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000
FXUS61 KPHI 110552
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
152 AM EDT TUE MAR 11 2014

.SYNOPSIS...
LOW PRESSURE, MOVING ACROSS SOUTHEASTERN CANADA INTO NORTHERN NEW
ENGLAND, TRAILS A WEAK FRONTAL BOUNDARY INTO THE MID ATLANTIC STATES
OVERNIGHT THEN STALLS. LOW PRESSURE IN THE CENTRAL PLAINS TUESDAY
WILL MOVE TO KENTUCKY WEDNESDAY MORNING, THEN INTENSIFY RAPIDLY AS
IT PASSES ACROSS NEW JERSEY WEDNESDAY EVENING AND EAST OF NEW
ENGLAND BY EARLY THURSDAY. HIGH PRESSURE WILL FOLLOW ACROSS THE
SOUTHEASTERN STATES BY FRIDAY MORNING. LOW PRESSURE IN EASTERN
CANADA THIS WEEKEND WILL SEND A COLD FRONT INTO THE MID ATLANTIC
STATES BY SUNDAY. LOW PRESSURE THEN DEVELOPS ALONG THE SOUTHEAST
COAST OF THE UNITED STATES NEXT MONDAY.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AN AREA OF LOW PRESSURE WILL CONTINUE TO MOVE ACROSS SOUTHEASTERN
CANADA AND THEN NEW ENGLAND OVERNIGHT, PULLING A WEAK FRONTAL
BOUNDARY INTO OUR AREA. THERE IS WAA ALOFT FORECAST TO OCCUR DURING
THE NIGHT, HOWEVER THE BEST LIFT AND MOISTURE IS FORECAST TO BE TO
OUR NORTH. THIS IS ALSO WHERE A SHORT WAVE IS TRACKING. THEREFORE,
ANY PRECIPITATION IS ANTICIPATED TO BE NORTH OF OUR REGION. OTHERWISE,
SOME MAINLY MID TO HIGH LEVEL CLOUDINESS WILL CROSS OUR CWA AT TIMES
WITHIN THE WAA REGIME.

THE HOURLY GRIDS WERE ADJUSTED BASED ON THE LATEST OBSERVATIONS,
THEN THE LAMP/LAV GUIDANCE WAS BLENDED IN. THE SKY COVER WAS
ADJUSTED BASED ON SATELLITE IMAGERY TRENDS, WHICH SHOWED A BAND OF
BROKEN TO OVERCAST MID LEVEL CLOUDS MOVING ACROSS NORTHEASTERN
PENNSYLVANIA AND NORTHERN NEW JERSEY. THIS SHOULD SHIFT MOSTLY TO
OUR NORTHEAST SHORTLY, THEN SOME ADDITIONAL MID TO HIGH LEVEL
CLOUDINESS ARE EXPECTED TO ARRIVE DURING THE OVERNIGHT. SOME SPOTS
HAVE DECOUPLED THIS EVENING AND WITH DEW POINTS NEAR 30F,
TEMPERATURES HAVE DROPPED A BIT FASTER. LOW TEMPERATURES WERE A
BLEND OF THE NAM/GFS MOS, WITH SOME MINOR TWEAKS MADE ATTM.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
THE FRONT THAT MOVES ACROSS THE AREA OVERNIGHT MAY GET HUNG UP ACROSS
THE SOUTHERN HALF OF THE AREA ON TUESDAY. AGAIN, THERE DOES NOT LOOK
TO BE MUCH VERTICAL MOISTURE, NOR ANY STRONG SHORT WAVE/VORT MAX
DURING THE DAY TUESDAY, SO WE DO NOT ANTICIPATE ANY PRECIPITATION.
THERE WILL LIKELY REMAIN SOME CLOUD COVER, MOSTLY MID-HIGH LEVEL
CLOUDS. WITH THE FLOW BECOMING MORE ZONAL ALOFT, THICKNESSES WILL
RISE INTO TUESDAY. THIS WILL ALLOW TEMPERATURES TO WARM, MAKING
TUESDAY ONE OF THE WARMEST DAYS IN QUITE A LONG TIME. MAV/MET MOS
NUMBERS WERE FAIRLY CLOSE OVERALL, SO A BLEND OF THE TWO WAS USED
FOR DAYTIME HIGHS, WHICH KEEPS ABOVE NORMAL TEMPERATURES EVERYWHERE.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
500MB: A SHARP SHORT WAVE MOVING SOUTHEAST FROM THE NORTHERN PLAINS
TUESDAY EVENING EVOLVES INTO A STRONG COLD NORTH SOUTH TROUGH CROSSING
THE EAST COAST THURSDAY. STRONG RIDGING FOLLOWS LATE IN THE WEEK
BEFORE SHORT WAVES DEVELOP A NEW TROUGH IN THE EAST EARLY NEXT
WEEK.

