Regional Impacts
Newfoundland… some thunderstorms giving locally 15 to 25mm possible.
NB… slight chance of thunderstorms today with low possibility of 15-25 mm rain and some strong winds. Overnight and tomorrow morning an enhance risk of heavy nocturnal rainfall for southern areas.
NS and PEI… Slight chance of TS today. Overnight and tomorrow morning an enhance risk of heavy nocturnal rainfall in vicinity of Bay of Fundy into central PEI. Could impact northern NS and the Annapolis Valley.
Convective Discussion
The subtleties of nailing down these convective outlooks continues to be a challenge as we move into the next couple of days. The high moisture content and unstable airmass will continue to linger until Friday when things begin to dry out somewhat. Most of the significant weather events over eastern Canada have been largely linked to the series of short-wave troughs that have been moving through, the system that impacted southern Ontario yesterday fortunately weakened as it approached the Maritimes overnight. However, we are looking at a potential event overnight and early tomorrow as the large-scale upper trough begins to push east. We should be able to watch how the convection develops today over northeastern US, this should give us a clue to weather we are impacted by a nocturnal MCS or not however any messaging in term of alerts would likely be a very short notice if anything is warranted at all. It should be noted that high-res models like the HRRR have been somewhat useful in forecasting these nocturnal events, perhaps not in the sense that the locations are completely accurate, but the general occurrences have been pretty good. The Day 1 night Outlook covers a large area yellow and represents the most probable location for intense storms but there is still some uncertainty in the exact location
For today newfoundland and Labrador will continue with there relatively active thunderstorm activity with some isolated and possibly more organized cells in NFLD, updrafts aren’t very strong but the moderate shear and high moisture content bring some concern for heavier rainfall amounts than individual cells might suggest. Keeping a close eye on radar rainfall estimates is likely the best approach.
It seems likely that most of NB will have slight capping aloft which should initially make deeper cells unlikely until later today. Givin the decent shear, likely above 40 knots of bulk shear (0-6 km) and dry mid-levels some isolated severe storms are possible should things initiate sooner than expected.
Thunderstorm Outlook for Today
Thunderstorm Outlook for Tonight
Thunderstorm Outlook for Tomorrow
Mel Lemmon