Throughout the night powerful thunderstorms complexes have lit up the skies and brought damaging winds across the Ohio Valley towards the Mid-Atlantic. Unfortunately through today, more thunderstorm clusters will form as upper level energy swings from the Lakes towards the Southeast while heat and humidity build underneath. The storms which fire over the Ohio Valley will drive straight into the ‘highly primed’ atmosphere out ahead and unfortunately, that area includes the heavily populated Mid-Atlantic urban corridor. The stage looks set for yet more converging thunderstorms and growing complexes which may fan out into dangerous ‘bowing’ squall lines which could unleash 70-90 mph winds even into major urban centres such as Washington, Baltimore and Philadelphia.

Large hail, flash flooding and isolated tornadoes are a very real threat with this situation but WIDESPREAD damaging wind is likely the greatest threat as countless storms merge, acting like a wall of powerful winds which is no ordinary wind. A wind which is highly likely to down trees and cause damage. Flash flooding, particularly in low lying areas and in urban areas is also a real concern.

These long lines of fast moving, powerful thunderstorms will target Pennsylvania, New Jersey, Delaware, Maryland and Virginia later today and tonight as surface temperatures approaching the mid-80s in Philadelphia but perhaps exceeding 90 down towards the DC-Baltimore area and with dew points into the 70s, this could be a very dangerous situation.

Here’s the moderate risk area outlined by the SPC.

Here’s AccuWeather’s outlined risk area.

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While the thunderstorm COMPLEX threat is great, so the threat is high from strong to possibly damaging winds along the Northeast coast from a deepening sub 992mb low off the coast. The New Jersey, Long Island shore up to Cape Cod Thursday night into Friday may be in for gale-force winds, battering waves and heavy rain.

Firstly, take a look at the energy digging into the trough and the depth of the trough for this time of year!

Here’s Saturday AM

How about the surface chart.

Fri AM

Sat AM

This unusually deep low (around 990mb) within an unusually deep trough for June, will present coastal wind gusts of 50+ mph from Cape May to Montauk late tonight till probably midday Friday with as much as 2-4 inches of rain falling and wave heights to 10ft along the coast.

That’s not forgetting the 2-4, locally 6 inches of rain expected from Ohio to Connecticut and down towards the Delmarva with the thunderstorm complexes.

Here’s the ECMWF total precip over the next 48 hours.

Here’s the QPF

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