Hail and Damaging Wind in New Jersey, April 21, 2012

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
915 PM EDT SAT APR 21 2012

.SYNOPSIS...
A COLD FRONT CROSSING THE AREA THIS EVENING WILL STALL OVER OR JUST
EAST OF THE AREA LATE TONIGHT AND SUNDAY. LOW PRESSURE DEVELOPING
OVER THE SOUTHEAST STATES WILL DEEPEN AS IT TRACKS NORTHEAST ALONG
THE FRONT...PASSING THROUGH THE AREA LATE SUNDAY NIGHT AND MONDAY.
THE LOW WILL PULL INTO EASTERN CANADA LATER MONDAY INTO TUESDAY. LOW
PRESSURE SHOULD PASS CLOSE TO THE REGION WEDNESDAY NIGHT AND
THURSDAY. WEAK HIGH PRESSURE IS EXPECTED TO BUILD INTO THE AREA FOR
THE END OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
AS OF MID-EVENING...900 PM...THE COLD FRONT EXTENDS FROM NW NJ TO
JUST W OF PHL TO JUST W OF SRN DE. THE FRONT HAD BEEN MOVING
RATHER SLOWLY BUT NOW SEEMS TO HAVE ACCELERATED AS A LOW PRES WAVE
HAS MOVED NEWD ALONG IT TO NWRN NJ...AND STRONG 3-HR PRES RISES
ARE NOTED FROM JUST W OF DC NWD INTO E-CNTRAL PA. CONSIDERABLE
T-STORM ACTIVITY HAS DEVELOPED ALONG THE FRONT AS THE AMS AHD OF
THE FRONT WAS ABLE TO WARM UP THIS AFTN AND DEVELOP SOME MODEST
INSTBY. THERE IS AN AREA OF SHOWERS THAT EXTENDS A COUPLE HUNDRED
MILES BEHIND THE FRONT AND WILL RESULT IN LINGERING RAIN AFTER THE
FRNT PASSES. A SHARP AND GUSTY WIND SHIFT IS ASSOCIATED WITH THE
COLD FRONT PASSAGE...ALONG WITH TEMPERATURES FALLING RAPIDLY
THROUGH THE 60S INTO THE 50S BY LATER THIS EVENING.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
AN AREA OF LOW PRESSURE DEVELOPING ACROSS THE EASTERN GULF OF MEXICO
WILL MOVE OFF THE SOUTHEAST COAST BY SUNDAY MORNING AND INTENSIFY AS
IT MOVES NORTHWARD DURING THE DAY. AS IT MOVES NORTHWARD, MOISTURE
WILL CONTINUE TO SURGE ACROSS OUR AREA, WITH PW VALUES INCREASING TO
1.25 TO 1.5 INCHES. MODERATE TO HEAVY RAIN SHOULD BEGIN TO SPREAD
FROM SOUTH TO NORTH DURING THE MORNING HOURS AND CONTINUE THROUGH
THE DAY. BEING WE WILL BE ON THE NORTH SIDE OF THE SYSTEM, OUR AIR
WILL BE QUITE STABLE, SO NO THUNDER IS EXPECTED THROUGH THE
AFTERNOON HOURS.

AS THE LOW MOVES NORTHWARD DURING THE DAY, THE PRESSURE GRADIENT
WILL CONTINUE TO STRENGTHEN ACROSS THE AREA, AND WINDS ARE STRONG
ABOVE THE SURFACE AS WELL. THIS WILL LEAD TO QUITE A BREEZY
AFTERNOON WITH WINDS INCREASING TO AT LEAST 25-30 MPH BY THE
AFTERNOON.

FOR TEMPERATURES, MOS NUMBERS WERE GENERALLY A COUPLE OF DEGREES
WITHIN EACH OTHER, SO WE DECIDED TO BLEND THE MAV/MET.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
THE MAIN FORECAST PROBLEMS FOR THE FIRST PART OF THIS PERIOD IS RAIN
AND WIND.

HEAVY RAIN SHOULD BE ONGOING DURING SUNDAY EVENING...ENDING FROM
SOUTHWEST TO NORTHEAST. THERE IS SOME POTENTIAL FOR FLOODING...
ESPECIALLY FLASHIER STREAMS AND SMALL RIVERS. MORE ON THE FLOODING
POTENTIAL IS INCLUDED IN THE HYDROLOGY SECTION BELOW.

THE NAM AND GFS HAS COME CLOSER TOGETHER WITH RESPECT TO MASS
FIELDS...AND THERE IS GROWING CONFIDENT FOR STRONG WINDS NEAR THE
COAST SUNDAY EVENING. A 50 TO 70 KT LOW LEVEL JET WILL WORK ITS WAY
NORTH ALONG THE COAST SUNDAY EVENING. THERE IS SOME POSITIONAL
DIFFERENCE IN THE PLACEMENT OF THE OF THE LOW LEVEL JET...WITH THE
NAM CLOSER (AND AFFECTING A LARGER INLAND AREA)...AND THE GFS
KEEPING MOST OF THE MOMENTUM NEAR THE COAST OF JUST OFFSHORE. ''

AS IT USUALLY THE CASE WITH A LOW LEVEL FLOW WITH AN EASTERLY
COMPONENT...THE DEPTH OF THE MIXED LAYER IS NOT THAT HIGH.
HOWEVER...MOST MODEL SOUNDINGS SHOW A WINDOW BETWEEN 0000 UTC AND
0600 UTC MONDAY FOR WINDS TO GET CLOSE TO THE SURFACE. RIGHT
NOW...IT APPEARS AS THOUGH THE IMMEDIATE COAST HAS THE GREATEST
CHANCE OF SEEING WIND GUSTS TO NEAR 50 MPH...BUT AGAIN THIS WILL BE
DEPENDENT ON THE DEPTH OF THE MIXED LAYER. WITH SOME QUESTION ABOUT
MIXING...THE WIND ADVISORY DECISION WAS PUSHED OFF FOR NOW.

