Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 082124 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 424 PM EST MON FEB 8 2016 .SYNOPSIS... STRONG LOW PRESSURE WELL OFF THE EAST COAST WILL CONINUE TO MOVE AWAY FROM THE AREA THIS EVENING. ANOTHER WEAKER LOW PRESSURE IS FORECAST TO DEVELOP OFF THE MID- ATLANTIC COAST OVERNIGHT. LOW PRESSURE AT THE SURFACE AND ALOFT WILL PERSIST OVER THE REGION THROUGH TUESDAY NIGHT BRINGING PERIODS OF SNOW TO THE AREA. THE LOW PRESSURE WILL GRADUALLY MOVE AWAY ON WEDNESDAY FOLLOWED BY COLDER AIR AND BELOW NORMAL TEMPERATURES FOR THURSDAY AND FRIDAY. AN ARCTIC COLD FRONT ON FRIDAY NIGHT OR SATURDAY WILL USHER IN PERHAPS THE COLDEST AIR OF THE WINTER FOR NEXT WEEKEND. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... WINTER STORM WARNING AND WINTER WEATHER ADVISORIES HAVE BEEN ISSUED FOR PORTIONS OF THE AREA. AS THE FIRST STRONG LOW PRESSURE SYSTEM CONTINUES TO PULL AWAY FROM THE AREA TONIGHT, ANOTHER IS EXPECTED TO DEVELOP AND STRENGTHEN OFF THE COAST TONIGHT, WHICH WILL HELP LEAD TO AN ACCUMULATING SNOWFALL. AN AREA OF LOW PRESSURE IS CURRENTLY LOCATED ACROSS THE EASTERN GREAT LAKES REGION, WITH A FRONTAL BOUNDARY EXTENDING SOUTH TOWARD THE GULF COAST. AN AREA OF LOW PRESSURE IS EXPECTED TO DEVELOP ALONG THIS BOUNDARY OVERNIGHT, BEFORE MOVING OFFSHORE TOWARD DAYBREAK. THE FRONT WILL WEAKEN AND STRETCH OUT INTO MORE OF A SURFACE TROUGH OVERNIGHT. MEANWHILE, A COUPLE OF SHORT WAVE/VORTICITY IMPULSES WILL SLIDE ACROSS THE AREA WITHIN THE SOUTHWEST FLOW. THE ASSOCIATED LIFT FROM THE SURFACE TROUGH AND VORTICITY IMPULSES, COMBINED WITH INCREASING MOISTURE IN THE DENDRITIC ZONE WILL LEAD TO DEVELOPING SNOWFALL THIS EVENING AND OVERNIGHT. THE HEAVIEST SNOWFALL IS EXPECTED TO BE ACROSS SOUTHEASTERN PENNSYLVANIA, SOUTHERN NEW JERSEY, AS WELL AS NORTHERN AND CENTRAL DELMARVA WHERE 1 TO 3 INCHES COULD FALL THROUGH DAYBREAK. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... SNOW IS EXPECTED TO BE ONGOING AT THE START OF TUESDAY AS THE SURFACE TROUGH WILL REMAIN IN PLACE ACROSS OUR AREA AS THE COASTAL LOW CONTINUES TO LIFT TO THE NORTHEAST. THE COMBINED LIFT FROM THE SURFACE TROUGH, ALONG WITH A STRONGER VORTICITY IMPULSE EXPECTED DURING THE DAY, WILL CONTINUE TO COMBINE WITH ENHANCED MOISTURE IN THE DENDRITIC ZONE AND IS EXPECTED TO LEAD TO A PERIOD OF ENHANCED SNOWFALL DURING THE DAY ACROSS THE AREA. IT MAY NOT SNOW THE ENTIRE TIME DURING THE DAY TUESDAY, BUT WHEN IT DOES SNOW, THERE COULD BE A FEW HEAVIER PERIODS. AN ADDITIONAL 1 TO 3 INCHES COULD FALL ACROSS PORTIONS OF THE AREA. ACROSS THE SOUTHERN AREAS, SNOWFALL COLD CHANGE OVER AND/OR MIX WITH RAIN AT TIMES DURING THE DAY WHICH WOULD LIMIT THEIR ACCUMULATIONS DURING THE DAY. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... A DEEP UPPER TROF/LOW WILL MOVE SLOWLY EASTWARD FROM THE MIDWEST ACROSS THE NORTHEAST AND MID ATLANTIC REGIONS OVER THE NEXT 2-3 DAYS. THIS WILL RESULT IN PERIODS OF SNOW ACROSS THE FORECAST AREA FOR MUCH OF THIS TIME. THE SNOW EVENT WILL BE IN PROGRESS OVER THE AREA AT THE BEGINNING OF THIS EXTENDED PERIOD...TUES EVE...ALTHO IT LOOKS LIKE THE MAJORITY OF THE SNOW MAY HAVE ALREADY FALLEN BY THAT TIME. THIS UPPER SYS IS FAIRLY COMPLEX WITH A NUMBER OF SHRTWV/VORT CENTERS ROTATING AROUND IT SO IT