Expires:No;;761514 FPUS51 KPHI 291911 ZFPPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 310 PM EDT MON SEP 29 2008 .SYNOPSIS... A WEAK HIGH PRESSURE SYSTEM OVER THE AREA WILL MOVE OFFSHORE ON TUESDAY. A STRONG COLD FRONT IS EXPECTED TO APPROACH FROM THE WEST ON TUESDAY NIGHT, AND IT SHOULD PASS THROUGH OUR REGION ON WEDNESDAY. A PAIR OF WEAK SURFACE TROUGHS SHOULD MOVE THROUGH THE AREA WEDNESDAY NIGHT AND AGAIN LATE ON FRIDAY. STRONG HIGH PRESSURE SHOULD THEN BUILD EAST FOR NEXT WEEKEND AND SLIDE OFFSHORE ON MONDAY. && .NEAR TERM /THROUGH TONIGHT/... THE GFS INITIALIZATION LOOKS SLIGHTLY BETTER THAN THE WRF-NMM. ALSO THE WRF-NMM APPEARED TO INITIALIZE THE CNTRL NOAM TROUGH A BIT TOO FAR TO THE WEST AND MAY EXPLAIN WHY IT HAS THE SLOWEST SOLUTION AMONG THE MODEL RUNS TODAY. THIS FCST PACKAGE WILL CONTINUE TO FOLLOW THE GFS SOLUTION WHICH WRT TIMING IS A MIDDLE OF THE PACK SOLUTION BETWEEN THE FASTER CANADIAN MODELS, UKMET AND SLOWEST WRF-NMM. WE WILL GIVE THE WRF-NMM A BIT MORE WEIGHT WRT CLOUDS IN THE FIRST PERIOD AS THE LATEST ACARS SOUNDINGS ARE STILL SHOWING AN INVERSION OVER THE REGION. SC HAS DEVELOPED UNDER IT. FCST SOUNDINGS OVERNIGHT DO NOT TOTALLY DISPT IT, SO WE WILL HANG ON TO THE MENTION OF SOME CLOUDS LONGER. ON THE OTHER HAND, ONCE THE CLOUDS BREAK, ALL THE RECENT HEAVY RAIN SHOULD MAKE IT EASY FOR SOME PATCHY FOG TO FORM AND WE ADDED IT TO OUR "VALLEY" ZONES, WHICH ALSO COINCIDED WITH THE HEAVIER RAIN. GFS MOS LOOKS TOO LOW FOR MIN TEMPS GIVEN CURRENT AND UPWIND DEW POINTS, WILL LEAN CLOSER TO ETA MOS. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... AS MENTIONED ABOVE GOING WITH THE FASTER THAN THE WRF GFS SOLUTION. WITH THAT SCENARIO THERE IS ENOUGH FCST INSTABILITY AND WEAK WAA TO POSSIBLY POP A COUPLE OF SHRAS AND TSRAS DURG TUE AFTN. THE GREATER CHANCE FOR THUNDER WOULD BE IN PA AND MD WHERE THE GREATEST INSTABILITY IS FCST TO OCCUR FIRST. THE WRF-NMM NEVER REALLY LOSES THE LOW LEVEL MOISTURE AND IF CORRECT OUR SKY FCST FOR TUESDAY WILL BE WAY TOO OPTIMISTIC. EVEN SO STAT GUIDANCE IS PRETTY TIGHTLY CLUSTERED WRT MAX TEMPS GIVING A SLIGHT NOD TOWARD ETA MOS BASED ON THE FULL SUN MACROS. WHILE THE WRF-NMM AND GFS ARE IN PRETTY GOOD AGREEMENT WITH THE OVERALL EVOLUTION OF THE UPCOMING SYSTEM, THE TWO MODEL SOLUTIONS ARE ABOUT 6 HRS AND A COUPLE OF DEGREES OF LONGITUDE APART. WE ARE LEANING TOWARD THE GFS SOLUTION BECAUSE IT IS MIDDLE OF THE ROADISH (BOTH CANADIANS AND THE UKMET WOULD HAVE PCPN DONE BEFORE 8 AM WED), THE WWD INITIALIZATION OF THE WRF