Damaging Wind in Pennsylvania, September 17, 2004

AREA FORECAST DISCUSSION...CORRECTED TO ADD MARINE SCA
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
410 PM EDT FRI SEP 17 2004

.SHORT TERM (TONIGHT THROUGH SATURDAY NIGHT)...
NO SHORTAGE OF THINGS TO TALK ABOUT WITH THIS FORECAST. I WILL BE
BRIEF THOUGH AS TIME IS RUNNING SHORT. RADAR IMAGERY DEPICTS A
SHIELD OF RAIN CREEPING EASTWARD INTO NORTHEASTERN PA WHILE
CONVECTION IS DEVELOPING ACROSS VA. SCATTERED SHOWERS ARE BEGINNING
TO DEVELOP IN MA AND SERN PA TOO. SHOWERS WILL INCREASE IN COVERAGE
AND INTENSITY THIS EVENING AS MOISTURE FROM IVAN AND COLD FRONT FROM
THE NORTH BOTH BEGIN TO CLOSE IN ON OR REGION.

TODAYS GFS AND ETA MODELS HANDLE THE REMNANTS OF IVAN MUCH
DIFFERENTLY. THE GFS WANTS TO MOVE THE LOW PRESSURE OFF THE COAST
SATURDAY MORNING AND THEN MOVE IT NORTHEAST INTO THE ATLANTIC. THE
ETA ALSO BRINGS THE LOW TO THE COAST...BUT THEN IT BEGINS TO DEEPEN
THE FEATURE AGAIN AND DROPS IT SOUTHWARD TOWARDS NC. THE STRONG HIGH
PRESSURE BUILDS ACROSS THE REGION SATURDAY NIGHT AND SUNDAY.

DESPITE THE DIFFERENCES WITH IVAN...BOTH MODELS BASICALLY AGREE THAT
RAIN WILL BE WIDESPREAD AND HEAVY OVERNIGHT. QPF TOTALS OF 1 TO 3
INCHES IN MANY AREAS OVERNIGHT WITH LOCALLY HIGHER TOTALS IN THE
NORTHERN PARTS OF THE REGION. HPC GUIDANCE SHOWS THAT 3 TO 5 INCHES
MAY FALL IN FAR NORTHERN NJ BY 12Z SATURDAY. ALL THIS BEING
SAID...THE FLOOD WATCH WILL CONTINUE OVERNIGHT FOR MUCH OF THE
REGION. RFC GUIDANCE SHOWS THAT MAY OF THE GAGED RIVERS WILL RISE
SHARPLY BUT REMAIN WITHIN THEIR BANKS. THE SMALLER CREEKS MAY HAVE
LOCAL FLOODING IF THE QPF FORECAST IS REALIZED.

THE LOW PRESSURE SYSTEM SLOWLY DEPARTS SATURDAY...YET RAINFALL WILL
LINGER THROUGH THE MORNING AND END FROM NORTH TO SOUTH (WITH THE
FRONT) DURING THE AFTERNOON. AN ADDITIONAL QUARTER TO HALF INCH OF
RAIN COULD FALL SATURDAY. CLEARING WILL SET IN SATURDAY NIGHT AS A
NORTH TO NORTHEAST WIND PICKS UP ACROSS THE REGION. WIND SPEEDS
REACH 15 TO 25 KNOTS SATURDAY NIGHT AND SUNDAY WITH HIGHER GUSTS.

&&

.LONG TERM (SUNDAY THROUGH FRIDAY)...

THE EXTENDED PERIOD HAS LESS UNCERTAINTY THAN EXISTS IN THE SHORT
TERM PERIOD. BOTH THE 12Z RUNS OF THE GFS AND ETA DEPICT SHARP
CLEARING MOVING ACROSS THE FA EARLY SUNDAY...RESULTING IN SUNNY AND
COOL WEATHER SUNDAY AND MONDAY. WINDS WILL BE BRISK SUNDAY WITH THE
TIGHT GRADIENT BETWEEN THE CANADIAN HIGH AND THE LOW PRESSURE
(REMNANTS OF IVAN) THAT WILL BE OFF THE EAST COAST. CONSIDERING THE
MAGNITUDE OF THE HIGH PRESSURE AND THAT IT WILL CONTINUE TO BUILD
OVER THE MIDDLE ATLANTIC REGION THROUGH THE WEEK...I FELT
COMFORTABLE REMOVING MOST OF THE PRECIP FROM THE EXTENDED PERIOD.
TEMPS WERE ONLY CHANGES SLIGHTLY FROM PREVIOUS VALUES.