ON MONDAY...THE SURFACE LOW TRACKS INTO EASTERN PENNSYLVANIA...BUT
THE CLOSED MID LEVEL SYSTEM IS SLOWER TO PULL OUT. THE WRAPAROUND
MOISTURE WILL AFFECT NORTHERN AND WESTERN AREAS MOST...AND AN
UPSLOPE COMPONENT COULD HELP IN THE SOUTHERN POCONOS. THE COLUMN
LOOKS TO REMAIN WARM ENOUGH FOR RAIN EVENT IN THE TERRAIN MONDAY.
HIGHS WERE GENERALLY BASED ON A MOS BLEND.

PERHAPS THE MOST IMPORTANT FORECAST PROBLEM FOR MONDAY MAY BE THE
WIND. MODEL SOUNDINGS ARE SUGGESTING THAT 40 TO 45 KNOT WINDS WILL
BE AVAILABLE AT THE TOP OF THE INVERSION. LACK OF SUBSTANTIAL
SUNSHINE PROBABLY MITIGATES SOME THIS POTENTIAL...BUT WIND GUSTS
COULD APPROACH 40 MPH MONDAY AFTERNOON AND EVENING.

THE WRAPAROUND MOISTURE COULD RESULT IN SNOW IN THE HIGHER TERRAIN
MONDAY NIGHT. MODEL SOUNDINGS SHOW THAT THE COLUMN COOLS ENOUGH
MONDAY NIGHT FOR SNOW ABOVE 1000 FEET...AND PLACES LIKE TOBYHANNA
COULD SEE 2 OR 3 INCHES OF SNOW BEFORE DAYBREAK TUESDAY.
ELSEWHERE...THE SHOWER ACTIVITY WANES...AND LOWS WERE BASED MAINLY
ON THE MOS BLEND.

THE FORECAST AREA REMAINS IN THE CYCLONIC FLOW TUESDAY AROUND THE
CLOSED ID LEVEL SYSTEM MOVING INTO ONTARIO. MID LEVEL TEMPERATURES
REMAIN COLD...SO ANY SUNSHINE WILL BE SELF DESTRUCTIVE...AND ALLOW
SCATTERED SHOWERS TO DEVELOP. WHILE TOO FAR OUT TO ADD...THE MID
LEVELS COULD BE COLD ENOUGH FOR GRAUPEL AND PERHAPS EVEN LOW TOPPED
THUNDERSTORMS...MAINLY ACROSS THE NORTH. THE FAR SOUTH COULD BE JUST
OUT OF THE REACH OF THE COLD POOL FOR SHOWERS...BUT AT THIS DISTANCE
WILL LEAVE THE MENTION IN.

THE MID LEVEL FLOW TRANSITIONS TO MORE OF A FAST QUASI ZONAL FLOW
DOMINATED BY THE NORTHERN STREAM. MID RANGE MODELS ARE LATCHING ONTO
A SHORT WAVE SPINNING UP A WEAK SURFACE LOW ON THE LOW LEVEL
BAROCLINIC ZONE CLOSE TO OR JUST SOUTH OF THE AREA. THIS PROBABLY
MEANS A DRY START TO WEDNESDAY...BUT LATER IN THE DAY AND AT NIGHT
PRECIPITATION IS POSSIBLE. THERE IS SOME INDICATION THAT THE MID
LEVEL FRONTOGENETIC FORCING COULD BE IMPRESSIVE JUST SOUTH OF THE
AREA...BUT FOR NOW WILL USE A BROADBRUSH APPROACH TO THE MENTION OF
RAIN.

THE WAVE SHOULD EXIT THURSDAY MORNING...THOUGH THERE ARE SOME TIMING
DIFFERENCES (WHICH SHOULD BE EXPECTED IN A FAST MID LEVEL FLOW).
THURSDAY SHOULD BECOME DRIER WITH TIME...ESPECIALLY ACROSS THE
NORTH. WEAK HIGH PRESSURE PROBABLY GIVES WAY TO A WEAK FRONT LATE
THURSDAY NIGHT INTO EARLY FRIDAY. THERE IS SOME MODEL SPREAD ON JUST
HOW THIS EVOLVES (WITH THE ECMWF SUGGESTING A STRONGER NORTHERN
STREAM SYSTEM AND THE POTENTIAL FOR SHOWERS DURING THIS TIME). THE
MODEL CONSENSUS HOWEVER IS DRY FOR FRIDAY...AND THIS WILL BE
REFLECTED IN THE FORECAST.

