Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 250230 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 930 PM EST SAT JAN 24 2015 .SYNOPSIS... STRONG LOW PRESSURE OFF THE NEW ENGLAND COAST WILL TRACK INTO THE CANADIAN MARITIMES THROUGH TONIGHT. A WEAK AREA OF HIGH PRESSURE WILL BUILD ACROSS THE AREA LATER TONIGHT INTO SUNDAY. A LOW PRESSURE SYSTEM WILL THEN MOVE ACROSS THE OHIO VALLEY AND MID ATLANTIC REGIONS SUNDAY NIGHT INTO MONDAY. ANOTHER STRONGER LOW WILL FORM OFF THE EAST COAST MONDAY, THEN MOVE UP ALONG THE OFFSHORE WATERS MONDAY NIGHT AND TUESDAY. HIGH PRESSURE BUILDS IN FOR THE MIDWEEK PERIOD, THEN ANOTHER LOW MAY AFFECT THE REGION ON THURSDAY. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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A DEEP SURFACE LOW OFF THE NEW ENGLAND COAST WILL TRACK INTO THE CANADIAN MARITIMES THROUGH THE OVERNIGHT. MEANWHILE, THE WATER VAPOR IMAGERY SHOWS THE MAIN TROUGH AXIS HAS SHIFTED TO OUR EAST. THE DRYING THAT OCCURRED ALLOWED THE CLOUDS TO DISSIPATE FROM WEST TO EAST, HOWEVER ADDITIONAL CLOUDS ARE ARRIVING FROM THE WEST WHICH IS BEING TRAPPED UNDER AN INVERSION. AS A RESULT, THE CLOUDS WERE INCREASED SOME FOR A TIME FROM WEST TO EAST. OTHER THAN A FEW FLURRIES POSSIBLE IN THE POCONOS, ANY SNOW SHOWERS OR DRIZZLE SHOULD REMAIN TO THE WEST WHERE THE BETTER MOISTURE IS LOCATED ALONG WITH SOME INCOMING WEAK WAA. THE WEST TO NORTHWEST FLOW HAS INCREASED SOME AND THIS WILL HELP TO DRY OUT THE GROUND MOISTURE A BIT. HOWEVER AS TEMPERATURES DROP TO AND BELOW FREEZING OVERNIGHT COMBINED WITH A COLD GROUND, WILL LEAD TO UNTREATED WET SURFACES REFREEZING. THE HOURLY GRIDS WERE ADJUSTED BASED ON THE LATEST OBSERVATIONS, WHICH INCLUDED SHOWING A BIT HIGHER TEMPERATURES TO START. THE LAMP/LAV GUIDANCE WAS BLENDED IN TO HELP WITH THE TEMPERATURE AND DEW POINT TRENDS. NO MAJOR CHANGES WERE MADE TO THE LOW TEMPERATURES ATTM.
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&& .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... OVERALL, A RELATIVELY QUIET DAYTIME IS EXPECTED FOR SUNDAY, WITH SOME BRIEF, WEAK RIDGING OVER THE AREA. THE MAIN FEATURE TO WATCH ON THE HORIZON WILL BE A CLIPPER LOW TRACKING INTO THE OHIO VALLEY BY LATE IN THE DAY. FOR MOST OF THE DAY, INCREASING CLOUDINESS WITH CONTINUED WEST-NORTHWEST WINDS ARE EXPECTED, BUT SOME LIGHT PRECIP MAINLY IN THE FORM OF LIGHT SNOW/RAIN IS ANTICIPATED GOING INTO THE EVENING FOR OUR SOUTHERN AND WESTERN ZONES WITH THE APPROACHING CLIPPER SYSTEM. MAINLY LIGHT RAIN IS EXPECTED AT THE ONSET, THOUGH, FOR THE CENTRAL TO SOUTHERN DELMARVA BEFORE TEMPERATURES FALL AND PRECIP INTENSITY INCREASES LATER SUNDAY NIGHT. A BLEND OF MET/MAV GUIDANCE WITH CONTINUITY WAS USED FOR DAYTIME MAX TEMPERATURES, AND WE ANTICIPATE HIGHS FOR MUCH OF THE FORECAST AREA TO RANGE FROM THE MIDDLE 30S TO THE LOWER 40S. