Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 090844 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 344 AM EST TUE FEB 9 2016 .SYNOPSIS... A TROUGH OF LOW PRESSURE WILL EXTEND FROM THE MID-ATLANTIC COAST INTO THE EASTERN GREAT LAKES TODAY. THIS LOW PRESSURE WILL MOVE NORTHEAST OF THE REGION TONIGHT AND WEDNESDAY. HIGH PRESSURE WILL WORK EASTWARD THROUGH THE REGION THURSDAY INTO FRIDAY BEFORE GIVING WAY ANOTHER AREA OF LOW PRESSURE WITH AN ARCTIC COLD FRONTAL BOUNDARY BY THE END OF THE WEEK. ON SUNDAY, ANOTHER AREA OF HIGH PRESSURE WILL BUILD SOUTHWARD INTO THE REGION AS LOW PRESSURE FORMS ACROSS THE SOUTHERN UNITED STATES BY MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... MODELS TRENDED WARMER THROUGH THE DAY, WITH SOME (INCLUDING THE NAM) EVEN SHOWING RAIN POSSIBLE AS FAR NW AS PHILLY BY THIS AFTERNOON. THIS IS A CONSIDERABLE CHANGE FROM WHAT THE MODELS WERE SHOWING JUST 24 HOURS AGO. THIS TREND, COMBINED WITH THE FACT THAT HEAVIER SNOW HAS NOT REALLY DEVELOPED ACROSS OUR REGION OVERNIGHT (AMOUNTS SO FAR HAVE BEEN LESS THAN ONE HALF INCH) HAS LEAD TO SOME CHANGES WITH THE FORECAST. STILL THINK THAT PRECIP WILL BE MOSTLY SNOW AS ONCE THE HEAVIER BANDS DO DEVELOP, TEMPERATURES COULD QUICKLY DROP TO NEAR THE DEW POINTS WHICH ARE GENERALLY NEAR OR BELOW FREEZING. THE EXCEPTION TO THIS IS CENTRAL AND SOUTHERN DE AND FAR SOUTHEASTERN NJ WHICH MAY SEE PERIODS OF RAIN THIS MORNING BEFORE CHANGING TO MOSTLY SNOW LATER THIS AFTERNOON. FIRST THE CHANGES TO THE SNOW TOTALS: GIVEN THE LACK OF SNOW ACCUMULATION OVERNIGHT, AND THE HIGHER BOUNDARY LAYER TEMPERATURES DURING THE DAY TODAY LEADING TO LOWER SNOW TO LIQUID RATIOS, FORECAST SNOW TOTALS HAVE GENERALLY BEEN DECREASED ACROSS THE REGION, WITH ONE EXCEPTION. ACROSS NORTHEASTERN NJ, HIGH RES MODELS ARE NOW SHOWING A POTENTIAL FOR FRONTOGENETICAL BANDS THIS EVENING OR LATE TONIGHT. SO INCREASED SNOW TOTALS SLIGHTLY IN THIS AREA, ALTHOUGH I`M CONCERNED THAT IF THE MODELS TREND EVEN FURTHER NORTH, THOSE BANDS MAY MISS OUR REGION ALL TOGETHER. CHANGES TO THE HEADLINES: GIVEN THE GENERALLY LOWER SNOW TOTALS, MUCH OF THE AREA THAT WAS IN THE WINTER STORM WARNING IS NOW IN A WINTER WEATHER ADVISORY, WITH THE EXCEPTION OF CHESTER AND DELAWARE COUNTIES WHICH HAVE THE HIGHEST RISK OF SEEING MESOSCALE BANDING THIS AFTERNOON. FOR THOSE TWO COUNTIES, THE WARNING REMAINS IN EFFECT. THE ADVISORY WAS ALSO EXPANDED ON THE NORTHERN END TO INCLUDE MORRIS COUNTY TO ACCOUNT FOR POTENTIAL BANDING OVERNIGHT. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... SNOW SHOULD GENERALLY MOVE OUT OF THE REGION BY LATE THIS EVENING EXCEPT ACROSS NORTHEASTERN NJ WHERE IT MAY LINGER THROUGH THE OVERNIGHT HOURS. AS THE SURFACE TROUGH LIFTS FURTHER NORTH, WINDS SHOULD SHIFT TO WESTERLY WHICH SHOULD HELP TO CONTINUE TO DIMINISH THE COASTAL FLOODING THREAT. