Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 262105 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 405 PM EST WED NOV 26 2014 .SYNOPSIS... A COASTAL LOW WILL QUICKLY MOVE TO THE NORTHEAST TONIGHT. HIGH PRESSURE IS FORECAST TO BUILD ACROSS THE EAST COAST FRIDAY INTO EARLY SATURDAY, BEFORE SQUEEZING TO THE SOUTH SATURDAY NIGHT. A COLD FRONT IS EXPECTED TO SAG DOWN ACROSS THE AREA SUNDAY NIGHT, BEFORE SLOWLY MOVING THROUGH THE AREA MONDAY INTO MONDAY NIGHT. HIGH PRESSURE WILL THEN RETURN TO THE NORTHEAST FOR TUESDAY, FOLLOWED BY ANOTHER POTENTIAL FRONTAL SYSTEM WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... THE 20Z OBJECTIVE SURFACE ANALYSIS SHOWS THE CENTER OF THE LOW WAS AROUND 1000 MB ABOUT 100 MILES EAST OF THE SOUTHERN DELMARVA COAST. THE COASTAL LOW WILL CONTINUE TO DEEPEN OFF THE MID-ATLANTIC COAST AS IT MOVES QUICKLY NORTHEASTWARD, PASSING JUST EAST OF LONG ISLAND AND CAPE COD THIS EVENING. WIDESPREAD PRECIP CONTINUES OVER THE REGION THIS AFTERNOON. RADAR TRENDS OVER THE PAST COUPLE OF HOURS INDICATES LIGHTER PRECIP RATES, WHICH WAS ASSOCIATED WITH SNOW CHANGING BACK OVER TO RAIN ACROSS THE GREATER I-95 CORRIDOR. THIS IS ALSO IN CONJUNCTION WITH A WARM NOSE IN THE 700-600 MB LAYER TO THE EAST OF THE TRACK OF THE MID-LEVEL LOW. SNOWFALL AMOUNTS WERE ALREADY CUT DOWN FOR THESE I-95 ZONES, WHERE A WINTER WEATHER ADVISORY REMAINS IN EFFECT THROUGH 10 PM. WE EXPECT LITTLE ADDITIONAL SNOW/SLEET ACCUMULATIONS THIS AFTERNOON FOR THESE AREAS, LIMITING THE TRAVEL ISSUES. IT IS A DIFFERENT STORY FARTHER NORTH AND WEST INTO THE HIGHER ELEVATIONS OF EASTERN PA AND NORTHWEST NJ, WHERE A WINTER STORM WARNING CONTINUES UNTIL 10 PM. WE HAVE ALREADY RECEIVED REPORTS OF 4-8 INCHES IN THESE AREAS, WITH AN ADDITIONAL 1-3 INCHES POSSIBLE. CURRENT FORECAST AMOUNTS AREA WIDE MAY BE A BIT ON THE HIGH SIDE, BUT DID NOT WANT TO CUT DOWN ON TOTALS TOO MUCH WITH THE DEFORMATION BAND YET TO MOVE THROUGH. WE WILL LIKELY BE ABLE TO CANCEL WINTER HEADLINES FROM SOUTH TO NORTH A FEW HOURS EARLIER. PRECIPITATION WILL END FROM SOUTH TO NORTH THIS EVENING. TEMPERATURES WILL REMAIN STEADY OR MAY EVEN RISE A BIT THIS EVENING ONCE THE PRECIPITATION ENDS. DO NOT EXPECT TEMPERATURES TO FALL MORE THAN A FEW DEGREES OVERNIGHT AS CLOUDS LINGER ACROSS THE AREA. && .SHORT TERM /THURSDAY/... THE COASTAL LOW THAT IS IMPACTING THE AREA TODAY WILL TRACK NORTHEASTWARD INTO THE CANADIAN MARITIMES ON THURSDAY. THE TRAILING SURFACE TROUGH/COLD FRONT IS FORECAST TO MOVE OFF THE NJ COAST AND THROUGH THE DELMARVA. THE 12Z GFS AND ECMWF HINT AT A WEAK WAVE OF LOW PRESSURE DEVELOPING ON THE LEE SIDE OF THE BLUE RIDGE MOUNTAINS BY 12Z THURSDAY. THIS LOW WOULD THEN MOVE EAST-NORTHEAST OFF THE NC COAST DURING THE AFTERNOON. A FEW SHOWERS NORTH OF THIS LOW MAY BRUSH THE DELMARVA DURING THE DAY. BOUNDARY LAYER THERMAL PROFILES MARGINALLY SUPPORTIVE OF A SNOW PERHAPS MIXING IN WITH THE RAIN BUT NO ACCUMULATIONS EXPECTED WITH SURFACE TEMPERATURES NEAR 40F. OTHERWISE, CLOUDS WILL LINGER ACROSS THE AREA FOR MOST OF THE DAY WITH THE UPPER TROUGH PROGRESSING EASTWARD ACROSS THE MID ATLANTIC AND NORTHEAST STATES. USED A BLEND OF THE MAV/MET GUIDANCE FOR TEMPS, GIVING US HIGHS IN THE 30S FROM I-95 WEST AND LOWER 40S TO THE EAST. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... THURSDAY NIGHT IS EXPECTED TO BE DRY, WITH THE EXCEPTION OF A FEW LAKE EFFECT SNOW SHOWERS THAT MAY MAKE THEIR WAY ACROSS OUR NORTHERN AREAS. THEY WOULD BE QUITE ISOLATED, SO WE ONLY CARRY 20 POPS. ON FRIDAY, HIGH PRESSURE BEGINS TO BUILD ACROSS THE EAST COAST, BEFORE SQUEEZING TO OUR SOUTH AND EAST BY SATURDAY NIGHT. MODEL GUIDANCE IS INDICATING A COUPLE OF SHORT WAVE/VORTICITY IMPULSES SLIDING ACROSS THE AREA, ALONG WITH AN INCREASE IN MOISTURE ALOFT ACROSS THE NORTHERN AREAS. THERE IS SOME TIMING DIFFERENCES, BUT WE WILL KEEP A SLIGHT CHANCE OF SHOWERS ACROSS OUR NORTHWESTERN ZONES WHERE THEY HAVE A BETTER CHANCE OF SQUEEZING OUT SOME MOISTURE. ANYTHING THAT WOULD FALL IS EXPECTED TO BE LIGHT. ON SUNDAY, WE WILL BE IN BETWEEN THE HIGH TO OUR EAST AND AN APPROACHING COLD FRONT. ANOTHER WEAK SHORT WAVE/VORTICITY IMPULSE AND MOISTURE PLUME ALOFT SPREAD ACROSS THE NORTHERN HALF OF THE AREA SUNDAY, SO THERE REMAINS A SLIGHT CHANCE OF SHOWERS SUNDAY. A FRONTAL BOUNDARY IS EXPECTED TO APPROACH THE AREA SUNDAY NIGHT INTO MONDAY. THERE IS SOME DIFFERENCES WITH THIS BOUNDARY AS THE GFS IS FAST THAN THE ECMWF AND CANADIAN, AND DRIES THE PRECIP OUT SIMILAR TO THE CANADIAN, BUT UNLIKE THE ECMWF WHICH KEEPS SOME LIGHT PRECIP ACROSS THE AREA. WE WILL CONTINUE WITH CHANCE/SLIGHT CHANCE POPS, WITH THE HIGHEST ACROSS THE NORTHERN AND WESTERN AREAS WHERE THE PRECIP WOULD IMPACT FIRST BEFORE DRYING OUT. THE FRONT SHOULD PUSH TO OUR SOUTH AS HIGH PRESSURE BUILDS ACROSS THE NORTHEAST TUESDAY, BUT THERE COULD BE SOME LIGHT PRECIP THAT LINGERS ACROSS THE SOUTHERN AREAS IF THE FRONT STALLS CLOSER TO THE AREA. ANOTHER FRONTAL BOUNDARY IS EXPECTED TO AFFECT THE AREA AROUND NEXT WEDNESDAY. HOWEVER, THERE IS A QUESTION OF WHETHER THE FRONT SURGES THROUGH LIKE THE ECMWF, OR GETTING HUNG UP TO OUR NORTH LIKE THE GFS. WE WILL INTRODUCE A CHANCE/SLIGHT CHANCE OF POPS ACROSS THE AREA AS BOTH ARE SHOWING THE POTENTIAL FOR PRECIP. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THIS AFTERNOON - THIS EVENING...IFR TO LIFR CONDITIONS ARE EXPECTED THIS AFTERNOON WITH MULTIPLE PRECIPITATION TYPES. RDG AND ABE WILL BE THE ONLY SITES TO REMAIN SNOW THROUGHOUT THE AFTERNOON WHILE ILG/PHL/TTN/PNE WILL BOUNCE AROUND QUITE A BIT BETWEEN RAIN/SNOW...ACY/MIV SHOULD REMAIN MOSTLY RAIN. EXPECTING A HEAVIER BAND OF PRECIPITATION TO MOVE IN FROM THE SOUTHWEST THIS AFTERNOON