396 FXUS61 KPHI 240434 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1234 AM EDT SUN MAR 24 2013 .SYNOPSIS... HIGH PRESSURE WILL APPROACH FROM THE WEST, REACH THE AREA ON SUNDAY AND THEN MOVE EAST. COMPLEX LOW PRESSURE WILL APPROACH FROM THE SOUTHWEST ON SUNDAY, CONSOLIDATE AS A LOW PRESSURE CENTER OFF THE NORTHERN MID ATLANTIC COAST ON MONDAY AND THEN DEEPEN AND MOVE AWAY FROM THE COAST. HIGH PRESSURE TO OUR WEST WILL STRUGGLE TO BUILD IN THROUGH THE REMAINDER OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... FEW CHANGES NEEDED WITH THE UPDATE. THE SC CLOUDS THAT WERE OVER THE NWRN SECTIONS HAVE RETREATED BACK UP TO THE NY/PA STATE LINE AREA. SOME CI CLOUDS ACROSS VA/WV MAY MOVE NE TONIGHT AND BE ACROSS THE AREA EARLY SUNDAY. MOSTLY CLR SKIES EXPECTED OVERNIGHT. MINS NOT CHANGES MUCH WITH MOSTLY 20S ACROSS THE AREA AND A FEW LOW 30S OVER METRO PHILADELPHIA. WINDS WILL CONTINUE TO DECREASE AND REMAIN LIGHT N/NW OVERNIGHT. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/... NO BIG CHANGES WERE MADE TO THE SUNDAY FORECAST. THE GFS ESPECIALLY PUNCHES A STRONG SHORT WAVE THROUGH THE RIDGE DURING THE DAY. EVEN WITHOUT THAT FEATURE, WOULD EXPECT SOME OF THE HIGHER CLOUDS TO START ARRIVING AS THERE IS NOT MUCH FORECAST RIDGING AND AS THE MODELS WERE INDICATING OFF OF THEIR INITIALIZATION, LESS THAN WHAT THEY THINK. WHILE THE GFS MAY FINALLY HAVE THE FLAVOR OF THE THERMAL FIELD CORRECT, WE ARE THINKING THAT THE CLOUDS MAY GET IN THE WAY OF ITS MOS MAX TEMPS VERIFYING. WE ARE CLOSER TO A STAT GUIDANCE COMPROMISE. EVEN WITH THE DRY MODELS THRU 00Z, THERE ARE ENOUGH FORCING INDICATORS (ISENTROPIC LIFT, ETC.) TO SHOW PRECIPITATION GENERATION. QUESTION IS WHETHER IT CAN MAKE IT TO THE GROUND BECAUSE OF THE INITIALLY DRY AIR MASS. WE LEFT IN THE CHANCE THAT IT MIGHT FAR SW BEFORE 00Z. BECAUSE THE BOUNDARY LAYER WILL BE WARM (MAX TEMPS THERE MID TO UPPER 40S) ANY PCPN THAT DOES MAKE IT BECAUSE IT SHOULD BE LIGHT IS DEPICTED AS RAIN. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... MAIN WEATHER FEATURE OF THIS TIME PERIOD IS THE STRONG UPPER LEVEL STORM AND ASSOCIATED SURFACE LOW COMPLEX WHICH AFFECTS THE REGION IN THE SUNDAY NIGHT THROUGH MONDAY NIGHT TIME-FRAME. AFTER REVIEW OF NEW NUMERICAL GUIDANCE AND COORDINATION WITH NEIGHBORING OFFICES, VERY LITTLE CHANGE WAS MADE TO THE PREVIOUS FORECAST. PER PMDHMD DISCUSSION, LEANED TOWARD 00Z ECMWF ENSEMBLE SOLUTION DURING CRITICAL TIME PERIOD ON MONDAY INTO EARLY MONDAY NIGHT. IF MORE VIGOROUS 12Z NAM SOLUTION COMES CLOSE TO VERIFYING DURING THAT TIME FRAME, THERE WILL BE CONSIDERABLE MORE SNOW THAN CURRENTLY FORECAST. VERY LITTLE CHANGE WAS MADE TO PREVIOUSLY FORECAST TEMPERATURES/WINDS AND PRECIPITATION IN THE SUNDAY NIGHT THROUGH MONDAY NIGHT FRAME. HIGH TEMPS ON MONDAY WERE NUDGED DOWN A DEGREE DUE TO EXPECTED SIGNIFICANT PRECIPITATION/VERTICAL LIFT. WE CONTINUE TO FORECAST AN ADVISORY LEVEL SNOWFALL NORTHWEST OF THE I-95 CORRIDOR (WHERE P-TYPE IS FORECAST TO STAY SNOW THROUGH THE EVENT) AND AND INCH OR LESS FROM THE I-95 CORRIDOR SOUTH (WHERE P-TYPE MAY START AS AND END AS SNOW). THIS CONTINUES TO PRESERVE CONTINUITY AND FITS WELL WITH THE 00Z ECMWF SOLUTION. GIVEN LOWER THAN AVERAGE CONFIDENCE AND A FORECAST FOR ONLY ADVISORY CRITERIA SNOW AMOUNTS, NO WINTER WEATHER HEADLINES ARE ISSUED WITH THIS PACKAGE. WINDS ON LAND WILL START