Thunderstorm Outlook for Today
Regional Impacts
NB: Isolated thunderstorms over southern areas.
NS: Isolated thunderstorms possible over inland areas of central mainland NS.
PEI: None
NF&Lab: Isolated thunderstorms over southeastern Labrador.
Marine waters: Isolated embedded thunderstorms over marine areas south of Newfoundland.
Convective Discussion
Surface based convection is possible over central areas of mainland NS and parts of southern NB as afternoon temperatures rise into the mid to high 20s. However, CAPEs over both areas are quite low as the profile is forecast to be quite warm in the 500-700 mb layer. There is very little shear over these areas of potential convection as a weak upper trough moves over NS and NB. The 500 mb winds are forecast to be in 5 to 10 knot range over NS and 20 knots over NB. So any thunderstorm cells that do form will be short lived and vertical. The threat is locally heavy downpours.
An area of rain and potential embedded convection south of NS and NF today will persist today and tonight as the upper trough will persist south of NS and slowly weaken. Isolated thundershowers are possible. However, lightning activity hasn’t occurred recently.
Surface based convection is possible over southeastern Labrador. Although CAPEs are not expected to huge, there is a lot of shear (50 to 60 knots sfc to 500mb). Also the upper 250 mb jet is over the region and is about 100 knots. Based on this scenario, severe conditions with gusty winds and hail can’t be ruled out if thunderstorms occur. The shear may be too strong for cells to organize and may be torn apart before they can form. There have been a few lightning strikes to the west of this region this morning.
Thunderstorm Outlook for Sunday
Regional Impacts
NB: None
NS: None
PEI: None
NF&Lab: None
Marine waters: Isolated embedded thunderstorms over marine areas south of Atlantic Canada.
Convective Discussion
Thunderstorms are not expected over land areas of Atlantic Canada on Sunday. Although lifted indices are forecast to be in the -2 to -4 range over parts of NS and NB, the profiles are dry and there is a subsidence inversion near 700 mb. The inversion is a result of a weak upper ridge moving in from the west.
Elevated convection within a band of moderate to occasionally heavy rain south of Atlantic Canada remains possible as the upper trough persists offshore and gradually weakens. Lift in this area of rain is from about 850 mb.
