Today’s Regional Impacts
New Brunswick… tornadic thunderstorms are possible this afternoon. These storms are forecast to form into squall lines by this evening with a straight line wind gust risk. Moderate hail is also possible.
NS/PEI/Iles-de-la-Madeleine/Nfld… thunderstorms are possible late this evening and tonight as the NB convection drifts S and SE across the rest of the Maritimes and the Gulf of St. Lawrence.
Labrador… scattered thunderstorms are possible along an advancing trof with small hail and gusty winds, similar to yesterday.
Convective Discussion
Today is a dynamic day across NB and parts of Quebec and Maine. Over northern and central parts of New Brunswick, effective shear values are topping 40kts, with MLCAPE values near 1750J/kg this afternoon. In the lowest levels, helicity values are also nearing 200. The morning shape of Caribou’s hodograph is a bit messy, but averaged out it has the correct curvature. Dewpoints are already at 18, giving Pwats near 45 in this airmass.
The trigger and its orientation are what become important later today. The advancing trof looks to be timed to pass through at the period of maximum daytime heating. As well, the orientation of the jet streak is NW to SE, and will drive at first discrete cells to then crowd each other and form squall lines. This means a tornadic risk initially in the supercell environment, and then a significant straight line wind gust threat throughout the evening hours. Squall watches/warnings may also be required for adjacent marine regions, ahead of this feature. Sig tor, hailcast, and other indices are flagging the same hazards that were identified on this morning’s Miller workup. Of additional note is the CIN (minor) at play as well: upper level forest fire smoke, and prevailing morning cloud cover.
A severe thunderstorm watch has been issued. An additional 18z ballon has been requested at Gagetown to aid in forecasting/alert upgrading.
Thunderstorm Outlook for Today
Thunderstorm Outlook for Tonight
Thunderstorm Outlook for Tomorrow
Forecaster: Tirone.