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... AN ACTIVE WINTRY PATTERN TO CONTINUE THROUGH THE PRESIDENTS DAY HOLIDAY. WEDNESDAY: SNOW ASSOCIATED WITH A TROUGH OF LOW PRESSURE WILL BE ENDING ACROSS NORTHERN PORTIONS OF THE REGION IN THE MORNING. HOWEVER, A SOMEWHAT UNSTABLE AIRMASS WILL BE LEFT ACROSS THE REGION IN THE AFTERNOON HOURS WITH STEEPING LOW LEVEL LAPSE RATES AND TT MODELED NEAR 50. ENOUGH MOISTURE MAY STILL BE PRESENT TO FORM A FEW SCATTERED SNOW SHOWERS AND FLURRIES ACROSS THE REGION WITH THE HIGHER TERRAIN ACROSS EASTERN PA AND NW NJ HELPING TO AID POTENTIAL DEVELOPMENT. A LOOK AT BUFKIT SOUNDINGS SHOWS THE POTENTIAL FOR A FAVORABLE MIXING AS WELL WHICH COULD RESULT IN SOME NORTHWEST WIND GUSTS AROUND 25 MPH IN THE AFTERNOON. HIGH TEMPERATURES WILL LIKELY STRUGGLE TO WHAT MET AND MAV GUIDANCE HAS DUE TO SOME SNOW COVER AND THE STRONG CAA PUSH DURING THE DAY. WEDNESDAY NIGHT THROUGH THURSDAY NIGHT: OUR REGION WILL BE SITUATED BETWEEN ARCTIC HIGH PRESSURE BUILDING INTO THE MIDWEST AND THE DEPARTING LOW PRESSURE SYSTEM. THIS PRESSURE GRADIENT WILL LEAD TO CONTINUED STRONG NORTHWEST WINDS WITH COLD AIR ADVECTION INTO THE REGION. THE WIND DIRECTION ALSO LOOKS TO SEND MOISTURE OFF THE GREAT LAKES INTO THE REGION AS WELL. INSTABILITY LOOKS LESS THAN DURING THE DAY WEDNESDAY BUT LOW LEVEL LAPSE RATES SHOULD STEEPEN THURSDAY AFTERNOON. THIS WILL RESULT IN THE CHANCES FOR SOME SCATTERED SNOW SHOWERS AND FLURRIES TO CONTINUE. ANY LIGHT SNOW ACCUMULATION COULD LEAD TO A FEW SLICK SPOTS AS TEMPERATURES WILL BE FALLING QUITE A BIT BELOW FREEZING. CLOUDS AND WIND SHOULD KEEP THE LOW TEMPERATURES UP WEDNESDAY NIGHT, SAY ONLY THE 10`S TO AROUND 20 WITH AFTERNOON HIGHS IN THE 20`S ON THURSDAY. WINDS WILL DECREASE THURSDAY NIGHT WITH CLEARING SKIES ALLOWING FOR A MORE FAVORABLE SETUP FOR RADIATIONAL COOLING AS HIGH PRESSURE BUILDS TOWARD THE REGION. LOW TEMPERATURES WILL LIKELY FALL INTO THE 10`S REGIONWIDE AND CONTINUED TO NUDGE THEM SLIGHTLY LOWER THAN WHAT MOST GUIDANCE INDICATES. FRIDAY AND SATURDAY: HIGH PRESSURE WILL MOVE THROUGH THE REGION ON FRIDAY. THIS HIGH PRESSURE SYSTEM WILL GIVE WAY TO ANOTHER ARCTIC COLD FRONT WITH A CLIPPER TYPE LOW PRESSURE SYSTEM ALONG IT. THIS MOVES THROUGH THE REGION FRIDAY NIGHT AND SATURDAY. MODELING IS STILL TRYING TO RESOLVE IF THE MORE CLIPPER LIKE LOW PRESSURE WILL DEVELOP INTO A COASTAL LOW ALONG THE BOUNDARY. RIGHT NOW ABOUT A THIRD OF ENSEMBLE MEMBERS FROM BOTH THE GFS AND ECMWF SUITES ARE SHOWING THE POTENTIAL FOR A COASTAL LOW FORMING NEAR OR SOUTHWEST OF THE REGION. THE OTHER TWO THIRDS OF ENSEMBLE MEMBERS PLUS THE 00Z CMC, UKMET AND GFS FORM A LOW PRESSURE MUCH FARTHER OFFSHORE. THE LESS LIKELY COASTAL LOW FORMATION SCENARIO COULD RESULT IN ANOTHER PERIOD OF ACCUMULATING SNOWFALL FOR THE REGION. HOWEVER, WITH THE BULK OF MODEL GUIDANCE STAYING FURTHER OFFSHORE WILL JUST ADD A GENERIC LOW