&&

.MARINE...

ELY WND FLOW W/B INCRG SAT NGT INTO SUN MRNG AS LOW PRES
SYS...REMNANTS OF IVAN...MOVES OFFSHORE NEAR HATTERAS. WIND GRADIENT
BTWN THIS LOW PRES SYS AND LARGE HIGH PRES SYS OVR SE CANADA WILL
TIGHTEN UP...BRINGING IN STRONG SCA CRITERIA. GFS MOS GUIDANCE
BRINGS IN WINDS AT 32 KT WITH GUSTS AT 19/0900Z. WAVES PROGS AT 9
FT. HAVE INCRD THAT BY A FT...WITH WAVES PSBLY REACHING 13 FT...PER
IN HOUSE 44009 STUDY.TPC PROG FOR JEANNE BRINGS A HURRICANE INTO THE
BAHAMAS THEN TWRD FL/GA BORDER. SWELLS WITH DANGEROUS RIP CURRENTS
CONT TO PSBLY BECOME AN ISSUE FM SUN INTO THE BEGINNING OF NEXT
WK...AS JEANNE W/B A SLOW MOVER.

&&

.AVIATION...

XPCT DETERIORATING WX OVRNGT TO MVFR THEN IFR. COND XPCTD TO LAST
INTO SAT. POCKETS OF LIFR PSBL. AS REMNANTS OF IVAN MOVE OFFSHORE
HATTERAS REGION...GRADIENT TIGHTENS UP BTWN LOW PRES SYS AND SE
CANADIAN HIGH. COND BACK TO VFR BUT STRONG GUSTY WIND XPCTD...ESP
NEAR COASTAL REGIONS SAT NGT AND SUN.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...FLOOD WATCH FOR ZONES PAZ054-055-060>062-067>071 TONIGHT.
NJ...FLOOD WATCH FOR ZONES NJZ001-007>010-012>019 TONIGHT.
MD...FLOOD WATCH FOR ZONE MDZ008 TONIGHT.
DE...FLOOD WATCH FOR ZONE DEZ001 TONIGHT.
MARINE...SMALL CRAFT ADVISORY NJ/DE COASTAL WATERS...ANZ450>455.

&&

SHORT TERM/LONG TERM...OHARA
AVIATION/MARINE....WOODWORTH

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
446 AM EDT FRI SEP 17 2004

DEZ001>004-MDZ008-012-015-019-020-NJZ001-007>010-012>027-PAZ054-055-
060>062-067>071-180900-
ATLANTIC NJ-ATLANTIC COASTAL CAPE MAY NJ-BERKS PA-BUCKS PA-CAMDEN NJ-
CAPE MAY NJ-CARBON PA-CAROLINE MD-CECIL MD-CHESTER PA-
COASTAL ATLANTIC NJ-COASTAL OCEAN NJ-CUMBERLAND NJ-DELAWARE PA-
DELAWARE BEACHES DE-EASTERN MONMOUTH NJ-GLOUCESTER NJ-HUNTERDON NJ-
INLAND SUSSEX DE-KENT MD-KENT DE-LEHIGH PA-MERCER NJ-MIDDLESEX NJ-
MONROE PA-MONTGOMERY PA-MORRIS NJ-NEW CASTLE DE-NORTHAMPTON PA-
NORTHWESTERN BURLINGTON NJ-OCEAN NJ-PHILADELPHIA PA-QUEEN ANNES MD-
SALEM NJ-SOMERSET NJ-SOUTHEASTERN BURLINGTON NJ-SUSSEX NJ-TALBOT MD-
WARREN NJ-WESTERN MONMOUTH NJ-
446 AM EDT FRI SEP 17 2004

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

A FLOOD WATCH REMAINS IN EFFECT FOR TODAY AND TONIGHT FOR EXTREME
NORTHERN DELAWARE, FAR NORTHEASTERN MARYLAND, EASTERN PENNSYLVANIA,
AND SOUTHWESTERN, CENTRAL, AND NORTHWESTERN NEW JERSEY. BETWEEN ONE
AND TWO INCHES OF RAIN IS EXPECTED, WITH LOCALIZED AMOUNTS BETWEEN
THREE AND FOUR INCHES.

.DAYS TWO THROUGH SEVEN...

A MODERATE RISK FOR RIP CURRENTS MAY EXIST FOR SATURDAY, AND POSSIBLY
SUNDAY AS WELL.

.SPOTTER CALL TO ACTION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.