AGAIN...AT THIS DISTANCE...SATURDAY LOOKS DRY WITH SURFACE HIGH
PRESSURE BUILDING EAST FROM THE GREAT LAKES. THE ECMWF IS ONCE AGAIN
THE MORE AGGRESSIVE WITH THE NORTHERN STREAM MID LEVEL FLOW...
BRINGING A CLOSED MID LEVEL SYSTEM THROUGH NORTHERN NEW ENGLAND. THIS
WOULD SUGGEST SHOWERS WITH A FRONTAL PASSAGE. SINCE THIS IS THE
ONLY MODEL REALLY SUGGESTING EFFECTS THIS FAR SOUTH...WILL LEAN
TOWARD THE MODEL CONSENSUS WITH A DRY FORECAST FOR SATURDAY.

&&

.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

IT HAS BEEN A LITTLE TRICKY TO TIME THE COLD FRONT PASSAGE THIS
EVENING AS IT HAS ACCELERATED ACROSS SE PA DURG THE LAST COUPLE OF
HOURS. AS OF 0100Z THE FRONT HAS PASSED RDG ABE AND ILG...AND
SHOULD PASS PHL PNE AND TTN IN THE NEXT HOUR. A BKN LINE OF
T-STORMS HAS DEVELOPED ALONG THE FRONT...AND THERE IS A SHARP
WSHFT FROM S TO WNW. WIND GUSTS AROUND 25 KT ARE ALSO OCCURING
WITH THE FRONTAL PASSAGE.

THERE IS A PRETTY EXPANSIVE AREA OF SHOWERS BEHIND THE FRONT THAT
WILL LIKELY AFFECT THE AREA FOR THE LATE EVENING INTO THE
OVERNIGHT HOURS. CONDITIONS WILL LIKELY DROP TO MVFR WITH THE
PRECIPITATION AND CONTINUE THROUGH THE EVENING HOURS AND INTO THE
OVERNIGHT HOURS. IT IS POSSIBLE THAT IF THE RAIN IS HEAVY ENOUGH,
IFR CONDITIONS COULD OCCUR, BUT WE ARE NOT CONFIDENT ENOUGH TO
INCLUDE THIS IN THE TAFS AT THIS TIME. THE RAIN ASSOCIATED WITH
AND JUST BEHIND THE FRONT SHOULD END OVERNIGHT, AND CONDITIONS
COULD IMPROVE BRIEFLY TO VFR, BEFORE DETERIORATING AGAIN ON
SUNDAY. WINDS WILL RANGE FROM SOUTHEASTERLY-SOUTHWESTERLY THIS
AFTERNOON/EVENING, BEFORE SWITCHING TO WEST, THEN NORTHWEST BEHIND
THE FRONT.

MORE RAIN IS EXPECTED ON SUNDAY AS A STORM SYSTEM STRENGTHENS TO OUR
SOUTH AND MOVES ALONG THE COAST AND TOWARD THE AREA. CONDITIONS WILL
DETERIORATE ON SUNDAY AND BECOME IFR THROUGH THE DAY FOR ALL TAFS
WITH MODERATE-HEAVY RAIN DEVELOPING. WINDS WILL LIKELY BECOME QUITE
GUSTY DURING THE AFTERNOON AS THE LOW GETS CLOSER TO OUR AREA.

OUTLOOK...
SUN NIGHT...IFR CONDITIONS IN RAIN. WINDS COULD BE AN ISSUE WITH
GUSTS NEAR 35 KNOTS.

MON...IFR CONDITIONS IN THE MORNING..POSSIBLY IMPROVING TO MVFR IN
THE AFTERNOON. SW WINDS COULD GUST TO 30 KNOTS...ESPECIALLY DURING
THE AFTERNOON AND EVENING.

TUE...VFR CONDITIONS ARE EXPECTED. LOCAL MVFR CONDITIONS ARE
POSSIBLE IN SCATTERED SHOWERS...BUT CONFIDENCE IN THIS IS LOW.

WED...VFR CONDITIONS ARE EXPECTED. MVFR CONDITIONS ARE POSSIBLE
WEDNESDAY NIGHT...ESPECIALLY SOUTH IN POSSIBLE RAIN.

THU...MVFR CONDITIONS ARE POSSIBLE...ESPECIALLY SOUTH IN THE
MORNING. VFR CONDITIONS ARE EXPECTED IN THE AFTERNOON AND AT
NIGHT.

&&

.MARINE...
A COLD FRONT WILL CROSS THE WATERS LATER THIS EVENING. WINDS ABOVE
THE SURFACE STILL SHOW WINDS 25-30 KNOTS WITH THE PASSAGE OF THE
FRONT, AND WINDS ARE ALREADY STARTING TO GUST 20-25 KNOTS ON THE BAY
AND 15-20 KNOTS ON THE COAST. WE HAVE DECIDED TO LEAVE THE SMALL
CRAFT ADVISORY ACROSS THE WATERS AND EXPAND IT INTO THE DELAWARE
BAY. WE DECIDED TO BRING THE ENDING TIME FORWARD TO 1 AM SINCE THIS
THE WINDS SHOULD BE DIMINISHING ABOVE THE SURFACE BY THEN.

AN AREA OF LOW PRESSURE WILL BE STRENGTHENING ALONG THE COAST ON
SUNDAY AND MOVING TOWARD THE AREA DURING THE DAY. WINDS SHOULD
INCREASE AHEAD OF THE LOW, AND EVENTUALLY REACH GALE FORCE LATE IN
THE DAY. THEREFORE WE WILL BE STARTING A GALE WARNING LATE IN THE
DAY ACROSS THE COASTAL WATERS AND SOUTHERN DELAWARE BAY. A SMALL
CRAFT ADVISORY WILL LIKELY BE ISSUED FOR THE NORTHERN BAY ONCE THE
CURRENT ADVISORY ENDS.

