Regional Impacts:
Today
NB: 15-25mm/hr, 70-90 km/h gusts, 1-2 cm hail.
Labrador: isolated lightning
Gulf waters: isolated lightning, possible squalls for western areas (70 km/h+ gusts).
PEI: western Prince County 15-25mm/hr, 70-90 km/h gusts, 1-2 cm hail. Elsewhere isolated lightning
NS: isolated lightning in the evening for northern areas.
Tonight
Labrador: isolated lightning in southern areas.
Gulf waters: isolated lightning
Tuesday:
Labrador: scattered lightning over southern areas with 0-1 cm hail, 10-15 mm/hr, isolated lightning elsewhere.
Gulf waters: scattered lightning over northern sections.
Convective Discussion:
Today: Clearing is already evident behind our initial shortwave that was responsible for showers and thundershowers in southern NB and western PEI this morning. This clearing in northeastern to central NB will allow for surface instability to build into the afternoon hours ahead of broad upper trough that will move into northern NB later this afternoon. Strong zonal flow across the Maritimes will provide 35-50 kts of bulk shear, given the linear character and steep moist low level lapse rates a wind hazard later this afternoon into the evening hours is possible. MLCAPE between 750-1000 J/kg with this type of shear and a lowering HGZ does support hail, however marginal lapse rates of 6.5C/km between 500-700mb should act to limit upward velocities into HGZ, capping the hail sizes to 1 to 2cm. Storm motion should be from west to east with the mean wind at ~30-35 kts, with any supercells moving to the right in a southeasterly direction. The fast motion will limit rainfall in general, however PWATs into the mid 30s, with moist profiles from the surface to 650mb and high 0-3km CAPE could still support rainfall rates hitting 25mm/hr despite the quick movement giving a rainfall hazard to go with a primary wind hazard. Watches may be issued earlier this afternoon primarily for the wind/ rainfall rate hazards. Storms should weaken later in the evening before reaching southernmost NB, central PEI and northern NS as solar insolation wanes. Across the gulf isolated lightning with our initial shortwave this morning will advect east-northeastward, however storms moving off eastern NB may provide a squall hazard. Meanwhile in Labrador isolated lightning is also likely with broad instability present ahead of the upper trough.
Tonight: Storms from the evening will weaken and become elevated moving northeastward across the gulf into southern Labrador as the base of the upper trough rounds the upper low analyzed at 12z over north-central Quebec.
Saturday: Scattered lightning with steep mid level lapse rates from the upper low is expected over southern Labrador. Storm motion will be variable and low with rainfall rates of 10-15mm/hr and small hail given the low freezing levels. Vertically stack vorticity, low LCLs and little vertical shear suggest that cold core funnel clouds are possible. Elsewhere across Labrador lightning should be more isolated in nature associated with general instability of the upper trough.
Thunderstorm outlook for today:
Thunderstorm outlook for tonight:
Thunderstorm outlook for Saturday:
