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Got back from a great vacation trip this afternoon just in time to fly around a severe thunderstorm across Southside Virginia. Missed chasing that one!

However Wednesday looks promising given the combination of a stalled cold front and an approaching upper level low pressure center. SPC has the Virginia Piedmont under a Marginal Risk in its Day 2 outlook but that could be upped in the morning.

The WRF-NSSL model captured today’s convection pretty accurately. This is the depiction of 0-6 km shear at 21Z (5 pm) tomorrow:deep-shear-at-21z-wed

Forty+ knots over the Piedmont is pretty decent. Now for the forecast CAPE at the same time:sbcape-at-21z-wed

The stalled boundary is readily apparent on this graphic with no CAPE west of it and 1000+ j/kg (blue shading) east of it. The NAM is a bit more optimistic (surprise surprise) with CAPE values reaching over 2000 and with the boundary one county west of the Rte 29 corridor. The GFS solution is somewhere in the middle of these two, with the boundary aligned somewhat with the WRF-NSSL solution but with CAPE values over 1500.

Upper level dynamics align with these solutions as 700 mb vertical velocities look decent over the same areas. (The upper level low is filtering in cooler air aloft that will enhance that upward velocity.) Thus Wednesday morning will involve checking the latest short range model runs for convection initiation times and locations plus monitoring surface observations to see how the front behaves. The low level helicity provided by the boundary could make tomorrow interesting.

We’ll see…

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