Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 252333 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 633 PM EST SUN JAN 25 2015 .SYNOPSIS... LOW PRESSURE IN THE OHIO VALLEY THIS EVENING WILL TRACK EASTWARD AND MOVE OFF THE MID ATLANTIC COAST ON MONDAY. THE LOW WILL THEN RAPIDLY INTENSIFY IS IT MOVES NORTHEASTWARD, PASSING NEAR CAPE COD LATE ON TUESDAY BEFORE REACHING NOVA SCOTIA ON WEDNESDAY. HIGH PRESSURE FROM THE WEST IS FORECAST FOR WEDNESDAY. A WEAK LOW IS EXPECTED TO FOLLOW AND PASS OVER OUR REGION ON EITHER THURSDAY NIGHT OR FRIDAY. ANOTHER AREA OF HIGH PRESSURE IS THEN ANTICIPATED FOR NEXT WEEKEND. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... AN ARCTIC FRONT CONTINUES TO OOZE ITS WAY SOUTHWARD ACROSS OUR AREA, WITH COLDER AIR AND MORE NOTABLY MUCH DRIER AIR SEEPING SOUTHWARD EARLY THIS EVENING. THIS BOUNDARY CONNECTS INTO LOW PRESSURE OVER THE OHIO VALLEY, AND THIS WILL TRACK OVER THE APPALACHIANS. THE ACCOMPANYING MID LEVEL SHORT WAVE IS SHOWN TO TAKE ON MORE OF A NEGATIVE TILT THROUGH THE OVERNIGHT TO EARLY MONDAY. WITH THESE FEATURES IN MIND, WE ANTICIPATE A LIGHT SNOW TO DEVELOP FROM WEST TO EAST ACROSS MUCH OF THE CWA GOING THROUGH LATE EVENING. THIS MAY TAKE AWHILE TO GET FARTHER NORTHEAST DUE TO DRIER AIR ADVECTING SOUTHWARD IN THE LOWER LEVELS. THE BOUNDARY LAYER IS JUST MILD ENOUGH EARLY ON THAT SOME SPRINKLES OR LIGHT RAIN MAY OCCUR AT THE START AS IT MOVES IN FROM THE WEST. MEANWHILE FOR THE FAR SOUTHERN DELMARVA, LIGHT RAIN OR A RAIN/SNOW MIX CAN BE ANTICIPATED BASED ON THE EXPECTED BOUNDARY LAYER TEMPERATURES DURING THE OVERNIGHT. THE MODEL GUIDANCE CONTINUES TO SHOW FAIRLY GOOD CONVERGENCE SETTING UP INTO THE CENTRAL PART OF THE CWA, AND OVERALL WE EXPECT A GENERAL 1 TO 3 INCHES OF SNOW ACCUMULATION FOR CENTRAL TO NORTHERN PARTS OF THE CWA FROM THE OVERNIGHT TO MONDAY AFTERNOON. ANY POSSIBLE MESOSCALE BANDING THAT DEVELOPS WILL ULTIMATELY DETERMINE WHERE THE SOMEWHAT HIGHER VALUES ARE REALIZED, WITH SOME LOCALIZED AMOUNTS CLOSER TO FOUR INCHES POSSIBLE MAINLY TOWARD THE LOWER SUSQUEHANNA VALLEY. A NORTHERLY WIND WILL TAKE OVER FROM NORTH TO SOUTH FOLLOWING THE FRONTAL PASSAGE AND AS LOW PRESSURE TRACKS EASTWARD. THIS IS EXPECTED TO INCREASE AND TURN MORE NORTHEAST BETWEEN 10 TO 15 MPH DURING THE OVERNIGHT. THE HOURLY GRIDS WERE ADJUSTED TO SHOW INITIAL WARMER TEMPERATURES AND HIGHER DEW POINTS ACROSS THE SOUTHERN HALF OF THE CWA, AND LOWER DEW POINTS ACROSS THE NORTH. THE LAMP/LAV GUIDANCE WAS USED TO HELP ASSIST WITH TRENDS. