Flash Flood Warning 40, NWS State College, PA

CENTRAL PENNSYLVANIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
825 PM EDT FRI MAY 10 1996

...COORDINATION...
PIT... KEEP FFA OVRNGT FOR AREAS IN CTP CWA CURRENTLY IN FFA.
THINK SVR TSTM WATCH FOR NW PA CAN SAFELY EXPIRE AT 9 PM.
PHL... SVR TSTM WATCH FOR NC PA CAN SAFELY EXPIRE AT 9 PM.

...DISCUSSION...
...SHORT-TERM...
RW/TRW ACVTY IN NRN CTP CWA SO FAR NOT SVR AS NO REPORTS OF
DAMAGE RECEIVED. WIND GUSTS MAINLY ABT 30 MPH OR SO REPORTED. TWO
CONCERN NEXT 6 HOURS. 1) PTNL FOR MORE HEAVY RAINFALL IN NRN MTNS
AND 2) SQLN APPRCHING PA FROM OH. KPBZ 88D SHWS NEXT BATCH OF
CNVTN HEADING INTO NW PA ATTM WITH MORE HVY RAINFALL IN STORE FOR
NRN MTNS NEXT FEW HOURS. SATL IMAGERY SHWS THAT TOPS WERE WARMING
OVR OH WITH THIS BATCH OF RW/TRW. ACVTY WAS MOVG INTO MORE STBL
AIR IN WRN PA/ERN OH ( SFC DWPTS IN THE 50S) AND IS PROBABLY
PLAYING A ROLE IN THE DECREASING INTENSITY OF THIS MCS. IN
ADDTN... THE MAIN SYNOPTIC SCALE SUPPORT IN THE FORM OF A STRG
LOW-LVL JET AND SIG UPR DVRG IS OVR NY STATE NOW WHERE MCS IS
BUDDING ON SATL... AND THUS SVR WX BEING OBSERVED ACRS NY. STILL
THINK MORE RAINFALL NEXT FEW HOURS FOR NRN MTNS WILL AGGRAVATE
CONDITIONS OVR NRN MTNS (ESCPLY WARREN CO) WHERE HVY RAINS HAVE
FALLEN ERLIER TODAY. THUS KEEP FFA GOING NRN MTNS. SQLN IS
APPRCHG WRN PA AND APPEARS TO BE DECREASING IN INTENSITY AS IT
WORKS INTO LWR SFC DWPTS AND STABILIZING B.L. THIS ACVTY WILL
LIKELY MAKE IT INTO SWRN CTP ZONES LATER THIS EVE AND MAINLY BE A
RAIN EVENT. (THOUGH WILL STILL HOLD EXTRA STAFF JUST IN CASE!).
THUS... KEEP FFA FOR LAURELS WITH LOW FFG VALUES FOR THIS NEXT
BATCH OF RW/TRW WORKG INTO SW PA.

...LONG TERM...
AFTER BATCH OF CNVTN OVR OH WORKS INTO PA LATE THIS EVE...
SIGNIFICANT S/W ENERGY (SEEN OVR PLAINS ON SATL) WORKS INTO MID-
WEST ACCELERATES A STRG LOW-LVL JET TO THE SW OF PA BY 12Z. THIS
UPR LVL S/W WILL BE THE IMPETUS TO PUSH FRNT ACRS PA SAT. THE
LOW-LVL JET (ABT 40 KTS) WILL FOCUS SIGNIFICANT MOISTURE AND CONV
NR AND BEHIND SFC FRNT DURG DAY SAT ACRS PA. MODELS INDICATE A
STRG JET ENTRANCE REGION CIRC ACRS PA WITH ASSCTD UPWARD BRANCH
OF THERMALLY DIRECT CELL AFFECTING PA. THIS AGEO TRANVERSE CIRC
SUPPORTS STRONG FRONTOGENETIC FRCG N OF SFC FRNT SAT. THUS...
INGREDIENTS ARE COMING TOGETHER FOR SIG RAINS ACRS PA SAT... A
LOW-LVL JET RUNNING INTO A FRONTOGENETIC LOW-LVL BNDRY THAT WILL
BE SLOWLY SLIDING SWRD ACRS PA. MODEL QPF/S ARE OVER AN INCH
WHICH LOOKS RSBL. FFA/S MIGHT BE NEEDED ERLY MORN ZONE PACKAGE
FOR SAT. MODELS DIFFER AS TO PLACEMENT OF QPF MAX. NGM HAS 1.5
INCH + MAX ACR SERN PA... ETA HAS 1.5+ MAX IN SWRN PA... WITH AVN
HVG 1 TO 1.5 INCHES ACRS NRN 1/2 OF PA. NGM DOESN/T DVLP LOW-LVL
JET AS MUCH AS OTHER TWO MODELS AND HAS LESS DVLPED SFC WV ALONG
FRNT THAN OTHER TWO MODELS AT F36. LIKE AVN/ETA SFC LO
PSTN/STRENGTH AND STRGER LOW-LVL JET. FOR NOW... WUD HV A STRIPE
OF 1 TO 1.5 INCHES BTWN 06Z SAT AND 12Z SUN FROM SW PA TO NE PA
SIMI(LAR TO ETA QPF.

NICOSIA

PAZ004>006-010>012-017>019-037-041-042-045-046-049>053-110200-

SPECIAL WEATHER STATEMENT - SEVERE THUNDERSTORM WATCH
NATIONAL WEATHER SERVICE STATE COLLEGE PA
345 PM EDT FRI MAY 10 1996

...SEVERE THUNDERSTORM WATCH IN EFFECT UNTIL 1000 PM EDT...

THE NATIONAL WEATHER SERVICE HAS ISSUED A SEVERE THUNDERSTORMS WATCH EFFECTIVE
UNTIL 1000 PM FOR THE FOLLOWING COUNTIES IN NORTHERN AND CENTRAL PENNSYLVANIA:

WARREN... MCKEAN... POTTER... ELK... CAMERON... CLINTON... CLEARFIELD...
CENTRE... TIOGA... LYCOMING... SULLIVAN... UNION... SNYDER... NORTHUMBERLAND...
MONTOUR... AND COLUMBIA.

WARM HUMID AIR HAS OVERSPREAD CENTRAL AND NORTHERN PENNSYLVANIA THIS AFTERNOON
IN THE WAKE OF A WARM FRONT WHICH MOVED NORTH INTO NEW YORK STATE EARLIER IN THE
DAY.  SHOWERS AND THUNDERSTORMS WILL DEVELOP THIS AFTERNOON AND EVENING AHEAD OF
A DISTURBANCE MOVING EASTWARD FROM OHIO.  SOME OF THESE THUNDERSTORMS COULD BE
SEVERE.

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE FOR SEVERE
THUNDERSTORMS IN AND NEAR THE WATCH AREA.  PERSONS IN THESE AREAS SHOULD BE ON
THE ALERT FOR THREATENING WEATHER...AND LISTEN FOR LATER STATEMENTS OR POSSIBLE
WARNINGS.

JUNG