OUTLOOK...
WITH THE GFS AND NAM SHOWING SIMILAR MASS FIELDS WITH THE UPCOMING
SYSTEM...IT IS TIME TO UPGRADE THE CURRENT GALE WATCH AND
PLACE...AND ADD SOME MORE OF THE OCEAN WATERS TO THE UPCOMING
WARNING.

THE LOW LEVEL FLOW INCREASES DRAMATICALLY LATE SUNDAY AFTERNOON INTO
SUNDAY EVENING AS THE BEST PRESSURE GRADIENT APPROACHES. AT THE SAME
TIME...THE 925 MB LOW LEVEL JET INCREASES TO NEAR 70 KNOTS. THE LOW
LEVEL INVERSION LOOKS TO REMAIN IN PLACE...AND SHOULD MITIGATE MUCH
OF THE MOMENTUM TRANSFER. HOWEVER...THERE IS A 3 TO 6 HOUR WINDOW
SURROUNDING THE IMPINGEMENT OF THE LOW LEVEL JET DURING WHICH THE
HEAVIER RAIN COULD BRING MOST OF THE MOMENTUM TO THE WATER SURFACE.

THE GALE WARNING WAS TIMED ON THE OCEAN WATERS TO COINCIDE WITH THE
PASSAGE OF THE LOW LEVEL JET. THE LOWER DELAWARE BAY WAS INCLUDED IN
THE GALE WARNING...SINCE PLATFORMS THERE PROBABLY EXPERIENCE GALE
FORCE WIND GUSTS WITH THE PASSING JET. THE UPPER DELAWARE BAY HAS
BEEN LEFT OUT FOR NOW...AS CONFIDENCE IN THIS IN NOT YET HIGH
ENOUGH. HOWEVER...IT COULD BE ADDED LATER IF THE MOMENTUM TRANSFER
APPEARS TO BE BETTER OVER THAT AREA.

AS THE LOW LEVEL JET PASSES EARLY MONDAY MORNING...WINDS PROBABLY
DROP TO SMALL CRAFT LEVELS ON ALL WATERS. IN FACT...WINDS COULD EVEN
DROP BELOW SMALL CRAFT LEVELS OVER THE BAY FOR A TIME. HOWEVER...THE
GRADIENT AT THE BOTTOM OF THE SURFACE LOW TRACKING INTO EASTERN
PENNSYLVANIA TIGHTENS...WINDS INCREASE AGAIN. THE GRADIENT IS
BORDERLINE TO SUPPORT GALES FOR MONDAY...BUT MODEL SOUNDINGS SUGGEST
THAT GALE FORCE GUSTS ARE POSSIBLE MONDAY AFTERNOON AND MONDAY
EVENING. THIS WILL BE ESPECIALLY TRUE OVER THE OCEAN WATERS. WITH
THE GALE WARNING IN PLACE NOW...WILL INSERT THIS POTENTIAL INTO THE
HAZARDOUS WEATHER OUTLOOK.

THE GRADIENT SHOULD BACK OFF ENOUGH LATE MONDAY NIGHT AND TUESDAY TO
ALLOW WINDS TO DROP TO SMALL CRAFT LEVELS...ESPECIALLY DURING THE
AFTERNOON. SEAS MAY TAKE SOME TIME TO SORT THEMSELVES OUT...SO SMALL
CRAFT SEAS ON THE OCEAN COULD LAST INTO TUESDAY NIGHT.

WINDS AND SEAS LOOK TO REMAIN BELOW SMALL CRAFT LEVELS WEDNESDAY.
THERE IS SOME MODEL SPREAD ON THE PLACEMENT OF LOW PRESSURE THAT IS
EXPECTED TO DEVELOP WEDNESDAY NIGHT OR THURSDAY MORNING. DEPENDING
ON THE EVENTUAL PLACEMENT OF THE LOW...SMALL CRAFT SOUTHERLY WINDS
ARE POSSIBLE WEDNESDAY NIGHT INTO EARLY THURSDAY.

AS THE LOW PULLS OUT THURSDAY MORNING...WINDS SHOULD COME AROUND TO
WEST OR NORTHWEST. FOR NOW...IT APPEARS AS THOUGH WINDS SHOULD
REMAIN BELOW SMALL CRAFT LEVELS...BUT MODEL SPREAD AT THIS DISTANCE
BRINGS DOWN CONFIDENCE.

&&

.HYDROLOGY...
WE WILL BE ISSUING A FLOOD WATCH FOR A PORTION OF THE AREA THIS
AFTERNOON.

WHILE WE HAVE BEEN DRY...ALL OF THE INGREDIENTS FOR HEAVY RAIN ARE
COMING TOGETHER FOR MUCH OF THE AREA. THE SOURCE OF THE AIR RIDING
UP THE FRONT OF THE MID LEVEL TROUGH IS THE EASTERN GULF STATES...
AND PRECIPITABLE WATER VALUES APPROACH 1.50 INCHES LATER SUNDAY INTO
SUNDAY NIGHT. THE HIGHEST PRECIPITABLE WATER VALUES ARE SUPERIMPOSED
WITH THE LOW TO MID LEVEL THETA E RIDGE POKING INTO EASTERN
PENNSYLVANIA AND NORTHERN NEW JERSEY DURING ROUGHLY THE SAME TIME.