IS SMWHT DIFFICULT TO SAY QUITE WHEN AND WHERE THE HEAVIER SNOW WILL FALL. OVERALL THIS DOES NOT LOOK TO BE A MAJOR STORM WITH NO STRONG SFC LOW DEVELOPMENT AND MAINLY JUST LIGHT OR MODERATE SNOW AT TIMES...AS NOTED ABOVE. FOR TOTAL SNOW...MOST GUIDANCE INCLUDING WPC SEEMED TO INDICATE A WEST-EAST BAND OF GREATER SNOWFALL ACROSS THE MIDDLE OF OUR FCST AREA AND THAT IS REFLECTED IN OUR TOTAL SNOW GRID. THE SNOW SHOULD HAVE MOSTLY ENDED BY EARLY WED MORNING...HOWEVER THE UPPER TROF WILL REMAIN OVER THE AREA DURING THE DAY ON WED SO SCATTERED SNOW SHOWERS WILL REMAIN A POSSIBILITY. THERE WILL BE DECENT COLD ADVECTION BEHIND THE SYSTEM FROM LATE WEDNESDAY INTO FRIDAY RESULTING IN TEMPS WELL BELOW NORMAL TOWARD THE END OF THE WEEK. HOWEVER EVEN COLDER ARCTIC AIR WILL PUSH INTO THE AREA ON SATURDAY WITH SOME OF THE COLDEST TEMPS OF THE WINTER EXPECTED AT THAT TIME. THIS PERIOD IS EXPECTED TO BE MOSTLY DRY HOWEVER THERE COULD BE SNOW SHOWERS OR SQUALLS WITH THE ARCTIC FRONTAL PASSAGE. && .AVIATION /20Z MONDAY THROUGH SATURDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDITIONS CONTINUE ACROSS THE TAF SITES THIS AFTERNOON, ALTHOUGH THERE ARE SOME MVFR CIGS AT OTHER SITES. WE EXPECT CONDITIONS TO LOWER INTO THIS EVENING, WITH EVERYONE BECOMING MVFR AFTER SUNSET. CONDITIONS WILL FURTHER DETERIORATE THROUGH THE NIGHT AS CIGS ARE EXPECTED TO LOWER TO IFR, AND SNOW DEVELOPS AND MOVES INTO THE AREA. VSBYS SHOULD DROP ONCE SNOW STARTS AND LOWER INTO THE IFR RANGE THROUGH THE NIGHT. SNOW MAY BECOME HEAVIER TOWARD DAYBREAK, AND ALSO DURING THE DAY TUESDAY, SO WE HAVE LOWER CIGS/VSBYS DURING THIS TIME. WINDS WILL REMAIN NORTHEAST TO EAST THROUGH THE ENTIRE TAF PERIOD. GUSTS HAVE DROPPED OFF, BUT A STEADY 5-10 KNOT FLOW SHOULD REMAIN. WINDS COULD BECOME GUSTY FOR THE DELAWARE VALLEY TAFS SOUTH AND EASTWARD TOWARD THE COAST DURING THE DAY TUESDAY WITH GUSTS AROUND 20 KNOTS POSSIBLE. OUTLOOK... TUESDAY NIGHT...PERIODS OF SNOW EXPECTED TUE NIGHT BUT TAPERING OFF TO SNOW SHOWERS WED MORNING. EXPECT WIDESPREAD MVFR/IFR CONDS AND THE POSSIBILITY FOR LIFR IF THE HEAVIER SNOW BANDS DEVELOP. LIGHT WINDS. WEDNESDAY...LEFTOVER SNOW SHOWERS WILL TAPER OFF FROM WEST TO EAST DURING THE DAY, WITH CONDITIONS IMPROVING TO VFR. BREEZY WLY WINDS GUSTING TO 25 KT. THURSDAY AND FRIDAY...VFR AND BREEZY NW WINDS GUSTING 20 TO 30 KT. SATURDAY...POSSIBLE BRIEF MVFR OR IFR CONDS IN SNOW SHOWERS WINDS BECOMING NW AND GUSTING TO 30 KT OR GREATER. && .MARINE... OUTLOOK... TUESDAY NIGHT THRU THURSDAY...SMALL CRAFT CONDITIONS EXPECTED TO CONTINUE THROUGH THE PERIOD WITH GALES POSSIBLE ON THURSDAY. FRIDAY...SUB SCA CONDTIONS EXPECTED. SATURDAY...WINDS/SEAS INCREASING AGAIN TO SCA AND POSSIBLY GALE CONDITIONS. && .TIDES/COASTAL FLOODING... TONIGHT`S HIGH TIDE... WITH RENEWED NORTHEAST FLOW AND WAVE ACTION, WIDESPREAD MODERATE COASTAL FLOODING IS EXPECTED ALONG THE DE AND NJ OCEANFRONT DURING THE HIGH TIDE AROUND 700 PM TO 8PM THIS EVENING, IN SPITE OF THE LOWER ASTRONOMICAL TIDE. FOR DELAWARE BAY, WHERE HIGH TIDE IS BETWEEN 11PM AND MIDNIGHT, EXPECT MINOR FLOODING WITH POCKETS OF MODERATE FLOODING, PARTICULARLY WITH RESIDUAL HIGH WATER LEVELS AND EKMAN TRANSPORT. THUS, A COASTAL FLOOD WARNING IS IN EFFECT FOR THE ENTIRE DE AND NJ OCEANFRONT, AS WELL AS DELAWARE