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... THROUGH THE DAYTIME MONDAY, THE PREVIOUSLY MENTIONED LOW PRESSURE WILL TRACK FROM AROUND THE CENTRAL APPALACHIANS EARLY MONDAY MORNING TO OFF THE NORTH CAROLINA COAST. MEANWHILE, THE PREVIOUSLY MENTIONED UPPER SHORTWAVE WILL DEEPEN AND BECOME A CLOSED UPPER LOW. THESE FEATURES WILL THEN ULTIMATELY ALLOW FOR QUICK INTENSIFICATION OF THIS SYSTEM AS IT TRACKS NORTHEAST FROM LATE- DAY MONDAY THROUGH MONDAY NIGHT. A GENERALLY LIGHT SNOW WILL BE ONGOING THROUGH MONDAY MORNING AS THE INITIAL CLIPPER LOW IS PASSING BY TO OUR SOUTH ON ITS WAY TO THE COAST, AND AS PREVIOUSLY MENTIONED ABOVE, A GENERAL ONE TO THREE OR FOUR INCH SNOW ACCUMULATION CAN BE ANTICIPATED THROUGH THE MIDDLE OF THE DAY MONDAY, WITH THE HIGHER AMOUNTS EXPECTED TO EXTEND FROM PORTIONS OF EASTERN PENNSYLVANIA INTO CENTRAL AND NORTHERN NEW JERSEY. MEANWHILE, AS TEMPERATURES BEGIN TO WARM THROUGH THE DAYTIME MONDAY, SOME MIXING OR CHANGE-OVER TO RAIN IN EXPECTED FOR SOUTHEASTERN PORTIONS OF NEW JERSEY AND DOWN INTO THE DELMARVA, GENERALLY LIMITING ANY SUNDAY NIGHT TO MONDAY DAYTIME ACCUMULATIONS TO AROUND AN INCH OR LESS. NORTHEAST WINDS THROUGH THE DAYTIME MONDAY WILL BE INCREASING, WITH GUSTS INTO THE 25 TO 30 MPH RANGE, ESPECIALLY BY THE END OF THE DAY. MAXIMUM TEMPERATURES INCORPORATED SOME MET AND MAV GUIDANCE WITH CONTINUITY, AND WE ANTICIPATE HIGHS TO RANGE FROM THE LOWER AND MIDDLE 20S NORTH TO THE UPPER 30S AND PERHAPS SOME 40S INTO THE FAR SOUTHERN DELMARVA. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... ***A MAJOR SNOWSTORM WILL AFFECT OUR REGION FOR MONDAY NIGHT INTO TUESDAY*** THE STORM FOR MONDAY NIGHT AND TUESDAY CONTINUES TO COME TOGETHER. THE SURFACE LOW WILL INTENSIFY RAPIDLY OFF THE MIDDLE ATLANTIC COAST ON MONDAY NIGHT BEFORE MOVING UP TOWARD THE WATERS OFF EASTERN LONG ISLAND AND SOUTHEASTERN NEW ENGLAND FOR TUESDAY. THE SYSTEM SHOULD THEN CONTINUE NORTHEASTWARD REACHING NOVA SCOTIA ON WEDNESDAY. ABUNDANT ATLANTIC MOISTURE WILL WRAP INTO THE STORM AND WE ARE ANTICIPATING SIGNIFICANT SNOWFALL TOTALS. FROM NEW JERSEY NORTHEASTWARD ONE TO TWO FOOT TOTALS ARE FORECAST TO BE COMMON. AMOUNTS IN EXCESS OF TWO FEET ARE POSSIBLE IN OUR FORECAST ARE TOWARD NORTHEASTERN NEW JERSEY AND THE NORTHERN PART OF THE NEW JERSEY COAST, INCLUDING MONMOUTH COUNTY AND OCEAN COUNTY. THE EASTERN EDGE OF PENNSYLVANIA MAY SEE AMOUNTS AROUND A FOOT. AS ONE WORKS WESTWARD TOWARD THE SUSQUEHANNA RIVER VALLEY, AMOUNTS MAY BEGIN TO LESSEN TOWARD THE 4 TO 6 INCH RANGE. THE SAME IS TRUE FOR THE UPPER DELMARVA. BASED ON HIGH CONFIDENCE, WE HAVE UPGRADED MOST OF OUR NEW JERSEY COUNTIES, AS WELL AS MUCH OF SOUTHEASTERN PENNSYLVANIA TO A WINTER STORM WARNING FOR MONDAY NIGHT AND TUESDAY. WE HAVE UPGRADED THE BLIZZARD WATCH TO A BLIZZARD WARNING FOR THE COUNTIES OF MIDDLESEX, MONMOUTH AND OCEAN. FOR THE WESTERN AND SOUTHWESTERN PARTS OF OUR FORECAST AREA, WE HAVE LEFT THE WINTER STORM WATCH IN PLACE UNTIL WE CAN GET A BETTER HANDLE ON THE EXPECTED IMPACTS ON THE EDGE OF THE PRECIPITATION SHIELD. THERE MAY VERY WELL BE A SHARP CUT OFF IN SNOWFALL AMOUNTS AS ONE APPROACHES THE SUSQUEHANNA RIVER VALLEY AND THE CHESAPEAKE BAY REGION. TEMPERATURES WILL BE MOSTLY IN THE 20 TO 30 DEGREE RANGE DURING THE SNOW EVENT WITH