Afternoon Update [5/28] Tornado Watch;

Synopsis:

Enhanced risk this afternoon for strong storms
Sunshine starting to heat up atmosphere
SPC issue mesoscale discussion
Tornado watch
Cold front with thundershowers/storms tonight as well

Discussion:

Storm Prediction Center: Mesoscale Discussion

Tornado Watch has been issued Storm Prediction Center

Current Radar showing some storms along the boundary in the Lehigh Valley, this area should continue to sink ESE.

Current MSLP and winds shows elongated area of low pressure

Satellite imagery shows our low pressure areas. The purple arrow is approximately where the cold front is located. Ahead of it we see some clearing of the clouds. The orange box indicates the environment where things will become unsettled over the next few hours. The purple arrow is the showers/thundershowers that will be moving through later tonight.

Forecasts

Soundings for this afternoon continue to indicate possibility of rotating cells. Plenty of instability with around 3000 J/kg of CAPE. Omega strong in the hail growth zone and SHIP value 1.8 (sig. hail parameter). SHIP explanation

Continue to see the potential for discrete cells forming with tornado still possible. Likely impacts C. PA but sounding above is for Philly at 6PM which suggests an environment for supercells. This means that radar watching is a must!

Still seeing convective inhibition in the area with LCL-LFC differences rather high on mesoanalysis (for now). However, with increased instability (sunshine), more low level forced ascent and less inhibition will lead to thunderstorm activity.

Overview:

Best chance for severe weather in Philly is between 5PM and 8 PM
Severe weather higher probability in C. PA
Storms likely overnight with passage of front (see red dashed lines in satellite imagery)
Hail and isolated tornado possible