Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 240928 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 428 AM EST SAT JAN 24 2015 .SYNOPSIS... RAPIDLY INTENSIFYING LOW PRESSURE CROSSING EASTERN NORTH CAROLINA EARLY TODAY WILL RACE PAST CAPE COD BY THIS EVENING. A WEAK RIDGE OF HIGH PRESSURE BRIEFLY FOLLOWS SUNDAY. ATTENTION THEN TURNS TO LOW PRESSURE IN KENTUCKY SUNDAY EVENING. IT MOVES TO THE NORTH CAROLINA COAST MONDAY THEN INTENSIFIES ALONG ITS TRACK EAST OF NEW ENGLAND ON TUESDAY. IN ITS WAKE...COLDER AIR FOR SEVERAL DAYS AS HIGH PRESSURE HEADS FOR THE EAST COAST THURSDAY. A REINFORCING SURGE OF COLD AIR ARRIVES AFTER A COLD FRONTAL PASSAGE FRIDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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WE HAVE UPGRADED OUR ADVISORIES NORTH AND WEST OF PHILLY TO WINTER STORM WARNINGS...THEY GO THROUGH THIS MORNING. THE WARM/ISENTROPIC LIFT FRONT END THUMP THIS MORNING WAS HANDLED PRETTY WELL BY ALL THE GUIDANCE THE PAST COUPLE OF RUNS. THERMALLY THE NAM SEEMED TO HAVE THE BETTER HANDLE ON THE MELTING LAYER MOVEMENT, OR LACK THEREOF THIS MORNING. AS OF THIS WRITING IT SEEMS THAT THE MELTING LAYER IS SITTING JUST TO THE SOUTH OF A LINE FROM TTN WESTWARD TO PTW. DECENT SNOWRATES ARE STILL OCCURRING NORTH OF THIS LINE AS A BIT MORE QPF WORKED ITS WAY INTO THE REGION LATE LAST NIGHT. THE OMEGA RATES WITHIN THE DGZ WERE VERY IMPRESSIVE FOR SEVERAL HOURS THIS MORNING ACROSS THE LEHIGH VALLEY AND NORTHWARD. SEVERAL REPORTS OF CLOSE TO 5 INCHES WERE REPORTED DURING THE PEAK INTENSITY OF THE MESO BANDS THAT SETUP IN SEPA AND NNJ. WE ALREADY HAD A 4-6" SWATH RUNNING THROUGH THESE AREAS BUT FELT THAT AN ADDITIONAL INCH OR TWO WOULD BE VERY POSSIBLE AND THEREFORE WE WENT TO WARNINGS. WITH THE HEAVY WET SNOW, SCATTERED POWER OUTAGES ACROSS THE WARNED AREA ARE QUITE POSSIBLE. WE SHOULD BEGIN TO DRY FROM WEST TO EAST AS THE SURFACE LOW PRESSURE TO OUR SOUTHEAST RAPIDLY MOVES NORTHEASTWARD AND CONTINUES TO DEEPEN. THE COLUMN ALOFT DRIES OUT/WARMS UP TO THE POINT WE LOSE OUR ICE CRYSTALS. MARGINAL SURFACE TEMPERATURES MAY MAKE FOR SOME FREEZING DRIZZLE THOUGH IT SHOULD BE VERY ISOLATED. COLD AIR WILL FILTER IN BEHIND THE DEPARTING LOW PRESSURE ALLOWING FOR ANY REMAINING MOISTURE TO TURN BACK OVER TO SNOW. A FEW SNOW SHOWERS ARE POSSIBLE THIS AFTERNOON/EVENING WITH MINIMAL ACCUMULATIONS AS BOUNDARY LAYER TEMPERATURES WILL BE ABOVE FREEZING, MID-30S ACROSS OUR EASTERN ZONES.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
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SNOW SHOWERS SHOULD COME TO AN END AS HIGH PRESSURE PRESSES IN FROM THE WEST, ALBEIT BRIEFLY. SKIES WILL CLEAR WITH BRISK WESTERLY WINDS. TEMPERATURES ARE EXPECTED TO DIP INTO THE MID TO UPPER-20S...SLIGHTLY COLDER IN FRESH PACK AREAS.