THE BRISK NORTHEAST WIND BACKING TOWARD THE NORTHWEST. FREQUENT GUSTS IN EXCESS OF 35 MPH ARE ANTICIPATED IN OUR NORTHERN COASTAL COUNTIES AND THAT IS THE REASON FOR THE THREE COUNTIES BEING INCLUDED IN THE BLIZZARD WARNING. THE SNOW SHOULD END GRADUALLY FROM SOUTHWEST TO NORTHEAST IN OUR FORECAST AREA FROM TUESDAY AFTERNOON THROUGH EARLY TUESDAY NIGHT. IT SHOULD BE DRY AND COLD FOR WEDNESDAY AND WEDNESDAY NIGHT. A CLIPPER SYSTEM FROM THE NORTHWEST AND WEST MAY BRING A SHOT OF LIGHT SNOW FROM LATE THURSDAY INTO FRIDAY. ANOTHER SHOT OF COLD DRY AIR IS ANTICIPATED FOR NEXT WEEKEND. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. **HIGH IMPACT EVENT EXPECTED MONDAY AND TUESDAY** TONIGHT...VFR CEILINGS LOWERING TO MVFR TOWARD MIDNIGHT THEN TO IFR BY DAYBREAK. SOME MAINLY LIGHT SNOW IS ANTICIPATED TO OVERSPREAD THE AREA FROM THE WEST TO EAST, GENERALLY IN THE 02Z TO 05Z TIME FRAME. SOME RAIN/SNOW MIX IS POSSIBLE FOR MAINLY KILG, KMIV AND KACY AT THE ONSET OF PRECIPITATION, BUT DURING THE OVERNIGHT A CHANGEOVER TO ALL LIGHT SNOW IS EXPECTED. SNOW ACCUMULATIONS ARE ANTICIPATED TO BE MAINLY 1 TO 2 INCHES FOR THE DELAWARE VALLEY AND WESTWARD, WITH GENERALLY LESS THAN AN INCH FOR KMIV/KACY. NORTHERLY WINDS AROUND 5 KNOTS, BECOMING MORE NORTHEASTERLY OVERNIGHT AND INCREASING TO 10 TO 15 KNOTS. SOME GUSTINESS SHOULD DEVELOP LATE. MONDAY...GENERALLY IFR TO POSSIBLE LOW-END MVFR CONDITIONS ARE ANTICIPATED TO CONTINUE WITH LIGHT SNOW. SOME RAIN/SNOW MIX IS EXPECTED BY LATE MORNING THROUGH THE AFTERNOON FOR KMIV/KACY. GUSTY NORTHEAST WINDS ARE ANTICIPATED, WITH GUSTS REACHING BETWEEN 25 TO 30 KNOTS. ADDITIONAL DAYTIME ACCUMULATIONS TO AROUND AN INCH, WITH HEAVIER SNOW DEVELOPING THEN INTO MONDAY NIGHT. OUTLOOK... MONDAY NIGHT AND TUESDAY...SIGNIFICANT SNOWFALL WILL LIKELY BRING AIR TRAFFIC TO A STANDSTILL ON MONDAY NIGHT AND TUESDAY. CONDITIONS ARE FORECAST TO BE LIFR AND SNOW ACCUMULATIONS IN EXCESS OF ONE FOOT ARE ANTICIPATED AT KPHL WITH GREATER AMOUNTS TO THE NORTHEAST AND SLIGHTLY LOWER AMOUNTS TO THE SOUTHWEST. TUESDAY NIGHT...CLEARING IS ANTICIPATED WITH A GUSTY NORTHWEST WIND. WEDNESDAY THROUGH THURSDAY MORNING...MAINLY VFR. THURSDAY AFTERNOON THROUGH FRIDAY...A CHANCE OF SNOW. CONDITIONS MAY LOWER INTO THE MVFR OR IFR RANGE FOR A TIME. && .MARINE... SUB-ADVISORY CONDITIONS ARE EXPECTED FOR THE COASTAL WATERS AND DELAWARE BAY FOR MOST OF TONIGHT. TOWARD THE EARLY MORNING OF MONDAY, CONDITIONS WILL BE RAMPING UP TO SCA LEVELS AS NORTHEAST WINDS WILL BE GUSTING UP TO AROUND 30 KNOTS BY THE 12Z TO 15Z MONDAY TIMEFRAME. FOR THE REST OF MONDAY THEN, CONTINUED DETERIORATING CONDITIONS ARE EXPECTED THROUGH MONDAY AFTERNOON, WITH GALE FORCE WIND GUSTS EXPECTED FOR DELAWARE BAY AND THE COASTAL WATERS. BY MONDAY NIGHT, STORM FORCE GUSTS ARE ANTICIPATED FOR THE COASTAL WATERS. SEAS WILL BE BUILDING TO BETWEEN 3 AND 6 FEET FOR DELAWARE BAY DURING MONDAY AND INTO