BAY. MINOR NUISANCE FLOODING IS ALSO POSSIBLE FOR TIDAL SECTIONS OF THE DELAWARE RIVER AND ITS TIDAL TRIBUTARIES WHEN HIGH TIDE OCCURS AROUND 2 AM TUESDAY, INCLUDING PHILADELPHIA, WHERE A COASTAL FLOOD ADVISORY IS IN EFFECT. OVERALL, FOR THE DE AND NJ OCEANFRONT, WE EXPECT SIMILAR FLOODING TONIGHT, COMPARED TO MONDAY MORNING`S HIGH TIDE. FOR DELAWARE BAY, WE EXPECT GREATER FLOODING TONIGHT COMPARED TO MONDAY MORNING`S HIGH TIDE WITH WIDESPREAD MINOR FLOODING AND POCKETS OF MODERATE FLOODING. TUESDAY MORNING`S HIGH TIDE... WITH A STRONGER NORTHEAST FLOW AND HIGHER WAVE ACTION, WIDESPREAD MODERATE COASTAL FLOODING WITH POCKETS OF MAJOR COASTAL FLOODING IS EXPECTED ALONG THE DE AND NJ OCEANFRONT DURING THE TIME OF HIGH TIDE AROUND 730 AM TO 830 AM. FOR DELAWARE BAY, THERE IS A HIGHER LIKELIHOOD OF MODERATE FLOODING NEAR THE TIME OF HIGH TIDE BETWEEN 11 AM AND 12 PM. THE COASTAL FLOOD WARNING CONTINUES FOR THE ENTIRE DE AND NJ OCEANFRONT AND DELAWARE BAY FOR THE TUESDAY MORNING HIGH TIDE. WE ALSO EXPECT MINOR FLOODING FOR TIDAL SECTIONS OF THE DELAWARE RIVER AND ITS TIDAL TRIBUTARIES WHEN HIGH TIDE OCCURS AROUND 2 PM TUESDAY, INCLUDING PHILADELPHIA, WHERE A COASTAL FLOOD ADVISORY CONTINUES. OVERALL, FOR THE DE AND NJ OCEANFRONT, INCLUDING DELAWARE BAY, WE EXPECT THE GREATEST IMPACT WITH THE HIGH TIDE TUESDAY MORNING COMPARED WITH THE PREVIOUS TWO HIGH TIDES. IN FACT, THERE WILL BE MORE WIDESPREAD ROAD FLOODING WITH ROAD CLOSURES IN SOME AREAS. THERE WILL ALSO BE THE POSSIBILITY OF DAMAGE TO MORE VULNERABLE STRUCTURES, ESPECIALLY FACTORING IN NEARSHORE WAVES OF 5 TO 10 FEET, WHICH COULD ALSO RESULT IN SIGNIFICANT BEACH EROSION. IN PARTICULAR, SOME BEACH AREAS WILL BE MORE SUSCEPTIBLE TO DAMAGE DUE TO BEACH EROSION AND DAMAGE TO SHORE STRUCTURES THAT OCCURRED IN LATE JANUARY, WITH EMPHASIS ON CAPE MAY COUNTY NJ AND THE DE OCEANFRONT. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 AM EST WEDNESDAY FOR PAZ060-061-103-105. WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 AM EST WEDNESDAY FOR PAZ070-071-101-102-104-106. COASTAL FLOOD ADVISORY UNTIL 6 PM EST TUESDAY FOR PAZ070-071- 106. NJ...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 AM EST WEDNESDAY FOR NJZ009-010-012>015. COASTAL FLOOD WARNING UNTIL NOON EST TUESDAY FOR NJZ012>014- 020>027. WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 AM EST WEDNESDAY FOR NJZ016>025-027. COASTAL FLOOD WARNING UNTIL 4 PM EST TUESDAY FOR NJZ016. COASTAL FLOOD ADVISORY UNTIL 6 PM EST TUESDAY FOR NJZ015- 017>019. DE...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 AM EST WEDNESDAY FOR DEZ003-004. COASTAL FLOOD WARNING UNTIL NOON EST TUESDAY FOR DEZ002>004. WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 AM EST WEDNESDAY FOR DEZ001-002. COASTAL FLOOD WARNING UNTIL 4 PM EST TUESDAY FOR DEZ001. MD...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 AM EST WEDNESDAY FOR MDZ019-020. WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 AM EST WEDNESDAY FOR MDZ008-012-015. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST WEDNESDAY FOR ANZ450>455. && $$ SYNOPSIS...AMC NEAR TERM...ROBERTSON SHORT TERM...ROBERTSON LONG TERM...AMC AVIATION...AMC/ROBERTSON MARINE...AMC/ROBERTSON TIDES/COASTAL FLOODING...LF

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