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&& .LONG TERM /SUNDAY THROUGH FRIDAY/... 500MB: A PAIR OF SHORT WAVES HEADING SOUTHEAST FROM CENTRAL NORTH AMERICA SUNDAY WILL PROBABLY EVOLVE INTO A STRONG LONG WAVE TROUGH OVER THE EASTERN SEABOARD STATES ON TUESDAY BEFORE RIDGING FOLLOWS THURSDAY. A SHORT WAVE PASSAGE THROUGH SOUTHEAST CANADA FRIDAY SEEMS TO WANT TO YANK THE POLAR VORTEX SOUTHWARD TO NEAR JAMES BAY BY THE START OF NEXT WEEKEND. TEMPERATURES: NEAR NORMAL SUNDAY THEN BELOW NORMAL MONDAY THROUGH THURSDAY WITH POTENTIALLY WELL BELOW NORMAL TEMPS TUESDAY AND WEDNESDAY. A BRIEF RETURN TO NEAR NORMAL TEMPS EXPECTED FRIDAY. FORECAST BASIS: UNLESS OTHERWISE NOTED WITHIN THE DAILIES. THIS FORECAST IS A 50 50 BLEND OF THE 00Z/24 MAV/MET FOR SUNDAY-MONDAY. THE 00Z/24 MEX MOS WAS APPLIED MONDAY NIGHT AND TUESDAY.NO CHANGES WERE MADE TO THE FORECAST BEYOND TUESDAY. THE DAILIES... SUNDAY...A QUIET DAY WITH WEAK COLD AIR ADVECTION. INCREASING CLOUDS AHEAD OF THE CLIPPER HEADING ESE FROM THE LOWER OHIO VALLEY. SUNDAY NIGHT-MONDAY NIGHT...SNOW OVERSPREADS THE AREA SUNDAY EVENING. PRECIP COULD BEGIN OVER NRN DELMARVA AS A MIX OF RAIN AND SNOW BUT SHOULD CHANGE TO ALL SNOW OVERNIGHT AS THE PRECIP RATE INCREASES AND SOME NOCTURNAL COOLING TAKES PLACE. PERIODS OF SNOW SHOULD CONTINUE INTO MONDAY AS LOW PRESSURE MOVES BY TO OUR SOUTH AND THEN BEGINS TO DEEPEN OFF THE MID-ATLANTIC COAST. THE MOST SIGNIFICANT SNOW COULD OCCUR MONDAY MORNING...ALTO OVERALL AMOUNTS SHOULD BE LIGHT THOUGH THERE IS OPPORTUNITY FOR THIS STORM TO DEEPEN CLOSER TO THE COAST ON MONDAY. THIS CERTAINLY PORTENDS TO BECOME AT LEAST AN ADVISORY SITUATION FOR THE DELMARVA AND COASTAL NEW JERSEY AND NEEDS TO BE MONITORED FOR MORE SIGNIFICANT POWDERY AMOUNTS OF SNOW. SNOW WATER RATIOS SHOULD BE MUCH DRIER THAN WHAT OCCURRED LAST NIGHT....IN OTHER WORDS FLUFFIER. A POTENTIAL HAZARDOUS MONDAY MORNING COMMUTE IS IN THE OFFING FOR A PORTION OF OUR FORECAST AREA. GUSTY NORTHERLY WINDS TO 20 TO 25 MPH MAY CAUSE SOME DRIFTING OF THE SNOW ON THE DELMARVA...ESPECIALLY THE DELAWARE COAST. WIND CHILLS WILL BE NOTICED! TIDAL SURGE: FAIRLY LARGE ON MONDAY AND TUESDAY DUE TO NORTHERLY FLOW WITH SMALL POTENTIAL FOR MINOR COASTAL FLOODING ALONG THE ATLANTIC SHORES. TUESDAY-WEDNESDAY...HIGH PRES AND DRIER AIR WILL GRADUALLY MOVE IN FOR MID WEEK ON CONTINUED NORTHERLY FLOW WITH GUSTS TO 20 MPH DURING THE DAYLIGHT HOURS. . THURSDAY...WAA CLOUDS AND POSSIBLE SNOW SHOWERS LATE THURSDAY AHEAD OF THE NEXT SHORT WAVE...THIS ONE IN CANADA WITH A STRONG COLD FRONT TO FOLLOW FRIDAY. FRIDAY...CAA DEVELOPS BEHIND THE CFP. && .