Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 242040 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 340 PM EST SAT JAN 24 2015 .SYNOPSIS... STRONG LOW PRESSURE EAST OF CAPE COD THIS EVENING WILL CONTINUE TO MOVE AWAY OVERNIGHT. A WEAK AREA OF HIGH PRESSURE WILL BUILD ACROSS THE AREA LATER TONIGHT AND INTO SUNDAY. A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE OHIO VALLEY AND MIDDLE ATLANTIC REGIONS SUNDAY NIGHT INTO MONDAY. ANOTHER STRONGER LOW WILL FORM OFF THE EAST COAST MONDAY AND MOVE UP ALONG THE OFFSHORE WATERS MONDAY NIGHT AND TUESDAY. HIGH PRESSURE BUILDS IN FOR THE MIDWEEK PERIOD. ANOTHER LOW MAY AFFECT THE REGION NEXT THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... AT LATE DAY, STRENGTHENING SURFACE LOW PRESSURE WAS LOCATED EAST AND OFFSHORE OF LONG ISLAND, WITH A MID-LEVEL TROUGH PRESENT JUST OFF TO THE WEST OF THE FORECAST AREA. OVERALL, FORECAST SOUNDINGS SHOW WANING MOISTURE ACROSS THE REGION WITH THE STRONG SURFACE LOW CONTINUING TO PULL AWAY FROM THE REGION, BUT THERE IS ENOUGH MOISTURE FOR SOME ADDITIONAL LIGHT SNOW/RAIN SHOWERS ACROSS THE AREA THROUGH EARLY THIS EVENING, UNTIL THE MID-LEVEL TROUGH AND ASSOCIATED VORTICITY PASSES EAST AND OFFSHORE. LITTLE OR NO ADDITIONAL ACCUMULATION IS EXPECTED AS TEMPERATURES WILL MOSTLY BE RUNNING IN THE MIDDLE 30S THROUGH EARLY EVENING. MEANWHILE, SOME AREAS NEAR THE COAST MAY SEE ANY ADDITIONAL LIGHT PRECIP AS MAINLY LIGHT RAIN, DEPENDING ON BOUNDARY LAYER TEMPERATURES. FOR LATER TONIGHT, PARTIAL CLEARING IS EXPECTED, WITH A CONTINUED WEST-NORTHWEST FLOW THROUGH THE OVERNIGHT, BRINGING SOME DRIER AIR ACROSS THE REGION, WITH DEW-POINTS DROPPING DOWN INTO THE 20S FOR THE FORECAST AREA. FOR THE MOST PART, WE USED A MET/MAV GUIDANCE BLEND FOR OVERNIGHT MINIMUM TEMPERATURES, BUT WE DID UNDERCUT GUIDANCE A LITTLE IN AREAS OF FRESH SNOWPACK. MINIMUM TEMPERATURES ARE ANTICIPATED TO RANGE MAINLY FROM THE LOWER 20S IN THE POCONOS TO THE LOWER 30S IN THE SOUTHERN DELMARVA. && .SHORT TERM /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 /20Z SATURDAY THROUGH THURSDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THE LOW LEVEL MOISTURE WILL GRADUALLY DECREASE, ALLOWING THE REMAINING IFR/MVFR CEILINGS TO RISE TO VFR THROUGH EARLY THIS EVENING. A DISTURBANCE IN THE UPPER ATMOSPHERE IS EXPECTED TO PASS FROM WEST TO EAST ACROSS OUR REGION AND IT SHOULD BE ACCOMPANIED BY SOME SHOWER ACTIVITY. THE SHOWERS SHOULD BE ON THE LIGHT AS DRYING IS ALSO ARRIVING FROM THE WEST, BUT MAY BE A MIX OF SNOW/RAIN. IT APPEARS AS THOUGH VISIBILITY VALUES CAN BE REDUCED TO AROUND 2 MILES AT TIMES. WE EXPECT VFR CONDITIONS FROM ABOUT 0000Z UNTIL THE END OF THE TAF PERIOD. WE HAVE INDICATED A CEILING AROUND 4000 FEET THROUGH MUCH OF THE NIGHT AND INTO SUNDAY MORNING. WE MAY BE A LITTLE PESSIMISTIC AS THE CLOUDS COULD FAVOR SCATTERED FOR AT LEAST PART OF THE TIME. A NORTHWEST WIND AROUND 8 TO 10 KNOTS IS EXPECTED TO GUST TO AROUND 20 KNOTS THROUGH THIS EVENING. THE WIND GUSTS ARE FORECAST TO DIMINISH LATE TONIGHT AND WIND SPEEDS SHOULD REMAIN IN THE 6 TO 10 KNOTS RANGE INTO SUNDAY. OUTLOOK... SUN NIGHT...LOWERING CIGS/VSBYS IN SNOW WHICH WILL ARRIVE AT MOST OF TH TERMINALS BY DAWN MON. MON AND MON NIGHT...IFR/LIFR SOUTH AND MVFR NORTH WITH A LOW PRESSURE SYSTEM CROSSING THE AREA. STEADY SNOW ILG/PHL/PNE/MIV/ACY. TUE...MOSTLY VFR INLAND BUT IFR/MVFR AT KACY/KMIV WITH A STRONG LOW PRESSURE SYSTEM MOVING UP THE COAST. STRONG NE/N WINDS TUE NIGHT THRU WED...MOSTLY VFR. && .MARINE... 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... SUN NIGHT...WINDS AND SEAS BUILDING. SCA CONDITIONS BY MON DAWN. MON AND MON NIGHT...MOSTLY GALE CONDITIONS ON THE WATERS. TUE THRU THU...SCA CONDITIONS WITH FREEZING SPRAY EXPECTED. && .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...O`HARA NEAR TERM...KLINE SHORT TERM...KLINE LONG TERM...O`HARA AVIATION...KLINE/O`HARA MARINE...KLINE/O`HARA TIDES/COASTAL FLOODING...IOVINO

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