Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 182334 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 734 PM EDT FRI APR 18 2014 .SYNOPSIS... A DISSIPATING FRONTAL BOUNDARY WILL MOVES ACROSS THE REGION TONIGHT AND INTO THE FIRST HALF OF SATURDAY. SURFACE HIGH PRESSURE WILL BUILD ACROSS EASTERN CANADA DOWN THROUGH THE NORTHERN MID-ATLANTIC ON SATURDAY AFTERNOON. THE HIGH WILL SHIFT TO THE EASTERN SEABOARD SUNDAY THROUGH MONDAY. ANOTHER FRONTAL BOUNDARY IS THEN EXPECTED TO AFFECT THE AREA NEXT TUESDAY OR WEDNESDAY, FOLLOWED BY HIGH PRESSURE THURSDAY INTO FRIDAY. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... THE WRF-NMMB INITIALIZATION WAS BETTER AT 500MB, BOTH THE WRF AND GFS ABOUT THE SAME AT 850MB AND THE GFS BETTER AT 925MB. OVERALL NOT THAT GREAT A DIFFERENCE TO SHOW MODELING IMPACT DIFFERENCES THROUGH THE SHORT TERM. NO HEADLINES FOR TONIGHT. WE DID ADD SOME PATCHY FROST IN THE PINE BARRENS. DEW POINTS AND UNCERTAINTIES TO CLOUD THICKNESSES SHOULD BE LIMITING FACTORS FOR WIDESPREAD FROST. THE STRATOCU LEVEL WINDS ARE IN THE PROCESS OF BECOMING OFFSHORE. COUPLED WITH LOWERING RAP FCST RH LEVELS AT THAT LEVEL TELL US THAT WHAT IS LEFT OF THOSE CLOUDS NEAR THE COAST SHOULD DRIFT OFFSHORE AND HAVE TO FIGHT AN INCREASINGLY WRLY FLOW TO ADVECT BACK. MUCH OF THE CLOUDINESS OVERNIGHT IS CIRRUS BASED. THERE MAY BE SOME DEBRIS STRATOCU FROM THE APPROACHING CDFNT LATER TONIGHT. OVERALL COVERAGE FROM THEM NOT EXPECTED TO BE MUCH. WINDS SHOULD BE LIGHT TONIGHT, SO IF THE CIRRUS THICKNESS WANES, WE MAY BE TOO HIGH WITH MIN TEMPS IN OUTLYING AREAS. DEW POINTS HAVE RESPONDED UPWARD IN THE EAST TO SOUTHERLY FLOW, SO WE DO HAVE A MUCH HIGHER FLOOR THAN WE HAVE HAD THE LAST COUPLE OF NIGHTS FOR MIN TEMPS. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... A DEFORMATION ZONE IS EXPECTED TO DEVELOP NORTH OF THE CLOSING LOW IN DELMARVA ON SATURDAY. THIS SHOULD BE THE CUT-OFF FOR ANY CLOUDINESS FROM THE SOUTHEAST COAST SYSTEM. BY THE MIDDLE OF SATURDAY MORNING CLOUDS SHOULD BE LIMITED TO DELMARVA AND BE CIRRUS. THE AIR MASS BEHIND THE COLD FRONT IS VERY DRY AND CONVECTIVE TEMPS ARE NOT PREDICTED TO BE REACHED. WE SIDED CLOSER TO 850MB FULL SUN MAX TEMP POTENTIAL THAN THE COLDER 925S GIVEN THE PREDICTED MIXING. MAX TEMPS ARE CLOSER TO HIGHER STAT GUIDANCE AND ALSO TOWARD THE FULL SUN SOUNDING FCST MACROS. THE BETTER MIXING WILL ALSO MAKE FOR A BREEZIER DAY, BUT NOT THAT FAR FROM TYPICAL FOR APRIL. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... THE PERIOD BEGINS WITH A SURFACE HIGH TO OUR NORTH AND A SURFACE LOW WELL TO OUR SOUTH. THE CENTER OF THE HIGH IS FORECAST TO MOVE OFF THE MAINE COAST ON SUNDAY. THE AXIS OF THE HIGH GETS STRETCHED ALONG THE EASTERN SEABOARD ON SUNDAY NIGHT. THIS HELPS TO PUSH THE LOW OFF THE CAROLINAS FURTHER OUT TO SEA. ON MONDAY, THE SURFACE HIGH STARTS TO WEAKEN, BUT REMAINS ACROSS THE REGION. ON MONDAY NIGHT, A SURFACE LOW IS FORECAST TO MOVE INTO THE GREAT LAKES AS A COLD FRONT TRACKS THROUGH THE OHIO VALLEY. AS OF NOW, IT LOOKS LIKE THIS COLD FRONT STAYS TO OUR WEST ON TUESDAY AND PASSES THROUGH TUESDAY NIGHT. THE UPPER LOW MOVES THROUGH ON