Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 280459 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1259 AM EDT TUE JUL 28 2015 .SYNOPSIS... WEAK HIGH PRESSURE BUILDING EASTWARD FROM THE GREAT LAKES IS FORECAST TO INFLUENCE OUR WEATHER TODAY THROUGH WEDNESDAY. A FRONTAL BOUNDARY FROM THE NORTHWEST IS EXPECTED TO ARRIVE THURSDAY NIGHT, FOLLOWED BY HIGH PRESSURE FOR FRIDAY AND THE WEEKEND. ANOTHER FRONT MAY APPROACH FROM THE NORTHWEST ON MONDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... A WEAK RIDGE OF HIGH PRESSURE WILL CONTINUE ITS HOLD ON THE MID- ATLANTIC REGION OVERNIGHT. WITHOUT AN ORGANIZED LIFTING MECHANISM IN PLACE, POPS WERE KEPT BELOW 15 PERCENT. THERE HAS BEEN A SHOWER OR TWO POPPING UP, HOWEVER THE COVERAGE IS VERY ISOLATED. CLOUD COVER WILL BE VARIABLE WITH SOME LINGERING DEBRIS CLOUDINESS FROM LAST EVENINGS ISOLATED TO SCATTERED CONVECTION. FROM ABOUT PHILADELPHIA TO THE SOUTH AND EAST, SOME LOWER CLOUDS ARE FLOATING AROUND HOWEVER THESE SEEM TO BE DISORGANIZED ATTM. OTHERWISE WHERE THE SKY FEATURES LESS CLOUD COVER THE LONGEST COMBINED WITH A MOIST AIR MASS AND LIGHT WINDS, SOME FOG SHOULD DEVELOP THROUGH THE EARLY MORNING HOURS. THE HOURLY GRIDS WERE ADJUSTED BASED ON THE LATEST OBSERVATIONS, THEN THE LAMP/LAV GUIDANCE WAS BLENDED IN. && .SHORT TERM /TUESDAY/... ONCE WE BURN OFF ANY FOG AND STRATUS THAT MAY FORM DURING THE EARLY MORNING HOURS WE SHOULD BE LEFT WITH CLEARING SKIES, ALBEIT SELF DESTRUCTING. A RAPID CU-FIELD SHOULD DEVELOP BY EARLY AFTERNOON AS CONVECTIVE TEMPERATURES ARE REACHED WITH TEMPERATURES CLIMBING INTO THE LOW-90S. WINDS WILL REMAIN RELATIVELY LIGHT SO NO RELIEF IN TERMS OF THE HUMIDITY. SEA AND BAY BREEZES SHOULD DEVELOP BY EARLY AFTERNOON AND GIVEN THE SOUPINESS OF THE AIR MASS, THEY MIGHT PROVIDE ENOUGH LIFT TO INITIATE ISOLATED SHOWERS. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... A MID LEVEL RIDGE AXIS IS FORECAST TO EXTEND ACROSS THE GREAT LAKES ON TUESDAY NIGHT. THE RIDGE IS EXPECTED TO PROGRESS EASTWARD AND ITS AXIS SHOULD PASS OVER OUR REGION ON WEDNESDAY NIGHT. A MID LEVEL LOW IS ANTICIPATED TO MOVE FROM SOUTHERN MANITOBA ON TUESDAY NIGHT TO HUDSON BAY ON WEDNESDAY NIGHT. THE LOW IS FORECAST TO MEANDER OVER THE HUDSON BAY REGION FROM WEDNESDAY NIGHT THROUGH MONDAY. MID LEVEL TROUGHING IS EXPECTED OVER THE NORTHEASTERN STATES FOR THURSDAY NIGHT THROUGH MONDAY WITH A RIDGE BUILDING OVER THE WESTERN STATES. THE HEAT IS FORECAST TO BE ON THE INCREASE FOR WEDNESDAY AND THURSDAY. WE ARE ANTICIPATING MAXIMUM TEMPERATURES MAINLY IN THE LOWER AND MIDDLE 90S ON BOTH DAYS WITH HEAT INDEX VALUES APPROACHING 100 EXCEPT IN THE ELEVATED TERRAIN AND IN THE COMMUNITIES ALONG THE COAST. DEW POINT READINGS ARE EXPECTED TO BE MAINLY IN THE MID TO UPPER 60S ON WEDNESDAY AFTERNOON AND IN THE UPPER 60S AND LOWER 70S ON THURSDAY AFTERNOON. THE MAXIMUM HEAT INDEX VALUES IN OUR HIGHLY URBANIZED AREAS ALONG THE INTERSTATE 95 CORRIDOR ARE EXPECTED TO BE IN THE UPPER 90S ON WEDNESDAY AND THURSDAY BASED ON THE LATEST GUIDANCE. AS A RESULT, WE WILL NOT ISSUE AN EXCESSIVE HEAT WATCH AT THIS TIME. THE GUIDELINE CRITERION IS 100. HOWEVER, WE WILL KEEP A CLOSE WATCH TO SEE IF THE GUIDANCE BEGINS TO CREEP UPWARD WITH EITHER THE TEMPERATURE OR DEW POINT FORECAST. WE ARE NOT