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 090238 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 938 PM EST MON FEB 8 2016 .SYNOPSIS... A WEAK LOW PRESSURE SYSTEM WILL DEVELOP OFF OF THE MID ATLANTIC COAST OVERNIGHT. THIS SYSTEM WILL THEN GRADUALLY MOVE OUT TO SEA LATER TUESDAY INTO WEDNESDAY. A COLDER AIRMASS THEN SETTLES IN FOR THURSDAY AND FRIDAY. AN ARCTIC COLD FRONT FRIDAY NIGHT OR SATURDAY WILL USHER IN PERHAPS THE COLDEST AIR OF THE WINTER FOR NEXT WEEKEND. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... THE WINTER STORM WARNINGS AND WINTER WEATHER ADVISORIES REMAIN UNCHANGED ATTM. A RATHER CHAOTIC SETUP TONIGHT AS A DEEP UPPER-LEVEL TROUGH CONTINUES TO SETTLE INTO THE EASTERN U.S. AN UPPER AIR ANALYSIS SHOWED NUMEROUS SHORT WAVES REVOLVING AROUND THIS TROUGH, WITH A WEAK ONE NOW MOVING ACROSS OUR SOUTHERN AREAS. A MUCH STRONGER SHORT WAVE IS IN THE VICINITY OF KENTUCKY EARLY THIS EVENING AND THIS FEATURE IS MORE EVIDENT ON THE WATER VAPOR IMAGERY. AT THE SURFACE, WEAK LOW PRESSURE IS IN THE VICINITY OF THE EASTERN GREAT LAKES WITH EVEN A WEAKER ONE IN EASTERN NORTH CAROLINA. ON A SIDE NOTE, THE RADAR IMAGERY THIS EVENING SO FAR IS SHOWING WHAT APPEARS TO BE SOME ATLANTIC MOISTURE SEEDING IN THE LOWER LEVELS WITH THE NORTHEAST TO EAST FLOW IN THE OCEAN TO MONMOUTH COUNTY AREAS. THE SYNOPTIC/MESOSCALE EVOLUTION THROUGH THE NIGHT IS TRICKY AS WE START A SERIES OF INCOMING SHORT WAVES, WHICH WILL LEAD TO PERIODS OF ENHANCED LIFT. THIS WILL RESULT IN PERIODS OF SNOW, ESPECIALLY THE FARTHER SOUTH AND WEST ONE GOES. THE THERMAL PROFILES ARE SUCH THAT SOME RAIN OR A RAIN/SNOW MIX OCCURS FOR AWHILE ACROSS PORTIONS OF THE SOUTHERN AREAS AS JUST ENOUGH BOUNDARY WARMTH HANGS ON A LITTLE LONGER. SOME OF THESE AREAS THAT ALREADY STARTED WITH LIGHT RAIN HAS GONE OVER TO SNOW. THE FORECAST SOUNDINGS INDICATE THAT THE MID LEVEL LAPSE RATES BEGIN TO STEEPEN SOME OVERNIGHT AND THIS WILL CONTRIBUTE TO MORE COOLING. THE FAR SOUTHERN ZONES OF MARYLAND AND DELAWARE TO PERHAPS FAR SOUTHEASTERN NEW JERSEY MAY HAVE MIXING ISSUES FOR QUITE AWHILE. AS A RESULT, WE ADDED MORE RAIN AND A RAIN/SNOW MIX FOR SOME OF THESE PLACES FOR AWHILE. FARTHER TO THE NORTH, LOWER DEW POINTS ALONG WITH SOME COOLING ALOFT SHOULD RESULT IN ALL SNOW /AFTER A BRIEF START AS SOME RAIN OR MIX INTO PHILADELPHIA/. THE FORECAST CHALLENGE IS THE COVERAGE OF PRECIPITATION THROUGH THE NIGHT. THIS WILL BE MOSTLY FOCUSED ON SHORT WAVES TRAVERSING THE AREA AND BOOSTING THE VERTICAL MOTION AT TIMES. AS A RESULT, PERIODS OF SNOW/RAIN IS ANTICIPATED WITH LESSER PRECIPITATION ACROSS THE FAR NORTHERN AREAS. THE POPS WERE LOWERED ACROSS THE FAR NORTH FOR AWHILE /NOTING MUCH LOWER DEW POINTS THERE THIS EVENING SO FAR/. IT IS POSSIBLE THE ONGOING SURGE IN LIGHT PRECIPITATION BACKS OFF FOR AWHILE OVERNIGHT. A MORE PRONOUNCED SHORT WAVE TOWARD MORNING MAY ALLOW FOR A BURST OF SNOW FOR PARTS OF THE REGION, HOWEVER IT LOOKS LIKE ANY SNOW ACCUMULATIONS WILL BE ON THE LIGHTER SIDE THROUGH THE NIGHT. THE HOURLY TEMPERATURES AND DEW POINTS WERE ADJUSTED BASED ON THE LATEST OBSERVATIONS, THEN THE LAMP/LAV GUIDANCE WAS BLENDED IN. