Day 1 Convective Outlook for Atlantic Canada Valid for June 3, 2018

Convective Discussion

Technical Discussion

There is a low southeast of the Avalon slowly moving away to the east. Further west is an upper level jet moving in ahead of ridging, and the left exit of the jet may give some upper lift. While there is no chance of surface forcing with a strong inversion and cold water, above 850 mb stability is less than moist adiabatic.

Regional Impacts

Minimal impacts over the southern Grand Banks, mostly isolated thundershowers possible near and west of the low center.

Doug Mercer

Day 1 Convective Outlook for Atlantic Canada Valid for June 2, 2018

Convective Discussion

 

Technical Discussion

A trough of low pressure could initiate some mid level convection over the contoured area today.  The upper levels are quite warm so if convection does get initiated, CAPE values of up to 200 J/kg could be realised but higher CAPE values are not likely so severe thunderstorms are not expected.

 

Regional Impacts

None

 

Barrie MacKinnon

 

Day 1 Convective Outlook for Atlantic Canada Valid for June 1, 2018

 

Convective Discussion

 

A warm and increasingly humid air mass is approaching New Brunswick today ahead of a low pressure system over Labrador with a cold front extending into central Quebec. The atmosphere will be conducive for the development of thunderstorms in the afternoon given falling 500mb heights, increasing moisture in the low levels and high maximum temperatures. These ingredients along with the approaching cold front will help de-stabilize the air mass and initiate showers and thundershowers over northwestern New Brunswick beginning in the afternoon and spread southeastward into the evening. Due to the high precipital water content in this air mass and not much wind aloft, showers that develop will move slow and local heavy downpours are possible. The risk of thundershowers may continue into Nova Scotia overnight.

 

Regional Impacts

 

The main threat with the thundershowers will be locally heavy downpours (20-40mm possible).

 

 

Roberta McArthur

 

 

Day 2 Convective Outlook for Atlantic Canada Valid for June 1, 2018

 

Convective Discussion

 

A warm and humid air mass will approach New Brunswick on Friday ahead of a low pressure system moving eastward over Quebec. The atmosphere will be conducive for the development of thunderstorms in the afternoon given increasing moisture in the low levels, moderate low level wind shear and high maximum temperatures. These ingredients along with an approaching cold front will help de-stabilize the air mass and initiate afternoon showers and potential thundershowers over northwestern New Brunswick beginning in the afternoon and spread southeastward into the evening.

 

Regional Impacts

 

The main threat with the potential thundershowers will be local heavy downpours and some moderate gusts.

 

 

Roberta McArthur

 

 

Day 1 Convective Outlook for Atlantic Canada Valid for May 31, 2018

 

Convective Discussion

 

No convection expected in the Maritimes and Newfoundland today mainly due to a warm but dry airmass providing wide scale subsidence under a ridge of high pressure. Meanwhile, a warm front is beginning to slide further east into Labrador giving rain overnight to western Labrador. Convection may be enhanced overnight due to nocturnal cooling but at this time thunderstorms are not expected.

Regional Impacts

 

None

 

 

Roberta McArthur