Flash Flood Warning 125, NWS State College, PA

CENTRAL PENNSYLVANIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
125 PM EDT TUE JUL 30 1996

...ZONE SUGGESTIONS...
FFA/S MIGHT BE NEEDED. CUD HOLD ON FOR NOW AS SYS IS STILL
PROGRESSING EWRD AT A DECENT PACE. SOMETHING TO CONSIDER IF
THE SYS SLOWS DOWN.
TONIGHT... RW/TRW FOR THIS EVE... HIGHLIGHTING HVY
DOWNPOURS/GUSTY WINDS. CLDY AFTER MIDNIGHT WITH PATCHY FOG.
WED INTO WED EVE... CHC POPS MORE TRW... OTHRW BECMG PS.

...DISCUSSION...
KCLE 88D SHOWS LINE OF CNVTN WORKG TWD WRN PA ATTM IN ASSCTN WITH
A PERSISTANT MCS THAT HAS TRACKED ACR NRN OH VLLY. THE MID-LVL
WINDS WERE QUITE IMPRESSIVE IN ASSCTN WITH THIS FEATURE AS PER
SPC DSCN AND THUS DAMAGING WINDS WILL BE THE MAIN THREAT FROM
BOW-ECHO LIKE ELEMENTS INTO PA. VSBL IMAGERY SHOWS SCT-BKN CU
ACRS WRN 1/2 OF PA WITH AMS DESTABILIZING DUE TO SFC HEATING.
CAPES SHUD TOP 2000 J/KG AS THE COMPLEX REACHED WRN PA LATER THIS
AFTRN AND SUPPORT CONTINUED DVLPMENT OF CONVECTION. ANTHR FEATURE
OF INTEREST IS THE BNDRY/CNVRGNCE ZONE (OLD WARM FRONT) THAT WAS
SETTING UP OVR CNTRL PA AS SEEN IN LATEST SFC ANYLS. VSBL IMAGERY
SHOWS THIS BNDRY WELL WITH DEEPER CLDS IN ERN 1/2 OF PA AS SERLY
FLO ASCENDS INTO MTNS. THESE CLDS SHUD TEND TO MIX OUT THIS AFTRN
SOME.

THE MAIN EFFECT OF THE PERSISTANT SERLY SFC FLO ACRS ERN PA IS
THAT IT WILL LEAD TO SIGNIFICANT MOISTURE CONV ACRS CNTRL PA THIS
EVE AS A MORE SSW FLO CONTINUES TO FLO ACRS WRN PA. NGM/ETA BOTH
HV STRG LOW-LVL MOISTURE CONV ACRS CNTRL PA THRU THIS EVE. MCS
WILL WORK INTO CNTRL PA AND SHUD INTERSECT THIS BNDRY W/ CUD LEAD
TO PTNLLY HVY RAINFALL AGAIN THIS EVE. ALSO... NOTICED SOMEWHAT
OF A DIFFLUENT THICKNESS PATTERN ACRS PA AT 00Z ON ETA/NGM WHICH
CUD SLOW DOWN OF THE PROGRESSION OF THE MCS. THIS MCS WILL REACH
ERN PA THIS EVE AND LIKELY WILL STRATIFORM OUT IN TIME AS IT
BEGINS TO OVERRUN THE MORE STBL AIR IN FAR ERN PA. THE SUS VLLY
STILL WILL BE VULNERABLE TO SVR CVTN HOWEVER. THE LARGE SCALE
SET-UP ASSCTD WITH THIS MCS IS ALSO QUITE FAVORABLE TO SUPPORT
CNVTN INTO PA THIS AFTRN/EVE. MODELS INDICATE THAT AN UPR JET
CORE WILL SHIFT E TWD PA BY 00Z WITH PA NEAR THE LEFT FRONT QUAD.
THIS WILL ENHANCE UPR LVL DRVG AS THE LOW-LVL/S RESPONSE WITH
CONVERGENCE SRLY AGEO FLO INTO PA.

THIS MCS PASSES E OF A CTP CWA LATE THIS EVE. A LOOP OF THE UPR
LVL PVOR FIELDS FOR LATE TONIGHT THRU WED SUGGESTS THAT THE UPR
LVL PV MAX DOESN/T PUSH THRU PA TONIGHT OR WED... THUS A WRINKLE
IN THE TROP WILL EXIST IN A SW-NE AXIS ACRS PA THRU WED AND THUS
SUPPORT AN UPR LVL JET CORE OVR PA. THIS WILL KEEP INTENSE UPR
LVL DRVG S OF PA FOR WED/WED NGT AND SUPPORT LOW-LVL CYCLONIC
DVLPMENTS ASSCTD WITH THE THERMALLY DIRECT CIRC NR ANTHR FRNTL
BNDRY THAT STAYS S OF PA. THUS THINK MAIN ACVTY WED/WED NGT WILL
BE S OF PA (MAYBE CLIPPING FAR SERN PA). THE COOL FRNT AND
LEADING EDGE OF DRIER AIR WILL STILL NOT REACH THRU PA WED GIVEN
THE POSITIONING OF THE UPR JET OVR PA. THE NGM SUGGESTS DRIER AIR
WORKS IN BY WED EVE WITH ETA A LITTLE SLOWER IN BRINGING IN THE
DRIER AIR. AMS WILL BECOME UNSTBL AGAIN WED INTO WED EVE SO WUD
HV STILL CHC POPS FOR TRW ALL ZONES WED INTO WED EVE.

NICOSIA

PAZ019-25>28-33>36-41-45>46-49>53-56>59-63>66-310400-
SPECIAL WEATHER STATEMENT- SEVERE THUNDERSTORM WATCH
NATIONAL WEATHER SERVICE STATE COLLEGE PA
715 PM EDT TUE JUL 30 1996

...SEVERE THUNDERSTORM WATCH IN EFFECT FOR CENTRAL PENNSYLVANIA...
...FLASH FLOOD WATCH FOR THE LAUREL HIGHLANDS...

THE NATIONAL WEATHER SERVICE HAS ISSUED A SEVERE THUNDERSTORM WATCH
FOR THE FOLLOWING COUNTIES:

BEDFORD       FULTON     LYCOMING    NORTHUMBERLAND   PERRY
BLAIR         FRANKLIN   UNION       MONTOUR          CUMBERLAND
CENTRE        MIFFLIN    SNYDER      COLUMBIA         ADAMS
HUNTINGDON    JUNIATA    DAUPHIN     LEBANON          YORK
CENTRE        LANCASTER

AT 720 PM...DOPPLER RADAR SHOWED A LINE OF SEVERE THUNDERSTORMS FROM
JUST SOUTH OF WILLIAMSPORT SOUTH TO THE MARYLAND BORDER. THESE STORMS
ARE MOVING EAST AND ARE CAPABLE OF PRODUCING HAIL...HIGH WINDS AND
HEAVY RAINS.

THE NATIONAL WEATHER SERVICE HAS ALSO ISSUED A FLASH FLOOD WATCH FOR
THE FOLLOWING PENNSYLVANIA COUNTIES EFFECTIVE UNTIL 10 PM:

 BEDFORD      FRANKLIN     FULTON     SOMERSET

 HEAVY RAINS HAVE ALREADY FALLEN IN THESE COUNTIES.  BE PREPARED TO
 TAKE QUICK ACTION. IF FLOODING IS OBSERVED...MOVE TO HIGHER GROUND.

 OSTUNO