Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 261447
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
947 AM EST THU FEB 26 2015

.SYNOPSIS...
LOW PRESSURE SYSTEM WILL QUICKLY MOVE OFF THE NORTH CAROLINA COAST
TODAY WHILE ANOTHER ARCTIC HIGH PRESSURE SYSTEM NOSES IN BY FRIDAY.
THE HIGH WILL MOVE OFF THE COAST BY EARLY NEXT WEEK FOLLOWED BY
ANOTHER COLD FRONT PASSAGE ON MONDAY. A LOW PRESSURE EJECTS OUT OF
THE CENTRAL PLAINS AND CROSSES OUR REGION ON TUESDAY INTO WEDNESDAY.
THE LOWS ASSOCIATED COLD FRONT PUSHES THROUGH LATER ON WEDNESDAY
WITH ANOTHER EXPANSIVE HIGH PRESSURE SYSTEM FILLING IN BEHIND IT.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

THE LATEST COASTAL LOW CONTINUES TO LIFT NORTHEAST OFF THE
CAROLINA COAST. SEVERAL INCHES OF SNOW HAVE FALLEN ACROSS THE
EASTERN SHORE OF MARYLAND, CENTRAL AND SOUTHERN DELAWARE AND
SOUTHEAST NEW JERSEY. THE HIGHEST TOTAL CLOSE TO 5 INCHES WAS
RECORDED ON FENWICK ISLAND SO FAR. SNOW TOTALS WERE UPDATED WITH
THESE CURRENT REPORTS AND WITH THE PROSPECTS FOR AN ADDITIONAL HOUR
OR TWO OF STEADY SNOW POSSIBLY MODERATE TO HEAVY FOR BRIEF
INTERVALS. THIS DID RAISE TOTALS ALONG THE DELAWARE BEACHES NORTH
THROUGH ATLANTIC CITY SLIGHTLY. FURTHER NORTHWEST, DRY AIR HAS
ERODED THE NORTHERN EDGE OF THE PRECIPITATION SHIELD SUFFICIENTLY
THIS MORNING. TOTALS WERE UNDER AN INCH THROUGH WILMINGTON AND
PHILADELPHIA THIS MORNING. THE NORTHERN EXTENT OF THE WINTER
WEATHER ADVISORY HAS BEEN CANCELLED WITH ONLY SOME LINGERING
FLURRIES POSSIBLE. THE RAP AND HRRR SHOW SNOW EXITING THE BEACHES
AROUND 17Z AND THE WINTER STORM ADVISORIES/WARNINGS GO THROUGH
18Z WHERE ACCUMULATING SNOW HAS FALLEN.

DRY AIR WILL CONTINUE TO PENETRATE FURTHER SOUTH THROUGHOUT THE
DAY AND HAVE POPS TAPERING DOWN TO SLIGHT CHANCE FOR THE AFTERNOON
HOURS. ADDITIONAL SNOW SHOULD JUST BE IN THE FORM OF FLURRIES OR
VERY LIGHT SNOW THIS AFTERNOON. TEMPERATURES WERE ADJUSTED
DOWNWARD SOME WITH THE PRECIPITATION IN THE AREA.  &&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
TONIGHT, A WEAK MID LEVEL SHORT WAVE TROUGH LOOKS TO SIDESWIPE THE
NORTHWESTERN PORTIONS OF OUR REGION. AS A RESULT...LIGHT SNOW IS
POSSIBLE GENERALLY NORTH AND WEST OF THE PHILLY SUBURBS. MOISTURE
AVAILABILITY IS GOING TO BE PROBLEMATIC FOR THIS SYSTEM AS THERE IS
LITTLE CHANCE FOR ANY MOISTURE ADVECTION BEHIND TODAYS SYSTEM.
THEREFORE, ANY SNOW AMOUNTS SHOULD BE BELOW AN INCH.

AS FOR TEMPERATURES...STAYED CLOSE TO GUIDANCE AS MID LEVEL CLOUDS
SHOULD HELP TO LIMIT RADIATIONAL COOLING EVEN FOR LOCATIONS THAT
STILL HAVE SNOW PACK.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
LAST PIECE OF MID-LEVEL ENERGY MOVES THROUGH THE REGION ON FRIDAY AS
THE BROAD SCALE TROUGHING FINALLY RELINQUISHING ITS GRASP ON OUR
REGION. THE MID-LEVELS TAKE ON MORE OF A ZONAL-ISH FLOW OVER THE
WEEKEND WITH THE NEXT EMBEDDED WAVE EXPECTED BY MONDAY FOLLOWED BY
RIDGING THROUGH THE REMAINDER OF THE PERIOD.