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... SUN NIGHT THRU MONDAY...A CLIPPER SYSTEM WITH A DECENT AMOUNT OF MOISTURE WILL MOVE FROM THE OHIO VALLEY SUN EVENING TO A POSITION OFF THE COAST MON AFTERNOON. IT WILL BRING A 24 HR PERIOD OF MOSTLY LIGHT SNOW ACROSS SRN PA/NE MD AND DEL DURING THE PERIOD. A COUPLE PERIODS OF MODERATE SNOW COULD OCCUR...BUT SNOW TOTALS OF 1 TO 3 INCHES SRN PA/SRN NJ AND 2 TO 4 NE MD AND DEL WILL OCCUR. THE LOW WILL NOT BE THAT STRONG...SO WINDS/BLOWING SNOW NOT EXPECTED TO BE THAT MUCH OF AN ISSUE. TEMPS BELOW NORMAL WITH HIGHS 20 NORTH AND LOW/MID 30S OVER THE DELMARVA AND SRN NJ. A BIT OF RAIN COULD MIX IN WITH THE SNOW OVER SRN DEL ON MONDAY. MON NIGHT THRU TUE...THE CLIPPER SYSTEM WILL BE OFFSHORE MON NIGHT AND OTHER ENERGY AT THE BASE OF THE TROUGH WILL MEET IT CAUSING A DEEP LOW TO DEVELOP OFF THE DELMARVA AND MOVE NORTHEAST. THIS SYSTEM WILL DEEPEN RAPIDLY CREATING GUSTY WINDS AND A SHIELD OF HEAVY QPF. THIS HEAVY QPF (SNOW) WILL FALL ACROSS THE DELMARVA AND SE NJ FOR A TIME MON NIGHT BEFORE MOVING OFFSHORE. THE OPERATIONAL MODELS HAVE SOME DEGREE OF UNCERTAINTY WITH THE SYSTEM...AND ANY TRACK FURTHER WEST WOULD BRING EXCESSIVE SNOWS INTO THE NJ AREA TUE. WE HAVE NOT GONE THIS ROUTE PRESENTLY...ALTHOUGH THE 12Z EC MODEL SEEMS TO SUGGEST THIS. THE 12Z EC MODEL HAS BEEN DISCOUNTED BY WPC DUE TO CONVECTIVE FEEDBACK ISSUES. WE HAVE GONE ALONG WITH THE WWD AND PAINTED SOME ACCUM SNOW ACROSS ERN NJ TUE. OUR TOTALS FOR THIS PERIOD ARE LIKELY TO CHANGE OVER THE NEXT FEW FCST CYCLES...SO PAY ATTENTION TO THE DETAILS IN FUTURE FCSTS. TUE NIGHT THRU WED NIGHT... HIGH PRESSURE WILL AFFECT THE WEATHER DURING THIS PERIOD WITH FAIR BUT COLD WEATHER EXPECTED. TEMPERATURES WILL BE AVERAGING AROUND 10 TO 12 DEGREES BELOW NORMAL. HIGHS WED MOSTLY IN THE LOW 20S UP NORTH AND MID TO UPPER 20S OVER THE SRN 2/3RDS OF THE AREA. COLD OVERNIGHT LOWS IN THE SINGLE DIGITS NORTH AND TEENS SOUTH. THU INTO FRI...MODELS ARE SHOWING ANOTHER CLIPPER TYPE SYSTEM APPROACHING FROM THE WEST AFTER THE MID WEEK PERIOD. TEMPERATURES WILL HAVE BEGUN TO MODERATE BY THE TIME THE PRECIP ARRIVES...SO SOME RAIN/SNOW LINE ISSUES WILL OCCUR. MOSTLY USED CHC POPS FOR NOW. TEMPS WILL STILL BE BELOW NORMAL...BUT NOT AS COLD AS WED. HIGHS IN THE MID/UPPER 30S SOUTH AND LOW 30S NORTH. