Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 192007 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 407 PM EDT TUE AUG 19 2014 .SYNOPSIS... A FRONTAL BOUNDARY WILL REMAIN WELL TO OUR SOUTH AND WEST FOR THE NEXT SEVERAL DAYS. SURFACE LOW PRESSURE AND AN ASSOCIATED LOW ALOFT WILL MOVE SOUTHEASTWARD FROM THE GREAT LAKES ON THURDAY INTO FRIDAY BRINGING A GOOD CHANCE FOR SHOWERS AND A FEW THUNDERSTORMS. A RIDGE OF HIGH PRESSURE WILL THEN BECOME ESTABLISHED OVER THE REGION AND BRING MAINLY FAIR WEATHER FOR THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A RECENT SURFACE ANALYSIS SHOWED WEAK LOW PRESSURE JUST OFF TO THE EAST OF THE SOUTHERN DELMARVA COAST, WITH A LINGERING FRONTAL BOUNDARY EXTENDING BACK THROUGH CENTRAL VIRGINIA AND NORTHERN WEST VIRGINIA. MEANWHILE, WEAK HIGH PRESSURE EXTENDED ACROSS PORTIONS OF NEW ENGLAND AND DOWN INTO NORTHERN PARTS OF PA AND NJ. WITH THIS OVERALL SET-UP, AN EASTERLY, ONSHORE FLOW WILL CONTINUE FOR THE REGION THROUGH THIS EVENING AND TONIGHT. WHILE WE ARE NOT EXPECTING PRECIP THROUGH THIS PERIOD, SOME SCT TO BKN CLOUDS WILL REMAIN FOR OUR AREA, THICKEST ACROSS OUR WESTERN ZONES, DUE TO THE PROXIMITY OF A LOW LEVEL THETA-E RIDGE EXTENDING ACROSS CENTRAL PA AND THE LINGERING FRONTAL BOUNDARY OFF TO THE SOUTHWEST. ANOTHER AREA TO WATCH FOR POSSIBLE LOWER CLOUDS OR EVEN SOME FOG WILL BE AREAS ALONG THE NJ AND DE COASTS DUE TO THE PERSISTENT ONSHORE FLOW. WHILE MODEL GUIDANCE IS NOT INDICATING A STRONG POTENTIAL FOR THIS TO OCCUR AT THIS TIME, THIS IS A RATHER FAVORABLE PATTERN FOR POSSIBLE STRATUS/FOG DEVELOPMENT. IN ADDITION, SOME PATCHY FOG WAS INCLUDED IN THE FORECAST FOR THE MORE OUTLYING AREAS AND THE RIVER VALLEYS IN THE HOURS LEADING UP TO DAYBREAK WEDNESDAY. WITH REGARDS TO MINIMUM TEMPERATURES, WE MOSTLY BLENDED THE SLIGHTLY MILDER MAV GUIDANCE WITH CONTINUITY ACROSS THE FORECAST AREA AND EXPECT LOW TEMPERATURES TO MAINLY BE IN THE 60S. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/... THE EASTERLY, ONSHORE FLOW IS FORECAST TO CONTINUE ACROSS THE REGION THROUGH WEDNESDAY AS WEAK LOW PRESSURE WILL SLOWLY EDGE FARTHER EAST AND AWAY FROM THE COAST, WITH WEAK HIGH PRESSURE REMAINING SITUATED ACROSS PORTIONS OF NEW ENGLAND. THE NEXT FEATURE OF INTEREST WILL BE A MID-LEVEL SHORTWAVE PROGRESSING EASTWARD FROM THE LOWER GREAT LAKES/UPPER OHIO VALLEY REGION ACROSS CENTRAL PA THROUGH THE DAYTIME WEDNESDAY. THERE IS FAIRLY GOOD MODEL AGREEMENT BETWEEN THE GFS, NAM, AND ECMWF WITH REGARDS TO THIS SHORTWAVE REMAINING OFF TO OUR WEST THROUGH THE DAYTIME AND THUS HOLDING MOST PRECIP CHANCES FOR OUR WESTERN ZONES UNTIL LATER WEDNESDAY EVENING/NIGHT, AND WE HAVE ONLY SOME LOW POPS FOR ISOLATED ACTIVITY INTO THE EVENING. FOR HIGH TEMPERATURES WEDNESDAY, WE MAINLY TOOK A MET/MAV BLEND, BUT THEN EDGED MAX TEMPERATURES DOWN A DEGREE OR TWO ALONG THE COAST WITH THE PERSISTENT ONSHORE FLOW. MAXIMUM TEMPERATURES SHOULD MOSTLY RANGE FROM THE UPPER 70S ALONG THE COAST AND IN THE SOUTHERN POCONOS TO THE LOWER 80S ELSEWHERE. && .LONG TERM /WEDNESDAY THROUGH TUESDAY/... AN OVERALL RATHER BENIGN AUGUST WEATHER PATTERN WILL CONTINUE FOR THE MID-ATLANTIC REGION FOR THE NEXT SEVERAL DAYS. AN UPPER LOW NOW OVER THE WESTERN GRTLKS IS FORECAST TO WEAKEN AS IT MOVES SOUTHEAST ACROSS THE LOWER GRTLKS AND NY STATE DURING THURSDAY AND FRIDAY...THEN REDEVELOPING