this event will be mostly driven by the surface trigger of the cold front and general instability caused by daytime heating.

 

Thunderstorm Outlook for Day 1

 

Convective Outlook Valid for the Maritimes Tomorrow

Regional Impacts

 

NS/PEI: A risk of thundershowers Tuesday.

NFLD/Labrador: Nil.

New Brunswick:  Isolated to scattered thundershowers tomorrow afternoon.  Potential for downpours and gusty winds.

 

Convective Discussion

 

In New Brunswick a cold front will be crossing the region Tuesday afternoon. ML cape of 500-1000 J/kg is expected and straight line wind shear of 20 to 30 kts.  Dry mid layers will allow for gusty conditions in the afternoon. Precipitable water values will be near 30 mm so rainfall maybe a concern.

 

Thunderstorm Outlook for Day 1

 

Convective Outlook for Atlantic Canada Valid for Today

Regional Impacts

 

NS/NB/PEI/NFLD: Nil.

Labrador: Isolated to scattered thundershowers this afternoon and evening.  Potential for downpours and gusty winds west.

 

Convective Discussion

 

In Labrador, ML cape is generally low (300-500 J/kg) and the shear is 40 to 50 kts so any storms that develop will be mostly pulse in variety. The low level jet is quite high (50 knots plus) so gusty winds are likely even without any thunderstorms. Dry mid layers will also help with gustiness this afternoon. Precipitable water values are near 35 mm so rainfall maybe a concern but the cells will be moving very fast.

 

Thunderstorm Outlook for Day 1

 

 

Convective Outlook for Atlantic Canada Valid for June 6th and June 7th, 2021

Thunderstorm Outlook for Today, Tonight and tomorrow

 

Regional Impacts for today (see below for tomorrow):

 

The trough that produced some thunderstorms over the Maritimes yesterday is now over the southern marine district.  Some higher gusts are possible with these thunderstorms but not likely to exceed 30 kts. 

Very slight chance of thundershowers over southern NB this afternoon with locally heavy showers.

 

Convective Discussion:

Now with the cold front mostly passed for the Atlantic region, conditions are not favourable for thunderstorm development.  The lower levels will realize some instability this afternoon so likely some Cu could develop over southern NB but mid levels are stable so the vertical extent of the Cu will likely be capped.  A sea breeze front could develop over southern NB this afternoon which will act as a kicker for Cu so maybe low chance of isolated TCU could develop along this front which could bring local heavy showers.  The chance of TCU ends this evening as insolation diminishes.

 

 

 

 

 

Convective Outlook For Tomorrow

 

 

 

 

Barrie MacKinnon

 

Convective Outlook for Atlantic Canada Valid for June 5th, 2021

Thunderstorm Outlook for Today

 

Regional Impacts:

 

Chance of Isolated thunderstorms are possible over Northwestern NB late in the day.  These thunderstorms could give wind gusts of 70 km/h with possibly higher gusts and heavy showers with 15 to 20 mm possible.  These isolated thunderstorms may move across the rest of New Brunswick this evening but with reduced severity.

Slight chance of thunderstorms across parts of NS today and early this evening.

 

Convective Discussion:

Moderately high low level moisture over the area with some marginal instability and decent wind shear could produce some thunderstorms over northwestern NB later this afternoon.  Looking at the 12Z tephis and adjusting for day time heating, moderate cape values of around 500 J/kg could be realised this afternoon.  All surrounding sounding are showing a mid level capping inversion which will likely inhibit further growth of CB if any develop…HOWEVER…a strong upper jet and the passing of a warm trough could help erode this capping inversion and destabilize the column which could result in higher CAPE realized and thus thunderstorms with gusts of up to 70 km/h and possibly higher gusts.  I am holding off on putting out watches for northwestern NB as I think the chance is low for severe thunderstorm formation as the timing of the trough which will help kick off the potential severe storms is not until this evening past max insolation but of course, I will be watching the situation closely.