Regional Impacts
Today
NB: scattered strong to severe thunderstorms expected this afternoon and into the evening across NW portions of the province.
Tonight/Friday morning
NB/Western NS/PEI: isolated thunderstorms possible.
Central LAB: isolated thundershowers possible.
Friday afternoon/evening
MRTMS/central LAB/western NL: isolated to scattered thunderstorms possible. Some of the cells could be strong.
Convective Discussion
It appears prime for possible strong to severe thunderstorms across northwestern NB this afternoon and evening. From top down: an approaching 250 jet maxima (right quadrant) and associated divergence by mid to late afternoon approaching northern ME and NW NB; an approaching 500mb trough currently over QC and a strong 50-50 knot jet just ahead of it; good dry air in the mid levels as is currently evident in conventional SAT PIX; Very moist air from 850mb to the surface and a strong LLJ of around 30 knots (~925mb) which was seen upstream in the 12Z Albany sounding. The really interesting area that would have been nice to have a sample from was missed, but adjusting the Grey and Albany soundings produces 1000-2000 j/kg SBCAPE, with 0-6 km effective westerly shear up around 50 knots and decent 0-3 km srh helicty of just shy of 200. That area will be advecting northeastward coinciding with the approaching trough (both at the surface and 500 mb), which in most circumstances spells trouble. Given the observed data and higher resolution model support we expect winds to be the main issue, however owning to the strong updrafts in the deeper cells hail is also a potential. PWAT is around 40, but storms should be moving fast enough to not produce a significant amount of rain (unless there is slight back-building or training of storms). In line with the Storm Prediction Center there is also a slight risk of seeing a tornadic supercell.
In summary: Strong to severe storms producing wind gusts of 60-100 km/h and hail up to 2 cm for northwestern counties in NB possible this afternoon and evening.
Thunderstorm Outlook for Day 1
Thunderstorm Outlook for tonight and Friday morning
Thunderstorm Outlook for Day 2 afternoon and evening
Jeremy