CHANCE OF SNOW SHOWERS TO THE FORECAST FOR FRIDAY NIGHT AND SATURDAY. EVEN IF THE LOW FORMS OFFSHORE SATURDAY, IT WILL BE A COLD AND WINDY WITH ANOTHER ROUND OF NW FLOW SNOW SHOWERS AND FLURRIES WITH THE HIGHEST COVERAGE IN THE HIGH TERRAIN AREAS IN EASTERN PA AND NW NJ, SIMILAR TO THE MIDDLE OF THIS WEEK. SATURDAY NIGHT THROUGH SUNDAY NIGHT: ANOTHER POTENT AREA OF ARCTIC HIGH PRESSURE WILL BUILD INTO THE REGION WITH THE COLDEST SHOT OF AIR OF THE SEASON SO FAR. 850 MB LOOK TO DIVE WELL BELOW -20C ACROSS MOST OF REGION AS CURRENTLY MODELED. AS IN OTHER PERIODS WILL CONTINUE TO NUDGE TEMPERATURES A COUPLE OF DEGREES COOLER THAN MOST ENSEMBLE GUIDANCE SETS. STRONG NORTHWEST WINDS IN THE WAKE OF THE DEPARTING SYSTEM ON SATURDAY WILL LIKELY LEAD TO BELOW ZERO WIND CHILLS, PUSHING ADVISORY CRITERIA IN SPOTS. PRESIDENTS DAY: HIGH PRESSURE WILL GRADUALLY MOVE EAST OF THE REGION AND WILL GIVE WAY TO A STORM SYSTEM THAT IS CURRENTLY MODELED TO FORM ACROSS THE SOUTHERN UNITED STATES. RIGHT NOW IT APPEARS THAT A TYPICAL GFS BIAS IS AT WORK FOCUSING STORM DEVELOPMENT IN THE NORTHERN BRANCH OF THE JET AND BEING TO PROGRESSIVE WITH MOVING THE TROUGH EASTWARD ACROSS THE COUNTRY. THE ECMWF, UKMET AND CMC SEEM TO HAVE A BETTER HANDLE OF A BROADER TROUGH WHICH GIVES THE SOUTHERN BRANCH MORE OF A CHANCE TO BE INVOLVED IN THE PATTERN. THIS ALLOWS FOR A STRONGER SYSTEM TO FORM ACROSS THE SOUTHERN PLAINS. RIGHT NOW IT LOOKS LIKE MONDAY WILL START DRY WITH PRECIPITATION CHANCES MOVING INTO THE REGION BY MONDAY AFTERNOON AND NIGHT. TIMING CAN ALWAYS CHANGE BY 24 HOURS OR MORE THIS FAR OUT. TEMPERATURES WILL ALSO REBOUND ON THE BACKSIDE OF THE HIGH PRESSURE SYSTEM. HOWEVER, GIVEN THIS IS SEVERAL DAYS A LOT OF ENSEMBLE SPREAD IS STILL PRESENT AND THE VARIOUS FEATURES INVOLVED WILL NOT EVEN SAMPLED BY OBSERVATIONAL DATA FOR SEVERAL MORE DAYS. && .AVIATION /09Z TUESDAY THROUGH SATURDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. WIDESPREAD MVFR AND IFR CEILINGS ARE EXPECTED THROUGH MUCH OF THE TAF PERIOD. THE LOWEST CONDITIONS, INCLUDING VISIBILITY RESTRICTIONS ARE EXPECTED WITH SNOW BANDS, WHICH ARE LIKELY TO MOVE THROUGH THE TAF SITES THIS AFTERNOON INTO THE EARLY EVENING HOURS. AFTER 00Z, SNOW SHOULD BEGIN TO LIFT OUT OF THE AREA FROM SOUTH TO NORTH, AND WITH IT, EXPECT IMPROVING VISIBILITIES AND EVENTUALLY (LIKELY NOT UNTIL AFTER 06Z) IMPROVING CEILING CONDITIONS. WINDS ARE ALSO EXPECTED TO SHIFT FROM NORTHEASTERLY THROUGH THE DAY TO WESTERLY OR NORTHWESTERLY AFTER 06Z. OUTLOOK... WEDNESDAY THROUGH THURSDAY: MAINLY VFR, SOME BRIEF MVFR RESTRICTIONS IN ISOLATED SNOW SHOWERS AND FLURRIES. NORTHWEST WINDS 15-25 KNOTS WITH HIGHER GUSTS. THURSDAY NIGHT AND FRIDAY: VFR. FRIDAY NIGHT AND SATURDAY: MAINLY VFR, POSSIBILE MVFR RESTRICTIONS IN SCATTERED SNOW SHOWERS. NORTHWEST WINDS INCREASING SATURDAY FROM 15-25 KNOTS WITH HIGHER GUSTS. && .MARINE... SCA