Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 250126 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 926 PM EDT THU JUL 24 2014 .SYNOPSIS... SURFACE HIGH PRESSURE WILL CONTINUE TO MOVE INTO THE REGION THROUGH TOMORROW BEFORE MOVING OFFSHORE ON SATURDAY. A WARM FRONT CROSSES THE REGION LATE ON SATURDAY WHILE THE PARENT LOW PRESSURE SYSTEM MOVES THROUGH THE GREAT LAKES. THE ATTENDANT COLD FRONT SWINGS THROUGH LATE ON SUNDAY INTO MONDAY FOLLOWED BY ANOTHER HIGH PRESSURE SYSTEM. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... FOR THE 930 PM EDT UPDATE...SEA BREEZE DID RECENTLY ARRIVE AT KACY. AS SUCH, THERE IS A MOIST POOL RIGHT ALONG THE COAST. DO NOT EXPECT THIS TO LAST LONG AS THE SEA BREEZE SHOULD DISSIPATE OVER THE NEXT FEW HOURS. OTHERWISE...NO MAJOR CHANGES AS THE FORECAST LOOKS ON TRACK. PREVIOUS NEAR TERM DISCUSSION...THE GFS INITIALIZATION LOOKED SLIGHTLY BETTER THAN THE WRF-NMMB AT MOST LEVELS, BUT THE OP RUN LOOKS A BIT ON THE WARM SIDE VS THE GEFS AND OP WRF-NMMB. THROUGH THE SHORT TERM, WE WILL IRON THE DIFFERENCES. THE 500MB TROF AXIS HAS STILL TO MOVE ENTIRELY THROUGH OUR CWA. PCPN ALONG THE WV/VA BORDER WILL COME CLOSE TO OUR SRN CWA AND WE MAINTAINED A LOW CHANCE OF SHOWERS THERE INTO EARLY THIS EVENING. OTHERWISE THE BATCH OF CAA CU (ODD TO TYPE THAT IN JULY) DONT LOOK WIDESPREAD OR DESTINED TO GET TRAPPED UNDERNEATH THE DEVELOPING SUBSIDENCE INVERSION. ONCE THE CIRRUS FROM THE CONVECTION MOVE THROUGH, THE SECOND HALF OF THE NIGHT SHOULD BE CLEARER. DONT SEE HOW THE WRF-NMMB HANGING ON SOLUTION WILL COME TO FRUITION, ESPECIALLY GEOGRAPHICALLY WHERE THE MODEL HAS IT (THE LESS LIKELY COAST). ANOTHER DRY AIR MASS WITH PLEASANT SLEEPING CONDITIONS. MAYBE SOMEONE WILL HAVE TO CLOSE THE WINDOWS IN OUR FAR NWRN CWA BECAUSE ITS TOO COOL OUTSIDE? MIN TEMPS ARE A NAM/GFS MOS BLEND. RECORD LOW TEMPS APPEAR SAFE WITH RDG (52 IN 1903) AND ABE (51 IN 1963) THE MOST LIKELY CLIMATE SITES TO COME CLOSE. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... WITH THE TROF AXIS THROUGH AND A MORE ZONAL FLOW ALOFT, NOT EXPECTING TOO MANY FAIR WEATHER CUMULUS CLOUDS OR ANY OTHER CLOUDS ON FRIDAY. THE SURFACE HIGH WILL BE NEAR/OVER OUR CWA. WITH LESS OF AN OFFSHORE FLOW AND HIGHER TEMPS, SEA AND BAY BREEZE FRONTS SHOULD FORM FASTER. MAX TEMPS ARE ABOUT 10-11C ABOVE THE MODEL BLEND COMBINED 925MB PREDICTED TEMPS. THIS IS CLOSE AGAIN TO A NAM AND GFS MOS BLEND. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... OVERALL THE MEDIUM RANGE GUIDANCE SHOWS A GOOD CONSENSUS WITH THE MID-LEVEL FEATURES THROUGH EARLY NEXT WORK WEEK. THE TROUGH CURRENTLY ACROSS THE EAST COAST FLATTENS WITH TIME BEFORE A VERY STRONG SHORTWAVE DIVES OUT OF THE UPPER MID-WEST. THIS WAVE WILL CARVE OUT A MUCH DEEPER TROUGH BY THE END OF THE OF THE WEEKEND ACROSS THE EASTERN U.S. BEYOND TUESDAY GUIDANCE BEGINS TO SEPARATE WITH RESPECT TO THE TIMING OF THE TROUGH RETROGRADING. SATURDAY...OVER THE PAST SEVERAL DAYS THE GUIDANCE HAS BECOME MURKIER AND MURKIER WITH THE POSSIBILITY OF SHOWERS DURING THE AFTERNOON/EVENING HOURS. TODAY IS NO DIFFERENT THOUGH IT SHOULD BE NOTED THAT A MAJORITY OF THE OPERATIONAL SUITES REALLY PUMP UP SURFACE DEWPOINTS, SOME INTO THE LOW-70S. THE FLOW ALOFT LOOKS