Flash Flood in Pennsylvania, September 15, 2003

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
300 PM EDT MON SEP 15 2003

THE GFS HAS INIT BETTER THAN THE ETA AND WILL BE FOLLOWED FOR
SENSIBLE WX THRU WED NGT AND THEN AFTER THAT THE TPC TRACK FOR
ISABEL. IN GENERAL TROPICAL SYS ACCELERATE FASTER THAN THE MDLS GIVE
THEM CREDIT FOR IN THE MID LATITUDES AND THERE IS NOTHING WRONG WITH
GETTING PREPAREDNESS WORK DONE EARLY. UNFORTUNATELY THE THREAT OF
HVY RAIN WILL CONT IN THE SHORT TERM UNTIL WE BREAK THE TROP
CONNECTION AND GET A CFP LATER TNGT. WE WILL BE ISSUING A FLOOD
WATCH FOR MOST OF OUR ZONES N AND W OF I95 CORRIDOR THAT HAVE BEEN
HIT BY HEAVY RAIN SINCE FRIDAY NGT.

THE GFS IN TERMS OF AXIS OF HVYR PCPN LOOKS BETTER THAN THE ETA
ALTHO ITS QPF IS UNDERDONE. THE GREATEST THREAT FOR HVYR S/B IN THE
FIRST HALF OF THIS EVE AND DIMINISH OVRNGT...ALTHO RUNOFF PBLMS WILL
CONT THRU THE NGT. THE E BRANCH OF THE BRANDYWINE AT DOWNINGTOWN HAS
ALRDY HAD ITS SECOND HIGHEST CREST ON RECORD SURPASSING THE FLOODING
WITH AGNES AND FLOYD. GUID MINS ARE CLOSE AND WILL FOLLOW.

A BREAK FROM THE HUMIDITY ON TUE AS THE TROF OVR THE CENTRL U.S.
LIFTS NEWD INTO CANADA AS BLOCKING RDG OVR THE WRN ATLC IS FCST TO
RMN IN PLACE. FULL SUN MACROS AND GUID TEMPS ARE CLOSE AND WE WILL
FOLLOW. CONVECTIVE TEMPS S/B REACHED AND THERE WILL BE SOME CU
ARND...BUT NOT MUCH CAA SO WOULDN/T EXPECT THEM TO GO BKN.

SHOULD HAVE DECENT SUBSIDE COME TUE NGT BOTH FROM THE APCHG HI PRES
SYS AND ALSO THE NEARING SUBSID FROM ISABEL. WE WILL GO WITH MINS
CLOSER TO THE DEWPTS WITH THE EXPECTED IDEAL RDTNL CONDS. WOULD
EXPECT EVEN LESS CLOUDS ON WED AS SUBSID AROUND ISABEL SHOULD OCR.

THE WORST OF ISABEL IS EXPECTED TO OCR ACRS OUR CWA THU AFTN INTO
FRI MRNG AS CONDS WILL IMPROVE AFT THAT. OUTLOOK FOR SAT THRU MON
RIGHT NOW APPEAR FAIR AS THE ERN SEABOARD.

PLEASE DO NOT KEY ON THE CUR TRACK OF ISABEL AS BEING GOSPEL.
THE MARGIN OF TRACK ERROR INCREASES WITH TIME AND IT WOULD NOT TAKE
MUCH OF A JOG OF THE TRACK TO THE RIGHT TO HAVE A MUCH STGR ISABEL
AFFECT MORE OF OUR CWA.

UNLIKE FLOYD IN 99 THERE WILL TAKE MUCH LESS WIND (BECAUSE OF
SATURATED GROUNDS) AND HVY RAIN TO PRODUCE SIMILAR WIND DAMAGE AND
FLOODING. ISABEL IS STRONGER THAN FLOYD EVER WAS.

USERS OF EXPERIMENTAL FORECAST GRIDS...BE AWARE THAT POLICY LIMITS
MAXIMUM SUSTAINED WIND STRENGTH TO 33 KTS OUT PAST THE 72 HOUR
FORECAST.  THIS IS TO REFLECT THE INHERENT UNCERTAINTY IN THE
HURRICANE FORECAST TRACK AT GREATER TIME RANGES NOT THE EXPECTED
WINDS. REFER TO NHC FOR THE OFFICIAL TRACK AND STRENGTH OF THE
STORM.

NOW IS THE TIME WHERE BEING PREPARED PAYS OFF.  KEEP UP TO DATE WITH
THE LATEST FORECASTS.   CHECK OUR WEB SITE...WWW.ERH.NOAA.GOV/PHI
FOR THE LATEST FORECAST INFORMATION...AS WELL AS PREPAREDNESS
INFORMATION IF THE HURRICANE THREATENS YOUR LOCATION.

ON THE COAST AND LWR DE BAY WE WILL CONT SCA DUE TO SEAS.

.PHI...
DE...FLOOD WATCH THROUGH TONIGHT FOR DE ZONE 1.
MD...FLOOD WATCH THROUGH TONIGHT FOR MD ZONE 8.
NJ...FLOOD WATCH THROUGH TONIGHT FOR NJ ZONES 1/7/8/9/10/15.
PA...FLOOD WATCH THROUGH TONIGHT FOR PA 54/55/60>62/67>69.
MARINE...SCA ALONG THE COAST AND LWR DE BAY.

TFG

DEZ001>004-MDZ008-012-015-019-020-NJZ001-007>010-012>027-PAZ054-055-
060>062-067>071-151100-

HAZARDOUS WEATHER OUTLOOK - CORRECTION FOR RIP CURRENTS
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
414 AM EDT MON SEP 15 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EAST CENTRAL AND SOUTHEAST
PENNSYLVANIA...DELAWARE...THE NORTHERN MARYLAND EASTERN SHORE...AND
NEW JERSEY EXCLUDING THE FIVE NORTHEAST COUNTIES.

.DAY ONE...TODAY

THERE IS A HIGH RISK OF RIP CURRENTS ALONG THE COAST.

SHOWERS ARE LIKELY TODAY ALONG WITH SCATTERED THUNDERSTORMS. SOME
RAIN COULD BE HEAVY.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

RIP CURRENTS ARE POSSIBLE THROUGH MOST OF THE PERIOD.

THE MAIN THREAT WILL BE FROM POWERFUL HURRICANE ISABEL. THE
FORECASTED TRACK FOR ISABEL HAS IT AFFECTING THE REGION
THURSDAY INTO FRIDAY.

SEE THE LATEST ADVISORY FROM THE NATIONAL HURRICANE CENTER.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.