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... A SURFACE TROUGH BECOMES BETTER DEFINED ACROSS OUR AREA AS LOW PRESSURE OFFSHORE SLOWLY LIFTS TO THE NORTHEAST. THE LIFT FROM THE SURFACE TROUGH, ALONG WITH A STRONGER SHORT WAVE EXPECTED DURING THE DAY, WILL CONTINUE TO COMBINE WITH ENHANCED MOISTURE IN THE DENDRITIC SNOW GROWTH ZONE AND IS EXPECTED TO LEAD TO A PERIOD OF ENHANCED SNOWFALL DURING THE DAY ACROSS PORTIONS OF OUR AREA. IT LOOKS TO NOT SNOW THE ENTIRE TIME, BUT WHEN IT DOES SNOW THERE COULD BE SOME HEAVIER BURSTS ESPECIALLY EARLY IN THE DAY AND THEN LATER IN THE DAY. ACROSS THE FAR SOUTHERN AREAS, A MIX OF RAIN AND SNOW WILL OCCUR AT TIMES WHICH WOULD LIMIT ACCUMULATIONS DURING THE DAYTIME. IT APPEARS THAT SOME OF THE HIGH RESOLUTION GUIDANCE ESPECIALLY CONTINUES TO KEY IN ON A STRONGER SHORT WAVE THAT ARRIVES LATER IN THE DAY. THIS FEATURE BOOSTS THE VERTICAL MOTION QUITE A BIT, WHICH IS ALSO TIED TO SOME AREAS OF 800-700 MB FRONTOGENESIS, AND IF THIS BECOMES REALITY THEN COMBINED WITH GOOD MOISTURE WITHIN THE SNOW GROWTH ZONE THE SNOWFALL RATES WILL INCREASE TOWARD EVENING. THIS MAY END UP BEING THE BEST CHC OF ACCUMULATING SNOW ACROSS MANY AREAS. DURING TIMES OF LIGHTER SNOW, ROADWAYS /TREATED ONES/ SHOULD BE IN GOOD SHAPE, HOWEVER WE WANT TO EMPHASIZE THAT HEAVIER SNOWFALL RATES WILL ALLOW FOR DETERIORATING ROAD CONDITIONS. IN ADDITION, THE PLACEMENT OF AN INVERTED TROUGH WILL BE KEY IN WHERE THE AXIS OF HEAVIER SNOW STARTS TO SET UP DURING THE COURSE OF THE DAY. THE MODEL GUIDANCE CONTINUES TO BATTLE THIS PLACEMENT OUT, HOWEVER OUR LATEST SNOWFALL GRAPHIC DEPICTS WHERE WE CURRENTLY THINK THE HEAVIEST AXIS WILL BE. && .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 /03Z TUESDAY THROUGH SATURDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. OVERNIGHT...VFR CEILINGS LOWERING TO MVFR/IFR FROM SOUTH TO NORTH. SOME WILL CONTINUE TO MOVE NORTHEASTWARD, TAKING THE LONGEST TO REACH KABE AND KTTN. SOME LIGHT RAIN WILL START FROM KPHL ON SOUTH AND EAST, HOWEVER THIS IS EXPECTED TO QUICKLY MIX WITH AND CHANGE TO SNOW. THE SNOW WILL LOWER VISIBILITIES TO IFR WITH PERHAPS A BURST OF SNOW OCCURRING ESPECIALLY TOWARD DAYBREAK TUESDAY. EAST-SOUTHEAST WINDS MAINLY LESS THAN 10 KNOTS BECOMING NORTHEAST. TUESDAY...IFR CONDITIONS WITH PERIODS OF SNOW, HOWEVER ESPECIALLY NORTH OF KPHL THE CEILINGS MAY IMPROVE TO MVFR FOR AWHILE. WE ANTICIPATE A PERIOD OF MODERATE TO PERHAPS HEAVY SNOW TOWARD THE LATE AFTERNOON HOURS. THE AXIS OF THIS HEAVIER SNOW WILL DEPEND ON THE POSITIONING OF A BOUNDARY THAT WILL BISECT OUR REGION. OUR CONFIDENCE IN THE TIMING OF THE HEAVIER SNOW IS ON THE LOWER SIDE, HOWEVER IT DOES APPEAR MOSTLY EARLY IN THE DAY AND THEN ESPECIALLY LATER IN THE DAY. NORTHEAST WINDS MOSTLY 10-15 KNOTS, BECOMING NORTH LATER IN THE DAY. 