Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 072219 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 519 PM EST SUN FEB 7 2016 .SYNOPSIS... LOW PRESSURE OFF THE SOUTHEASTERN UNITED STATES WILL RAPIDLY STRENGTHEN AS IT MOVES NORTHEASTWARD TO THE CANADIAN MARITIMES THROUGH MONDAY NIGHT. ANOTHER LOW PRESSURE SYSTEM IS FORECAST TO DEVELOP IN ITS WAKE NEAR THE MID-ATLANTIC COAST MONDAY NIGHT INTO TUESDAY. BEHIND THESE TWO LOWS, ARCTIC HIGH PRESSURE WILL THEN BUILD INTO THE CENTRAL PORTION OF THE NATION AROUND MIDWEEK AND WORK ITS WAY TOWARD THE EAST COAST BY THE WEEKEND. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... QUIET WEATHER WILL CONTINUE THROUGH THE EVENING HOURS, BEFORE THE POSSIBILITY OF SNOWFALL DEVELOPS ALONG COASTAL PORTIONS OF DELAWARE AND NEW JERSEY. STRONG LOW PRESSURE OFFSHORE OF THE SOUTHEAST STATES WILL LIFT NORTHEASTWARD, OFFSHORE OF THE EAST COAST TONIGHT INTO MONDAY MORNING. THE PRECIPITATION SHIELD IS EXPECTED TO EXPAND SLIGHTLY ON THE WEST SIDE OVERNIGHT INTO MONDAY MORNING AS THE LOW LIFTS TO THE NORTHEAST. AS OF NOW THE QUESTION FOR OUR AREA IS HOW FAR WEST. BASED ON RECENT MODEL DIAGNOSTICS AND COLLABORATION, WE EXPECT THE MAJORITY OF THE PRECIPITATION TO REMAIN RIGHT NEAR THE COAST AND OFFSHORE, THEN EXTEND TO OUR NORTH AND EAST. THE NAM AND SREF ARE CURRENTLY THOUGHT TO BE HIGH WITH THEIR AMOUNTS, WHILE A BLEND OF THE GFS AND ECMWF GIVE A BETTER EXPECTATION OF AMOUNTS. ANOTHER CONCERN WOULD BE HOW MUCH WOULD ACCUMULATE BASED ON TEMPERATURES, AS TEMPERATURES AT THE ONSET WILL LIKELY BE ABOVE FREEZING. SO FOR NOW WE ARE EXPECTING AROUND AN INCH FOR MUCH OF THE CENTRAL AND SOUTHERN COASTAL AREAS, WITH 1-2 INCHES ACROSS AREAS FURTHER NORTH INTO NORTHERN OCEAN AND MONMOUTH COUNTIES AND EASTERN MIDDLESEX. SO WE WILL NOT ISSUE ANY WINTER ADVISORIES AT THIS TIME AND LET LATER SHIFTS MONITOR FUTURE GUIDANCE AND SEE IF A SHORT FUSED ADVISORY IS NEEDED. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... ON MONDAY, THE STRONG LOW PRESSURE SYSTEM OFFSHORE WILL CONTINUE TO LIFT NORTHEASTWARD WELL OFFSHORE OF THE EAST COAST. MEANWHILE, A WEAKENING BACKDOOR FRONT MAY SAG DOWN INTO OUR NORTHERN AREAS AS WELL. THERE MAY LIKELY BE SOME SNOWFALL REMAINING ON THE BACKSIDE OF THE LOW, AND AS THE BACKDOOR FRONT WEAKENS AS IT MOVES SOUTHWARD INTO OUR AREA, IT COULD HELP ENHANCE SOME LIGHT SNOWFALL ACROSS THE NORTHERN AREAS. SO THERE WILL REMAIN A CHANCE OF SNOW ACROSS OUR NORTHEASTERN AREAS THROUGH MUCH OF THE DAY MONDAY. AGAIN, THE HIGHEST ACCUMULATIONS THROUGH THE PERIOD ARE EXPECTED TO BE OFFSHORE AND TO OUR NORTHEAST, SO WHILE THERE COULD BE A LIGHT ACCUMULATING SNOWFALL, WE DO NOT EXPECT ADVISORY LEVEL SNOWS TO BE MET AT THIS TIME. ESPECIALLY IF SNOWFALL MIXES WITH OR CHANGES OVER TO RAIN. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... AN AREA OF LOW PRES IS EXPECTED TO DEVELOP NR THE MID ATLC CST MON NIGHT. THE GUID IS IN AGREEMENT ON THIS PART. THE DISAGREEMENT LIES IN THE DETAILS, WHICH ARE IMPORTANT. YESTERDAY, THE ECMWF, WENT OUT ON ITS OWN, WITH A STRONGER AND MORE EWD SOLN. IT CONTINUED THAT TREND ON THE OVERNIGHT RUN AND AGAIN ON TODAY`S RUN. IT HAS A MORE CONSOLIDATED LOW CENTER, BRINGS THAT CENTER FURTHER AWAY FROM THE CST, AND HAS MUCH LESS IMPACT ON OUR AREA. WHILE THE ECMWF`S PERFORMANCE HAS BEEN LESS THAN STELLAR THIS WINTER, AND IT IS A CLEAR OUTLIER IN THIS CASE. HOWEVER, ITS OVERALL STATISTICS MEAN IT`S SOLUTION CAN NOT BE TOTALLY IGNORED, AND STRANGER THINGS HAVE HAPPENED. THE REST OF THE OTHER MDLS DO BRING A GENLY LIGHT SNOWFALL TO THE AREA MONDAY NIGHT INTO TUE. PRECIP WILL BEGIN LATER MON AND TEMPS WILL BE WARM ENOUGH TO SUPPORT RAIN OR SNOW THAT HAS A HARD TIME ACCUMULATING IN MOST AREAS AND ON MANY SURFACES DURING THE DAYLIGHT HOURS. AFTER SUNSET, THE SNOW WOULD START TO ACCUMULATE MORE. THE GUID ALSO DIFFERS ON THE AREAS THAT WOULD SEE THE MOST QPF AND CHCS OF HEAVIEST SNOWS. WHILE MOST OF THE SNOW LOOKS TO FALL WOULD BE ON THE LIGHTER SIDE, EVEN WITH THE JANUARY BLIZZARD, THE MDLS WERE HAVING TROUBLE DECIPHERING THIS EVEN 12 HOURS BEFOREHAND. SO FOR NOW, WILL ONLY MAKE INCREMENTAL CHANGES TO THE SNOWFALL AMOUNTS. ATTM, THIS LOOKS LIKE AN ADVY EVENT OR PSBLY LOW END WRNG IN SOME AREAS. ANOTHER COMPLICATING FACTOR IS TEMPS DURG THE DAY ON TUE. TEMPS WILL BE ABV FREEZING IN MANY AREAS, SO THERE CUD BE A MIX OR CHANGEOVER TO RAIN, ESPECIALLY IN SRN AND ERN AREAS, AND MUCH LIKE WE HAD THE OTHER DAY, EVEN WHERE IT SNOWS, IT COULD END UP ACCUMULATING MAINLY ON GRASSY SFCS AND LESS TRAVELED ROADS DURG DAYLIGHT HOURS, IF IT IS NOT COMING DOWN HARD. THINGS SHUD BEGIN TO TAPER OFF TUE NIGHT INTO WED. THEN, A LARGE AREA OF ARCTIC HIGH PRES WILL MOVE INTO THE CNTRL CONUS. THIS HIGH WILL GRADUALLY MOVE EWD THRU THE END OF THE WEEK. EXPECT A GENLY DRY AND BREEZY NWLY FLOW WED THRU SAT. HOWEVER TEMPS WILL NOT MAKE IT ABV FREEZING FROM THU ON. WITH OVERNIGHT LOWS IN THE TEENS. NRML LOWS ARE IN THE LOWER 40S NOW. SO WE ARE LOOKING AT HIGH TEMPS THAT WILL AVERAGE 15 TO 20 DEGREES BELOW NRML, AND WITH THE DAYS GETTING INCREASINGLY LONGER, THIS IS INCREASINGLY DIFFICULT TO ACCOMPLISH, ESPECIALLY FOR AN EXTENDD PD. && .AVIATION /22Z SUNDAY THROUGH FRIDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDITIONS WILL REMAIN ACROSS THE TAF SITES FOR AT LEAST THE FIRST HALF OF THE OVERNIGHT. HOWEVER, WE EXPECT CLOUDS TO LOWER ON THE NORTHWESTERN SIDE OF THE STRONG LOW PRESSURE MOVING TO THE NORTHEAST WELL OFFSHORE OF THE EAST COAST. LOOKING AT THE SOUNDINGS, MVFR CIGS SHOULD BEGIN AFFECTING ALL AREAS BY AROUND 10-12Z, AND COULD REMAIN ACROSS THE AREA THROUGH THE DAY MONDAY. ANOTHER CONCERN WITH THIS SYSTEM WILL BE THE POSSIBILITY OF SNOWFALL. BASED ON LATEST MODEL DIAGNOSTICS AND COLLABORATION, WE EXPECT SNOWFALL TO REMAIN ACROSS MOSTLY COASTAL AREAS OF NEW JERSEY AND DELAWARE AND OFFSHORE. THE MAIN TAF SITES THAT WOULD BE AFFECTED WOULD BE ACY, WHICH COULD EXPERIENCE IFR CONDITIONS WITH ANY SNOWFALL, IN ADDITION TO MIV WHICH COULD ALSO EXPERIENCE SOME LIGHTER SNOWFALL AS WELL. WINDS WILL REMAIN MOSTLY EAST-NORTHEASTERLY AROUND 5-10 KNOTS FOR THE REST OF TODAY INTO THIS EVENING. WINDS WILL BEGIN INCREASING OVERNIGHT AS THE LOW LIFTS NORTHWARD, AND LIKELY BECOME GUSTY 20-25 KNOTS BY MONDAY MORNING AND CONTINUE GUSTY THROUGH THE FIRST HALF OF THE DAY, BEFORE THE GUSTS DROP OFF BY AFTERNOON. OUTLOOK... MON NIGHT AND TUE...PRECIP WILL BE ONGOING DURG THIS TIME AND FOR FOR KPHL, KPNE, KMIV, KACY WILL TRANSITION FROM RAIN OR MIX TO SNOW MON NIGHT. ELSEWHERE WILL BE SNOW MON NIGHT. PRECIP SHUD BE LIGHT FOR THE MOST PART BUT THERE CUD BE SOME MDT OR HVY BURSTS. EXPECT MVFR/IFR CONDS. ON TUE, TEMPS SHUD WARM ENOUGH THAT FOR KPHL, KPNE, KACY, KMIV SHUD AGAIN SEE A MIX OR CHANGEOVER TO RAIN, DEPENDING ON HOW WARM TEMPS GET. LOW TO MDT CONFIDENCE. WED...SOME LINGERING SHSN, THEN IMPROVING TO VFR. BREEZY WITH W TO NW WIND GUSTS AROUND 20 KT. HIGH CONFIDENCE. THU...VFR AND BREEZY WITH NW WIND GUSTING 25 TO 30 KT. HIGH CONFIDENCE. && .MARINE... GALE WARNING REMAINS IN PLACE OVERNIGHT INTO MONDAY AS A STRONG COASTAL LOW PRESSURE SYSTEM WILL BE LIFTING EAST OF THE WATERS TONIGHT INTO MONDAY AND THE PRESSURE GRADIENT STRENGTHENS THROUGH THE NIGHT AS THE LOW LIFTS NORTHWARD. AS WE PROGRESS THROUGH MONDAY AND THE LOW LIFTS AWAY FROM THE AREA, THE PRESSURE GRADIENT WEAKENS AND WINDS SHOULD BEGIN TO SUBSIDE INTO SMALL CRAFT ADVISORY LEVELS. OUTLOOK... MON NIGHT THROUGH WED...ANOTHER LOW PRESSURE SYS WILL DEVELOP OFF THE MID-ATLANTIC COAST. AN EXTENDED PERIOD OF SCA CONDITIONS LIKELY DURING THIS TIME. IT IS PSBL THAT THERE CUD BE SOME GALES, ESPECIALLY ON WED, BUT CONFIDENCE REMAINS LOW ON THE TRACK AND STRENGTH OF THE LOW. THU...SOLID SCA CONDITIONS. NW WINDS BEHIND A CFP, WITH THE BEST CHC FOR GALES. && .TIDES/COASTAL FLOODING...
