Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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808
FXUS61 KPHI 031041
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
541 AM EST WED FEB 3 2016

.SYNOPSIS...
STRONG LOW PRESSURE WILL TRACK NORTHEASTWARD TODAY THROUGH THE GREAT
LAKES AND INTO EASTERN CANADA AS ITS ASSOCIATED WARM FRONT LIFTS
NORTH THROUGH OUR AREA. A COLD FRONT WILL THEN CROSS OUR REGION LATE
TONIGHT AND LINGER ALONG THE COAST THROUGH THURSDAY. LOW PRESSURE
WILL DEVELOP ON THE FRONT OFF THE MID ATLANTIC COAST THURSDAY NIGHT
AND DEPART FRIDAY. HIGH PRESSURE WILL GRADUALLY BUILD INTO OUR AREA
FROM THE SOUTHWEST LATE FRIDAY AND SATURDAY. A COLD FRONT FROM
THE NORTHWEST IS FORECAST TO CROSS THE AREA SUNDAY, FOLLOWED BY
ANOTHER LOW PRESSURE SYSTEM AFFECTING THE REGION EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
**HIGH CONFIDENCE FOR COMBINATION OF WIDESPREAD 3/4 TO 1.5 INCH
 RAINFALL BY DAYBREAK THURSDAY ALONG WITH RECORD OR NEAR RECORD
 WARMTH THIS AFTERNOON**

KEEPING THIS SIMPLE SINCE WE`VE BEEN TALKING ABOUT IT FOR SEVERAL
DAYS. ITS ONLY A MATTER OF TIMING FOR MODERATE TO HEAVY RAINFALL
AS A CORRIDOR OF MUCH ABOVE NORMAL MOISTURE FOR FEBRUARY, PRECEDES
A SLOW MOVING COLD FRONT INTO EASTERN PENNSYLVANIA LATE TODAY.

AHEAD OF IT, A GUSTY SOUTHERLY FLOW OF 25 TO 35 MPH WILL DEVELOP
OVER THE DELMARVA UP TO I-95 THIS AFTERNOON, WHIPPING NEAR RECORD
WARMTH INTO THE REGION. MEANWHILE THE RIP SNOWPACK IN EASTERN PA
AND CENTRAL-NNJ WILL BE RAINED ON AND AS DEWPOINTS APPROACH
50...DENSE FOG SHOULD FORM THIS AFTERNOON SINCE WINDS THERE WILL
BE LIGHTER OUT OF THE SOUTH.

THE REGION EAST OF I-95 MAY NOT SEE ANY RAIN UNTIL MIDDAY OR THIS
AFTERNOON.

THUNDER POSSIBLE LATE TODAY DELMARVA.

THE HYDRO SECTION HAS MUCH MORE ON REASONING AND THE RELATIVELY HIGH
PROBABILITY OF MINOR TO MODERATE SMALL STREAM FLOODING.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
RAIN WILL STILL BE FALLING IN OUR REGION ON THIS EVENING AND
PROBABLY HEAVY AT TIMES NEAR AND EAST OF I-95 EARLY IN THE NIGHT.

THE ENTRANCE REGION OF A 60+ KNOT LOW LEVEL JET IS FORECAST TO BE
OVER SOUTHERN NEW JERSEY AND DELAWARE AT THAT TIME ALONG WITH AN
AXIS OF 1.5+ INCH PRECIPITABLE WATER VALUES.

RAIN DIMINISHES SUBSEQUENT TO THE WIND SHIFT TO WEST AND NORTHWEST.

DENSE FOG MAY DEVELOP IN THE FRONTAL ZONE. M RIGHT NOW I HAVE
AREAS OF FOG MAINLY OVER THE REMAINING SNOW PACK OF EASTERN PA
AND NORTHERN NJ BUT WE MAY NEED TO EXPAND THAT TO THE COASTS AND
DELMARVA IN LATER FORECASTS.