TEMPERATURES: CALENDAR DAY AVERAGES NEAR OR SLIGHTLY ABOVE NORMAL
WEDNESDAY AS MINIMUM TEMPS OCCUR AT 1159 PM WED...THEN WELL BELOW
NORMAL THURSDAY AND FRIDAY WITH DAYTIME MAX TEMPS ABOUT 20 DEGREES
BELOW NORMAL THURSDAY. TEMPS AVG NEAR NORMAL THIS WEEKEND BEFORE
PROBABLY SLIPPING BELOW NORMAL EARLY NEXT WEEK.

FORECAST BASIS...

12Z/10 50 50 BLENDED GFS/NAM MOS GUIDANCE TUE NIGHT-WED NIGHT,  MEX
MOS GUIDANCE THURSDAY AND THURSDAY NIGHT THEN 1522Z/10 WPC GUIDANCE
FRI-MON. THE 12Z ECMWF IS RECEIVED A LITTLE TOO LATE AT WFO LEVEL
FOR CONFIDENT ADJUSTMENTS TO THE 12Z PACKAGE. THE 09Z/10 SREF 3 HR
POPS AND 12Z/GEFS 6 HR POPS FOR .05 WERE REVIEWED WITH ANY
SIGNIFICANT ADJUSTMENTS TO THE ABOVE FORECAST BASIS NOTED.

THE DAILIES BELOW...

WEDNESDAY...MOSTLY RAIN FOR OUR AREA EXCEPT MAYBE SEVERAL INCHES OF
SNOW POSSIBLE AT THE END OF THE EVENT ALONG AND N OF I80 FROM SUSSEX
COUNTY INTO THE POCONOS AND EVEN HERE...CONFIDENCE FOR SNOW ACCUMULATION
IS BELOW AVG DESPITE THE 12Z/10 ECMWF. SREF SNOW ACCUM PROBS HAVE
DROPPED SUBSTANTIALLY SINCE 03Z/10. DEPENDING ON THE TRACK OF THE
SFC LOW...STRONG ISALLOBARIC GRADIENT WITH ASSOCIATED STRONG PRES
FALLS THRU NNJ WILL DRAW COLD SFC AIR SWD BENEATH ABOVE 32F AIR
ALOFT POSSIBLY LEADING TO A BRIEF PERIOD OF FREEZING RAIN IN THE
POCONOS LATE IN THE DAY WEDNESDAY. HUGE COLD AIR ADVECTION FLUX
WITH 10MB 3 HR PRES RISES DURING THE EVENING MAY PERMIT 1 TO 4
INCHES OF SNOW IN THE POCONOS IN THE 8PM TO 1 AM THURSDAY TIME
FRAME. THIS IS STILL HIGHLY UNCERTAIN. ITS POSSIBLE THAT SPOTTY
COVERINGS OF SNOW WILL EXTEND SOUTHWARD TO I78 BUT AM NOT AT ALL
CONVINCED SINCE NW FLOW IS DOWNSLOPE.

LOW PROB ISOLATED SVR DELMARVA AND S NJ IN THE 3PM TO 7 PM TIME
FRAME WEDNESDAY AHD OF THE COLD FRONT. HOWEVER...ML CAPE IS LESS
THAN 200J SO PLAYED IT AS SLIGHT CHC THUNDER ATTM.

IN FACT...IT MAY NOT RAIN AT ALL PRIOR TO 6 PM WEDNESDAY FROM PHL
SOUTH AND EAST.

TURNING QUITE WINDY LATE WED NIGHT WITH STG NNW CAA. WIND ADVY
POTENTIAL WITH 10MB 3 HRLY RISES AT 03Z/THURSDAY E PA AS BL WIND
INCREASES TO 30 KT AND CAA PERMITS TRANSFER TO ABOUT 3500 FT
(42-48KT).

THURSDAY....WINDY AND VERY COLD FOR THE TIME OF YEAR WITH DAYTIME
TEMPS ABOUT 20 DEGREES BELOW NORMAL. MIXED CLOUDS AND SUN.

THURSDAY NIGHT...DIMINISHING WIND AND COLD.

FRIDAY-SATURDAY...MILDER AHEAD OF THE NEXT COLD FRONT AND PRETTY MUCH
WPC GRIDS. NOT MUCH ENERGY EXPENDED HERE AS THE PRIMARY FOCUS WAS
WED-WED NIGHT-THU.