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... SMALL CRAFT ADVISORY REMAINS IN EFFECT ACROSS THE ATLANTIC COASTAL WATERS THROUGH TODAY AND TUESDAY. WINDS HAVE DIMINISHED AS THE FIRST STRONG LOW PRESSURE SYSTEM PULLS AWAY, BUT WAVES WILL REMAIN ELEVATED. ALSO, WINDS MAY INCREASE AGAIN TUESDAY AS ANOTHER LOW LOW STRENGTHENS OFF THE COAST. OUTLOOK... TUESDAY NIGHT THRU THURSDAY...SMALL CRAFT CONDITIONS EXPECTED TO CONTINUE THROUGH THE PERIOD WITH GALES POSSIBLE ON THURSDAY. FRIDAY...SUB SCA CONDITIONS EXPECTED. SATURDAY...WINDS/SEAS INCREASING AGAIN TO SCA AND POSSIBLY GALE CONDITIONS. && .TIDES/COASTAL FLOODING... WIDESPREAD MINOR COASTAL FLOODING OCCURRED ALONG THE COASTS OF NEW JERSEY AND DELAWARE THIS EVENING. THE MINOR FLOODING WILL LINGER OVERNIGHT AND IT WILL WORK ITS WAY UP DELAWARE BAY AND INTO THE TIDAL DELAWARE RIVER. 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. FOR DELAWARE BAY, THERE IS A HIGHER LIKELIHOOD OF MODERATE FLOODING NEAR THE TIME OF HIGH TIDE. THE COASTAL FLOOD WARNING CONTINUES FOR THE ENTIRE DE AND NJ OCEANFRONT AND DELAWARE BAY THROUGH THE TUESDAY MORNING HIGH TIDE. WE EXPECT MINOR FLOODING FOR TIDAL SECTIONS OF THE DELAWARE RIVER AND ITS TIDAL TRIBUTARIES WHEN HIGH TIDE OCCURS ON TUESDAY AFTERNOON. A COASTAL FLOOD ADVISORY CONTINUES THERE. 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 BREAKING WAVES OF 4 TO 8 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 UNTIL 6 AM EST WEDNESDAY FOR PAZ060- 061-103-105. WINTER STORM WARNING UNTIL 6 AM EST WEDNESDAY FOR PAZ070-071- 101-102-104-106. COASTAL FLOOD ADVISORY UNTIL 5 PM EST TUESDAY FOR PAZ070-071- 106. NJ...WINTER WEATHER ADVISORY UNTIL 6 AM EST WEDNESDAY FOR NJZ009- 010-012>015. COASTAL FLOOD WARNING UNTIL 1 PM EST TUESDAY FOR NJZ012>014- 020>027. WINTER STORM WARNING UNTIL 6 AM EST WEDNESDAY FOR NJZ016>025- 027. COASTAL FLOOD WARNING UNTIL 3 PM EST TUESDAY FOR NJZ016. COASTAL FLOOD ADVISORY UNTIL 5 PM EST TUESDAY FOR NJZ015- 017>019. DE...WINTER WEATHER ADVISORY UNTIL 6 AM EST WEDNESDAY FOR DEZ003- 004. COASTAL FLOOD WARNING UNTIL 1 PM EST TUESDAY FOR DEZ002>004. WINTER STORM WARNING UNTIL 6 AM EST WEDNESDAY FOR DEZ001-002. COASTAL FLOOD WARNING UNTIL 3 PM EST TUESDAY FOR DEZ001. MD...WINTER WEATHER ADVISORY UNTIL 6 AM EST WEDNESDAY FOR MDZ019- 020. WINTER STORM WARNING UNTIL 6 AM EST WEDNESDAY FOR MDZ008-012- 015. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST WEDNESDAY FOR ANZ450>455. && $$ SYNOPSIS...AMC/GORSE NEAR TERM...GORSE SHORT TERM...GORSE/ROBERTSON LONG TERM...AMC AVIATION...AMC/GORSE MARINE...AMC/ROBERTSON TIDES/COASTAL FLOODING...FRANCK/IOVINO

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