MONDAY NIGHT, WITH SEAS EVENTUALLY BUILDING TO BETWEEN 10 AND 16 FEET FOR THE COASTAL WATERS LATER MONDAY NIGHT. MARINE HEADLINES INCLUDE A GALE WARNING FOR DELAWARE BAY AND FOR THE COASTAL WATERS FROM CAPE MAY TO FENWICK ISLAND, FROM MONDAY AFTERNOON THROUGH THE DAYTIME TUESDAY, WITH STORM WARNINGS ISSUED FOR THE COASTAL WATERS FROM SANDY HOOK TO CAPE MAY, NJ THROUGH THE DAYTIME TUESDAY. OUTLOOK... MONDAY NIGHT AND TUESDAY...A MARINE STORM WARNING IS IN EFFECT FOR OUR OCEAN WATERS OFF NEW JERSEY. A GALE WARNING IS IN EFFECT FOR THE WATERS OFF DELAWARE AND FOR DELAWARE BAY. TUESDAY NIGHT...GALE FORCE WIND GUSTS ARE LIKELY. FREEZING SPRAY WILL BE AN ISSUE, AS WELL. WEDNESDAY...SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED WITH ADDITIONAL FREEZING SPRAY ISSUES. WEDNESDAY NIGHT THROUGH FRIDAY...NO MARINE HEADLINES ARE ANTICIPATED. && .TIDES/COASTAL FLOODING... WE HAVE ISSUED A COASTAL FLOOD WATCH FOR MONDAY NIGHT`S HIGH TIDE ALONG THE COASTS OF NEW JERSEY AND DELAWARE AND ON DELAWARE BAY. WITH THE STRENGTHENING STORM OFF THE MIDDLE ATLANTIC COAST AND THE STRONG NORTHEAST TO NORTH WIND, MODERATE TIDAL FLOODING APPEARS LIKELY. WE ARE THINKING THAT THERE COULD BE SOME MINOR TIDAL FLOODING ON THE TIDAL DELAWARE RIVER AND PERHAPS ON THE UPPER EASTERN SHORE OF CHESAPEAKE BAY. HOWEVER, WE HAVE TIME TO ADDRESS THAT WITH AN ADVISORY, IF NECESSARY. ALSO, WE WILL KEEP AN EYE ON THE DAYTIME HIGH TIDE ON TUESDAY. IF THE WIND IS SLOW TO BACK TO THE NORTHWEST, WE MAY EXPERIENCE ANOTHER CYCLE WITH MINOR TO MODERATE TIDAL FLOODING. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...WINTER STORM WARNING FROM NOON MONDAY TO 6 PM EST TUESDAY FOR PAZ070-071-103>106. WINTER STORM WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY MORNING FOR PAZ054-055-060>062-101-102. NJ...WINTER STORM WARNING FROM NOON MONDAY TO 6 PM EST TUESDAY FOR NJZ001-007>010-015>019-021>025-027. COASTAL FLOOD WATCH FROM MONDAY EVENING THROUGH LATE MONDAY NIGHT FOR NJZ012>014-016-020>027. BLIZZARD WARNING FROM NOON MONDAY TO 6 PM EST TUESDAY FOR NJZ012>014-020-026. DE...COASTAL FLOOD WATCH FROM MONDAY EVENING THROUGH LATE MONDAY NIGHT FOR DEZ001>004. WINTER STORM WATCH FROM MONDAY EVENING THROUGH TUESDAY MORNING FOR DEZ002>004. WINTER STORM WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY MORNING FOR DEZ001. MD...WINTER STORM WATCH FROM MONDAY EVENING THROUGH TUESDAY MORNING FOR MDZ012-015-019-020. WINTER STORM WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY MORNING FOR MDZ008. MARINE...STORM WARNING FROM NOON MONDAY TO 6 PM EST TUESDAY FOR ANZ450>453. GALE WARNING FROM NOON MONDAY TO 6 PM EST TUESDAY FOR ANZ430- 431-454-455. && $$ SYNOPSIS...GORSE/IOVINO NEAR TERM...GORSE/KLINE SHORT TERM...KLINE LONG TERM...IOVINO AVIATION...GORSE/IOVINO/KLEIN MARINE...IOVINO/HEAVENER/KLINE TIDES/COASTAL FLOODING...IOVINO

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