STORM TOTAL RAINFALL AMOUNTS OF 2 TO 3.5 INCHES OF RAIN ARE
EXPECTED. THE INITIAL SHOT OF HEAVY RAIN AFFECTS SOUTHERN AREAS
DURING THE AFTERNOON. RAINFALL AMOUNTS IN THIS SHOT COULD APPROACH
2.5 INCHES ACROSS PORTIONS OF NORTHERN DELAWARE AND SOUTHEAST
PENNSYLVANIA. THESE QPF NUMBERS PUSH SOME OF THE FLASHIER STREAMS
AND SMALL RIVERS (SUCH AS COOCHS BRIDGE) ABOVE THEIR BANKS. THIS IS
THE REASON NORTHERN DELAWARE AND MUCH OF SOUTHEAST PENNSYLVANIA WERE
INCLUDED IN THE WATCH.

FURTHER NORTH...WHERE THE RICH THETA RICH AIR PUSHES IN DURING THE
LATE AFTERNOON AND EARLY EVENING...HIGHER QPF VALUES ARE EXPECTED.
IN THESE AREAS...STORM TOTAL RAINFALL VALUES CLOSE TO 3.5 INCHES ARE
POSSIBLE IN PLACES IN MORRIS COUNTY. WHILE THIS MUCH RAIN DOES NOT
RESULT IN MAINSTEM RIVER FLOODING...SMALLER RIVERS AND STREAMS (SUCH
AS THOSE IN MORRIS COUNTY) SHOULD RESPOND QUICKLY TO THESE AMOUNTS.
IF CLOSER TO 4 INCHES OF RAIN FALLS IN THE PASSAIC BASIN...MAINSTEM
FLOODING COULD BECOME POSSIBLE.

THE HEAVIEST RAIN TAPERS OFF FROM SOUTHWEST TO NORTHEAST LATE SUNDAY
EVENING INTO EARLY MONDAY MORNING. THE FLOOD WATCH WAS EXTENDED
THROUGH MUCH OF THE NIGHT TO ALLOW FOR THE RAINFALL TO WORK ITS WAY
THROUGH THE SYSTEM.

RUNNING SOME CONTINGENT FORECASTS AND USING SOME MMEFS DATA, THESE
ARE SOME NUMBERS TO WATCH FOR (BASIN-WIDE AVERAGES) FOR POTENTIAL
FLOODING...

QUICK RESPONDERS ACROSS SE PA AND NRN DE...2.25 TO 2.50"
SLOWER RESPONDERS ACROSS SE PA...3.00"
RANCOCAS BASIN...3.00"
RARITAN BASIN...3.75"
PASSAIC BASIN...4.00"
LEHIGH BASIN...4.00+"
POCONOS...4.00+"

&&

.TIDES/COASTAL FLOODING...
WE ARE IN THE NEW MOON PHASE OF THE HIGH TIDE CYCLE TODAY.

THE HIGH TIDE THAT IS MOST VULNERABLE DURING THE UPCOMING EVENT IS
SUNDAY EVENING ON THE OCEAN WATERS...LOWER DELAWARE BAY AND CHESAPEAKE
BAY...AND EARLY MONDAY MORNING ON THE UPPER DELAWARE BAY AND TIDAL
PORTION OF THE DELAWARE RIVER. FOR MOST LOCATIONS...TIDE DEPARTURES
OF ONE AND ONE-HALF FEET WOULD BE NEEDED FOR MINOR TIDAL FLOODING...
AND TWO AND ONE-HALF FEET FOR MODERATE FLOODING.

THE TRACK OF THE SURFACE LOW WILL BE CRITICAL...AND FOR NOW THE
FORECAST IS BASED ON MORE OF A GFS/ECMWF BASED RATHER THAN THE NAM.
THE GFS BASED EXTRATROPICAL SURGE GUIDANCE SUGGESTS THAT WHILE SOME
LOCATIONS MAY GET CLOSE TO THE MINOR TIDAL FLOODING BENCHMARK DURING
THE EVENING TIDE CYCLE...NO LOCATIONS ARE FORECAST TO EXCEED IT.

THIS IS SUPPORTED BY THE CMS STORM SURGE GUIDANCE PROVIDED BY
STEVENS INSTITUTE...AS WELL AS CBOFS AND DBOFS. BASED ON THE
CONSENSUS OF GUIDANCE...WILL HOLD OFF ON ISSUING A COASTAL FLOOD
WATCH. WHILE IT IS POSSIBLE THAT COASTAL FLOOD ADVISORIES COULD BE
NEEDED (ESPECIALLY WHEN HEAVY RAIN IS INVOLVED)...IT IS TOO EARLY
FOR THESE HEADLINES.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...FLOOD WATCH FROM 8 AM EDT SUNDAY THROUGH LATE SUNDAY NIGHT FOR
     PAZ067>071.
NJ...FLOOD WATCH FROM 8 AM EDT SUNDAY THROUGH LATE SUNDAY NIGHT FOR
     NJZ008>010-012-015.
DE...FLOOD WATCH FROM 8 AM EDT SUNDAY THROUGH LATE SUNDAY NIGHT FOR
     DEZ001.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT SUNDAY FOR ANZ430-431-
     450>455.
     GALE WARNING FROM 5 PM SUNDAY TO 2 AM EDT MONDAY FOR ANZ431-
     452>455.
     GALE WARNING FROM 8 PM SUNDAY TO 5 AM EDT MONDAY FOR ANZ450-
     451.