AGAIN...THE UKMET AND ECMWF ARE BLENDED IN WITH THE THINKING FOR
TONIGHT.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
WHILE THE BULK OF HEAVIER RAIN WILL HAVE ENDED BY THURSDAY MORNING
ACROSS THE FORECAST AREA WITH THE COLD FRONT HAVING PUSHED OFFSHORE,
THE POTENTIAL FOR SOME LINGERING LIGHTER RAIN DOES EXIST FOR EASTERN
PARTS OF THE CWA AS THE COLD FRONT LINGERS NEARBY TO THE EAST. AS
NOTED BY THE PREVIOUS SHIFT, THE SOUTHWESTERLY MID LEVEL FLOW WILL
SLOW THE PROGRESS OF THE FRONT AND THE ASSOCIATED CLEARING BEHIND
IT. BUT AS THE DAY WEARS ON, THE FRONTAL BOUNDARY WILL DRIFT A
LITTLE FARTHER OUT TO SEA WITH ANY LINGERING LIGHT RAIN MOSTLY
ENDING INTO MIDDAY/EARLY AFTERNOON. TEMPERATURE-WISE, THURSDAY IS
STILL EXPECTED TO BE A RELATIVELY MILD DAY WITH THE MID LEVEL TROUGH
AXIS STILL OFF TO OUR WEST DURING THE DAYTIME, AS HIGH TEMPERATURES
REACH MOSTLY THE UPPER 40S AND LOWER 50S ACROSS OUR AREA. A COLDER
AIRMASS BEGINS TO RETURN ACROSS THE AREA INTO THURSDAY NIGHT, AND TO
COMPLICATE MATTERS, THE UKMET AND SREF ARE INDICATING THE POTENTIAL
FOR SOME ACCUMULATING SNOW LATE THURSDAY NIGHT ACROSS EASTERN
PORTIONS OF NJ AND PERHAPS INTO SOUTHERN DE AS AN AREA OF LOW
PRESSURE DEVELOPS ALONG THE STILL LINGERING OFFSHORE COLD FRONT
BOUNDARY. POPS HAVE BEEN INCREASED INTO THE 40 TO 50 PERCENT RANGE
TO REFLECT THIS POTENTIAL. THE LOW PRESSURE AND THE LINGERING FRONT
ARE THEN FORECAST TO DEPART OUT TO SEA INTO FRIDAY MORNING.

THE RETURN OF COLDER, MORE SEASONAL FEBRUARY-LIKE TEMPERATURES WILL
NOT BE FAR BEHIND AS THE MID LEVEL TROUGH AXIS PASSES TO OUR EAST
FRIDAY MORNING. MAINLY QUIET CONDITIONS AND AMPLE SUNSHINE ARE
ANTICIPATED FOR THE BULK OF FRIDAY AS HIGH PRESSURE TO THE SOUTHWEST
GRADUALLY BUILDS OVER THE MID ATLANTIC REGION. WITH NORTHWEST WINDS
AROUND 10 TO 15MPH, DAYTIME HIGHS ON FRIDAY SHOULD MAX OUT MOSTLY IN
THE LOWER 40S, WITH SOME MID/UPPER 30S FOR OUR NORTHERN ZONES.
SIMILAR CONDITIONS ARE ANTICIPATED SATURDAY FOR THE REGION, BUT WITH
MILDER DAYTIME TEMPERATURES AND SOME CLOUDS ADVANCING IN FROM THE
WEST AS THE AREA OF HIGH PRESSURE ADVANCES EAST AND OFFSHORE.

BY SUNDAY, A COLD FRONT MAY APPROACH OUR REGION FROM THE NORTHWEST,
BUT WITH LIMITED MOISTURE ASSOCIATED WITH THIS BOUNDARY, WE HAVE
KEPT A DRY FORECAST FOR SUNDAY, WITH DAYTIME HIGHS REACHING MAINLY
IN THE 40S, EXCEPT FOR SOME MID/UPPER 30S INTO THE SOUTHERN POCONOS.
OF NOTE, THE GFS AND ECMWF CONTINUE TO DEVELOP AN AREA OF LOW
PRESSURE OFF THE SOUTHEASTERN SEABOARD SUNDAY, TAKING IT OUT TO SEA
SUNDAY NIGHT, WITH LITTLE OR NO IMPACT FOR OUR REGION.

