Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 061948 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 348 PM EDT MON JUL 6 2015 .SYNOPSIS... A WARM FRONT IS FORECAST TO LIFT NORTHWARD THROUGH OUR REGION FROM TONIGHT INTO TUESDAY MORNING. ANOTHER FRONTAL BOUNDARY IS EXPECTED TO ARRIVE FROM THE NORTHWEST ON WEDNESDAY. THE FRONT IS ANTICIPATED TO MEANDER IN OUR VICINITY FROM WEDNESDAY NIGHT THROUGH THURSDAY NIGHT AS WEAK AREAS OF LOW PRESSURE MOVE ALONG IT. THE FRONT IS FORECAST TO MOVE TO OUR SOUTH FOR FRIDAY AND FOR THE WEEKEND, ALLOWING HIGH PRESSURE TO NUDGE DOWN FROM THE NORTHWEST AND NORTH. THE BOUNDARY MAY RETURN AS A WARM FRONT EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... LARGE MID-LEVEL CLOSED LOW TO OUR SOUTHWEST IS ALLOWING FOR NUMEROUS SHOWERS AND EMBEDDED THUNDER TO DEVELOP JUST TO THE WEST OF OUR CWA. WE ARE HOWEVER, STARTING TO SEE AN UPTICK IN THE HOMEGROWN CONVECTION ACROSS SOUTHERN DELMARVA AT THIS TIME, AS THE STORMS PROPAGATE TOWARDS THE NORTH-NORTHEAST THIS EVENING. THE GREATEST AMOUNT OF MLCAPE EXISTS ACROSS DELMARVA NORTHWARD TOWARDS PHILLY BEFORE TAPERING OFF, SO WHILE WE CAN NOT RULE OUT ISOLATED SHOWERS NORTH OF PHILLY THIS EVENING AND TONIGHT, THE CHANCES OF THUNDER DECREASE GREATLY. AT THIS POINT THE SEVERE THREAT SHOULD BE CONFINED TO DELMARVA WITH GREATER SHEAR FOR BETTER ORGANIZED STORMS, HIGHER MLCAPE VALUES, AND A BETTER LOW-LEVEL VEERING PROFILE. THAT BEING SAID IT LOOKS MARGINAL AS SPC CONTINUES THE MENTION OF ISOLATED SEVERE IN THIS AREA. ONE THING OF CONCERN IS THE CONTINUED NORTHWARD PROGRESSION OF THE STORMS WHICH MAY LEAD TO TRAINING SHOULD MORE STORMS CONTINUE TO INITIATE ACROSS DELMARVA...LOCALIZED FLOODING MAY BE AN ISSUE. THE ABOVE MENTIONED LOW IS FORECAST TO OPEN AND MOVE TOWARDS THE NORTHEAST LATE TONIGHT. OUR NORTHWESTERN ZONES WILL STILL HAVE THE BETTER CHANCES FOR SHOWERS THROUGH THE OVERNIGHT HOURS, EVEN WITH THE LACK OF INSTABILITY...ILL-DEFINED COLD CORE ALOFT, BUT DOES NOT APPEAR COLD ENOUGH FOR STRONGER UPDRAFTS. OVERNIGHT TEMPERATURES WILL DROP BACK INTO THE UPPER-60S TO LOW- 70S AS DEW POINTS REMAIN QUITE MOIST ACROSS THE REGION. THIS WILL SETUP POCKETS OF FOG, NOT SURE HOW DENSE AT THIS TIME, WITH THE PROLONGED ONSHORE FLOW IN PLACE. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... AS ONE MID-LEVEL WAVE MOVES OUT THERE IS ANOTHER ONE RIGHT ON ITS TAILS. TIMING IS STILL A BIT SUSPECT BUT IT APPEARS THAT THE MID TO LATE AFTERNOON TIME PERIOD IS WHEN THE BETTER CHANCES FOR SHOWERS EXISTS...PEAK HEATING, AND MOSTLY ACROSS OUR NORTHWESTERN ZONES. BY THE TIME WE WILL BE IN THE WARM SECTOR, AS THE WARM FRONT FROM MONDAY CONTINUES TO LIFT TOWARDS THE NORTH-NORTHEAST. PWATS SHOULD BE AT THEIR HIGHEST, AROUND 1.75-2.00 INCHES, SO ANY OF THE SHOWERS WILL BECOME HEAVY RAINERS. TEMPERATURES WILL BE SEVERAL DEGREES WARMER WITH THE ADDITION OF A MORE WESTERLY SURFACE FLOW COMPONENT SO WE COULD REACH 90F IN AND AROUND THE PHILLY METRO AREA TOMORROW AFTERNOON. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... THE MID LEVEL FLOW IS EXPECTED TO REMAIN SOMEWHAT ZONAL EAST OF THE ROCKIES FROM TUESDAY NIGHT THROUGH WEDNESDAY NIGHT AS LOW PRESSURE MEANDERS OFF THE CALIFORNIA COAST, MOVES INLAND AND FILLS. THE MODEL GUIDANCE IS TRENDING TOWARD GREATER AMPLIFICATION OF THE MID LEVEL PATTERN OVER THE CENTRAL AND EASTERN STATES LATE IN THE WEEK WITH RIDGING DEVELOPING OVER THE GREAT LAKES. EVENTUALLY, A LONG WAVE RIDGE IS ANTICIPATED TO RETURN OVER THE ROCKY MOUNTAIN STATES DURING THE WEEKEND WITH A TROUGH SETTLING OVER THE EAST. A MID LEVEL SHORT WAVE