Chase Forecast No. 3 ~ 2025-03-31

Good morning from a cafe in Allentown, Pennsylvania! I’m chasing a semi-local severe weather setup this morning over the Northeastern region ahead of what’ll likely be another trip out Midwest midweek. Today is not a perfect setup by any stretch, but there are positive signs as the sun reflects off of a windshield in the parking lot into my eyes. That wasn’t the case earlier when I made my way westward from New Jersey. 

Overhead we’ve got an ejecting 500mb trough that’ll bring strong southwesterly flow. This jetstream is advancing a strong occluded surface low over southwestern Quebec. Out ahead of the cold front is a boundary that is established over Central PA and the warm front has worked its way up into northern New England. Shear is in place, however it is more speed than directional shear. However, there is some good low-level hodograph curvature which is promising, though winds aren’t fully backed. Moisture is advecting northward thanks to the strong surface low with current dew points in the low fifties here in eastern PA, but already in the low sixties in MD. Current RAP trends have mid sixties dews maturing into New Jersey.

With kinematics and moisture well established, the problem today will be instability. But as aforementioned sun beats off the windshield in the parking lot into my eyes, maybe there is some optimism here. MLCAPE looks to be very marginal, well below 1000 J/kg, but the HRRR seems to maintain strong cloud cover over the warm sector, which does not seem to be the case right now thanks to this pesky car windshield. I’m hoping this trend maintains as instability will ultimately be the limiting factor in my estimation. Capping may be a issue as well if the cloud cover persists.

Nevertheless, CAMs are producing consistent isolated cells that eventually grow upscale as they advance eastward into NJ. It appears though that they should remain isolated for some time which will make for some beneficial chasing. The Storm Prediction Center maintains a 2% tornado risk up this way, which makes sense if one supercell becomes dominant in a slightly more unstable than forecasted environment. I really enjoy the chasing terrain out this way in Southeastern PA, which I hope will be the location where storms track. I really do not want to deal with the logistics of the Delmarva Peninsula. Great Terrain, but it's a narrow corridor to work with and is difficult to get in and out of.

As of 11 AM EDT, my plan is to station myself more towards Reading, PA and watch how observations evolve. It’s always a great day to chase this part of PA and I’ll treat it as the warm up for if I decide to venture to the Midwest later this week.

Cheers,

Ethan