Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 060903 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 403 AM EST SAT FEB 6 2016 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OVER THE AREA TODAY. LOW PRESSURE IS FORECAST TO DEVELOP OFF THE SOUTHEAST COAST THIS WEEKEND AND TRACK NORTHEASTWARD LATE SUNDAY AND MONDAY. ANOTHER LOW PRESSURE SYSTEM MAY DEVELOP IN ITS WAKE NEAR THE MID-ATLANTIC COAST MONDAY NIGHT INTO TUESDAY. ARCTIC HIGH PRESSURE IS THEN EXPECTED TO BUILD IN FROM THE NORTH AND WEST DURING THE LATTER PART OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A QUIET AND PLEASANT FEBRUARY DAY IS EXPECTED WITH AN AREA OF HIGH PRESSURE STRETCHING ACROSS THE MID-ATLANTIC STATES. OTHER THAN SOME CIRRUS SPILLING INTO THE REGION, AMPLE SUNSHINE IS ANTICIPATED. LIGHT AND VARIABLE WINDS IN THE MORNING WILL INCREASE SOME AND TAKE ON A SOUTHWESTERLY DIRECTION DURING THE AFTERNOON, WITH SPEEDS AVERAGING 5 TO 10MPH. DAYTIME HIGH TEMPERATURES WILL BE RIGHT AROUND NORMAL FOR EARLY FEBRUARY, REACHING MOSTLY INTO THE LOWER 40S, EXCEPT SOME UPPER 30S ACROSS NORTHWEST NJ AND THE SOUTHERN POCONOS. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/... FAIR WEATHER IS EXPECTED TO CONTINUE THROUGH TONIGHT ACROSS OUR AREA AS HIGH PRESSURE GRADUALLY MOVES EAST AND OFFSHORE. THERE MAY BE SOME REMAINING CIRRUS ACROSS THE REGION INTO THE EVENING, AND THEN CLEARING CONDITIONS ARE EXPECTED INTO THE OVERNIGHT. WINDS WILL AGAIN BECOME LIGHT AND VARIABLE, AS WELL. GUIDANCE SHOWS SOME WARMING WILL BE TAKING PLACE IN THE LOW LEVELS OVERNIGHT, SO DESPITE THE LIGHT TO CALM WINDS AND MAINLY CLEAR CONDITIONS, MINIMUM TEMPERATURES OVERALL SHOULD BE A COUPLE OF DEGREES MILDER THAN FRIDAY NIGHT. WE BLENDED MET/MAV GUIDANCE WITH CONTINUITY AND ANTICIPATE LOWS TO BE MOSTLY IN THE MIDDLE TO UPPER 20S. && .LONG TERM /SUNDAY THROUGH FRIDAY/... WATER VAPOR SATELLITE IMAGERY CAPTURES TWO SEPARATE SHORTWAVE TROUGHS OVER THE CENTRAL AND SOUTHERN PLAINS OVERNIGHT. THESE SYSTEMS ARE FORECAST TO PHASE TO SOME DEGREE AS THEY MOVE INTO THE GULF COAST REGION THIS WEEKEND. SURFACE CYCLOGENESIS IS FORECAST TO OCCUR OFF THE SOUTHEAST COAST SATURDAY NIGHT AS SIGNIFICANT HEIGHT FALLS AHEAD OF THE UPPER LOW REACH THE WARM WATERS OF THE GULF STREAM. THE EXACT TRACK THE LOW TAKES AND HOW QUICKLY IT DEEPENS WILL DETERMINE THE IMPACTS TO OUR AREA, IF ANY, LATE SUNDAY INTO EARLY MONDAY. UNFORTUNATELY, THERE IS STILL PLENTY OF MODEL DISAGREEMENT THAT HAS MADE IT CHALLENGING TO DETERMINE WHAT THE OUTCOME WILL BE. ONE GENERAL CAMP OF MODELS HAS THE LOW BOMBING OUT AND TRACKING CLOSER TO THE EASTERN SEABOARD. THE OTHER CAMP IS MORE PROGRESSIVE/LESS AMPLIFIED WITH THE UPPER TROUGH, RESULTING IN A TRACK THAT IS HARMLESSLY OUT TO SEA. REGARDLESS OF THE DIFFERENCES, JUST ABOUT