Thunderstorm Outlook for Today
Regional Impacts
NB: None
NS: None
PEI: None
NF&Lab: Isolated thunderstorms over western Labrador possible.
Marine waters: Isolated embedded thunderstorms over marine areas south of Nova Scotia.
Convective Discussion
Surface based convection is possible over western Labrador this afternoon. Maximum unstable CAPEs are around 900 J/kg. Shear is decent, at about 30 knots and is unidirectional from the SW. The 250 mb jet over Goose Bay at 12Z was 90 knots. However, the upper jet is positioned south and east of the area where initiation is most likely to occur. The threats of thunderstorms if they occur are heavy downpours and gusty winds. Warning criteria conditions are not expected.
Elevated convection within a band of moderate to occasionally heavy rain south of NS is possible. Lift in this area of rain is from about 850 mb. This area of rain and embedded convection is ahead of a slow-moving upper trough. Severe conditions are not expected.
Thunderstorm Outlook for Saturday
Regional Impacts
NB: None
NS: Isolated thunderstorms possible over inland areas of mainland NS.
PEI: None
NF&Lab: Isolated thunderstorms over southeastern Labrador and southeastern Newfoundland possible.
Marine waters: Isolated embedded thunderstorms over marine areas south of Newfoundland.
Convective Discussion
Surface based convection is possible over inland areas of mainland NS as afternoon temperatures rise into the mid to high 20s. However, CAPEs are quite low as the profile is forecast to be quite warm in the 500-700 mb layer. There is very little shear over this area of potential convection as the aforementioned upper trough moves over NS on Saturday. The 500 mb winds are forecast to be in 5 to 10 knot range. So any thunderstorm cells that do form will be short lived and vertical. The threat is locally heavy downpours.
The area of rain and embedded convection south of NS today is expected to shift eastward on Saturday as the upper trough moves eastward. Isolated thundershowers over southeastern Newfoundland are possible. Severe conditions are not expected.
Surface based convection is possible over southeastern Labrador. Although CAPEs are not expected to huge, there will be a lot of shear (50 knots sfc to 500mb). Also the upper level jet is forecast to move over the region. Based on this scenario, severe conditions with gusty winds and hail can’t be ruled out.
