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.

 

 

 

Convective Outlook Valid for Today

Regional Impacts

 

NB/PEI: Chance of a thundershower this afternoon/evening with the potential for small hail and gusty winds.

NS/NFLD: None.

Labrador: Chance of a scattered thundershower this afternoon in the east.

 

Convective Discussion

 

A cold front approaching from Labrador and weak surface troughing well ahead of it, will give a  chance of thundershowers in New Brunswick and western Prince Edward Island.  The ML cape is generally low (300-500 J/kg) and the shear is 30-40 kts so any storms that develop will be mostly pulse in variety. Precipitable water values are 20 to 25 mm, so rainfall is not so much of a concern. Dry mid layers will allow possible wind gusts of 60-70 km.

 

Thunderstorm Outlook for Day 1

 

 

 

Convective Outlook Valid for Today

Thunderstorm Outlook for Day 1

 

Regional Impacts

 

PEI/NB/NS/NL: no thunderstorms expected.

 

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

 

Convective Discussion

 

In Labrador, moderately dry mid layers and inverted V profiles will allow for the potential of gusts in thundershowers this afternoon and evening. With low freezing levels but skinny CAPE in the hail growth zone, thundershowers could produce small hail. However with low surface dewpoints and bulk 0-6km shear generally below 20kts, we are not expecting anything beyond pulse thunderstorms.

 

 

Thunderstorm Outlook for Day 2

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