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. REST OF TONIGHT...VFR OVERALL. A CEILING MAINLY 4000-7000 FEET SHOULD SLIDE EAST ACROSS MUCH OF THE AREA THROUGH LATE TONIGHT, THEN SOME THINNING IS ANTICIPATED TO OCCUR. SOME MVFR CEILINGS SHOULD STAY WEST OF KABE AND KRDG. WEST OR NORTHWEST WINDS 10-15 KNOTS OVERALL /LOCAL GUSTS TO AROUND 20 KNOTS AT TIMES THROUGH ABOUT 06Z/. SUNDAY...VFR OVERALL, WITH AN INCREASE IN MID TO HIGH CLOUDS. THERE SHOULD BE SOME STRATOCUMULUS AROUND, WHICH COULD BECOME BROKEN IN COVERAGE AT TIMES. NORTHWEST WINDS AROUND 10 KNOTS WITH SOME LOCAL GUSTS UP TO 20 KNOTS THROUGH EARLY AFTERNOON, THEN BECOMING NORTH OR NORTHEAST AND DIMINISHING BY LATE IN THE DAY. OUTLOOK... SUNDAY NIGHT...LOWERING CIGS/VSBYS IN SNOW WHICH WILL ARRIVE AT MOST OF TH TERMINALS BY DAWN MON. MONDAY AND MONDAY NIGHT...IFR/LIFR SOUTH AND MVFR NORTH WITH A LOW PRESSURE SYSTEM CROSSING THE AREA. STEADY SNOW ILG/PHL/PNE/MIV/ACY. TUESDAY...MOSTLY VFR INLAND BUT IFR/MVFR AT KACY/KMIV WITH A STRONG LOW PRESSURE SYSTEM MOVING UP THE COAST. STRONG NE/N WINDS. TUESDAY NIGHT THROUGH WEDNESDAY...MOSTLY VFR.
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&& .MARINE...
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WEST-NORTHWEST WINDS ARE EXPECTED THROUGH TONIGHT AND SUNDAY, AND SOME GUSTS IN THE 25 TO 30 KNOT RANGE WILL CONTINUE THROUGH LATE TONIGHT FOR DELAWARE BAY AND THROUGH AROUND MIDDAY SUNDAY FOR THE COASTAL WATERS. AS A RESULT, A SMALL CRAFT ADVISORY CONTINUES FOR DELAWARE BAY THROUGH 11Z SUNDAY, WITH THE SMALL CRAFT ADVISORY EXTENDED UNTIL 18Z SUNDAY FOR THE COASTAL WATERS. IN ADDITION TO THE WIND GUSTS THROUGH THIS PERIOD, SEAS WILL ALSO REMAIN ELEVATED, ESPECIALLY FOR THE COASTAL WATERS, MAINLY IN THE 5 TO 8 FOOT RANGE, BEFORE GRADUALLY DIMINISHING DURING THE DAYTIME SUNDAY. OUTLOOK... SUNDAY NIGHT...WINDS AND SEAS BUILDING. SCA CONDITIONS BY MON DAWN. MONDAY AND MONDAY NIGHT...MOSTLY GALE CONDITIONS ON THE WATERS. TUESDAY THROUGH THURSDAY...SCA CONDITIONS WITH FREEZING SPRAY EXPECTED.
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&& .TIDES/COASTAL FLOODING... ANOTHER NORTHEASTER IS EXPECTED TO AFFECT THE COASTAL WATERS OF DELAWARE AND NEW JERSEY FROM MONDAY NIGHT INTO TUESDAY. MINOR TIDAL FLOODING MAY OCCUR AROUND THE TIMES OF HIGH TIDE. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...GALE WATCH FROM MONDAY MORNING THROUGH MONDAY AFTERNOON FOR ANZ430-431-450>455. SMALL CRAFT ADVISORY UNTIL 1 PM EST SUNDAY FOR ANZ450>455. SMALL CRAFT ADVISORY UNTIL 6 AM EST SUNDAY FOR ANZ430-431. && $$ SYNOPSIS...GORSE/O`HARA NEAR TERM...GORSE SHORT TERM...KLINE LONG TERM...O`HARA AVIATION...GORSE/O`HARA MARINE...KLINE/O`HARA TIDES/COASTAL FLOODING...IOVINO

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