Convective Outlook for Atlantic Canada Valid for June 25th, 2018

Convective Discussion

Technical Discussion

Two areas will have a chance of convection, for northwestern New Brunswick for this afternoon ending this evening, and for the Atlantic coasts of Newfoundland and Nova Scotia.

For New Brunswick there is marginal moisture and low CAPEs from the 12Z Caribou sounding. But there is an upper level  thermal  trough approaching from the northwest giving some cooling aloft, combined with some good insolation and a weak trough  as a trigger.  Showers should not be heavy, but the cells are moving slowly, so there is a chance of training.. Given high shear near 60 knots and low CAPEs, warning level  downdrafts are unlikely, but there may be some good gusts .

For Atlantic  waters there is a developing low moving across the Scotian Shelf to lies near the Southwestern Grand Banks. Isolated thundershowers are occurring near and a little west of the low center, and are mainly elevated convection. Precipitable water is good, between 35-40 mm. Heavy showers are likely offshore, but gusty winds due to convection are unlikely. Leave that for the main low.

Regional Impacts

New Brunswick: a few thundershowers with a chance for gusty winds northwest.

Nova Scotia: slight chance of thundershowers along the Atlantic Coast this afternoon into the evening.

Newfoundland: slight chance of thundershowers for southern Burin Peninsula and southern Avalon Peninsula tonight into Tuesday morning..

Doug Mercer

Day 1 Convective Outlook for Atlantic Canada Valid for June 23rd, 2018

 

Convective Discussion

 

A ridge of high pressure will continue to maintain fair conditions over the region today. Moisture from a frontal system currently south of New England is starting push northward. The leading edge of the high cloud is already over the Maritimes and it should move over southern Newfoundland this afternoon. The stream of moisture, along with some instability, will reach Nova Scotia tonight bringing an increase in the likelihood of thundershowers. Isolated thundershowers are expected over westernmost regions later this evening, and after midnight for the rest of southwestern shore.

 

Regional Impacts

 

Localised downpours giving 20+mm are expected over western Nova Scotia.

 

 

 

Jean-Marc

 

Day 1 Convective Outlook for Atlantic Canada Valid for June 22nd, 2018

 

Convective Discussion

 

Very quiet day across the region with no thunderstorms expected as a ridge of high pressure builds in today through the Maritimes. A trough of low pressure will bring gusty winds and showers to western Labrador however thunderstorms are not expected.

 

Regional Impacts

 

No impacts do to convective weather expected.

 

Mel Lemmon

 

 

Day 1 Convective Outlook for Atlantic Canada Valid for June 21st, 2018

 

 

Convective Discussion

Alas the first day of summer is here, however this is not reflected in the weather and this is true for convective weather as well. A cool somewhat dry airmass will move across the region today, there is a very low chance that TCU’s could become CB’s over western NFLD early this afternoon as the cold pool moves westward today. By late this afternoon surface moisture will begin to deplete and deep convection will become less likely.

 

 

Regional Impacts

 

Labrador… NB… PEI… NS… No Impacts expected

 

NFLD… There is a greater than zero probability that low topped thunderstorms  could pop up. Brief showers with nil sig weather expected should they happen.

 

Mel Lemmon

Day 1 Convective Outlook for Atlantic Canada Valid for June 19th, 2018

 

Convective Discussion

In general the potential for thunderstorm development is quite low across the region today. There is a slight chance of TCU’s developing just behind the through while low level moisture is still present. There is a slight chance that TCU’s over western Newfoundland could develop into weak thunderstorms. There will likely be some cooling aloft which will aid in destabilizing the atmosphere, this along with some solar insulation and convergence in the general trough area could generate some weaker updrafts. The risk may continue into the evening along a secondary surface trough.  

 

Regional Impacts

 

NB PEI and NS

No impacts are expected.

 

For Newfoundland

Isolated CB possible this afternoon and early this evening for western and central parts of the island. No hazardous weather expected.

 

Mel Lemmon