&&

SYNOPSIS...HAYES
NEAR TERM...AMC/ROBERTSON
SHORT TERM...ROBERTSON
LONG TERM...HAYES
AVIATION...AMC/HAYES/ROBERTSON
MARINE...HAYES/ROBERTSON
HYDROLOGY...
TIDES/COASTAL FLOODING...

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
405 PM EDT SAT APR 21 2012

NJZ008>010-015-PAZ067>069-222015-
MORRIS-HUNTERDON-SOMERSET-MERCER-CHESTER-MONTGOMERY-BUCKS-
405 PM EDT SAT APR 21 2012

...FLOOD WATCH IN EFFECT FROM SUNDAY MORNING THROUGH LATE SUNDAY
NIGHT...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL NEW JERSEY...NORTHERN
NEW JERSEY...NORTHWEST NEW JERSEY AND SOUTHEAST PENNSYLVANIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

SOME THUNDERSTORMS THIS AFTERNOON AND EVENING MAY PRODUCE LOCALLY
HEAVY RAIN AND GUSTY WINDS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   FLOOD WATCH.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

NJZ001-007-PAZ054-055-060>062-222015-
SUSSEX-WARREN-CARBON-MONROE-BERKS-LEHIGH-NORTHAMPTON-
405 PM EDT SAT APR 21 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHERN NEW JERSEY...EAST
CENTRAL PENNSYLVANIA AND NORTHEAST PENNSYLVANIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

SOME THUNDERSTORMS THIS AFTERNOON AND EVENING MAY PRODUCE LOCALLY
HEAVY RAIN AND GUSTY WINDS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

A COASTAL STORM WILL AFFECT THE AREA SUNDAY AND SUNDAY NIGHT. THE
SYSTEM WILL PRODUCE PERIOD OF HEAVY RAINS AND GUSTY WINDS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

DEZ002>004-NJZ013-014-016>027-222015-
KENT-INLAND SUSSEX-DELAWARE BEACHES-WESTERN MONMOUTH-
EASTERN MONMOUTH-SALEM-GLOUCESTER-CAMDEN-NORTHWESTERN BURLINGTON-
OCEAN-CUMBERLAND-ATLANTIC-CAPE MAY-ATLANTIC COASTAL CAPE MAY-
COASTAL ATLANTIC-COASTAL OCEAN-SOUTHEASTERN BURLINGTON-
405 PM EDT SAT APR 21 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL DELAWARE...SOUTHERN
DELAWARE...CENTRAL NEW JERSEY AND SOUTHERN NEW JERSEY.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

SOME THUNDERSTORMS THIS AFTERNOON AND EVENING MAY PRODUCE LOCALLY
HEAVY RAIN AND GUSTY WINDS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

A COASTAL STORM WILL AFFECT THE AREA SUNDAY AND SUNDAY NIGHT. THE
SYSTEM WILL PRODUCE PERIOD OF HEAVY RAINS. WINDS COULD GUST TO 45
MPH AT TIMES...ESPECIALLY ALONG THE IMMEDIATE COAST LATE SUNDAY
AFTERNOON AND SUNDAY EVENING.

MINOR TIDAL FLOODING IS POSSIBLE AS WELL. THE HIGH TIDE CYCLE MOST
AT RISK IS THE SUNDAY EVENING TIDE. THERE IS A LOW PROBABILITY OF
MODERATE TIDAL FLOODING...ESPECIALLY ALONG THE OCEAN AND MONMOUTH
COUNTY COASTS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

DEZ001-NJZ012-PAZ070-071-222015-
NEW CASTLE-MIDDLESEX-DELAWARE-PHILADELPHIA-
405 PM EDT SAT APR 21 2012

...FLOOD WATCH IN EFFECT FROM SUNDAY MORNING THROUGH LATE SUNDAY
NIGHT...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHERN DELAWARE...NORTHERN
NEW JERSEY AND SOUTHEAST PENNSYLVANIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

SOME THUNDERSTORMS THIS AFTERNOON AND EVENING MAY PRODUCE LOCALLY
HEAVY RAIN AND GUSTY WINDS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   FLOOD WATCH.

IN ADDITION...GUSTY WINDS ARE POSSIBLE LATE SUNDAY AFTERNOON AND
SUNDAY EVENING. MINOR TIDAL FLOODING IS POSSIBLE AS WELL. THE HIGH
TIDE CYCLE MOST AT RISK IS THE LATE SUNDAY EVENING AND EARLY
MONDAY MORNING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

MDZ008-012-015-019-020-222015-
CECIL-KENT MD-QUEEN ANNES-TALBOT-CAROLINE-
405 PM EDT SAT APR 21 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST MARYLAND.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

SOME THUNDERSTORMS THIS AFTERNOON AND EVENING MAY PRODUCE LOCALLY
HEAVY RAIN AND GUSTY WINDS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

A COASTAL STORM WILL AFFECT THE AREA SUNDAY AND SUNDAY NIGHT. THE
SYSTEM WILL PRODUCE PERIOD OF HEAVY RAINS. GUSTY WINDS ARE
EXPECTED AS WELL.

