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

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