Convective Outlook Valid for June 11, 2019

 

 

Convective Discussion: There is a deep dry ridge over the Maritimes and Labrador moving east today. Behind it there is a deep trough extending from east of Hudson Bay south to New England, with an embedded weak low south of Long Island, New York. The only areas with a chance of convection are western Nova Scotia and New Brunswick, and it should be non-severe, except for the possibility of training.

 

The weak low will move just south of Nova Scotia this evening, giving some extra moisture.  There will also be midlevel destabilisation, partially due to cooling  aloft in the wake of the 500 mb thermal ridge currently over western Nova Scotia and New Brunswick moving out ahead of the 850-700mb thermal ridge just west of the Maritimes.. The moisture will mainly help Nova Scotia and southern New Brunswick get enough energy for possible thundershowers this afternoon into this evening.. For west to northwest New Brunswick, moisture will be less, but the deep upper trough, a weak left entrance region from an associated jet approaching the northwest of the province, and some PVA and indications of lift from 700 mb upwards, again gives a possibility of thundershowers.

 

 

Regional Impacts:

 

Newfoundland and Labrador: No significant convective weather expected.

 

Prince Edward Island: No significant convective weather expected.

 

New Brunswick: A chance of thundershowers this afternoon into this evening over western parts of the province. If they happen, expects local heavy rain, and gusty winds.

 

Nova Scotia: A chance of thundershowers this afternoon over parts of the southwestern mainland.. If they happen, expects local heavy rain, with a lesser risk of  gusty winds.

 

Marine Areas: Non-severe thundershowers this afternoon into this evening over southwestern Maritimes waters.

 

Doug Mercer

Lead Meteorologist

Atlantic Storm Prediction Centre

Meteorological Service of Canada

45 Alderney Drive, Dartmouth

Nova Scotia, B2Y 2N6

Doug.mercer@canada.ca

Office: (902) 426-9200

 

Premier Météorologue
Centre de prévision des intempéries de la région de l'atlantique

Service météorologique du Canada

45 promenade Alderney, Dartmouth

Nouvelle-Écosse, B2Y 2N6

Doug.mercer@canada.ca

Bureau: (902) 426-9200

Cell: (902) 403-7951

 

Convective Outlook for Atlantic Canada Valid for June 10th, 2019

 

Convective Discussion

 

Another quiet day across the region as we remain on the cold side of a large ridge of high pressure. The atmosphere is stable through a significant layer and with the very limited low level moisture no deep convection is expected.

 

Regional Impacts

 

None expected

 

 

Mel Lemmon

 

 

 

Convective Outlook Valid for June 9th, 2019

Convective Discussion:

Upper low at 500mb will continue to move eastward to the Grand Banks later today. The St John’s west sounding is indicating some mid-level instability which is producing weak shower activity over eastern portions of the island. In the cold pool, the weakening available energy is extending to 500mb where temperatures are around -25 to -30. Given these conditions,  there is a slight risk of an isolated CB/ACB east of the island during the next few hours.  

An upper ridge over western Quebec will continue to build over the rest of the Atlantic provinces maintaining fair weather conditions through Monday.  

Regional Impacts:

Newfoundland and  Labrador: No thunderstorms expected.

Prince Edward Island: No thunderstorms expected.

Nova Scotia: No thunderstorms expected.

New Brunswick: No thunderstorms expected.

Jean-Marc

Convective Outlook Valid for June 8th, 2019

Convective Discussion:

The focus for surface-based convection will be over eastern Newfoundland this afternoon…

A convergence line at the surface currently advancing over central parts of the island will be the main forcing mechanism. The airmass ahead of the line is moisture limited (dewpoint values below 10 and precip. Water around 15mm), however modifying the Stephenville sounding for a worst-case scenario (20,9) gives surface-based CAPE in the order of 400-450 J/kg. This would be enough for isolated thunderstorms to form. The freezing level is down to 7 000 ft, and the distribution of the area of CAPE above it indicates the possibility of hail - the size of pellets. The storm motion for any isolated cells that form would be eastward at 40 km/h, these fast moving storm would limit the amount of rain produced over a locality, and finally  the gust potential is 70 km/h.       

For offshore waters,  isolated thunderstorms are possible over the southern Grand Banks, upper support include a 100+ kt southwesterly jet, PVA and cold air advection along a surface front.

Regional Impacts:

Newfoundland and  Labrador: Isolated non-severe thunderstorms over eastern areas.

Prince Edward Island: No thunderstorms expected.

Nova Scotia: No thunderstorms expected.

New Brunswick: No thunderstorms expected.

Jean-Marc Couturier

Convective Outlook Valid for June 7, 2019

 

Convective Discussion:

 

A broad upper trough over Quebec is rotating down towards New Brunswick this afternoon. This may cause weak thundershowers, as there is some upper dynamic support However, the  lower airmass is very dry, with 850 mb dewpoints near or below zero, and surface dewpoints generally less than 5 C over New Brunswick, Maine, and northwest towards the trough.  For Nova Scotia, moisture levels are higher, with dewpoints near 10-13 C, and with afternoon highs into the low 20’s inland. There will also be some midlevel destatbilisation from cold advection ahead of the upper trough.

 

For offshore waters especially for the southeaster grand Banks, upper support and  PVA ahead of an approaching cold front should give a few elevated thundershowers.  thundershowers

 

Regional Impacts:

 

Newfoundland and  Labrador: No significant chance for  thundershowers.

Prince Edward Island: No significant chance for  thundershowers.

Nova Scotia: Chance of non-severe thundershowers this afternoon into early this evening.

New Brunswick: Slight chance of non-severe thundershowers this afternoon into  this evening.

Marine regions: Chance of non-severe thundershowers.

 

 

Doug Mercer

Lead Meteorologist

Atlantic Storm Prediction Centre

Meteorological Service of Canada

45 Alderney Drive, Dartmouth

Nova Scotia, B2Y 2N6

Doug.mercer@canada.ca

Office: (902) 426-9200

 

Premier Météorologue
Centre de prévision des intempéries de la région de l'atlantique

Service météorologique du Canada

45 promenade Alderney, Dartmouth

Nouvelle-Écosse, B2Y 2N6

Doug.mercer@canada.ca

Bureau: (902) 426-9200

Cell: (902) 403-7951