Heavy Rain Return to the Southwest U.S.; Potential Atlantic Tropical System Interaction

Heavy to excessive rainfall from monsoon thunderstorms may bring isolated flash and urban flooding to the Desert Southwest into Sunday. The tropical wave (AL94) continues to bring heavy rainfall to Puerto Rico and the US Virgin Islands. The close proximity of Tropical Storm Humberto and AL94 could lead to interaction between them, but details of their track and intensity forecasts remain uncertain Read More >

Overview

A significant hailstorm moved through Lycoming, Northumberland, and Columbia counties on August 17th, 2007 producing hail stones as large as 1.75 inches in diameter in Muncy. Golfball to baseball sized hail fell during the afternoon as a severe thunderstorm moved southeast across southern Lycoming county toward Columbia county from about 12:30 pm until 2:00 pm.

The storm was strong enough to produce rotation in the mid and upper levels of the atmosphere prompting a tornado warning for Lycoming county at 12:56 pm. Although there were some unconfirmed funnels reported by the public, an NWS State College survey team concluded there was no evidence of a tornado touching down.

In Muncy the storm's large hail shattered windows and damaged windshields. Strong straight-line winds also blew down large trees in Millville in northwest Columbia county disrupting power to about 800 PPL customers.


Sterling, VA upper air sounding showing 1245 J/Kg of CAPE Friday morning	Visible Satellite loop from 12:00 to 2:30 pm	Surface analysis 1:00 pm showing low pressure and high dewpoints over the area

Radar
Storm Reports

Radar


KCCX Radar reflectivity showing storm over Muncy at 1:17 pm	KCCX Radar reflectivity showing storm over Millville at 1:42 pm	KCCX Radar showing rotation, Tornado Vortex Signature, and forecast Storm Track at 12:56 pm	KCCX Storm Relative Velocity loop 12:39 to 1:55 pm

KCCX Radar Reflectivity loop from 12:35 to 1:51 pm	KCCX Vertical Integrated Liquid loop from 12:43 to 1:42 pm

Storm Reports

NWUS51 KCTP 200226
LSRCTP

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1026 PM EDT SUN AUG 19 2007

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0100 PM     HAIL             1 W WILLIAMSPORT        41.24N 77.04W 
08/17/2007  M0.88 INCH       LYCOMING           PA   TRAINED SPOTTER 

            NICKEL SIZED HAIL AND 40-50 MPH WINDS

0100 PM     HAIL             WILLIAMSPORT            41.24N 77.02W 
08/17/2007  M1.00 INCH       LYCOMING           PA   TRAINED SPOTTER 

0104 PM     HAIL             LOYALSOCKVILLE          41.32N 76.92W 
08/17/2007  E0.88 INCH       LYCOMING           PA   PUBLIC          

0108 PM     HAIL             MONTGOMERY              41.17N 76.88W 
08/17/2007  E1.50 INCH       LYCOMING           PA   TRAINED SPOTTER 

0117 PM     HAIL             LANDISVILLE             40.09N 76.42W 
08/17/2007  E0.88 INCH       LANCASTER          PA   PUBLIC          

0120 PM     HAIL             1 N MUNCY               41.22N 76.79W 
08/17/2007  M0.88 INCH       LYCOMING           PA   PUBLIC          

            HAIL COVERS GROUND IN PENNSDALE.

0122 PM     HAIL             MUNCY                   41.20N 76.79W 
08/17/2007  E1.75 INCH       LYCOMING           PA   PUBLIC          

            GOLFBALL TO BASEBALL SIZED HAIL RELAYED THROUGH STORM 
            SPOTTER.

0125 PM     HAIL             TURBOTVILLE             41.10N 76.77W 
08/17/2007  E1.25 INCH       NORTHUMBERLAND     PA   PUBLIC          

0130 PM     HAIL             LANCASTER               40.04N 76.30W 
08/17/2007  E0.88 INCH       LANCASTER          PA   EMERGENCY MNGR  

0130 PM     HAIL             1 ENE EXCHANGE          41.12N 76.67W 
08/17/2007  M1.50 INCH       MONTOUR            PA   PUBLIC          

            HAIL MEASURED AT HOME ON THE MONTOUR SIDE OF THE COUNTY 
            LINE. HAIL HAS BEEN ON GROUND FOR OVER HALF HOUR BEFORE 
            MEASUREMENT.

0135 PM     TSTM WND DMG     LANCASTER               40.04N 76.30W 
08/17/2007                   LANCASTER          PA   EMERGENCY MNGR  

            TREES DOWN IN COUNTY PARK. ROCKFORD AND WILLIAMSON ROADS 
            CLOSED.

0140 PM     TSTM WND DMG     2 W MILLVILLE           41.12N 76.57W 
08/17/2007                   COLUMBIA           PA   EMERGENCY MNGR  

            MULTIPLE TREES AND WIRES DOWN ON ROD AND GUN CLUB ROAD.

0143 PM     HAIL             MILLVILLE               41.12N 76.53W 
08/17/2007  M0.88 INCH       COLUMBIA           PA   TRAINED SPOTTER 

0200 PM     TSTM WND DMG     RINGTOWN                40.86N 76.24W 
08/17/2007                   SCHUYLKILL         PA   PUBLIC          

            ROOF BLOWN OFF SHED.

0205 PM     HAIL             MCADOO                  40.90N 75.99W 
08/17/2007  E1.75 INCH       SCHUYLKILL         PA   LAW ENFORCEMENT 

0216 PM     HAIL             BLOOMSBURG              41.00N 76.46W 
08/17/2007  M1.00 INCH       COLUMBIA           PA   PUBLIC          

0235 PM     HAIL             MCADOO                  40.90N 75.99W 
08/17/2007  E1.75 INCH       SCHUYLKILL         PA   LAW ENFORCEMENT 

            SECOND ROUND OF GOLFBALL SIZED HAIL AFTER A 15 TO 20 
            MINUTE BREAK


&&
CHANGED SEVERAL EVENT TIMES BASED ON RADAR DATA. FINAL VERSION.
$$

STEINBUGL