ANTICIPATING ANY PRECIPITATION FOR TUESDAY NIGHT, WEDNESDAY AND WEDNESDAY NIGHT DUE TO THE LACK OF ANY SUBSTANTIAL TRIGGERING MECHANISMS. WE WILL MENTION A CHANCE OF SHOWERS AND THUNDERSTORMS FOR THURSDAY AFTERNOON INTO THURSDAY NIGHT AS A FRONTAL BOUNDARY IS EXPECTED TO APPROACH AND PASS THROUGH OUR REGION DURING THAT PERIOD OF TIME. A WEAK WAVE OF LOW PRESSURE MAY DEVELOP ALONG THE FRONT CAUSING PRECIPITATION TO LINGER INTO EARLY FRIDAY MORNING IN OUR SOUTHEASTERN COUNTIES. HIGH PRESSURE IS EXPECTED TO FOLLOW THURSDAY NIGHT`S FRONTAL PASSAGE. THE HIGH IS ANTICIPATED TO INFLUENCE OUR WEATHER FOR FRIDAY AND THE WEEKEND. WE WILL CARRY A PRECIPITATION-FREE FORECAST ALONG WITH SLIGHTLY ABOVE NORMAL DAYTIME TEMPERATURES. EVEN WITH THE MID LEVEL TROUGHING, IT APPEARS AS THOUGH OUR WEATHER WILL REMAIN QUITE WARM. HOWEVER, HUMIDITY LEVEL SHOULD DROP A BIT FROM THOSE EXPECTED DURING THE MID WEEK PERIOD. ANOTHER FRONTAL BOUNDARY MAY APPROACH FROM THE NORTHWEST ON MONDAY AND WE WILL MENTION A CHANCE OF SHOWERS AND THUNDERSTORMS FOR THAT PERIOD OF TIME. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THROUGH EARLY TUESDAY MORNING...VFR OVERALL, HOWEVER SOME MVFR CEILINGS WILL BE AROUND AT TIMES ALTHOUGH AREAL COVERAGE IS OF LOWER CONFIDENCE. WE CONTINUED WITH A TEMPO GROUP ALONG WITH SOME VISIBILITY RESTRICTIONS AT SOME TERMINALS DUE TO SOME FOG DEVELOPMENT. AN ISOLATED SHOWER COULD DEVELOP. LIGHT SOUTHERLY TO CALM WINDS. TUESDAY...ANY LOWER CLOUDS/FOG DISSIPATE BY MID MORNING, OTHERWISE VFR WITH A CLOUD BASE MOSTLY SCATTERED BETWEEN 3500-5000 FEET. A FEW ISOLATED SHOWERS OR A THUNDERSTORM MAY DEVELOP THROUGH THE DAY, HOWEVER COVERAGE IS EXPECTED TO BE RATHER LOW. LOCAL SEA/BAY BREEZES SHOULD OCCUR AT KACY, KMIV AND KILG BY MID AFTERNOON WITH WINDS TURNING MORE FROM THE SOUTHEAST. TUESDAY NIGHT...MAINLY VFR. HOWEVER DUE TO THE WARM AND MOIST AIR MASS IN PLACE, SOME LATE NIGHT LOW CLOUDS, HAZE OR FOG MAY DEVELOP. LIGHT SOUTHERLY TO CALM WINDS. OUTLOOK... WEDNESDAY THROUGH THURSDAY MORNING...MAINLY VFR. HOWEVER, THE HIGH HUMIDITY LEVELS MAY RESULT IN SOME LATE NIGHT AND EARLY MORNING LOW CLOUDS, HAZE AND FOG. THURSDAY AFTERNOON AND THURSDAY NIGHT...A CHANCE OF SHOWERS AND THUNDERSTORMS THAT MAY RESULT IN MVFR OR IFR CONDITIONS AT TIMES. FRIDAY THROUGH SATURDAY...MAINLY VFR. && .MARINE... SUB-SCA CONDITIONS TONIGHT AND TUESDAY UNDER PROLONGED SOUTHERLY FLOW. WINDS WILL CONTINUE TO DECREASE TONIGHT AND TOMORROW AS THE PRESSURE GRADIENT SLACKENS. SEAS WILL ALSO BE ON THE DOWNWARD TREND RUNNING CLOSER TO 2-3 FEET THROUGH TUESDAY. OUTLOOK... TUESDAY NIGHT THROUGH SATURDAY...NO MARINE HEADLINES ARE ANTICIPATED. && .RIP CURRENTS... A MEDIUM TO LONG PERIOD (AROUND 10 SECONDS) SWELL OUT OF THE E-SE WILL CONTINUE TUESDAY. SLY WINDS WILL BE AROUND 10 KT AND 2-3 FT WAVES ARE FORECAST IN THE SURF ZONE. GIVEN SIMILAR CONDITIONS TO MONDAY`S MODERATE RISK AND THE INFLUENCE OF AN APPROACHING FULL MOON LATER IN THE WEEK, TOOK A CAUTIOUS APPROACH AND WENT WITH A MODERATE RISK OF DANGEROUS RIP CURRENTS. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...IOVINO NEAR TERM...GORSE/KLEIN SHORT TERM...HEAVENER LONG TERM...IOVINO AVIATION...GORSE/IOVINO MARINE...IOVINO/HEAVENER RIP CURRENTS...KLEIN

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