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***MINOR COASTAL FLOODING IS LIKELY NEAR THE MONDAY MORNING HIGH TIDE. THERE IS INCREASING POTENTIAL FOR MODERATE COASTAL FLOODING NEAR THE TUESDAY MORNING HIGH TIDE*** HIGH PRESSURE WILL ANCHOR OVER EASTERN QUEBEC/LABRADOR WHILE LOW PRESSURE PASSING OFFSHORE WELL TO THE SOUTHEAST UNDERGOES EXPLOSIVE DEEPENING OVERNIGHT AND THROUGH THE DAY MONDAY. WITH THE AFOREMENTIONED HIGH REMAINING TO OUR NORTH, A BROAD AREA OF LOW PRESSURE WILL DEVELOP OFF THE OUTER BANKS MONDAY NIGHT AND PASS OFFSHORE SOUTHEAST OF OUR REGION DURING THE DAY TUESDAY. THESE TWO SYSTEMS WILL MAINTAIN AN ONSHORE FLOW ALONG THE COAST THRU TUESDAY, WITH ONLY A BRIEF PAUSE MONDAY AFTERNOON AND VERY EARLY MONDAY NIGHT, AS THE PRESSURE GRADIENT RELAXES BETWEEN SYSTEMS. SETTING THE STAGE, ASTRONOMICAL TIDES WILL BE HIGH EARLY THIS WEEK, TO DUE TO THE NEW MOON ON MONDAY. FOR THE MONDAY MORNING HIGH TIDE, WE THINK THE NAM BACKS THE WINDS TOO MUCH /MORE NORTHERLY/ AS WE APPROACH HIGH TIDE, POSSIBLY DUE TO AN ISALLOBARIC EFFECT WITH THE DEEPENING OFFSHORE SYSTEM, AND IT WAS DEEMED AN OUTLIER. WITH HIGH ASTRONOMICAL TIDES AND NORTHEAST WIND GUSTS QUICKLY RAMPING UP TO GALE FORCE JUST OFFSHORE OVERNIGHT, WE EXPECT A SURGE OF 1 TO 1.5 FEET. WE HAVE HIGH CONFIDENCE IN WIDESPREAD MINOR COASTAL FLOODING, ESPECIALLY ALONG THE NORTHERN NEW JERSEY COAST WHERE POCKETS OF MODERATE FLOODING ARE POSSIBLE, DUE TO THE PRESENCE OF A GREATER COMPONENT OF ONSHORE FLOW. WE HAVE ALSO TEMPERED DOWN THE HIGH-BIASED ET AND ESTOFS GUIDANCE DUE TO A RESIDUAL OF NEARLY 1 FOOT IN SPOTS. A COASTAL FLOOD ADVISORY HAS BEEN ISSUED FOR THE MONDAY MORNING HIGH TIDE ALONG THE NJ AND DE OCEANFRONT, AS WELL AS DELAWARE BAY. THERE IS A BIT MORE UNCERTAINTY ON WHETHER WE REACH THE MINOR THRESHOLD AT REEDY POINT, WHICH IS LARGELY DEPENDENT ON EKMAN TRANSPORT IN A NORTHEAST FLOW, BUT WE EXPECT IT TO BE CLOSE NONETHELESS. A COASTAL FLOOD ADVISORY CONTINUES FOR THE NJ AND DE OCEANFRONT FOR THE MONDAY EVENING HIGH TIDE, AS MINOR COASTAL FLOODING IS EXPECTED TO LINGER. FOR THE TUESDAY MORNING HIGH TIDE, A MORE EASTERLY COMPONENT/LONGER FETCH TO THE WIND WILL HAVE A GREATER IMPACT