CONDITIONS, ESPECIALLY FOR SEAS ARE EXPECTED TO CONTINUE TODAY AND TONIGHT. THERE MAY BE A BIT OF A LULL IN THE WINDS DURING THE DAY TODAY, BUT A SHIFT TO WESTERLY OR NORTHWESTERLY WINDS IS EXPECTED TONIGHT, AND WITH IT, AND INCREASE IN WIND SPEEDS ONCE AGAIN. OUTLOOK... THE SCA HAS BEEN EXTENDED TILL 6PM WEDNESDAY BASED ON A HIGH CONFIDENCE OF NORTHWEST WIND GUSTS NEAR 25 KNOTS OCCURRING THROUGHOUT THE DAY AND SEAS STAYING AROUND FIVE FEET. WIND GUSTS NEAR 25 KNOTS MAY CONTINUE THROUGH THURSDAY NIGHT EVEN WITH DECREASING WAVEHEIGHTS. ANOTHER ROUND OF STRONG NORTHWEST WIND GUSTS OVER 25 KNOTS IS BECOMING LIKELY SATURDAY. THESE GUSTS MAY EVEN REACH GALE FORCE FOR A TIME. && .TIDES/COASTAL FLOODING... MODERATE COASTAL FLOODING, WITH ISOLATED MAJOR COASTAL FLOODING IS POSSIBLE WITH HIGH TIDE THIS MORNING FOR THE NJ SHORE, DELAWARE BEACHES, AND LOCATIONS ALONG THE DELAWARE BAY. MINOR COASTAL FLOODING IS EXPECTED FOR THE TIDAL DELAWARE RIVER WITH THIS HIGH TIDE CYCLE. THANKS TO DECREASING ASTRONOMICAL TIDES, AND AN EXPECTED WIND SHIFT, WE ARE NOT EXPECTING COASTAL FLOODING WITH THE HIGH TIDE CYCLE THIS EVENING, THOUGH IT COULD GET CLOSE TO MINOR FLOODING THRESHOLDS FOR THE OCEANSIDE. MINOR COASTAL FLOODING IS POSSIBLE FOR THE NORTHEASTERN SHORE OF THE CHEASPEAKE BAY WITH THE HIGH TIDE CYCLE EARLY THIS MORNING AND AGAIN THIS EVENING. THERE IS SOME RISK THAT MODERATE COASTAL FLOODING COULD BE REACHED WITH THE EVENING HIGH TIDE, BUT CONFIDENCE IS LOW, SO WILL CONTINUE WITH THE COASTAL FLOOD ADVISORY FOR NOW. THE POTENTIAL FOR BLOWOUT TIDES IS PRESENT FOR THE THURSDAY LOW TIDAL CYCLES. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...WINTER WEATHER ADVISORY UNTIL 6 AM EST WEDNESDAY FOR PAZ060- 061-071-103>106. WINTER STORM WARNING UNTIL 6 AM EST WEDNESDAY FOR PAZ070-101- 102. COASTAL FLOOD ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR PAZ070-071-106. NJ...WINTER WEATHER ADVISORY UNTIL 6 AM EST WEDNESDAY FOR NJZ008>010-012>027. COASTAL FLOOD WARNING UNTIL 1 PM EST THIS AFTERNOON FOR NJZ012>014-020>027. COASTAL FLOOD WARNING UNTIL 3 PM EST THIS AFTERNOON FOR NJZ016. COASTAL FLOOD ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR NJZ015-017>019. DE...WINTER WEATHER ADVISORY UNTIL 6 AM EST WEDNESDAY FOR DEZ001>004. COASTAL FLOOD WARNING UNTIL 1 PM EST THIS AFTERNOON FOR DEZ002>004. COASTAL FLOOD WARNING UNTIL 3 PM EST THIS AFTERNOON FOR DEZ001. MD...WINTER WEATHER ADVISORY UNTIL 6 AM EST WEDNESDAY FOR MDZ008- 012-015-019-020. COASTAL FLOOD ADVISORY UNTIL 10 PM EST THIS EVENING FOR MDZ008- 012-015-019-020. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST WEDNESDAY FOR ANZ450>455. && $$ SYNOPSIS...GAINES NEAR TERM...JOHNSON SHORT TERM...JOHNSON LONG TERM...GAINES AVIATION...GAINES/JOHNSON MARINE...GAINES/JOHNSON TIDES/COASTAL FLOODING...JOHNSON

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