Thunderstorm Outlook for Day 1
Regional Impacts
Scattered showers with a slight possibility of embedded thundershowers early this afternoon over parts of the Bay of Fundy, Annapolis Valley, and northern Nova Scotia. The main threat with these will be some localised heavy rain.
Convective Discussion
A broad trough from a low pressure system over the northern Labrador Sea extends from western Newfoundland southwestward through the Gulf of St. Lawrence, PEI and the Bay of Fundy region this morning. The trough has not seen any lightning over our area this morning but some elevated convection is still possible into this afternoon. This area is in the right entrance of a 110 KT 250 mb jet with a weak low level jet over Nova Scotia. A cold pool lies south of New Jersey where the convection has been firing up this morning but the upper levels remain warmer further north, which is likely the main inhibiting factor. There is still a good amount of precipitable water available from the Yarmouth and Shearwater 12Z soundings of around 40 mm so locally heavy downpours are possible.
This trough will continue to weaken and somewhat stall over Nova Scotia and western Newfoundland into Saturday.
Later this afternoon, another trough will slide in from central Quebec into northwestern New Brunswick this evening. The main threat for convection will remain north of the St. Lawrence River extending north possibly reaching southwestern Labrador. Some TCUs reaching 18,000 ft in showers are expected to reach New Brunswick this evening.
Thunderstorm Outlook for Day 2
Regional impacts
None
Convective Discussion
The second trough will continue eastward over southern Labrador and northern Newfoundland with just scattered showers expected. A sea breeze convergence over the Annapolis Valley and northern Nova Scotia may kick off some TCU in showers but a warm 700-500mb layer will likely inhibit any CB formation. The quasi-stationary trough over the southern maritime marine areas may prompt some embedded convection in the early morning hours Sunday morning.
Roberta McArthur