555 FXUS61 KPHI 210454 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1154 PM EST WED FEB 20 2013 .SYNOPSIS... DEEP LOW PRESSURE OVER NEW ENGLAND AND THE CANADIAN MARITIME PROVINCES WILL CONTINUE TO MOVE SLOWLY AWAY TOWARD THE NORTHEAST THROUGH FRIDAY. A RIDGE OF HIGH PRESSURE WILL BUILD IN...REACHING OUR AREA FRIDAY. ANOTHER LOW FROM THE PLAINS WILL MOVE TOWARDS THE GREAT LAKES AREA EARLY THIS WEEKEND. A SECOND LOW WILL DEVELOP TO THE SOUTH ACROSS THE CAROLINAS ON SATURDAY. THIS LOW WILL MOVE NORTHEAST OVER THE WEEKEND. ANOTHER HIGH PRESSURE SYSTEM WILL ARRIVE EARLY NEXT WEEK. && .NEAR TERM /THROUGH THURSDAY/... BLUSTERY NW FLOW WILL INCREASE SPEEDS 5 KTS FROM THAT OF THE THIS OVERNIGHT-EARLY THU MORNING. CLOUDINESS MAINLY IN E PA AND NW NJ THIS OVERNIGHT-EARLY THU MORNING WILL AGAIN SPREAD OUT AND BECOME PREDOMINANT DURING MIDDAY THURSDAY THEN CLEAR LATE THIS AFTN. TEMPS/WINDS WILL PROBABLY BE BLENDED 00Z/21 NCEP MOS. YESTERDAYS NAM WAS INDEED TOO COLD AND THE GFS TOO WARM AND SO THE BLEND WORKED PRETTY WELL. MAX TEMPS RELATIVELY LATE IN THE DAY TODAY...PROBABLY CLOSE TO 330 PM. && .SHORT TERM /THURSDAY NIGHT/... A WSHIFT BOUNDARY FM NW TO N PASSES RAPIDLY SOUTH THROUGH THE AREA EARLY THIS EVENING AND THE WIND SETTLES DOWN ABRUPTLY. IF ANYTHING THAT WSHIFT MAY SIGNAL DRY WAA FROM THE NORTH NEAR 950MB. DIMINISHING WINDS DURING THE NIGHT WITH CIRRUS INCREASING. NOT PERFECT FOR RADIATIONAL COOLING BUT SOME CONSIDERATION. BLENDED 00Z/21 NCEP MOS TEMPS/WINDS. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... HIGH PRESSURE WILL CONTINUE ACROSS THE AREA DURING THE BEGINNING OF THE LONG TERM. DRY WEATHER IS EXPECTED FRIDAY. CLOUDS WILL BE ON THE INCREASE FRIDAY AS THE NEXT SYSTEM APPROACHES. HIGHS ON FRI WILL BE MOSTLY IN THE LOW 40S...A LITTLE BELOW NORMAL. THE NEXT SYSTEM WILL CONSIST OF A DEEP LOW PRESSURE SYSTEM MOVING FROM THE PLAINS INTO THE UPPER GREAT LAKES REGION FRI-SAT. A WARM ADVECTION PATTERN AHEAD OF THE LOW WILL BRING CLOUDS/PCPN TO THE AREA BEGINNING FRI NIGHT. THE AREA OF PCPN WILL BE LIGHT AND DISORGANIZED AS IT ARRIVES...SINCE A SECOND LOW WILL BE DEVELOPING ACROSS THE SOUTH. ANY PCPN THAT ARRIVES OVERNIGHT MAY BEGIN AS SOME LIGHT SNOW OR POSSIBLY SOME MIXED WINTRY PCPN. OVER THE WEEKEND...A MOSTLY RAIN EVENT AS LOW PRESSURE FORMS ALONG THE NC COAST AND MOVES NORTHEAST. THE GREATEST PCPN TOTALS SHOULD BE FROM SAT LATE MORNING THEN OVERNIGHT. THERE MAY BE SOME WARP AROUND PCPN SUNDAY. BY THEN THE TEMPERATURES WILL PROBABLY BE COLD ENOUGH FOR SOME SNOW ACROSS THE HIGHER ELEVATIONS NORTH/WEST. SOME OF THE PCPN SAT NIGHT MAY BE SNOW ACROSS THE SRN POCONOS AND NRN NJ...JUST DEPENDS ON HOW STUBBORN THE COLD AIR REMAINS ACROSS THESE AREAS. WE HAVE PLACED SOME LIGHT SNOW ACCUMS ACROSS THESE AREAS..WITH 'STORM TOTALS' 2.0 TO 3.5 INCHES ACROSS THESE AREAS FOR THE 24 HR PERIOD ENDING SUNDAY MORNING. SMALL CHANGES IN THE TRACK OF THE SYSTEM MAY CAUSE A READJUSTMENT OF THE TOTALS. HIGH PRESSURE BUILDS BACK IN FOR MONDAY WITH MOSTLY FAIR WEATHER EXPECTED. ANOTHER SYSTEM...SIMILAR IN APPEARANCE TO THE WEEKEND STORM SETS UP FOR THE MIDDLE OF NEXT WEEK. MORE RAIN/SNOW (HIGHER ELEVATIONS) IS FORESEEN. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THROUGH 12Z...VFR CLEAR TO SCT CLOUDS NEAR 4000 FT WITH NW G15-25 KT. EXCEPTION POCONOS WHERE CIGS NEAR 3000 FT AND A CHANCE OF FLURRIES. AFTER 12Z THU...VFR SCT CLOUDS NEAR 4000 FT BECOME WIDESPREAD BKN CIGS NEAR 4000 FT. LESS CHANCE OF FLURRIES THAN YDY...IF ANY MAYBE NE NJ. NW WIND G25-30 KT. THU NIGHT...VFR INCREASING CIRRUS. EVENING WSHIFT FM NW TO N BUT GUSTINESS DECREASES CONSIDERABLY TO NON EXISTENT BY 06Z. OUTLOOK... FRIDAY...VFR WITH LOWERING CIGS. FRI NIGHT THROUGH SUNDAY ...SUB-VFR WITH LOW CLOUDS AND PCPN. SUN NIGHT THRU MONDAY...MOSTLY VFR. GUSTY WINDS SUNDAY. && .MARINE... PLAN IS TO EXTEND THE GALE WARNING THROUGH 8 PM THIS THURSDAY EVENING IN OUR 330 AM THURSDAY FORECAST PACKAGE. NAM MOMENTUM TRANSFER IS LESS THAN THE GFS BUT BOTH MODELS PULSE UP AGAIN DURING THE DAY WITH MIXING TO NEAR 900 MB AND THE STRONGEST WINDS SHOULD NOT OCCUR UNTIL LATE THURSDAY AFTERNOON...ESPECIALLY DE WATERS. ONCE THE WSHIFT OCCURS FROM NW TO N DURING THU EVENING...THE INVERSION LOWERS AND CUTS OFF THE GUST TRANSFER AND WINDS DIMINISH RAPIDLY THU NIGHT AROUND MIDNIGHT. FREEZING SPRAY...SPOTTY LIGHT THIS MORNING AS PER THE GFE TOOL AND THE GFS MODEL FCST. SO FAR 5 OF OUR 8 GALE WARNED ZONES HAVE VERIFIED WITH GUSTS MOSTLY HOVERING BETWEEN 34-37 KTS THIS PAST WED AFTN/EVENING...MARGINAL BUT AT MANY SENSOR LOCATIONS. THAT WOULD MEAN THE GFS DID A LITTLE BETTER THAN THE NAM IN HIGHLIGHTING THE POTENTIAL FOR 34 KT WIND GUSTS. OUTLOOK... SUB SCA CONDITIONS WILL BE ACROSS THE WATERS FRIDAY INTO EARLY SATURDAY. WINDS AND SEAS WILL INCREASE AHEAD OF THE NEXT SYSTEM WITH A PERIOD OF SCA CONDITIONS EXPECTED SAT AFTERNOON THROUGH SUN NIGHT. LOWERING WINDS/SEAS MONDAY. NEAR BLOWOUT TIDE LEVELS POSSIBLE ALONG NORTHERN DEL BAY AND TIDAL DEL RIVER THU. && .TIDES/COASTAL FLOODING... NO PLANS ATTM TO ISSUE ANY STATEMENTS FOR THE THU AFTN LOW TIDE CYCLE. WE NEED TO SEE WHAT ACTUALLY OCCURS HERE EARLY THIS THURSDAY MORNING. AT AROUND 845 PM EST, REEDY POINT WAS RUNNING WITH A DEPARTURE OF ABOUT 0.6 FT BELOW WHAT IT WOULD TAKE TO CAUSE BLOWOUT TIDES TONIGHT. LOW TIDE OCCURS ON UPPER DELAWARE BAY BETWEEN MIDNIGHT AND 2 AM, AND ALTHOUGH THE MAGNITUDE OF THE DEPARTURE MIGHT DIMINISH WE WANTED TO HAVE SOME LEAD TIME. WE ISSUED A LOW WATER ADVISORY FOR UPPER DELAWARE BAY EARLIER THIS EVENING. AT PHILADELPHIA, THE DEPARTURE HAD REACHED WHAT WOULD BE NECESSARY TO CAUSE BLOWOUT TIDES. WE HAVE ISSUED A SPECIAL WEATHER STATEMENT FOR LOW WATER ON THE TIDAL DELAWARE RIVER. LOW TIDE THERE HAPPENS BETWEEN ABOUT 2 AM AND 7 AM. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...GALE WARNING UNTIL 6 AM EST THURSDAY FOR ANZ430-431-450>455. LOW WATER ADVISORY UNTIL 3 AM EST THURSDAY FOR ANZ430. && $$ SYNOPSIS...O'HARA NEAR TERM...DRAG 1153 SHORT TERM...DRAG/IOVINO 1153 LONG TERM...O'HARA AVIATION...DRAG/O'HARA 1153 MARINE...DRAG/O'HARA 1153 TIDES/COASTAL FLOODING...1153