SLIGHTLY LESS ZONAL THAN THE PAST COUPLE OF RUNS, WITH AN EMBEDDED WEAK SHORTWAVE, ACROSS THE BOARD AND THE ENSEMBLE GUIDANCE KEEPS THE NOISE DIRECTLY OVERHEAD OUR REGION...LESS CONFIDENCE. ONE WOULD THINK THAT IT WOULD TAKE A BIT LONGER THAN 24 HOURS TO COMPLETELY MODIFY THE AIRMASS FROM THE 50S TO THE 70S AND WITH WARMING TEMPERATURES WE SHOULD HAVE A BETTER CAP IN PLACE, PLUS BETTER MIXING. ALL THAT BEING SAID, WE KEEP THE SLIGHT CHANCE POPS IN PLACE WITH DAYTIME HIGHS REACHING INTO THE UPPER-80S. SUNDAY - MONDAY...STRONGER PIECE OF MID-LEVEL ENERGY DIVES OUT OF THE UPPER MID-WEST EARLY SUNDAY MORNING AND BEGINS TO CARVE A MORE DEFINED TROUGH ACROSS THE EASTERN U.S. MULTIPLE WAVES EMBEDDED WITHIN THE MEAN SOUTHWESTERLY FLOW ALOFT SWING THROUGH, TIMING OF THE WAVES IS STILL UNCERTAIN BUT GETTING BETTER, TOUCHING OFF SHOWERS AND THUNDERSTORMS...VERY UNSETTLED PATTERN EXPECTED. PERIODS OF HEAVY RAIN IS POSSIBLE WITH UPPER LEVEL JET DYNAMICS AIDING IN LARGE SCALE ASCENT AND THE APPROACH OF SURFACE COLD FRONT LATE SUNDAY NIGHT, TIED TO A SURFACE LOW PRESSURE IN SOUTHERN QUEBEC. NO MATTER HOW YOU DICE IT, UNSETTLED WEATHER PREVAILS. TEMPERATURES SHOULD END UP BEING AT OR SLIGHTLY ABOVE NORMAL. TUESDAY - THURSDAY...DRYING TREND SHOULD CONTINUE ACROSS A MAJORITY OF THE REGION, BUT WITH THE MID-LEVEL TROUGH/COLD POOL ALOFT, AND THE SLIGHTEST HINT OF INSTABILITY AROUND, ISOLATED SHOWERS ARE POSSIBLE ON TUESDAY...BETTER FURTHER NORTH. THE CHANCES FOR SHOWERS DECREASES EACH AFTERNOON THEREAFTER. TEMPERATURES SHOULD END UP BEING BELOW NORMAL FOR LATE JULY STANDARDS. && .AVIATION /01Z FRIDAY THROUGH TUESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. FOR THE 00Z TAFS...VFR CONDITIONS EXPECTED THROUGH OUT THE TAF PERIOD. FEW IF ANY CLOUDS EXPECTED. SEA BREEZE AT KACY NOW SHOULD DISSIPATE IN THE NEXT FEW HOURS. ON FRIDAY A VFR DAY WITH JUST FEW MID LEVEL CUMULUS. A SEA BREEZE FRONT SHOULD FORM AGAIN AND WITH HIGHER TEMPS FASTER, MAKE ITS WAY TO KACY BY 18Z AND KMIV A FEW HOURS LATER. LESS CONFIDENT THAT IT WILL MAKE IT TO KPHL OR KILG LATER IN THE AFTERNOON, SO NOT INCLUDED IN THIS TAF. OUTLOOK... SATURDAY...MAINLY VFR. ISOLATED SHOWERS POSSIBLE WEST...CONFIDENCE IS LOW ON SHOWERS. GUSTY SOUTHWEST WINDS POSSIBLE. SUNDAY - MONDAY...SUB-VFR CONDITIONS EXPECTED IN AREAS OF SHOWERS AND THUNDERSTORMS. TUESDAY...VFR. && .MARINE... NO MARINE HEADLINES THROUGH THE SHORT TERM. THE FLOW BEHIND A WEAK SEA BREEZE FRONT IS GOING TO CAUSE SOME VARIABLE WIND DIRECTIONS INTO THIS EVENING BEFORE THE NORTH TO NORTHWEST FLOW RESUMES. A MORE PRONOUNCED SEA AND BAY BREEZE ARE EXPECTED TO FORM ON FRIDAY AFTERNOON WITH A SLIGHTLY STRONGER ONSHORE AND UP THE DELAWARE BAY WIND OCCURRING. OUTLOOK... SATURDAY...HIGH PRESSURE OVERHEAD WILL KEEP SEAS AND WINDS BELOW SCA CRITERIA. SUNDAY...SUB-SCA EXPECTED WITH SCATTERED SHOWERS AND THUNDERSTORMS. MONDAY...SEAS MAY BUILD TO SCA LEVELS UNDER A STRENGTHENING SOUTHWEST SURFACE FLOW. TUESDAY...SUB-SCA CONDITIONS EXPECTED. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...HEAVENER/JOHNSON NEAR TERM...GAINES/GIGI SHORT TERM...GIGI LONG TERM...HEAVENER AVIATION...GIGI/HEAVENER/JOHNSON MARINE...GIGI/HEAVENER

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