THROUGH THE REMAINDER OF THE LONG TERM PERIOD, THERE IS MORE MODEL
SPREAD WITH REGARDS TO A POSSIBLE LOW PRESSURE SYSTEM PASSING ACROSS
THE GREAT LAKES MONDAY AND ANOTHER AREA OF LOW PRESSURE POSSIBLY
DEVELOPING OFF THE EAST COAST TUESDAY. WHILE THE TIMING OF
PRECIPITATION ACROSS OUR REGION REMAINS A LOW CONFIDENCE FORECAST AT
THIS TIME, THE OVERALL PATTERN AND A BROAD LONGWAVE TROUGH OVER THE
GREAT LAKES TO NORTHEAST AND MID ATLANTIC SUGGESTS A COLDER TREND
INTO EARLY NEXT WEEK, AND WE GENERALLY FOLLOWED SUPERBLEND AND/OR
WPC GUIDANCE WITH REGARDS TO TEMPS AND POPS AT THIS EXTENDED TIME
RANGE.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

TODAY...VFR CIGS DETERIORATE TO MVFR CIGS FROM SW TO NE TODAY AND
THEN EVENTUALLY THIS AFTERNOON TO IFR IN SHOWERY RAINS/FOG. SMALL
CHC LATE DAY TSTM DELMARVA. RAIN SHOULD BECOME HEAVY THIS AFTN
FROM WEST TO EAST. GUSTY SOUTHERLY WINDS OF 20-30 KT THIS AFTERNOON
I95 EASTWARD WITH POSSIBLE GUSTS 35-38 KT DELMARVA. LIGHTER
SOUTHEAST TO SOUTH WINDS WITH GUSTS GENERALLY UNDER 20 KT FOR
KABE/KRDG.  LLWS POSSIBLE.

TONIGHT....IFR CONDS IN RAIN FOG SLOWLY IMPROVE FROM WEST TO
EAST, ESPECIALLY AFTER 06Z/4.


OUTLOOK...
THURSDAY...CONDITIONS IMPROVING BACK TO VFR FOR MUCH OF THE REGION,
EXCEPT SOME LINGERING LOWER MVFR IN LIGHT RAIN POSSIBLE FOR THE
SOUTHEAST SITES, INCLUDING KACY/KMIV.

FRIDAY THROUGH SUNDAY...MAINLY VFR CONDITIONS.

&&

.MARINE...
SCA CONTINUES AS POSTED...REMAINING IN EFFECT UNTIL MIDNIGHT ON
DELAWARE BAY. A SMALL CRAFT ADVISORY WILL REMAIN IN EFFECT FOR OUR
OCEAN WATERS FOR THE ENTIRE NIGHT.

SEAS INCREASE ON THE ATLC WATERS TO BETWEEN 7 AND 9 FEET LATE TODAY
AND TONIGHT. A FEW SOUTHERLY GUSTS TO 35 KT ARE POSSIBLE THIS
AFTERNOON BUT THIS MAY BE BE HANDLED WITH AN SMW. SMALL CHC OF A
TSTM DE WATERS LATE TODAY.

OUTLOOK...
THURSDAY...A SMALL CRAFT ADVISORY WILL CONTINUE THROUGH THE DAYTIME
THURSDAY FOR THE ATLANTIC COASTAL WATERS DUE TO WAVE HEIGHTS STILL
RUNNING IN THE 5 FOOT RANGE.

FRIDAY...BREEZY NORTHWEST WINDS ARE EXPECTED, AND GUSTS TO AROUND 25
KNOTS MAY OCCUR LEADING TO MARGINAL SCA CONDITIONS.

