Summary

June 9th turned out to be a very busy day - with early reports totalling more than 10 severe events (and many sub-severe hail and wind events) occurring from late morning to the evening.

The wet-bulb zero level of around 6-7kft AGL and freezing level near 8kft (over the higher ground of Central PA vs. KPIT) helped many cells to produce hail early and throughout their lifetimes. The storms were aided by a strong wind profile at all levels - much stronger than the severe pulse storms of May 30th and 31st.

This wind profile eventually lead to more organization to the cells, but as with the events two weeks before, the thunderstorms started out as mainly pulse thunderstorms with short durations/life-spans, fired up by the (modest) heating of the day.

Preliminary Damage Reports in Text format

Images

Pittsburgh, PA (KPIT) morning (12z) SkewT Balloon Sounding Note the strong winds aloft (reaching 55kts by 20kft, and as high as 99kts around 35kft). The Convective Temperature (temperature at which cumulus clouds will start to grow) of 74°F was reched very early in the day. Modest/respectable CAPEs of 600 to 700 J/kg were possible, and were most likely realized by late that morning.

Visible Satellite Pic from 1715z (115 PM EDT) with past 15 minutes of Cloud to Ground Lightning Strikes (CGs) overlaid. Note the widespread thunderstorm activity by 1 PM! They started early and lasted into the early evening.

KCCX 0.5° Reflectivity from 1751z (151PM EDT) with warning box plots and Spotter Storm Reports overlaid. Later in the afternoon, the storms had evolved from scattered cells into a bit of linear/mini-bow-echo organization thanks to the strong NW winds aloft. Many storms produced wind damage and large hail. See two of the reports we received from spotters and law enforcement officials plotted in black (one near Williamsport - A=Hail 0.88=diameter in inches - and another report west of Harrisburg). Current warnings (outlines) are also seen in pink on this picture.

KCCX Reflectivity Cross Section from 2044z (444PM EDT) from storm near Williamsport. Note the storm reached up to 28kft or so...with a strong reflectivity core held aloft (strong updraft) in an excellent place for hail generation/growth (above the wet-bulb zero and freezing levels all the way to the top of the storm cell). The storm was also apparently able to tap the 50+kt winds at the top of the storm cell (see SkewT above), and bring them down to the surface, as it blew a couple of trees down in western Lycoming County.