FRIDAY - SATURDAY...HIGH PRESSURE WILL BE SQUEEZING IN LATER ON
FRIDAY FROM THE WEST-NORTHWEST. JUST AHEAD OF THE RIDGING WILL BE A
LAST DITCH EFFORT BY THE BROAD TROUGH TO PUSH A DAMPENING SHORTWAVE
THROUGH THE REGION. WITH LIMITED AMOUNTS OF MOISTURE EXPECTED WE
CONFINED THE SLIGHT CHANCE POPS TO OUR WESTERN ZONES BEFORE DRYING
OUT LATER FRIDAY AFTERNOON. AT THIS POINT THE RIDGING WILL BE ABLE
TO EXERT ITSELF UPON THE AREA AND WE REMAIN DRY, BUT COLD, THROUGH
SATURDAY.

SUNDAY - MONDAY...ZONAL-ISH FLOW TURNS A BIT SHARPER AS THE BROAD
TROUGH RELOADS WELL TO OUR WEST. ANOTHER PASSING SHORTWAVE ALOFT
APPROACHES AND PUSHES A COLD FRONT THROUGH THE REGION  LATE SUNDAY
INTO MONDAY MORNING. OUT AHEAD OF THE FRONT TEMPERATURES ARE ABLE TO
MODIFY A BIT THANKS TO THE DEPARTING HIGH PRESSURE NOW OFF THE COAST
AND A LIGHT RETURN FLOW SETTING UP. WE CONFINED THE HIGHER POPS
UNTIL LATE SUNDAY NIGHT JUST AHEAD AND WITH THE FRONTAL PASSAGE.
DECENT AMOUNT OF THETA-E ADVECTION OCCURRING AHEAD OF THE FRONT WITH
ENOUGH LIFT FOR A LIGHT SNOW TO START BEFORE A WINTRY MIX/
CHANGEOVER, MOSTLY ACROSS THE SOUTHERN HALF OF THE CWA, BY MONDAY
MORNING. THE FRONT THEN MOVES THROUGH AND ALLOWS FOR ANOTHER SHOT OF
COOLER AIR AND MORE PRECIPITATION PHASE CHANGES.

TUESDAY - WEDNEDSAY...WITH THE COLD FRONT TO OUR EAST AND A BRIEF
SHOT OF HIGH PRESSURE BEHIND IT, THE NEXT SYSTEM, FORMING DEEP IN
THE SOUTH, BEGINS TO ENTER THE REGION FROM THE SOUTHWEST LATER ON
TUESDAY. A LIGHT ONSHORE FLOW WILL HELP TO ENHANCE THE LOW-LEVEL
MOISTURE FLUX WHEN COMBINED WITH A STRONG LOW-LEVEL SOUTHERLY SURGE
OF WARM/MOIST AIR. THIS EVENT COULD HAVE A COPIOUS AMOUNT OF
MOISTURE WITH IT, GIVEN ITS ORIGIN AND THE MODIFYING AIRMASS WE`LL
HAVE IN PLACE. TOO EARLY FOR PTYPE SPECIFICS BUT IT DOES APPEAR TO
BE A MIXED EVENT. IT SHOULD BE NOTED THAT SEVERAL TIMES THIS WINTER
THE NUMERICAL GUIDANCE HAS BEEN TOO STRONG WITH THE LOW PRESSURE AS
IT CROSSES THE MID-WEST AND THEREFORE OVER AMPLIFIES/WARMS THE LOW-
LEVELS. A SHIFT TO THE EAST AND A WEAKER SOLUTION WOULD LEAD TO LESS
MIXING.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE,
KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS.