ALL OF THE GUIDANCE KEEPS THE LOW FAR ENOUGH OFFSHORE TO SPARE OUR AREA FROM DIRECT IMPACTS FROM THIS STORM (E.G., HEAVY SNOW AND STRONG WINDS). WITH THAT SAID, THIS STORM STILL BARES WATCHING. MANY OF THE MODELS FOR DAYS LEADING UP TO THE PAST TWO STORMS (THE LATE JANUARY BLIZZARD AND THE ONE YESTERDAY) HAD A DISTINCT EASTWARD BIAS IN THE TRACK. BOTH OF THESE STORMS WOUND UP TAKING VERY SIMILAR TRACKS CLOSER TO THE COAST AND FOLLOWED THE STRONG SST GRADIENT THAT HAS BEEN PRESENT JUST TO THE WEST OF THE ANOMALOUSLY WARM GULF STREAM CURRENT. ACCORDINGLY, WE FAVOR THESE WESTERN SOLUTIONS AND HAVE INTRODUCED LOW CHANCES FOR RA/SN IN DE AND NJ. FORECAST UNCERTAINTY STILL TOO HIGH TO INCLUDE SNOWFALL AMOUNTS ALTHOUGH WE CANNOT RULE OUT THE POTENTIAL FOR LIGHT ACCUMULATIONS. OUR ATTENTION THEN TURNS UPSTREAM TO A DIGGING UPPER LOW OVER THE GREAT LAKES REGION ON MONDAY. AS THIS SYSTEM APPROACHES THE EASTERN SEABOARD, MODEL GUIDANCE INDICATES SECONDARY CYCLOGENESIS OCCURRING OFF THE MID-ATLANTIC COAST MONDAY NIGHT-TUESDAY AS THE PRIMARY LOW APPROACHES FROM THE WEST BUT THEY DIFFER WITH REGARDS TO WHERE EXACTLY THE SECONDARY LOW FORMS. THESE MILLER-B TYPE SETUPS ARE NOTORIOUSLY TRICKY. IF THE MILLER B LOW FORMS TO OUR SOUTH AND FARTHER OFFSHORE LIKE THE 12Z ECMWF AND 00Z NAM INDICATED, THEN SETUP WOULD FAVOR LIGHTER SNOW (STARTING OUT AS A RAIN/SNOW MIX OR JUST RAIN ESPECIALLY AS YOU GET CLOSER TO THE COAST) FROM THE PRIMARY LOW FOR OUR AREA. IF THE LOW DEVELOPS AT OUR LATITUDE AND DEEPENS QUICKLY CLOSER TO THE COAST LIKE THE 00Z GFS/ECMWF/GEM HAD INDICATED, THEN PARTS OF OUR AREA COULD BE IN LINE FOR A BAND OF HEAVIER SNOW BACK TO THE WEST ALONG AN INVERTED/NORLUN TROUGH. SINCE OUR SNOWFALL FORECAST ONLY GOES OUT 72 HOURS FROM NOW (THRU MONDAY NIGHT), THE AMOUNTS ON THE WEBPAGE ONLY INCLUDE PART OF THE STORM. DID NOT STRAY TOO FAR FROM WPC AND NEIGHBORING OFFICES...A GENERAL 1- 2 INCHES OF SNOW FOR MONDAY NIGHT. STAY TUNED TO THE LATEST FORECASTS SINCE THEY WILL BE REFINED AS THE UNCERTAINTY DECREASES OVER TIME. AFTER AN ACTIVE START TO THE LONG TERM, A MORE DOCILE WEATHER PATTERN APPEARS TO BE IN STORE THE SECOND HALF OF THE WEEK. WE COULD SEE A FEW SNOW SHOWERS WITH THE PASSAGE OF THE MAIN UPPER TROUGH ON WEDNESDAY. BEHIND THAT, A SHOT OF ARCTIC AREA TAKES AIM FOR THE MID- ATLANTIC AND NORTHEAST STATES TOWARD THE END OF THE WEEK. MEANWHILE, SURFACE HIGH PRESSURE BUILDING IN FROM THE WEST WILL KEEP US DRY ON THURSDAY AND FRIDAY. FOLLOWED GUIDANCE FROM WPC/SUPER BLEND CLOSELY IN DAYS 4-7. TEMPS ALONG AND WEST OF THE FALL LINE MAY NOT REACH FREEZING LATE IN THE WEEK. && .