Thunderstorm Outlook valid for TODAY – FRIDAY, Aug 26th:
Regional Impacts
Scattered thunderstorms are expected to enter into NB this afternoon along an approaching frontal feature. Moderate rain is expected, and wind gusts near 80km/h are possible. Pockets of stronger severe weather are possible IF the dynamics align favourably with storm motion and the overhead jet support. A squall line/bow echo signature cannot be completely ruled out with this feature. If ingredients build, a watch will be used to achieve lead time for residents of NB.
Convective Discussion
The aforementioned frontal feature is digging quite deep as it comes through upstate NY, New Hampshire and Vermont at this hour. This is the main forcing of the day for NB. With surface moisture pooling ahead of the front (Pwats over 30mm), and 0-6k shear values near 35kTs, thunderstorms are forecast to develop this afternoon and evening. Morning soundings across the Maritimes show quite a dry level above 700mb, but this will saturate as the day progresses. A challenge does remain with the existing junky cloud, but clearing is expected to occur at the prime time for peak insolation. The HRRR solution remains as an outlier, bringing a very strong bow echo signature through Maine and all the way to Bathurst this evening. The probability of this particular scenario remains low at this time, but forecasters are closely monitoring upstream data to alert to a strong signature should it develop. In this case, the yellow hazard area for wind may be underdone for max gusts. (A stationary boundary is also offshore still producing ongoing lightning and shower activity on the southern Grand Banks of the marine district.)
TODAY
Thunderstorm Outlook valid for TOMORROW – SATURDAY, Aug 27th:
Thundershowers are expected to continue through the overnight hours and affect areas in Nova Scotia early Saturday morning. These partially elevated storms will likely bring bouts of showery weather and lightning. Mainland NS will clear out by noon at the latest. Late day weekend events do not need to be rescheduled due to svr weather. Nfld can expect the same thundershowers and dynamics in the afternoon, near Gander. Lightning will be the main hazard with any cell that does develop.
TOMORROW
Forecaster: TIRONE/ASPC