Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KPHI 261152 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 652 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/...
-- Changed Discussion --
630 AM UPDATE...NO MAJOR CHANGES FROM THE PREVIOUS FORECAST. HEAVIER SNOW BANDS MOVING THROUGH SOUTHERN DELMARVA AND FAR SOUTHERN NJ NOW. EXPECT THE BULK OF THE SNOW TO OCCUR BETWEEN NOW AND LATE THIS MORNING. PREVIOUS NEAR TERM DISCUSSION...THE LATEST COASTAL LOW CONTINUES TO LIFT NORTHEAST OFF THE CAROLINA COAST. SNOW HAS BEEN REPORTED IN SOUTHERN DELMARVA, BUT AS OF 330 AM REMAINS JUST SOUTH OF OUR CWA. TIMING STILL LOOKS ON TRACK WITH A MAJORITY OF THE SNOW OCCURRING FROM NOW THROUGH THE MORNING RUSH HOUR, THEN THE SNOW TAPERING OFF MID DAY THROUGH THE AFTERNOON HOURS. AS FOR AMOUNTS, TRENDED THE AMOUNTS DOWN SLIGHTLY FOR THE FOLLOWING REASONS. FIRST, THERE HAS BEEN PERSISTENT CONVECTION OFF THE NC COAST WHICH COULD LIMIT THE MOISTURE AND ENERGY THIS FAR NORTH. SECOND, LATEST WV AND IR SATELLITE IMAGERY SHOW A MID AND UPPER LEVEL DRY SLOT QUICKLY SLIDING IN FROM THE SW. AS OF 3 AM THE DRY SLOT EXTENDED FROM SW VA UP TO THE POCONOS. THIS COULD HAVE A SIGNIFICANT IMPACT FOR THE WESTERN EXTENT OF THE PRECIP. ALSO RELATED TO SATELLITE, EVEN EAST OF THE DRY SLOT OVER SOUTHERN DELMARVA AND THE ATLANTIC COASTAL WATERS THERE HAS BEEN A CLOUD TOP WARMING TREND FOR THE LAST FEW HOURS. FINALLY, MOST OF THE HEAVIER BANDS OF SNOW WE`VE SEEN UP STREAM SEEM TO BE ASSOCIATED WITH A BAND OF FRONTOGENESIS WHICH HAS BEEN WELL DEPICTED BY THE RAP. THE RAP SHOWS THIS FRONTOGENESIS BAND SLIDING EAST BEFORE IT GETS AS FAR AS OUR REGION. FOR NOW THOUGH, WILL KEEP THE WINTER WEATHER ADVISORY AND WINTER STORM WARNING AS SOME MODEL SOUNDINGS CONTINUE TO SHOW MODEST OMEGA VALUES WITHIN THE DENDRITIC GROWTH ZONE, PRIMARILY IN THE FEW HOURS AROUND THE MORNING RUSH HOUR. THUS THE TIMING OF THE SNOW MAY BE MORE IMPACTFUL THAN THE ACTUAL AMOUNTS.
-- End Changed Discussion --
&& .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 /12Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. CEILINGS SHOULD GRADUALLY LOWER THROUGH 12Z AS SNOW APPROACHES FROM THE SOUTH. STILL SOME UNCERTAINTY IF THE WESTERN TAF SITES, KABE AND KRDG, WILL 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). 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 OPTOMISTIC 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.
-- End Changed Discussion --
&& .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...
-- Changed Discussion --
PA...NONE. NJ...WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR NJZ016>027. DE...WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR DEZ001-002. WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR DEZ003- 004. MD...WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR MDZ008-012-015-019-020. 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.
-- End Changed Discussion --
&& $$ SYNOPSIS...HEAVENER NEAR TERM...JOHNSON SHORT TERM...JOHNSON LONG TERM...HEAVENER AVIATION...HEAVENER/JOHNSON MARINE...HEAVENER/JOHNSON

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.