WEDNESDAY. SURFACE HIGH PRESSURE IS FORECAST TO BUILD ONCE AGAIN ON WEDNESDAY NIGHT AND PERSIST AT LEAST THROUGH THURSDAY NIGHT. TEMPERATURES WILL BE SLIGHTLY BELOW NORMAL ON SUNDAY, NEAR NORMAL ON MONDAY, ABOVE NORMAL ON TUESDAY, NEAR NORMAL WEDNESDAY AND THURSDAY, AND ABOVE NORMAL ON FRIDAY. THE ONLY PRECIPITATION EXPECTED DURING THE EXTENDED IS ASSOCIATED WITH THE COLD FRONT ON TUESDAY NIGHT. AS OF NOW, WE WON`T MENTION ANY THUNDER AS THE BEST CAPE AND LI`S ARE SOUTH AND WEST OF THE REGION. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. PREDOMINATELY VFR CONDITIONS WITH THE 00Z TAFS. HIGH CIRRUS CLOUDS EXPECTED THROUGH MUCH OF THE 00Z TAF CYCLE. A SMALL RISK OF MVFR CEILINGS AND MVFR VISIBILITIES AFTER 06Z, BUT THE CHANCE OF THIS HAPPENING IS QUITE REMOTE SO HAVE NOT MENTIONED IT IN THE TAFS FOR NOW. WINDS WILL BE LIGHT...GENERALLY AT OR BELOW 5 KT, AND MAY BE VARIABLE AT TIMES AS THE GENERAL DIRECTION SHIFTS FROM SOUTHEASTERLY TO SOUTHWESTERLY TO NORTHWESTERLY. SATURDAY. A COLD FRONTAL PASSAGE EARLY WITH A BRISKER NORTH TO NORTHWEST WIND EXPECTED WITH PEAK GUSTS NEAR 20 KTS. NOT TOTALLY CONFIDENT ABOUT GUSTINESS, MAY END UP BEING A SUSTAINED 10 TO 15 KT DAY. ANY SEA BREEZE FRONT WOULD FORM IN THE AFTERNOON AND BE CONFINED CLOSE TO THE COAST, INCLUDING KACY. OUTLOOK... SAT NIGHT THRU MON...MOSTLY VFR, BUT WITH A SURFACE HIGH SETTING UP TO THE NORTH, THEN NORTHEAST, SUNDAY INTO SUNDAY NIGHT, WE`LL NEED TO WATCH FOR ANY STRATUS DEVELOPMENT THAT COULD LOWER CEILINGS. MON NIGHT THROUGH WEDNESDAY...MOSTLY VFR WITH SCT SHOWERS LATE TUESDAY AND TUESDAY NIGHT.
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&& .MARINE... WE WILL CONTINUE THE SCA FOR SEAS ON THE OCEAN THROUGH TONIGHT. WAVE WATCH CONTINUES TO BE SLIGHTLY TOO LOW, ALTHOUGH THE GAP IS CLOSING. EARLY THIS EVENING THERE MAY BE AN UP THE DELAWARE BAY WIND MAX, OTHERWISE WINDS TONIGHT WINDS SHOULD BE RELATIVELY LIGHT PRECEDING THE FRONT. ON SATURDAY, WINDS SHOULD START INCREASING BEHIND THE FRONT, BUT THE BETTER MIXING DURING THE DAYTIME WILL BE ON LAND. SEAS ON THE OCEAN SHOULD BE BELOW SMALL CRAFT ADVISORY CRITERIA FOR MOST OF THE DAYTIME HOURS. OUTLOOK... SATURDAY NIGHT...SUB-SCA CONDITIONS. SUNDAY AND SUNDAY NIGHT...SCA CONDITIONS ON THE OCEAN AND POTENTIALLY THE LOWER DELAWARE BAY. MONDAY THRU TUESDAY...SUB-SCA CONDITIONS. TUESDAY NIGHT INTO WEDNESDAY...SCA CONDITIONS. && .FIRE WEATHER... IN NJ AND PA FINE FUELS MOISTURE HAVE FALLEN WITHIN RED FLAG CRITERIA AND MEAN RH(S) ON SATURDAY AFTERNOON SHOULD FALL BELOW 30 PERCENT. BUT WE ARE NOT CONFIDENT ABOUT FREQUENT GUSTS EXCEEDING 20 MPH. WE WILL MAKE MENTION IN THE FIRE WEATHER FORECAST, BUT CONFIDENCE IS TOO LOW TO ISSUE A WATCH. IN DE AND MD, THE POTENTIAL AND CRITERIA FOR STRONGER WINDS DO NOT LOOK LIKE THEY WILL BE REACHED PLUS THE AFTN RH LEVELS MAY ALSO BE MORE MARGINAL. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 AM EDT SATURDAY FOR ANZ450>455. && $$ SYNOPSIS...KRUZDLO NEAR TERM...GIGI SHORT TERM...GIGI LONG TERM...KRUZDLO AVIATION...GIGI/JOHNSON/KRUZDLO MARINE...DRAG/GAINES/GIGI/KRUZDLO FIRE WEATHER...

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