Regional Impacts
Today.
Scattered thunderstorms expected for central and western LAB as well as most of NB. There is a chance that a couple of the storms will become severe across northwestern NB giving strong wind gusts, small hail and torrential downpours.
Tonight.
Scattered thunderstorms are possible across most of LAB. Isolated thunderstorms possible for NE NB and most of NL.
Wednesday.
Scattered thunderstorms likely again for a portion of LAB, central and NE NL and northern NB. Some of these storms could approach severe limits.
Convective Discussion
A couple features today will be responsible for some thunderstorm activity – the first one being an upper level low/trough currently over ME that will drift northeastward and the second a frontal trough ahead of the upper low that is currently just south of NS. The upper trough could give a severe thunderstorm or 2 to northwestern NB this afternoon and into this evening. Adjusting upstream TEP over New England gives 700-1000 MLCAPE. Wind shear is in the 30-35 knot range with PWAT values of 35-40 mm. The only thing that could limit the growth of the cells would be the available sunshine and associated instability. If things clear sufficiently it will allow for a fairly buoyant atmosphere to exist which would give way to some strong to severe cells. Also of note is some storms will be fairly slow-moving owing to a threat for locally heavy rainfall amounts. Right now things are pretty overcast so time will tell. Slightly falling atmospheric heights and a surface trough should be enough to trigger some non-severe thunderstorms across central and western LAB this afternoon and evening. Locally heavy downpours seem to be the main threat.
Isolated thunderstorms are expected for northeastern NB and a portion of NL tonight as that frontal trough ahead of the upper low/trough moves through the region. High PWATs will give way to locally intense rainfall rates. There is a little history of lightning south of NS associated with this feature. Scattered thunderstorms could persist into tonight across LAB associated with the surface trough.
On Wednesday that same upper trough impacting NB today will cross central/northeastern NL giving some scattered thunderstorms with some approaching severe limits. Of course this is based on model information and what happens today in NB will be a better gauge on what could happen tomorrow. Lastly another upper trough will approach NB and LAB on Wednesday giving some scattered afternoon/evening thunderstorms.
Thunderstorm Outlook for Today
Thunderstorm Outlook for Tonight
Thunderstorm Outlook for Tomorrow
Jeremy