Summary

July 9th turned out to be a very busy day (as was June 9th) - with early reports totalling over 30 severe events (and many sub-severe hail reports) occurring from early afternoon through early evening.

The Storms fired up on the ridges of west-central PA, as the heating of the day and the cold pool aloft from an upper low combined to create great instability. See the KLWX (Washington DC) 18z sounding for the details on the environment just to our south. We must have been even more unstable, since hardly any convection fired south of the Mason-Dixon Line that day.

The weak wind profile (also seen on the LWX sounding) contributed to the slow movement of many of the cells, and kept wind damage from being a primary threat. The main threat was hail - and large hail at that (0.88 to 1.00 inch hail was common).

Preliminary Damage Reports in Text format
Graphical Plot of Reports from the Storm Prediction Center

Images

Click to see a full-size version of the images below...

Sterling, VA Sounding from 18z 7/9/06

Storm over Juniata County dropping large inch hail

Storm over Williamsport dropping large hail

Multiple Severe Thunderstorms near Harrisburg, Lebanon, and Lancaster

Visible satellite image and lightning plot of storms over Centre,
Huntingdon, Mifflin and Juniata counties around 3:45 pm.