SUNDAY...A CFP.  WPC GRIDDED GUIDANCE.

MONDAY...COMPLEX AND COLDER THAN NORMAL WITH LOTS OF UNCERTAINTY. THE
ECMWF HAS BEEN OFF AND ON WITH A LARGE COLD STORM FOR MONDAY BUT
RIGHT NOW...WE`RE TALKING DAY 7. CONFIDENCE BELOW AVG.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

TODAY...VFR. A COLD FRONT WILL MOVE THROUGH THE REGION EARLY THIS
MORNING AND WINDS WILL BACK TOWARDS THE WEST AND REMAIN UNDER 10
KNOTS. HIGH LEVEL CLOUDS WILL CONTINUE TO STREAM IN FROM THE WEST
WELL AHEAD OF THE NEXT LOW PRESSURE SYSTEM. SHOULD BE ABLE TO REACH
CONVECTIVE TEMPERATURES LATER THIS AFTERNOON SO A FEW STRATOCU ARE
POSSIBLE. ANOTHER CHANCE FOR A SEABREEZE TO DEVELOP AND MOVE THROUGH
ACY LATER THIS AFTERNOON.

TONIGHT...MOSTLY VFR. WINDS BECOME LIGHT AND VARIABLE FOR A TIME
AHEAD OF THE NEXT SYSTEM....ULTIMATELY VEERING TOWARDS THE
SOUTHEAST. WILL START TO SEE THE LOWERING CLOUD BASES TOWARDS MVFR
LATE TONIGHT.

OUTLOOK...

WEDNESDAY...MVFR/IFR CONDS WITH SHOWERY RAINS DEVELOPING IN THE
AFTN OR EVENING. MDT TO HIGH CONFIDENCE. SLIGHT CHC OF A TSTM
DELMARVA LATE IN THE DAY. A GUSTY SSW WIND TO 25 KT DEVELOPING
VCNTY KPHL SOUTH AND E DURING THE AFTN AS VERY STRONG LOW PRES
CROSSES NJ.

WEDNESDAY NIGHT...MVFR/IFR CONDS IN SHOWERS DURING THE EVENING
POSSIBLY ENDING AS SNOW SHOWERS OR A PERIOD OF SNOW...MAINLY KRDG-
KABE NORTH. BECOMING VERY WINDY WITH NW WIND GUST 28-38KT. MDT TO
HIGH CONFIDENCE.

THURSDAY-FRIDAY...VFR. GUSTY NW WINDS 25-35 KT THURSDAY. HIGH
CONFIDENCE.

SATURDAY...PROBABLY VFR. MDT CONFIDENCE.

&&

.MARINE...
SUB-ADVISORY CONDITIONS EXPECTED OVERNIGHT INTO TUESDAY. A FRONTAL
BOUNDARY WILL MOVE INTO THE COASTAL WATERS TONIGHT INTO TUESDAY,
WHICH COULD HELP WINDS GUST TO AROUND 20 KNOTS. WINDS WILL BEGIN OUT
OF THE SOUTH-SOUTHWEST, THEN BECOME MORE WEST TO NORTHWEST TOWARD
DAYBREAK TUESDAY AND INTO THE DAY.

OUTLOOK...
TUE NIGHT...SUB-ADVISORY CONDITIONS EXPECTED.

WEDNESDAY...INCREASING SCA CONDITIONS AS LOW PRESSURE APPROACHES.
SCA ISSUED. AVG TO ABOVE AVG CONFIDENCE

WEDNESDAY NIGHT-THURSDAY...GALE CONDITIONS EXPECTED. WELL ABOVE
AVG CONFIDENCE. FREEZING SPRAY EXPECTED FOR A TIME THURSDAY
MORNING.

THURSDAY NIGHT-FRIDAY...SCA CONDITIONS.

SATURDAY...SCA POSSIBLE.

&&

.HYDROLOGY...
WE WILL CONTINUE TO TAKE A CLOSER LOOK AT THE QPF FOR THE
WEDNESDAY INTO THURSDAY SYSTEM, ALONG WITH ANTICIPATED RUNOFF AND
ANY POTENTIAL FOR ANY MINOR FLOODING BEFORE IT ALL FREEZES UP
AGAIN THURSDAY.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON TO 6 PM EDT WEDNESDAY FOR
     ANZ430-431-450>455.

&&

$$
SYNOPSIS...DRAG
NEAR TERM...GORSE/ROBERTSON
SHORT TERM...ROBERTSON
LONG TERM...DRAG
AVIATION...DRAG/HEAVENER
MARINE...DRAG/ROBERTSON
HYDROLOGY...