SATURDAY AND SUNDAY...WINDS AND SEAS LOOK TO REMAIN BELOW ADVISORY
CRITERIA FOR THE MOST PART, BUT THERE IS SOME POTENTIAL FOR OFFSHORE
LOW PRESSURE TO PASS EAST OF OUR WATERS ON SUNDAY, WHICH COULD
ENHANCE SEAS AND WIND GUSTS.

&&

.HYDROLOGY...
**THE RISK FOR EXTENSIVE MINOR TO MODERATE FLOODING APPEARS TO BE
  INCREASING**

THE UPSTREAM TROUGH AND ASSOCIATED RIDGE AHEAD OF IT ARE LIKELY
TO SLOW THE FRONTAL PASSAGE ACROSS OUR AREA PERMITTING A LONGER
DURATION IN 4 TO 5 SD ABOVE NORMAL PWAT OF 1.4" OR GREATER. THIS
PLUS DIFFLUENT 1000-500 THICKNESS AND WEAK LOW PRESSURE ALONG THE
FRONT CROSSING THE DELMARVA IN THE WARMEST SECTOR OF THE FRONT IN
OUR AREA SHOULD ENHANCE LOW LVL CONVERGENCE AND ASSOCIATED RFALL.
MODELS ARE SLOWING AND THE DEPARTURE OF THE RAIN TONIGHT.
ADDITIONALLY...PROBABILITIES OF 1 INCH OF RAIN BY BOTH THE SREF
AND GEFS ARE MERGING. THE UKMET FOR 3 CONSECUTIVE CYCLES HAS
FORECAST 1+ INCHES ALONG THE I95 CORRIDOR.

THIS COMBINED WITH THE MELTING OF THE 1-2" SWE IN THE SNOWPACK
NEAR I-78 SHOULD RESULT IN CONSIDERABLE POOR DRAINAGE FLOODING
LATE TODAY AND TONIGHT WITH NUMEROUS CREEKS AND STREAMS RESPONDING
TO BANKFULL OR EXCEEDING FLOOD STAGE TONIGHT AND THURSDAY WITH
SOME OF THE FLOODING LINGERING INTO FRIDAY.

SREF AND GEFS ARE MERGING AND INCREASING PROBS FOR 1" THROUGH MOST
OF THE FORECAST AREA NOW. ITS STILL POSSIBLE TO GET AWAY WITH ONLY
3/4 INCH FOR THIS ENTIRE EVENT... BUT I THINK THAT WOULD BE ONLY N
OF I80. A FEW POCKETS OF 1.5 TO 1.75 INCHES STILL FAVOR ALONG AND
NW OF I-95 BY 12Z THURSDAY.

THE DAY SHIFT WILL UPDATE MORE FULLY AND WE MAY ADD MORE INFORMATION
HERE. OTHERWISE...THOSE LIVING NEAR SMALL STREAMS THAT TEND TO
EASILY FLOOD SHOULD BE PREPARED FOR ANOTHER EPISODE. ADDITIONALLY
FROZEN GROUND AND RUNOFF MAY FORCE BASEMENT FLOODING IN AREAS OF
POOR DRAINAGE.


IMPACTS...THE THREAT OF MINOR TO MODERATE RIVER FLOODING APPEARS
TO BE INCREASING FURTHER FOR THE PASSAIC AND RARITAN BASINS IN
NJ AND AM THINKING THIS ALSO INCLUDES SCHUYLKILL BASIN IN PA.
ADJACENT BASINS (TO THOSE MENTIONED ABOVE) IN NJ AND ACROSS SOUTHEAST
PA, SHOULD ALSO PLAN FOR SOME FLOODING AND KEEP UP WITH THE LATEST
FORECASTS IN CASE.