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY AND TONIGHT...VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD WITH ONLY SOME CIRRUS PASSING OVERHEAD. LIGHT AND VARIABLE WINDS ARE EXPECTED THROUGH THE MORNING HOURS, FOLLOWED BY A SOUTHWEST WIND DEVELOPING DURING THE AFTERNOON WITH SPEEDS MOSTLY BETWEEN 6 TO 8 KNOTS. INTO THIS EVENING AND TONIGHT, WINDS WILL AGAIN BECOME LIGHT AND VARIABLE WITH A LITTLE REMAINING CIRRUS OR CLEAR SKIES. OUTLOOK... SUNDAY...VFR AND LIGHT WINDS. SUNDAY NIGHT...THE GREATEST IMPACTS FROM STRONG STORM SYSTEM IS CURRENTLY EXPECTED TO REMAIN OFFSHORE. HOWEVER, ANY WESTWARD SHIFT IN THE TRACK MAY BRING A PERIOD OF LIGHT RAIN AND/OR SNOW TO EASTERN TERMINALS. MONDAY AND TUESDAY...PRECIP MAY OVERSPREAD THE AREA MONDAY AFTERNOON AND EVENING. IT MAY BE WARM ENOUGH TO START OUT AS RAIN NEAR THE COAST AND A RAIN/SNOW MIX NEAR I-95. EVENTUALLY IT WILL LIKELY TURN OVER TO SNOW FROM NW TO SE MONDAY NIGHT AND CONTINUE INTO TUESDAY EVENING. POTENTIAL FOR IFR RESTRICTIONS ESPECIALLY ONCE IT CHANGES OVER TO SNOW. THERE IS MODERATE UNCERTAINTY IN THE TIMING OF THE CHANGEOVER AND HIGH UNCERTAINTY WITH REGARDS TO SNOWFALL AMOUNTS. WEDNESDAY...IMPROVING CONDITIONS. MAINLY VFR ALTHOUGH THERE IS A SMALL RISK FOR A BRIEF RESTRICTION WITH A PASSING SNOW SHOWER. && .MARINE... WE LET THE SCA EXPIRE EARLY THIS MORNING FOR OUR OCEAN WATERS AS WINDS HAVE STEADILY DECREASED AND SEAS HAVE SETTLED MOSTLY INTO THE 3 TO 4 FOOT RANGE. SEAS AT BUOY 44009 ARE SLIGHTLY HIGHER, CLOSER TO 5 FEET, BUT A DECREASING TREND WILL CONTINUE OVER THE NEXT HOUR OR TWO MAKING AN EXTENSION OF THE SCA FLAG UNNEEDED. FOR THE REMAINDER OF TODAY AND TONIGHT, SUB-ADVISORY CONDITIONS WILL CONTINUE WITH WINDS OUT OF THE NORTHWEST THIS MORNING BECOMING MORE SOUTHWESTERLY THIS AFTERNOON AND EVENING. SEAS ARE MAINLY EXPECTED TO RANGE BETWEEN 2 TO 4 FEET FOR THE ATLANTIC COASTAL WATERS, WITH 1 TO 2 FOOT SEAS INTO DELAWARE BAY. OUTLOOK... SUNDAY...NO MARINE HAZARDS ARE EXPECTED. SUNDAY NIGHT AND MONDAY...A GALE WATCH WAS ISSUED FOR THE COASTAL ATLANTIC WATERS FOR SUNDAY NIGHT AND MONDAY MORNING. AN OFFSHORE LOW IS EXPECTED TO DEEPEN RAPIDLY TO OUR EAST DURING THIS TIME. THERE IS A POTENTIAL FOR N-NELY WINDS TO REACH 35 KT IF THE LOW TAKES A MORE WESTWARD TRACK. IF THE LOW TAKES A MORE OFFSHORE TRACK, THEN WINDS WILL BE WEAKER AND CAPPED AT SCA LEVELS. MONDAY NIGHT THROUGH WEDNESDAY...ANOTHER AREA OF LOW PRESSURE WILL DEVELOP OFF THE MID-ATLANTIC COAST. AN EXTENDED PERIOD OF SCA CONDITIONS LIKELY DURING THIS TIME. IT COULD POTENTIAL REACH GALE FORCE LATE WEDNESDAY BUT UNCERTAINTY IS VERY HIGH REGARDING THE STRENGTH OF THE WINDS. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...GALE WATCH FROM SUNDAY EVENING THROUGH MONDAY MORNING FOR ANZ450>455. && $$ SYNOPSIS...KLEIN NEAR TERM...KLINE SHORT TERM...KLINE LONG TERM...KLEIN AVIATION...KLEIN/KLINE MARINE...KLEIN/KLINE

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