Severe Thunderstorm Warning 39, NWS State College, PA

CENTRAL PENNSYLVANIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
335 AM EDT MON MAY 25 1998

...WRKZNS SENT TO NWSFO/S PIT AND PHL VIA PHLADMCTP...

...DISCUSSION...
SCATTERED SHRA/TSRA WORKG INTO CNTRL/SRN PA IN ASSCTN WITH LL
THETA-E ADVTN IN ADVANCE OF WELL-DEFINED UPR LVL SHRT WAVE OVR THE
ERN LAKES. SCTRD SHRA/TSRA WERE FIRING CLSE TO THE GRADIENT OF 850
MB THETA-E CLSE TO THE LL WRM FRNT. AS THIS WAVE PASSES TO THE E...
IT WILL ALLOW A LL THETA-E RDG TO BECOME ESTABLISHED ACROSS
CNTRL/ERN PA THIS AM AS THE WRM FRNT PASSES THRU PA. THUS... SCTRD
SHRA/TSRA WILL CONT DURG THE ERLY AM HOURS ACRS CNTRL PA. THINK THIS
ACVTY WILL DIE DOWN AFTER SUNRISE AS BNDRY LYR HEATING AND GROWTH
BEGIN TO DISRUPT THE NOCTURNALLY ENHANCED LL INFLO OF THESE STORMS.

ANTHR UPR LVL WAVE WAS CLEARLY SEEN OVR SRN MINN/IA THIS AM. THIS
FEATURE IS PROGGED TO SLIDE E REACHING THIS ERN LAKES BY 0000
UTC THIS EVE. THIS FEATURE WILL BE THE IMPETUS TO PUSH A CD FRNT
THRU PA WITH STRG LL DRY ADVECTION TAKING PLACE. THE LL THETA-E RDG
OVR PA IS PUSHED TO THE E BY THIS EVE AS A RESULT. THE AMS BECOMES
SOMEWHAT UNSTBL BY AFTRN... ESP FM THE SUS VLLY EWRD. THINK THIS
NEXT WAVE WILL FORCE THE NEXT ROUND OF ACVTY FOR CWA SO KEPT CHC
POPS IN ZONES ALL DAY TO ACCOUNT FOR THIS AM/S ACVTY AND THE
EXPECTED RESURGENCE OF SHRA/TSRA THIS AFTRN. THINK SOME OF THIS
ACVTY BLEEDS OVR INTO THE EVE HOURS IN ERN ZONES.

WINDS FIELDS WILL BE RATHER POTENT THIS AFTRN AS AN 850 MB JET WORKS
THRU PA. MID-LVL WINDS WILL BE ROARING UP TO 50 KTS OR GREATER. WITH
PLENTY OF MID-UPR LVL DRY AIR AVBL AS PER WV CHANNEL... THINK PTNL
EXISTS FOR SOME STRG TO SVR STORMS MAINLY FOR ERN PA THIS AFTRN/EVE.

AFTER THIS SECOND UPR LVL WAVE PASSES TONIGHT COOLER DRIER AIR
PRESSES S INTO PA. THEN... A THIRD SHRT WAVE SEEN OVR CO ATTM MOVES
INTO THE PICTURE. THIS WAVE REACHES THE MID-WEST BY LATE MON NGT AS
AN ANTHR IMPRESSIVE UPR LVL WAVE DROPS S FM CANADA. THE COMBINATION
OF THESE TWO WAVES WILL CREATE A STRG JET STREAK OVR THE NERN U.S.
THIS WILL LEAD A FRONTOGENETICALLY ACTIVE REGION N OF THE SFC BNDRY
WHICH WILL RESIDE SOMEWHERE OVR THE MID-ATLANTIC STATES MON NGT
SUGGESTIVE OF SOME POST FRONTAL LIGHT RAINS. ETA FGEN FIELDS SHWG
SOME FGEN FRCG FOR SRN PA MON NGT AND INTO ERLY TUE FOR SERN ZONES.
THUS HV LO CHC POPS MON NGT SRN ZONES WITH SOME POPS BLEEDING OVR
INTO TUE AM IN THE LWR SUS VLLY. REST OF ZONES DRY TONIGHT/TUE GIVEN
STRG LL CAA AND DRY ADVECTION.

NICOSIA