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY...IFR/LIFR, POSSIBLE VLIFR, IN AREAS OF MODERATE TO HEAVY WET SNOW. TTN-ABE-RDG SHOULD REMAIN MOSTLY SNOW THROUGH THE MORNING BEFORE POSSIBLY DRYING OUT SOME AS WE NEAR MID-DAY. ELSEWHERE MOSTLY RAIN IS EXPECTED TO CONTINUE THROUGH THE DAY WITH SOME DRYING TOWARDS THE AFTERNOON HOURS. TONIGHT...VFR. BRISK WNW WINDS. OUTLOOK... SUN...VFR. ABOVE AVERAGE CONFIDENCE. SUN NIGHT...CONDITIONS DIMINISHING WITH IFR POSSIBLE AND SNOW BY EARLY MONDAY MORNING....ESPECIALLY KTTN SOUTHWARD. CONFIDENCE: ABOVE AVERAGE MON...MVFR/IFR WITH LOWER CIGS/VSBYS IN SNOW...ESPECIALLY KILG AND KMIV. CONFIDENCE: ABOVE AVERAGE. MON NIGHT - CONDITIONS SLOWLY IMPROVING TO MVFR...POSSIBLY VFR LATE. CONFIDENCE: AVERAGE SINCE THE DEVELOPING STORM MAY FORCE SNOW TO LINGER ALONG THE COAST. TUE - WED...MOSTLY VFR. CONFIDENCE: ABOVE AVERAGE.
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&& .MARINE...
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TODAY - TONIGHT...CONTINUED SCA CONDITIONS EVERYWHERE AS COASTAL LOW PRESSURE RAPIDLY DEEPENS TODAY AND RACES OFF TOWARDS THE NORTHEAST. NORTHEAST WINDS SHIFT TOWARDS THE WEST-NORTHWEST LATER TODAY BEHIND THE DEPARTING LOW PRESSURE. OUTLOOK... STRONG SMALL CRAFT ADVISORY CONDS ARE EXPECTED TO DEVELOP EARLY MONDAY MORNING AND MAY CONTINUE THROUGH WEDNESDAY. POTENTIAL GALES MONDAY AND MONDAY NIGHT DELAWARE COAST. SEAS COULD EASILY BUILD TO 12 FEET EAST OF CAPE MAY TO EAST OF DELAWARE IN PERSISTENT NNE FLOW. LIGHT TO POSSIBLY MODERATE FREEZING SPRAY POTENTIAL MONDAY NIGHT AND WEDNESDAY NIGHT.
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...WINTER STORM WARNING UNTIL 11 AM EST THIS MORNING FOR PAZ054- 055-060>062-103-105. WINTER WEATHER ADVISORY UNTIL 8 AM EST THIS MORNING FOR PAZ070- 071-101-102-104-106. NJ...WINTER STORM WARNING UNTIL 11 AM EST THIS MORNING FOR NJZ001- 007>010. WINTER WEATHER ADVISORY UNTIL 8 AM EST THIS MORNING FOR NJZ012- 013-015. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST SUNDAY FOR ANZ450>455. SMALL CRAFT ADVISORY UNTIL 6 AM EST SUNDAY FOR ANZ430-431. && $$ SYNOPSIS...DRAG NEAR TERM...HEAVENER SHORT TERM...HEAVENER LONG TERM...DRAG/HEAVENER AVIATION...DRAG/HEAVENER MARINE...DRAG/HEAVENER

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