TO PICK UP ON MONDAY AS THE SECONDARY LOW STRENGTHENS OFF THE COAST, BUT WE AREN'T EXPECTING LAND ADVISORY WINDS. WPC LONGER RANGE GUIDANCE WAS INCORPORATED HEAVILY FOR THE TIME PERIOD AFTER THE STORM THROUGH THE REMAINDER OF THE WEEK. GIVEN THE LARGE-SCALE PATTERN WITH NW FLOW AT THE SURFACE AND ALOFT CONTINUING THROUGH THE PERIOD...WE MAINTAINED THE FORECAST OF A FEW SNOW SHOWERS OR FLURRIES IN THE POCONOS THROUGH FRIDAY. TEMPERATURES SHOULD CONTINUE TO BE SOMEWHAT BELOW NORMAL AS WELL THROUGH THE UPCOMING WEEK. CONDITIONS MODERATE A BIT AS WE GO INTO NEXT WEEKEND. && .AVIATION /04Z SUNDAY THROUGH THURSDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. 00Z TAF PACKAGE CONTINUED VFR INCLUDING PHL THRU 00Z MON. SKIES ARE MOSTLY CLR ACROSS THE AREA EARLY TONIGHT. ONLY A FEW SC FAR N/NW OVERNIGHT AND SOME CI APPROACHING TOWARD DAWN. WINDS MOSTLY LIGHT FROM THE NW/N OVERNIGHT. ON SUNDAY MORNING THE FIRST CLOUDS ASSOCIATED WITH THE NEXT SYSTEM WILL START ARRIVING AT THE CIRRUS LEVEL. WINDS SHOULD BE FROM THE NORTH AND MIGHT SHIFT TO THE EAST AT KACY BEFORE THE TAF FORECAST PERIOD ENDS. OUTLOOK... SUNDAY NIGHT...CONDITIONS EXPECTED TO LOWER SUNDAY NIGHT WITH POSSIBLE RAIN/SNOW. CONFIDENCE IS MODERATE. MONDAY...LIKELY IFR CONDITIONS WITH AREAS OF RAIN/SNOW. BRISK BUT SUB-ADVISORY NORTHEAST WINDS EXPECTED. CONFIDENCE IS MODERATE. TUESDAY...GENERALLY VFR CONDITIONS BUT POSSIBLY MVFR AT TIMES. CONFIDENCE IS MODERATE. WEDNESDAY...VFR CONDITIONS BUT NORTHWEST WINDS POSSIBLY GUSTING 20 TO 25 KT. CONFIDENCE IS MODERATE. && .MARINE... SCA WIND GUSTS WERE STILL OCCURRING AT 44065 AT MIDNIGHT. THE SCA FLAG HAS THEREFORE BEEN EXTENDED FOR ANZ450 UNTIL 6AM THIS MORNING. THIS IS ALSO SUPPORTED BY NEARBY WEATHERFLOW OBSERVATIONS ALONG THE MONMOUTH COUNTY COAST. FARTHER SOUTH FOR ANZ451, WIND GUSTS LOOK TO HAVE DIMINISHED BELOW SCA LEVELS, AND THE SMALL CRAFT ADVISORY WAS ALLOWED TO EXPIRE AT MIDNIGHT. THE PRESSURE GRADIENT WILL CONTINUE TO WEAKEN OVERNIGHT AND THE EXTENSION IS CLOSEST TO THE WRF-NMMB TIMING OF WHEN WINDS ARE FORECAST TO DROP BELOW SMALL CRAFT ADVISORY CRITERIA. THE HIGH PRESSURE SYSTEM WILL BRIEFLY BUILD OVER OUR AREA WATERS ON SUNDAY. WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA THROUGH THE DAY ON SUNDAY. OUTLOOK... LOW PRESSURE WILL BE DEVELOPING OFF THE NORTH CAROLINA COAST SUNDAY NIGHT AND MOVE TO EAST OF THE DELMARVA COAST ON MONDAY. THE INTENSIFYING LOW WILL RESULT IN INCREASING NE WINDS AND ROUGH SEAS WITH POSSIBLE GALE CONDITIONS DEVELOPING, CENTERED ON MONDAY AND MONDAY NIGHT. ADVISORY CONDITIONS MAY BE THE RULE RATHER THAN THE EXCEPTION AFTER THAT AS SEAS WILL BE SLOW TO SUBSIDE AND A GUSTY NW WIND SHOULD DEVELOP THROUGH WEDNESDAY. && .TIDES/COASTAL FLOODING... THERE IS THE THREAT OF MINOR COASTAL FLOODING AT THE TIMES OF HIGH TIDE FOR THE ATLANTIC COASTS OF NEW JERSEY AND DELAWARE, THE RARITAN BAY, AND THE LOWER DELAWARE BAY WITH THE UPCOMING COASTAL STORM. THE HIGH TIDES TO WATCH ARE THE ONES MONDAY EVENING AND AGAIN TUESDAY MORNING. NO COASTAL FLOODING THREAT IS CURRENTLY EXPECTED ON THE UPPER DELAWARE BAY, AS WELL AS THE CHESAPEAKE BAY. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR ANZ450. && $$ SYNOPSIS...SZATKOWSKI NEAR TERM...O'HARA SHORT TERM...GIGI LONG TERM...SZATKOWSKI AVIATION...GIGI/SZATKOWSKI MARINE...GIGI/SZATKOWSKI/KLINE TIDES/COASTAL FLOODING...