Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Today

 

Regional Impacts:

 

Over southeastern Labrador and northern and central Newfoundland, there is a slight risk of a popup thundershower this afternoon and Sunday afternoon.

 

Convective Discussion

 

A slow moving deep layer trough from the surface to 250 mb extends from an upper low over Labrador to the Gulf of St. Lawrence. As this trough moves very slowly eastward, upper level temperatures will drop east of it over southern Labrador and northern and central Newfoundland. With daytime heating, there is a slight possibility of CBs topped at 30,000 to 35,000 feet in a low shear environment. West of the trough, over the Maritimes, the environment is strongly capped near 700 mb, inhibiting thunderstorm activity.

 

Similar conditions are forecast for Sunday afternoon except that the trough will be slightly farther east making the risk area slightly farther east.

 

Thunderstorm Outlook for Today:

 

 

Thunderstorm Outlook for Sunday:

 

 

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Today

 

Regional Impacts

No thunderstorms forecast.

 

Convective Discussion

Cool northwesterly flow continues across the region under a 100+kt NWly upper Jet extending from James Bay to NS. Generally over the Atlantic provinces, Instability is limited to the lower levels with most morning soundings over the region showing two inversions, at 700mb and 550mb. Moisture is more prevalent over NF and Lab where multiple layers of cloud are analysed. Freezing levels have risen somewhat and are between above 2,000ft.

 

 

 

Thunderstorm Outlook for Saturday

An upper low will slide over central Labrador, and the cold air aloft will destabilize the airmass further. A sligh risk of thunderstorms is suggested by some of the forecast guidance.

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for today

 

Regional Impacts

Isolated Non-severe thunderstorms are expected today with sporadic downpours over southwestern NF and the Burin.

 

Slight risk of a thunderstorm over the Cape Breton Highland.

 

Convective Discussion

A cool and dry northwesterly flow prevails over the Maritimes this morning. Over the Gulf of St. Lawrence, a cold low is triggering widespread showers mainly over southwestern NF and the Burin. The airmass is unstable enough (CAPE values of 200-300 J/kg) to support thunderstorm activity. One such cluster is currently detected by CLDN at the intersection of Cabot strait, southwest coast and Banquereau regions. A few lightning flashes were also detected along the coast east of Port-aux-Basques. The instability will be maintained ahead of the cold pool aloft. Some of the forecast guidance is suggesting a slight risk of thunderstorm over the Cape Breton Highlands in response the approach of the cold pool and some extra orographic lift.

 

 

Thunderstorm Outlook for Friday

 

Some of the global guidance is suggesting the possibility of some shower activity associated with a weak surface feature

over central NB.

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Today

 

Regional Impacts

No thunderstorms forecast.

 

Convective Discussion

The hot and humid airmass is slowly exiting the region to the south this morning. The axis of moisture (linked to precitable water of 40+ mm) is now extending from southern New England and then offshore to the Scotian Slope. This where convective activity persists at this hour. Otherwise, no thunderstorms are forecast over land today.

 

Convective Outlook Valid for Today

Regional Impacts

 

New Brunswick:  Isolated to scattered thundershowers this afternoon and evening.  Potential severe thundershowers giving downpours, gusty winds and hail.

NS/PEI: A risk of thundershowers this afternoon and evening.

NFLD/Labrador: Nil.

 

Convective Discussion

 

A cold front will cross New Brunswick afternoon and Nova Scotia this evening. ML cape values of 1000-1500 J/kg are expected and straight line wind shear near 30 kts.  Freezing levels are high but decent cape exists in the hail growth zone. Dry mid layers will allow for gusty conditions this afternoon. Precipitable water values will be near 40 mm so rainfall is a concern. The upper support/dynamics are not strong so this event will be mostly driven by the surface trigger of the cold front and general instability caused by daytime heating.

 

Thunderstorm Outlook for Day 1