SOMEWHAT EAST OF NEW ENGLAND OVER THE WEEKEND. MEANWHILE AN UPPER LEVEL RIDGE IS FORECAST TO BUILD OVER THE MS VALLEY...RESULTING IN CONFLUENT/SUBSIDENT FLOW OVER THE REGION FOR MOST OF THE WEEKEND INTO EARLY NEXT WEEK. AS THE UPPER LOW/TROF MOVE BY ON THU/FRI...THERE IS SOME FORCING FOR UVV ALONG WITH INCREASING PW AND MODEST INSTBY. THUS A PERIOD OF SHOWERS/TSTMS IS EXPECTED WITH HIGHEST POPS LATE THU AND THU NIGHT. THE CHC POPS CONTINUE INTO FRI ALTHOUGH INSTBY SEEMS MARGINAL AT THAT TIME. FOR THE WEEKEND A SURFACE HIGH PRESSURE RIDGE IS EXPECTED TO BUILD OVER NEW ENGLAND...RESULTING IN A SOMEWHAT COOLER AND DRIER FLOW INTO THE MID-ATLANTIC REGION. MAX/MIN TEMPS THROUGH THE PERIOD ARE FORECAST TO REMAIN WITHIN A FEW DEGREES OF NORMAL. && .AVIATION /20Z TUESDAY THROUGH SUNDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THROUGH THIS EVENING/TONIGHT...MAINLY VFR CONDITIONS. SCATTERED CUMULUS/STRATOCU EXPECTED WITH BASES AROUND 4,000 TO 5,000 FEET. MAINLY EASTERLY WINDS WILL PREVAIL IN THE 5 TO 9 KT RANGE THROUGH THIS EVENING, THEN BECOMING UNDER 5 KT FOR THE OVERNIGHT, WITH SOME SITES BECOMING LIGHT AND VARIABLE. WITH THE CONTINUED ONSHORE FLOW, THERE IS SOME POSSIBILITY FOR SOME LOWER STRATUS AND/OR PATCHY FOG TO FORM FOR OUR SOUTHEASTERN SITES, NAMELY KMIV AND KACY. ALSO SOME BRIEF MVFR VSBY RESTRICTIONS MAY BE POSSIBLE IN PATCHY FOG FOR SOME OUTLYING WESTERN AREAS, INCLUDING KRDG, LEADING UP TO DAYBREAK WEDNESDAY. WEDNESDAY...POSSIBLE MVFR VSBYS AND/OR CIGS TO START THE DAY FOR OUR SOUTHEASTERN TAF SITES, NAMELY KMIV AND KACY. OTHERWISE, MAINLY VFR CONDITIONS ELSEWHERE IN THE MORNING AND THROUGH THE DAYTIME. AN OVERALL EASTERLY TO EAST-SOUTHEAST FLOW IS EXPECTED THROUGH THE DAY, WITH SPEEDS MAINLY IN THE 5 TO 8 KNOT RANGE. OUTLOOK... WEDNESDAY NIGHT THROUGH FRIDAY...CHANCE FOR SHRA/TSRA AS A SERIES OF DISTURBANCES MOVE THRU THE REGION. LOCAL/TEMPORARY FLIGHT MVFR RESTRICTIONS POSSIBLE. WINDS MAINLY EAST TO SOUTHEAST. FRIDAY NIGHT THROUGH SUNDAY...PREDOMINATELY VFR CONDITIONS WITH NORTHEAST WINDS. && .MARINE... AN OVERALL EASTERLY TO EAST-SOUTHEAST FLOW IS EXPECTED TO CONTINUE ACROSS OUR COASTAL WATERS AND DELAWARE BAY TONIGHT THROUGH WEDNESDAY. WIND SPEEDS WILL MOSTLY BE IN THE 10 TO 20 KNOT RANGE FOR OUR WATERS THROUGH THIS PERIOD, STRONGEST FOR OUR SOUTHERN COASTAL WATERS, AND IN GENERAL, THE WINDS WILL TEND TO DECREASE SOME DURING THE OVERNIGHT AND INTO EARLY WEDNESDAY AS WEAK LOW PRESSURE MOVES FARTHER EAST AND OFFSHORE. SEAS WILL MOSTLY BE IN THE 2 TO 4 FOOT RANGE FOR THE COASTAL WATERS TONIGHT THROUGH WEDNESDAY, WITH 1 TO 3 FOOT SEAS FOR DELAWARE BAY. OUTLOOK... THURSDAY THROUGH FRIDAY... NO SCA FLAGS EXPECTED WITH WINDS/SEAS BELOW THRESHOLDS. HOWEVER... LOCALLY ROUGH CONDS ARE POSSIBLE IN SCATTERED SHOWERS AND THUNDERSTORMS. SATURDAY AND SUNDAY... A PERSISTENT NORTHEAST FLOW WILL LIKELY RESULT IN BUILDING SEAS AND GUSTY WINDS. MARGINAL SCA CONDS ARE POSSIBLE ATTM. && .RIP CURRENTS... A STRENGTHENING EASTERLY FLOW WILL CONTINUE THROUGH THIS EVENING, PRODUCING A MODERATE RISK OF RIP CURRENTS FOR THE NEW JERSEY BEACHES AND A LOW RISK FOR THE DELAWARE BEACHES. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...AMC NEAR TERM...KLINE SHORT TERM...KLINE LONG TERM...AMC AVIATION...AMC/KLINE MARINE...AMC/KLINE RIP CURRENTS...KLINE

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