Afternoon thunderstorms erupted over southeastern Pennsylvania during the late afternoon on Sept 28, 2006 producing severe weather in a few locations, namely Franklin and Cumberland counties. The storm reports of this damage show the severe weather occurred around 4:00 to 6:30 pm. The surface map at 18:00 UTC showed a cold front moving across Central PA but by 21:00 UTC it had stalled allowing a narrow tongue of moisture to ride up ahead of it from Franklin to Cumberland Counties. At 20:00 UTC surface dewpoints were in the upper 50's and lower 60's in this area. The vertical wind profile from the KCCX and KLWX Radar showed weak wind shear with more of a veering profile at LWX than at CTP.

The thunderstorms moved northeast out ahead of the cold front during the late afternoon as the front slowly migrated east and southeast. One cluster of storms moved northeast out of Maryland and entered southern Franklin county 20:15 UTC. The topography of Franklin County (higher terrain shaded darker) indicated that the storms moved from southwest to northeast along the valley. Out ahead of that cluster an isolated, weak storm developed and as the cluster approached and merged with this cell, it strengthened as it moved toward Chambersburg and St. Thomas. The KLWX Reflectivity and Storm Relative Velocity (SRM) products show only broad and weak circulation with this storm at 20:42 and 20:50 UTC. By 20:50 UTC the storm had evolved into a bowing segment and Emergency Managers reported trees and wires down in Chambersburg. An animation loop shows how this storm evolved.

Another cluster of storms moved into northern Cumberland county around 5:00 pm. At 20:53 UTC the KCCX radar showed the center of the storm just to the northwest of Wertzville. The topography of Cumberland county indicated this storm was hugging the terrain to the northwest of Wertzville. However an interesting weak circulation was evident at 20:57 UTC on the SRM display just to the southeast of this ridge line. Also there is an indication of the high reflectivity core reaching low levels and a flare echo. The SRM data at 20:57 UTC showed the weak circulation around mile markers 58 and 59 on I-81 near Wertzville. This is the location where an Emergency Manager reported a tornado which was confirmed through a storm damage survey. NWS personnel completed the survey on Friday the 29th and determined that a 3 mile long F1 tornado tracked northeast across Northen Cumberland county around 5:00 pm. The storm and weak circulation persisted at 21:01 and 21:05 UTC as it continued northeast.

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE STATE COLLEGE PA
958 AM EDT FRI SEP 29 2006
 
..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0450 PM     TSTM WND DMG     CHAMBERSBURG            39.93N 77.66W 
09/28/2006                   FRANKLIN           PA   EMERGENCY MNGR  
 
            911 CENTER REPORTED TREES AND WIRES DOWN IN THE 
            VICINITIES OF CHAMBERSBURG, GREEN CASTLE AND ST.THOMAS. A
            HOME CAUGHT FIRE DUE TO AN UNCONFIRMED LIGHTNING STRIKE.
 
0510 PM     TORNADO          3 NE HOGESTOWN          40.26N 77.00W 
09/28/2006                   CUMBERLAND         PA   EMERGENCY MNGR  
 
            EMA DIRECTOR REPORTED THAT SEVERAL HOMES WERE DAMAGED BY 
            A POSSIBLE TORNADO NEAR THE INTERSECTION OF SR 944 AND 
            LANDS GAP RD. NEAR THE BORDER OF SILVER SPRING AND HAMDEN
            TOWNSHIPS. THE UNCONFIRMED TORNADO IS BELIEVED TO HAVE 
            CROSSED I-81 BETWEEN MILE MARKERS 58 AND 59.
 
0540 PM     TSTM WND DMG     RED LION                39.90N 76.61W 
09/28/2006                   YORK               PA   EMERGENCY MNGR  
 
            TREES DOWN IN RED LION
 
0612 PM     TSTM WND DMG     EPHRATA                 40.18N 76.18W 
09/28/2006                   LANCASTER          PA   COUNTY OFFICIAL 

            911 CENTER REPORTED TREES AND POWER POLES DOWN ON ROUTE 
            272.
 
0630 PM     HEAVY RAIN       5 SE EAST PETERSBURG    40.04N 76.30W 
09/28/2006  M2.10 INCH       LANCASTER          PA   TRAINED SPOTTER 

            SPOTTER MEASURED RAIN AT ROHERSTOWN, 3 MILES WEST OF 
            LANCASTER. RAIN FELL BETWEEN 515 AND 630 PM. WIND WAS 
            ESTIMATED AT 55 MPH AT 615 PM.