WHICH COULD ALLOW FOR MODERATE TO HEAVY SNOW UP THE I-95 CORRIDOR, THOUGH IT SHOULD BE RATHER SHORT LIVED. GUSTY NORTHERLY WINDS, UPWARDS OF 30 KNOTS, ARE EXPECTED. TONIGHT...IFR TRENDING TO MVFR AND POSSIBLY VFR LATE. LATER THIS EVENING WE SHOULD SEE THE PRECIPITATION BEGIN TO SLOW DOWN AS THE SURFACE LOW MOVES TO OUR NORTHEAST. THERE IS A CHANCE THAT WE COULD SEE ANOTHER CHANGE OVER TO A LIGHT RAIN/DRIZZLE AS WELL WHICH SHOULD HELP TO IMPROVE CONDITIONS A BIT...WINDS BACK TOWARDS THE NORTHWEST LATE. TOMORROW...VFR CONDITIONS EXPECTED. WINDS TURN MORE WESTERLY WITH MOSTLY DRY CONDITIONS EXPECTED. COULD BE SOME ISOLATED SHOWERS AT ILG/MIV/ACY DURING THE AFTERNOON HOURS. OUTLOOK... THURSDAY NIGHT...MOSTLY VFR. FRIDAY-MONDAY...MOSTLY VFR. WIND GUSTS 15-20 KNOTS EACH DAY; NW FRIDAY, SW SATURDAY & SUNDAY, AND NW ON MONDAY. && .MARINE... GALE WARNING REMAINS IN EFFECT FOR THE ATLANTIC WATERS THROUGH 10 PM WITH WINDS 30-35 KT. INCREASED SEAS TO 7-12 FT AS WELL. BUOY 44009 IS REPORTING 11 FT WAVES. THERE IS ALSO A POTENTIAL FOR A FEW HIGHER GUSTS IN EXCESS OF 40 KT LATE THIS AFTERNOON IN THE FAR EASTERN PART OF ATLANTIC WATERS IF A GRAVITY WAVE MOVES CLOSE ENOUGH TO THE COAST. WINDS SHOULD DIMINISH BY MIDNIGHT, BUT SEAS WILL LIKELY REMAIN ABOVE 5 FT ON THE COASTAL WATERS OVERNIGHT. THUS, ONCE WINDS DROP BELOW GALE CONDITIONS, AN SCA WILL LIKELY BE NEEDED. SUB-SCA CONDITIONS FOR THURSDAY. OUTLOOK... THURSDAY NIGHT...WINDS ARE EXPECTED TO BE BELOW SMALL CRAFT ADVISORY LEVELS, BUT SEAS MAY REMAIN ELEVATED INTO THURSDAY NIGHT. FRIDAY-FRIDAY NIGHT...SUB-SMALL CRAFT ADVISORY CONDITIONS EXPECTED AS HIGH PRESSURE BUILDS OVER THE AREA. SATURDAY-SUNDAY...NEAR SMALL CRAFT ADVISORY CONDITIONS POSSIBLE AS HIGH PRESSURE PUSHES TO OUR SOUTH AND COLD FRONT APPROACHES LATE ON SUNDAY NIGHT. && .CLIMATE... HERE ARE THE DAILY SNOWFALL RECORDS FOR OUR 4 SNOW CLIMATE SITES FOR NOVEMBER 26. ACY - TRACE IN 1977, 1957, 1955 PHL - 6.0 INCHES IN 1898 ILG - 0.1 INCHES IN 1950 ABE - 1.7 INCHES IN 1925. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...WINTER STORM WARNING UNTIL 10 PM EST THIS EVENING FOR PAZ054- 055-060>062-101-103-105. WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR PAZ070-071-102-104-106. NJ...WINTER STORM WARNING UNTIL 10 PM EST THIS EVENING FOR NJZ001- 007>010. WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR NJZ012-015. DE...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR DEZ001. MD...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR MDZ008. MARINE...GALE WARNING UNTIL 10 PM EST THIS EVENING FOR ANZ431-450>455. SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ430. && $$ SYNOPSIS...ROBERTSON NEAR TERM...KLEIN SHORT TERM...KLEIN LONG TERM...ROBERTSON AVIATION...HEAVENER/ROBERTSON MARINE...KLEIN/ROBERTSON CLIMATE...

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