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

 

Convective Outlook Valid for June 6th, 2019

Convective Discussion

A weak low pressure system with an associated tropical moisture feed will move across Nova Scotia today. Rain at times heavy is occurring ahead of this feature. Cloudiness will limit daytime and any severe weather threat.

 

Regional Impacts

Maritimes…

A risk of non-severe thunderstorms over southwestern sections. Synoptic rainfall warnings of 50 mm in 24 hours are in place for parts of Nova Scotia. Severe rainfall warning criteria of 25 mm in 1 hour is not expected to be met.

 

Newfoundland and Labrador…

Significant rainfall but no warnings currently in place.

 

 

 

Andy Firth

Lead Meteorologist

Atlantic Storm Prediction Centre, MSC
Environment Canada / Government of Canada

3rd Floor, 45 Alderney Drive

Dartmouth NS B2Y 2N6

andrew.firth@canada.ca / Tel: 902-426-7779 / Fax: 902-426-4873

 

Andy Firth

Premier Météorologue

Le Centre de prévision des intempéries de l'Atlantique, SMC
Environnement Canada / Gouvernement du Canada
3e étage, 45 Alderney Drive

Dartmouth NS B2Y 2N6

andrew.firth@canada.ca / Tél: 902-426-7779 / Télécopieur: 902-426-4873

 

Convective Outlook Valid for June 5th, 2019

Convective Discussion

Satellite images are showing multiple bands of convective clouds ahead of an advancing upper low located just west of Labrador. The instability is limited to the low and mid levels for the time being. A cyclonic southwesterly upper level jet over western Newfoundland is supporting isolated TCU/CB’s east of Stephenville, and with the advancing cold air aloft the mid-level lapse rates are expected to favorable for continued development of isolated cells over central and eastern NF. The moisture available in this airmass is limited so rainfall amounts should remain low.

 

 

Regional Impacts

Newfoundland and Labrador…

Isolated non-severe thunderstorms are expected this afternoon over much of Newfoundland and Southeastern Labrador

The main threat ahead of these isolated clusters would be gusts of around 70 km/h.

 

Maritimes…

No thunderstorms expected

 

 

Jean-Marc Couturier

 

Forecaster / Meteorological Service of Canada

Environment and Climate Change Canada / Government of Canada

Jeanmarc.couturier@canada.ca

 

Prévisionniste / Service météorologique du Canada

Environnement et Changement climatique Canada / Gouvernement du Canada

Jeanmarc.couturier@canada.ca

 

Convective Outlook Valid for June 4th, 2019

 

Convective Discussion

 

Not much on the go today. A weakening frontal trough affecting some offshore waters and NL will give rise to a slight risk of an embedded TSRA today. OTWZ a weak upper trough will give some ISOL TCU to NB this afternoon. KCAR has a freezing level of 4,300 ft…so would not be surprised if there are some IP mixed in with some of the heavier showers.

 

Regional Impacts

 

Newfoundland: slight risk of an embedded TSRA across the SE.

Elsewhere: nil

 

Jeremy