AND THE TREND OF THE WRF TO BE SLIGHTLY MORE NE WITH THE CLOSED LOW. THE WRF DOES NOT SEPARATE THIS CLOSED LOW WITH THE NEXT ONE DIVING SEWD IN THE TROF. THE FIRST LOW ALMOST GETS FUJI-WARAED AND THUS CARVES A DEEPER TROF AND MORE WAVINESS ALG THE CDFNT. WE BELIEVE THE OTHER MODELS THAT SEPARATE THE TWO AND ARE MORE PROGRESSIVE ARE THE CORRECT WAY TO GO SINCE THAT PHASED SOLUTION DEPENDS ON A CLOSED LOW THAT IS OUTSIDE OF THE WRF'S INITIAL MODEL GRID. THAT IS THE NOT THE CASE WITH THE GLOBAL MODELS. AS FAR AS THE SENSIBLE WEATHER GOES, THERE IS DECENT DPVA AND DIFFLUENCE ALF FCST PRECEDING THE FNT. THERE IS STILL ENUF INSTABILITY ALF TO MAINTAIN OR PRODUCE THUNDER THRU THE NGT. FCST WIND FIELDS AOB 850MB ARE NOT THAT STRONG AND COUPLED WITH THE PCPN INVERSION BELIEVE THIS SHOULD KEEP THE STORMS BLO SEVERE LIMITS. AGREE WITH CURRENT SWODY2 SENT BY SPC. WITH EVERYTHING SAID IN THE PREVIOUS PARAGRAPH, ITS ALWAYS UNCOMFORTABLE FCSTG A FAST CFP WITH THE TROF STILL LINGERING TO OUR W. TO THAT END WE DID SLOW THE GFS SOLUTION DOWN ENUF TO CARRY A MENTION OF PCPN EARLY ON WED MRNG. INSTABILITY ALF WOULD STILL SUPPORT THUNDER IN DE AND NJ EVEN FOLLOWING THE GFS SOLUTION. THERE MAY VERY WELL BE A PCPN LULL IF NOT A DOWNRIGHT BREAK FOR THE REST OF THE DAY AS CWA WILL BE IN DNVA BEFORE THE NEXT FCST SHORT WAVE ARRIVES AT NIGHT. IT IS AMAZING HOW A TOTALLY DIFFERENT MODEL SOLUTION ARRIVES AT SIMILAR MAX TEMPS FOR WED DAY. IN SPITE OF DOWNSLOPING CONTRIBUTIONS OR IF THE FNT ENDS UP BEING AS SLOW AS MOLASSES AND THERE ARE MORE CLOUDS, BOTH THE GFS AND ETA MOS SEEM TOO HIGH. WE WILL TAKE A LITTLE BIT OFF. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... THE LONG WAVE TROUGH IS STILL EXPECTED TO MOVE THROUGH OUR CWA ON WEDNESDAY NIGHT. WE WILL MAINTAIN THE LOW CHC POPS IN ABOUT THE NRN HALF OF OUR REGION IN CONJUNCTION WITH WHERE THE LOWER HEIGHTS OR COLDER AIR ALOFT EXIST. ANOTHER WEAK SURFACE TROUGH REFLECTING ANOTHER TROUGH ALOFT SHOULD MOVE THROUGH FRIDAY AFTERNOON OR NIGHT. ONCE AGAIN IT APPEARS THAT THE NORTHERN PART OF OUR CWA WOULD HAVE THE BEST CHANCE AT SEEING ANY SHOWERS. LIKE WEDNESDAY NIGHT, THEY SHOULD BE FAIRLY LIGHT IF THEY DO OCCUR. SURFACE HIGH PRESSURE SHOULD THEN BUILD EAST IN WAKE OF THE LAST TROUGH AND BRING A COUPLE OF DAYS OF FAIR WEATHER. WE WILL PROBABLY HAVE OUR FIRST FROST OR FREEZE OF THE FALL SEASON IN THE NORTHERN PART OF OUR CWA ON OR BY THE WEEKEND. WITH THE LONG WAVE TROF CENTERED OVER THE EASTERN CONUS TEMPS SHOULD AVERAGE NEAR OR BELOW NORMAL. THE 00Z ECMWF WAS MUCH CHILLIER THAN THE 00Z GFS SUN AND MON AND TEMPS. THE 12Z GFS HAS TRENDED LOWER ALTHOUGH RAIN IS THE REASON FOR MONDAY'S DROP. WE COMPROMISED DOWNWARD FROM THE 00Z GFS RUN, BUT WENT HIGHER THAN THE 12Z GFS MEX MOS FOR MONDAY BASED ON THE GFS BEING TOO FAST WITH ADVECTING THE NEXT SYSTEM EASTWARD. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... WEATHER IS VFR BUT CEILINGS BOUNCING BETWEEN 25 AND 4,500 FT. CONDITIONS TO REMAIN VFR OVERNIGHT. CLOUDS ON VAD WIND PROFILE FROM KDIX TOPPING OFF AT 8,000 FT AND CLEAR ABOVE. HIGH PRESSURE OVER THE REGION TONIGHT WILL SLOWLY MOVE TO THE EAST TUESDAY AFTERNOON. VERY ACTIVE UPPER PATTERN WILL DRIVE A SURFACE FRONT THROUGH TUESDAY NIGHT INTO WEDNESDAY SPREADING PRECIPITATION EAST WITH A COUPLE OF THUNDERSTORMS. THE FRONT MOVES OFFSHORE WEDNESDAY NIGHT WITH A FRESH OFFSHORE FLOW DEVELOPING. CONDITIONS FOR THE MOST PART WILL BE VFR POST FRONTAL BUT THERE WILL BE SOME INSTABILITY SHOWERS ON FRIDAY. THE UPPER FLOW TO REMAIN CYCLONIC FOR MUCH OF THE WEEK WITH SOME COLD AIR ADVECTION AND FROM TIME TO TIME SOME LIGHT SHOWERS. && .MARINE... IT HAS BEEN A ROUGH STRETCH OF MARINE WEATHER FOR ABOUT A WEEK. BUT SOME FAVORABLE WINDS/SEAS ON THE WAY FOR A COUPLE DAYS. WE'RE STILL GETTING AN OCCASIONAL WAVE BETWEEN 5 AND 6 FEET IN LONG PERIOD SWELLS BECAUSE OF THE DEPARTING HURRICANE AND FRONT MOVING OFFSHORE. IT IS NOT SO MUCH WHAT THE SURFACE WEATHER PATTERNS HOLD BUT WHAT IS HAPPENING ALOFT FOR THIS TIME OF YEAR. OUR WEATHER PATTERN WILL CHANGE AS A STRONG UPPER LOW DIPS SOUTH FROM THE GREAT LAKES BEGINNING TUESDAY. THIS WILL BRING SOME GUSTY WINDS AHEAD OF THE DEVELOPING SURFACE SYSTEM AND THEN COLD AIR WILL MOVE IN BEHIND THE MID LEVEL CLOSED LOW LATE WEDNESDAY INTO THURSDAY. END RESULT COULD BE A RETURN TO SMALL CRAFT ADVISORY CONDITIONS. THE COLD FRONT WILL PUSH THROUGH THURSDAY MORNING AND WE CONTINUE INTO A CYCLONIC FLOW INTO THURSDAY WITH THE COLD AIR SUPPORTING GUSTY OFFSHORE WINDS INTO FRIDAY. RIP CURRENTS STILL NOTICEABLE ON THE NJ BEACHES TODAY AND MAY BE THERE AGAIN ON TUESDAY. THE LAST RIP CURRENT FORECAST WILL BE ISSUED TUESDAY AND RESUME AGAIN AROUND MEMORIAL DAY 2009. HOWEVER...THE WATERS ARE STILL RELATIVELY WARM AND IF YOU ARE THINKING ABOUT GOING IN...DON'T GO IN AT NIGHT AND NEVER ALONE. MOST IF NOT ALL THE RIP CURRENT RELATED DEATHS OCCUR ON UNGUARDED BEACHES OR AT NIGHT. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...GIGI NEAR TERM...GIGI SHORT TERM...GIGI LONG TERM...GIGI AVIATION...EBERWINE MARINE...EBERWINE