SNOW IS TRYING TO BUILD FURTHER NORTH THROUGH THE REGION. HOWEVER, IT
IS ENCOUNTERING A WALL OF DRY AIR. WESTERN TAF SITES, KABE AND
KRDG, WILL LIKELY NOT SEE ANY SNOW AT ALL. FOR THE DELAWARE VALLEY
SITES, KPHL, KPNE, AND KTTN, A 2 TO 3 HOUR PERIOD OF MOSTLY LIGHT
SNOW IS POSSIBLE BETWEEN 12 AND 16Z (SOONER AT KILG, WHILE KTTN
WILL BE THE LAST TO BE AFFECTED). THOUGH IT APPEARS THE MAIN
WINDOW FOR THIS WILL BE ENDING SOON BY 14Z-15Z. AT KILG, KMIV AND
KACY, MOSTLY LIGHT BUT SOME PERIODS OF MODERATE TO HEAVY SNOW SNOW
WILL BE POSSIBLE FOR A MAJORITY OF THE MORNING. BY 18Z HOWEVER,
SNOW SHOULD BE OUT OF THE REGION. TAFS REFLECT MORE OPTIMISTIC
CONDITIONS THAN WHAT IS DEPICTED IN THE GFS LAMP AS IT APPEARS TO
BE UNDERESTIMATING THE DRY AIR IN THE BOUNDARY LAYER. THUS...THINK
THAT ONCE THE SNOW MOVES OUT CONDITIONS SHOULD RETURN TO
VFR...THOUGH THERE REMAINS A SMALL CHANCE THAT MVFR CEILINGS WILL
LINGER THROUGH THE DAY.

OVERNIGHT, CEILINGS SHOULD INCREASE BACK TO VFR, ALBEIT THE LOWER
END OF VFR. THERE IS SOME RISK OF BR DEVELOPING ACROSS THE REGION,
AND A LOW CHANCE OF ANOTHER ROUND OF -SN FOR KRDG AND KABE AFTER
06Z. HOWEVER, IN BOTH CASES THE CHANCE IS TOO LOW TO MENTION IN THE
TAFS AT THIS TIME.

OUTLOOK...
FRIDAY - SATURDAY...MOSTLY VFR. SLIGHT CHANCE FOR EARLY
AFTERNOON MVFR SNOW SHOWERS. NORTHERLY WINDS PREVAIL AS HIGH
PRESSURE NOSES IN FROM THE WEST.

SUNDAY - MONDAY...VFR TO START. CONDITIONS DETERIORATE LATE IN THE
DAY AS THE NEXT SYSTEM APPROACHES FROM THE WEST-SOUTHWEST. SOUTHERLY
WINDS EXPECTED.

&&

.MARINE...
WINDS SHOULD INCREASE SOON RESULTING IN SCA CONDITIONS FOR THE LOWER
BAY AND THE ATLANTIC COASTAL WATERS FOR MUCH OF THE DAY. WITH THE
INCREASE IN WINDS, SEAS WILL SLOWLY BUILD AS WELL (PRIMARILY ON THE
OCEAN). FOR THE OCEAN WATERS A FEW GUSTS ABOVE 30 KT ARE POSSIBLE
PRIMARILY LATE THIS MORNING INTO EARLY THIS AFTERNOON. BY EARLY THIS
EVENING, WINDS SHOULD DIMINISH BELOW 25KT, BUT SEAS ON THE OCEAN
WILL BE SLOW TO DIMINISH. THUS, HAVE EXTENDED THE SCA FOR THE OCEAN
ZONES THROUGH 06Z FOR THE NORTHERN WATERS AND 11Z FOR THE SOUTHERN
WATERS.

OUTLOOK...

FRIDAY - SATURDAY...SUB-SCA EXPECTED, THOUGH PERSISTENT
NORTHEAST WINDS MAY ALLOW FOR BUILDING SEAS ACROSS OUR SOUTHERN
ZONES.

SUNDAY - MONDAY...POSSIBLE SCA CONDITIONS LATE ON SUNDAY AHEAD OF AN
APPROACHING COLD FRONT. INCREASING SOUTHERLY WINDS AND BUILDING SEAS
EXPECTED.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
     NJZ021>025.
DE...WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
     DEZ002.
     WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR DEZ003-
     004.
MD...WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
     MDZ012-015-019-020.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ452>455.
     SMALL CRAFT ADVISORY UNTIL 1 AM EST FRIDAY FOR ANZ450-451.
     SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR ANZ431.

&&

$$
SYNOPSIS...HEAVENER
NEAR TERM...GAINES/JOHNSON
SHORT TERM...JOHNSON
LONG TERM...HEAVENER
AVIATION...GAINES/HEAVENER/JOHNSON
MARINE...HEAVENER/JOHNSON


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