MINOR TIDAL FLOODING IS POSSIBLE AS WELL. THE HIGH TIDE CYCLE MOST
AT RISK IS THE SUNDAY EVENING TIDE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

ANZ431-452>455-222015-
DELAWARE BAY WATERS SOUTH OF EAST POINT NJ TO SLAUGHTER BEACH DE-
COASTAL WATERS FROM LITTLE EGG INLET TO GREAT EGG INLET NJ OUT 20 NM-
COASTAL WATERS FROM GREAT EGG INLET TO CAPE MAY NJ OUT 20 NM-
COASTAL WATERS FROM CAPE MAY NJ TO CAPE HENLOPEN DE OUT 20 NM-
COASTAL WATERS FROM CAPE HENLOPEN TO FENWICK ISLAND DE OUT 20 NM-
405 PM EDT SAT APR 21 2012

...GALE WARNING IN EFFECT FROM 5 PM SUNDAY TO 2 AM EDT MONDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR ATLANTIC COASTAL WATERS AND
DELAWARE BAY WATERS.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

HAZARDOUS WEATHER NOT IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   GALE WARNING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

ANZ450-451-222015-
COASTAL WATERS FROM SANDY HOOK TO MANASQUAN INLET NJ OUT 20 NM-
COASTAL WATERS FROM MANASQUAN INLET TO LITTLE EGG INLET NJ OUT 20 NM-
405 PM EDT SAT APR 21 2012

...GALE WARNING IN EFFECT FROM 8 PM SUNDAY TO 5 AM EDT MONDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR ATLANTIC COASTAL WATERS.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   GALE WARNING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

ANZ430-222015-
DELAWARE BAY WATERS NORTH OF EAST POINT NJ TO SLAUGHTER BEACH DE-
405 PM EDT SAT APR 21 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR DELAWARE BAY WATERS.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

SOME THUNDERSTORMS MAY PRODUCE GUSTY WINDS AND HEAVY RAIN THIS
AFTERNOON AND THIS EVENING.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

GALE FORCE WINDS ARE POSSIBLE MONDAY AFTERNOON AND MONDAY EVENING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
514 PM EDT SAT APR 21 2012

PAZ060-212215-
BERKS PA-
514 PM EDT SAT APR 21 2012

...STRONG THUNDERSTORMS WILL AFFECT BERKS COUNTY...

AT 507 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
THUNDERSTORMS...SOME OF THEM STRONG...FROM ABOUT 30 MILES NORTHWEST
OF READING TO ABOUT 15 MILES NORTHWEST OF LANCASTER TO ABOUT 20
MILES WEST OF LANCASTER...MOVING NORTHEAST AT 25 MPH. THE
THUNDERSTORMS WILL BE NEAR HAMBURG AROUND 545 PM AND STRAUSSTOWN
AROUND 600 PM.

THE STRONGEST STORMS WILL WILL CAUSE HEAVY DOWNPOURS AND DANGEROUS
CLOUD TO GROUND LIGHTNING...AND THEY MAY GENERATE SMALL HAIL AND
WIND GUSTS TO 40 MPH.

PLEASE MOVE INDOORS IF YOU HEAR THUNDER.

LAT...LON 4050 7643 4052 7635 4052 7624 4058 7606
      4058 7602 4063 7601 4065 7597 4053 7594
      4050 7595 4033 7618 4049 7643

MPD

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
655 PM EDT SAT APR 21 2012

NJZ001-007-220000-
SUSSEX NJ-WARREN NJ-
655 PM EDT SAT APR 21 2012

...A STRONG THUNDERSTORM WILL AFFECT SUSSEX AND WARREN COUNTIES...

AT 650 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 9 MILES WEST OF NEWTON...MOVING NORTHEAST AT 30
MPH. THE THUNDERSTORM WILL BE NEAR FIVE POINTS AROUND 700 PM...
CRANDON LAKES...NEWTON AROUND 705 PM...BRANCHVILLE AROUND 715 PM...
HAINESVILLE...FRANKLIN AROUND 720 PM...HAMBURG AROUND 725 PM AND
SUSSEX AROUND 730 PM.

WIND GUSTS TO 45 MPH AND SMALL HAIL ARE POSSIBLE WITH THIS STORM.
VERY HEAVY RAIN WILL FALL FROM THIS STORM AND DANGEROUS CLOUD TO
GROUND LIGHTNING WILL OCCUR.

PLEASE MOVE INDOORS UNTIL THIS STORM PASSES.

LAT...LON 4122 7439 4092 7490 4103 7505 4106 7502
      4108 7497 4110 7500 4111 7499 4116 7491
      4121 7488 4136 7470

MPD

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
719 PM EDT SAT APR 21 2012

MDZ008-NJZ001-007>009-PAZ054-055-060>062-067>069-220115-
BERKS PA-BUCKS PA-CARBON PA-CECIL MD-CHESTER PA-HUNTERDON NJ-
LEHIGH PA-MONROE PA-MONTGOMERY PA-MORRIS NJ-NORTHAMPTON PA-SUSSEX NJ-
WARREN NJ-
719 PM EDT SAT APR 21 2012

...THUNDERSTORMS AND A COLD FRONT...