FORECAST...WHEN THURSDAY ROLLS AROUND, IT APPEARS MUCH IF NOT ALL
THE SNOW THAT IS ON THE GROUND ACROSS THE HSA WILL BE GONE. THE
SNOW HAS REALLY RIPENED THE LAST 24 HOURS AND IS READY TO GO. THIS
SNOWMELT COMBINED WITH 0.75 TO 1.5 INCHES OF RAIN EXPECTED
WEDNESDAY INTO WEDNESDAY NIGHT IS GOING TO RESULT IN FLOODING FOR
SOME OF THESE RIVER BASINS. WE WILL PROVIDE A LISTING AROUND 5 AM.

THE THREAT OF FLOODING WILL BE TWO-FOLD.

FIRST THIS AFTERNOON AND EARLY TONIGHT, AND THEN LATER TONIGHT
THROUGH THURSDAY. THE FIRST THREAT WILL INCLUDE LOW-LYING, POOR
DRAINAGE, STREET, AND SMALL CREEK FLOODING. THIS WILL HAVE AN
IMPACT ON THE WEDNESDAY EVENING COMMUTE FROM THE I95 CORRIDOR
WESTWARD THROUGH EASTERN PA AND EASTERN MD. THE THREAT STEMS FROM
RAPIDLY MELTING SNOW, PERIODS OF HEAVY RAIN, FROZEN GROUND, AND
POSSIBLY CLOGGED OR RESTRICTED STORM DRAINS.

THE SECOND THREAT STEMS FROM THE RUNOFF FLOWING FROM THE TRIBUTARIES
INTO THE LARGER RIVERS. IT`S AT THIS TIME, WEDNESDAY NIGHT THROUGH
THURSDAY, WHERE WE SHOULD SEE AS MANY AS A DOZEN RIVER FORECAST
POINTS EXCEED FLOOD STAGE.

SNOW WATER EQUIVALENT, OR SWE, IS HIGHEST RIGHT ALONG THE I78
CORRIDOR AND LOCATIONS JUST TO THE NORTH AND SOUTH. GENERALLY, SWE
VALUES ARE RUNNING BETWEEN 1.5 AND 2.0 INCHES HERE. COMBINE THIS
WITH THE EXPECTED RAINFALL, THIS AREA COULD HAVE TO DEAL WITH OVER
3.00 INCHES OF POTENTIAL RUNOFF.

HEADLINES...THE FLOOD WATCH CONTINUES AS UPDATED YESTERDAY.
THE WATCH IS FROM MIDDAY WEDNESDAY THROUGH THURSDAY AFTERNOON
COVERING BOTH OF THE POTENTIAL FLOOD THREATS MENTIONED ABOVE. AT
PREPARE FOR THE POSSIBILITY OF FLOODING INCLUDING DETOURS BECAUSE
OF CLOSED ROADS NEAR SOME OF THE STREAMS AND RIVERS AND POOR
DRAINAGE AREAS.

OUR FORECAST AREA BREAKDOWN...UPPER EASTERN SHORE OF MARYLAND (KENT,
QUEEN ANNE`S, TALBOT AND CAROLINE)...SOME NUISANCE FLOODING IS LIKELY
THIS AFTERNOON AND EARLY TONIGHT. THE FLOOD WATCH INCLUDES CECIL
COUNTY WHERE BOTH THE HEAVIER RAIN IS EXPECTED AND REMAINING SWE
IS HIGHEST.

DELAWARE...NUISANCE FLOODING IS LIKELY LATE TODAY AND TONIGHT,
ESPECIALLY IN NEW CASTLE COUNTY WHERE BOTH THE RAIN IS EXPECTED
AND REMAINING SWE IS HIGHEST. SMALL CREEKS AND STREAMS WILL LIKELY
APPROACH OR EXCEED BANKFULL, ESPECIALLY ACROSS NORTHERN NEW
CASTLE.