TROUGH IS FORECAST TO BE PULLING AWAY FROM OUR AREA ON TUESDAY EVENING. ANY RESIDUAL SHOWERS AND THUNDERSTORMS SHOULD COME TO AN END AT THAT TIME. A BREAK IN THE PRECIPITATION POTENTIAL IS ANTICIPATED FOR MUCH OF TUESDAY NIGHT INTO EARLY WEDNESDAY. IT CONTINUES TO APPEAR AS THOUGH A FRONTAL BOUNDARY WILL DROP INTO OUR REGION ON WEDNESDAY AND IT SHOULD REMAIN ACROSS OUR FORECAST AREA THROUGH THURSDAY NIGHT. THE NEARLY ZONAL FLOW WILL MAKE IT DIFFICULT TO TIME ANY MID LEVEL IMPULSES AND ASSOCIATED WEAK SURFACE WAVES. REGARDLESS, A CHANCE OF SHOWERS AND THUNDERSTORMS WILL EXIST THROUGH THAT PERIOD OF TIME. THE GUIDANCE IS SUGGESTING THAT A MID LEVEL SHORT WAVE TROUGH AND WEAK SURFACE LOW MAY PASS ACROSS OUR FORECAST AREA ON THURSDAY NIGHT PULLING THE SURFACE BOUNDARY TO THE SOUTH OF MARYLAND AND DELAWARE. PRECIPITABLE WATER VALUES ARE FORECAST TO RISE NEAR OR ABOVE 2 INCHES DURING THE MID WEEK PERIOD IN MUCH OF OUR REGION. ANY THUNDERSTORMS COULD BRING HEAVY DOWNPOURS ALONG WITH LOCALIZED FLOODING OF ROADWAYS AND AREAS OF POOR DRAINAGE. ALSO, WE WILL KEEP AN EYE ON THE FLASH FLOODING POTENTIAL ESPECIALLY IF CERTAIN AREAS ARE AFFECTED BY HEAVY RAINFALL ON MORE THAN ONE DAY. THE AMPLIFYING MID LEVEL FLOW SHOULD ALLOW HIGH PRESSURE TO WORK ITS WAY TOWARD OUR REGION FROM THE NORTHWEST AND NORTH FOR THE COMING WEEKEND. AS A RESULT, WE WILL NOT INDICATE A CHANCE OF SHOWERS AND THUNDERSTORMS FOR THAT PERIOD OF TIME. WE WILL FORECAST A RETURNING CHANCE OF SHOWERS AND THUNDERSTORMS FOR EARLY NEXT WEEK WITH THE SURFACE BOUNDARY EXPECTED TO RETURN NORTHWARD AS WARM FRONT. DAYTIME TEMPERATURES ARE ANTICIPATED TO BE WITHIN A FEW DEGREES OF NORMAL FOR THE PERIOD FROM TUESDAY NIGHT THROUGH MONDAY. NIGHTTIME TEMPERATURES ARE FORECAST TO BE ABOVE NORMAL. && .AVIATION /20Z MONDAY THROUGH SATURDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THIS AFTERNOON...MOSTLY VFR WITH POCKETS OF MVFR CLOSER TOWARDS THE COAST. ISOLATED TO WIDELY SCATTERED SHOWERS EXPECTED THIS AFTERNOON AND EVENING ACROSS THE REGION. SOME THUNDERSTORM ACTIVITY IS ALSO POSSIBLE WITH BETTER CHANCES ACROSS THE I-95 TERMINALS INTO EASTERN PENNSYLVANIA AND SOUTHWARD INTO DELMARVA. SOUTHEASTERLY WINDS AROUND 10 KNOTS EXPECTED TO CONTINUE. TONIGHT...VFR TRENDING TOWARDS MVFR/IFR. WE BEGIN TO LOSE THE SHOWERY ACTIVITY LATE TONIGHT. CONTINUED ONSHORE FLOW KEEPS ENOUGH LOW-LEVEL MOISTURE SURGING INTO THE REGION TO BRING CIGS AND VSBYS INTO THE IFR RANGE LATE TONIGHT. TUESDAY...TRENDING TO VFR. CIGS AND VSBYS REBOUND BY LATE TUESDAY MORNING WITH BETTER SURFACE HEATING AND THE WINDS VEERING TOWARDS THE SOUTHWEST. MORE SCATTERED SHOWERS ARE POSSIBLE DURING THE AFTERNOON, BUT MOSTLY NORTH OF RDG-ABE. OUTLOOK... TUESDAY NIGHT AND WEDNESDAY MORNING...CONDITIONS POSSIBLY LOWERING TO MVFR OR IFR IN LOW CLOUDS, HAZE AND FOG ESPECIALLY DURING THE LATE NIGHT AND EARLY MORNING HOURS. WEDNESDAY AFTERNOON THROUGH THURSDAY NIGHT...A CHANCE OF SHOWERS AND THUNDERSTORMS WHICH MAY CAUSE CONDITIONS TO LOWER TO MVFR OR IFR AT TIMES. FRIDAY THROUGH SATURDAY...MAINLY VFR. && .MARINE... SUB-SCA CONDITIONS EXPECTED TONIGHT AND TOMORROW WITH SOUTHEASTERLY WINDS VEERING TOWARDS THE SOUTH-SOUTHWEST BY TUESDAY AFTERNOON AROUND 15 KNOTS. SEAS WILL INCREASE UPWARDS OF 4 FEET BY TUESDAY AFTERNOON AS WELL. OUTLOOK... TUESDAY NIGHT THROUGH SATURDAY...NO MARINE HEADLINES ARE ANTICIPATED. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...IOVINO NEAR TERM...HEAVENER SHORT TERM...HEAVENER LONG TERM...IOVINO AVIATION...IOVINO/HEAVENER MARINE...IOVINO/HEAVENER

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