AT 715 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
SCATTERED THUNDERSTORMS...A FEW OF THEM STRONG...ALONG A COLD FRONT
THAT WAS FROM ABOUT 20 MILES NORTHWEST OF NEWTON TO ABOUT 10 MILES
NORTHEAST OF READING TO ABOUT 10 MILES NORTH OF BALTIMORE. THE FRONT
WAS MOVING EAST AT ABOUT 20 MPH. IT WILL MOVE ACROSS THE
NORTHWESTERN PORTION OF NEW JERSEY...MOST OF EASTERN
PENNSYLVANIA...AND THE NORTHERN MARYLAND EASTERN SHORE THROUGH 900
PM.

THE STRONGEST THUNDERSTORMS WITH THE FRONT ARE CAPABLE OF GENERATING
WIND GUSTS UP TO 45 MPH...SMALL HAIL...HEAVY DOWNPOURS AND DANGEROUS
CLOUD TO GROUND LIGHTNING. ALSO...THE FRONT WAS CAUSING A
TEMPERATURE DROP OF 10 TO 20 DEGREES ON GUSTY WINDS OVER THE COURSE
OF ONE TO THREE HOURS.

IF YOU HEAR THUNDER...PLEASE MOVE INDOORS.

LAT...LON 4122 7438 4037 7515 3972 7579 3967 7579
      3939 7598 3945 7602 3952 7599 3954 7607
      3972 7623 3974 7610 3979 7605 4003 7594
      4011 7595 4014 7589 4030 7613 4042 7585
      4105 7546 4109 7502 4136 7471

MPD

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
841 PM EDT SAT APR 21 2012

DEZ001>003-MDZ008-012-015-019-020-NJZ001-007>010-012-015>019-021-
PAZ055-060>062-067>071-220230-
BERKS PA-BUCKS PA-CAMDEN NJ-CAROLINE MD-CECIL MD-CHESTER PA-
CUMBERLAND NJ-DELAWARE PA-GLOUCESTER NJ-HUNTERDON NJ-INLAND SUSSEX DE-
KENT DE-KENT MD-LEHIGH PA-MERCER NJ-MIDDLESEX NJ-MONROE PA-
MONTGOMERY PA-MORRIS NJ-NEW CASTLE DE-NORTHAMPTON PA-
NORTHWESTERN BURLINGTON NJ-PHILADELPHIA PA-QUEEN ANNE'S MD-SALEM NJ-
SOMERSET NJ-SUSSEX NJ-TALBOT MD-WARREN NJ-
841 PM EDT SAT APR 21 2012

...THUNDERSTORMS AND A COLD FRONT...

SCATTERED THUNDERSTORMS ACROSS EASTERN PENNSYLVANIA...NORTHWEST NEW
JERSEY AND MUCH OF THE DELMARVA WERE OCCURRING WITH AND BEHIND A
SHARP COLD FRONT THIS EVENING. AS OF 835 PM EDT...THE FRONT HAD
MOVED INTO NORTHWESTERN NEW JERSEY...MOST OF EASTERN PENNSYLVANIA
AND WAS MOVING INTO THE DELMARVA FROM CHESAPEAKE BAY. IT WILL CLEAR
THE ATLANTIC COAST DURING THE REMAINDER OF THE EVENING.

THE STRONGER THUNDERSTORMS...WHICH WERE SCATTERED FROM ABOUT 20
MILES WEST OF PHILADELPHIA DOWN TO ABOUT 20 MILES SOUTHWEST OF
GEORGETOWN AT 835 PM...WERE CAPABLE OF GENERATING WIND GUSTS TO AROUND
40 MPH...DANGEROUS CLOUD TO GROUND LIGHTNING AND HEAVY DOWNPOURS.

GUSTY WINDS OUTSIDE OF THUNDERSTORMS WERE ASSOCIATED WITH THE FRONT
AND THE COLDER AIR BEHIND IT. TEMPERATURES BEHIND THE FRONT OVER
MUCH OF MARYLAND AND PENNSYLVANIA HAD DROPPED IN EXCESS OF 20
DEGREES OVER THE COURSE OF A FEW HOURS.

IF YOU ARE OUTSIDE THIS EVENING AND HEAR THUNDER...PLEASE MOVE
INDOORS.

LAT...LON 3845 7569 3868 7576 3857 7604 3876 7640
      3943 7600 3972 7623 4014 7589 4032 7616
      4082 7547 4124 7545 4109 7502 4136 7469
      4121 7437 4067 7445 4056 7420 4018 7462
      3918 7500 3948 7558 3883 7520 3845 7541

MPD

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
937 PM EDT SAT APR 21 2012

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0907 PM     HAIL             GREEN LANE              40.34N  75.47W
04/21/2012  M0.75 INCH       MONTGOMERY         PA   PUBLIC

0915 PM     TSTM WND DMG     THE WOODLANDS           40.17N  75.15W
04/21/2012                   MONTGOMERY         PA   911 CALL CENTER

            TREES DOWN IN HORSHAM TOWNSHIP.

&&

EVENT NUMBER PHI1200038 PHI1200039

G

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
956 PM EDT SAT APR 21 2012

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0848 PM     TSTM WND DMG     WILLISTOWN              39.96N  75.50W
04/21/2012                   CHESTER            PA   911 CALL CENTER

            PROPERTY DAMAGE ON SUGARTOWN ROAD. PARTIAL ROOF
            COLLAPSE OF ONE BLDG.

&&

EVENT NUMBER PHI1200040

G