NEW JERSEY...NUISANCE FLOODING WILL LIKELY OCCUR THIS AFTERNOON
INTO TONIGHT ACROSS THE WATCH AREA. A NUMBER OF SMALL CREEKS AND
STREAMS WILL APPROACH OR EXCEED BANKFULL IN CENTRAL AND NORTHERN
NEW JERSEY. IN ADDITION, THERE IS A THREAT OF RIVER FLOODING
TONIGHT INTO THURSDAY. THIS THREAT LIES FROM NEAR TRENTON
NORTHEASTWARD WHICH INCLUDES PORTIONS OF THE PASSAIC AND RARITAN
BASINS. NO FLOODING IS EXPECTED ALONG THE DELAWARE.

PENNSYLVANIA...NUISANCE FLOODING WILL OCCUR, MAINLY THIS AFTERNOON
AND EVENING ACROSS THE WATCH AREA. SMALLER CREEKS AND STREAMS
SUCH AS THE NESHAMINY, PERKIOMEN, BRANDYWINE, AND CHESTER WILL
LIKELY EXCEED FLOOD STAGE. IN ADDITION, THERE IS A THREAT OF RIVER
FLOODING TONIGHT INTO THURSDAY. THIS THREAT LIES ACROSS THE SCHUYLKILL
BASIN. NO FLOODING IS EXPECTED ALONG THE DELAWARE.

&&

.TIDES/COASTAL FLOODING...
TIDAL FLOODING IS POSSIBLE AT THE TIMES OF HIGH TIDE MONDAY AND
TUESDAY OF NEXT WEEK ALONG THE ATLANTIC COASTS OF NEW JERSEY AND
DELAWARE, DEPENDING ON THE TIMING OF NORTHWARD DEVELOPMENT OF A
STRONG COASTAL STORM.

&&

.CLIMATE...
LISTED BELOW ARE THE RECORD HIGH TEMPERATURES AND RECORD RAINFALL
FOR TODAY.

WE CONTINUE TO FORECAST TEMPS WITHIN 3F OF RECORD THIS AFTERNOON
AT ALL SITES EXCEPT KRDG AND KABE.

ALSO...IT APPEARS THERE IS A SOMEWHAT BETTER CHANCE OF A RECORD
BREAKING DAILY RAINFALL AT ONE OF THE 8 CLIMATE SITES...BEST CHC
BEING KILG OR KABE. THIS BECAUSE THE FRONTAL BOUNDARY AND FAVORABLE
UPPER AIR PATTERN AND ASSOCIATED CAUSATIVE SHORT WAVE ARE SLOWING
DOWN....PERMITTING A LONGER DURATION IN THE PWAT AXIS OF GREATER
THAN 1.4 INCHES (4-5 SD ABOVE NORMAL FOR THIS TIME OF YEAR).


    RECORD MAX    RECORD RAIN    PERIOD OF RECORD
    ----------    -----------    ----------------

ACY...66-2006      1.61-1880           1874

PHL...62-2006      1.64-1939           1872

ILG...64-1991      1.40-1939           1894

ABE...63-1991      1.37-1982           1922

TTN...62-2006      1.57-1939           1865

GED...68-2006      1.47-1973           1948

RDG...63-1991      1.40-1939           1869

MPO...52-1973      2.19-1983           1901

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...FLOOD WATCH FROM NOON EST TODAY THROUGH THURSDAY AFTERNOON FOR
     PAZ060-061-070-071-101>106.
NJ...FLOOD WATCH FROM NOON EST TODAY THROUGH THURSDAY AFTERNOON FOR
     NJZ009-010-012-013-015>019.
DE...FLOOD WATCH FROM NOON EST TODAY THROUGH THURSDAY AFTERNOON FOR
     DEZ001.
MD...FLOOD WATCH FROM NOON EST TODAY THROUGH THURSDAY AFTERNOON FOR
     MDZ008.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THURSDAY FOR ANZ450>455.
     SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR ANZ430-431.

&&

$$
SYNOPSIS...DRAG/KLINE
NEAR TERM...DRAG
SHORT TERM...DRAG
LONG TERM...KLINE
AVIATION...DRAG/KLINE
MARINE...DRAG/KLINE
HYDROLOGY...
TIDES/COASTAL FLOODING...
CLIMATE...



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