ALONG THE ENTIRE COAST, INCLUDING DELAWARE BAY, AND PORTIONS OF THE TIDAL DELAWARE. WE AGREE WITH THE STRONGER GFS WINDS, ESPECIALLY GIVEN THE SYNOPTIC SETUP. THE MAIN UNCERTAINTY IS REGARDING A BROAD LOW PRESSURE/TROUGH MOVING NORTHEASTWARD ALONG THE COAST, WHICH MAY ALLOW WINDS TO QUICKLY RELAX NEAR THE TIME OF HIGH TIDE, PARTICULARLY DELMARVA AND FAR SOUTHERN NJ. NEVERTHELESS, ASIDE FROM A BRIEF LULL IN THE FLOW MONDAY AFTERNOON AND VERY EARLY MONDAY NIGHT, WE`LL HAVE HAD NEARLY 48 HOURS DURATION OF ONSHORE FLOW, WHICH WILL MAKE FOR HIGHER TIDAL DEPARTURES COMPARED TO MONDAY MORNING, IN ADDITION TO THE ASTRONOMICALLY HIGHER TIDES. IN TERMS OF GUIDANCE, WE SIDED MORE WITH THE HIGHER ETSS SURGE OF 2 TO 2.5 FEET, EVEN CONSIDERING THE AFOREMENTIONED RESIDUAL. A COASTAL FLOOD WATCH HAS BEEN ISSUED FOR THE TUESDAY MORNING HIGH TIDE FOR THE NJ AND DE OCEANFRONT WITH THE HIGHEST CONFIDENCE IN WIDESPREAD MODERATE COASTAL FLOODING FOR CENTRAL AND NORTHERN NJ. ELSEWHERE, WIDESPREAD MINOR COASTAL FLOODING IS ANTICIPATED, PERHAPS UP TO PHILADELPHIA, GIVEN THE MORE EASTERLY FLOW UP DELAWARE BAY. FOR THESE AREAS, A COASTAL FLOOD ADVISORY WILL LIKELY BE NEEDED.
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&& .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...NONE. NJ...COASTAL FLOOD WATCH FROM LATE MONDAY NIGHT THROUGH TUESDAY AFTERNOON FOR NJZ012>014-020>027. COASTAL FLOOD ADVISORY FROM 5 AM MONDAY TO 4 AM EST TUESDAY FOR NJZ012>014-020>027. COASTAL FLOOD ADVISORY FROM 9 AM TO 1 PM EST MONDAY FOR NJZ016. DE...COASTAL FLOOD WATCH FROM LATE MONDAY NIGHT THROUGH TUESDAY AFTERNOON FOR DEZ002>004. COASTAL FLOOD ADVISORY FROM 5 AM MONDAY TO 4 AM EST TUESDAY FOR DEZ002>004. COASTAL FLOOD ADVISORY FROM 9 AM TO 1 PM EST MONDAY FOR DEZ001. MD...NONE. MARINE...GALE WARNING UNTIL NOON EST MONDAY FOR ANZ450>455. SMALL CRAFT ADVISORY UNTIL 6 AM EST MONDAY FOR ANZ430-431.
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&& $$ SYNOPSIS...NIERENBERG NEAR TERM...ROBERTSON SHORT TERM...ROBERTSON LONG TERM...NIERENBERG AVIATION...NIERENBERG/ROBERTSON MARINE...NIERENBERG/ROBERTSON TIDES/COASTAL FLOODING...FRANCK

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