Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 080739 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 339 AM EDT TUE JUL 8 2014 .SYNOPSIS...
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HIGH PRESSURE WILL REMAIN OVER THE ATLANTIC AS LOW PRESSURE MOVES ACROSS EASTERN CANADA. THE COLD FRONT ASSOCIATED WITH THIS LOW WILL CROSS THE AREA ON WEDNESDAY AND SETTLE JUST TO THE SOUTH THROUGH FRIDAY. HIGH PRESSURE WILL THEN BUILD OVER THE MIDWEST AND INFLUENCE THE WEATHER FOR THE END OF THE WEEK AND INTO THE FIRST PART OF THE WEEKEND. ANOTHER COLD FRONT WILL ARRIVE LATE SUNDAY OR MONDAY.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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NOT MUCH CHANGE TO THE GOING FORECAST THROUGH THIS PERIOD. GIVEN STRONGER SOUTHWESTERLY FLOW THROUGH THE DAY TODAY, EXPECT THIS TO BE THE WARMEST DAY OF THE WEEK. ALSO, EXPECT MOISTURE ADVECTION THROUGH THE DAY, LEADING TO INCREASING DEW POINT TEMPERATURES. ALL OF THIS WILL COMBINE FOR AN UNSTABLE ATMOSPHERE BY MID DAY. HOWEVER...BEST LIFT WILL REMAIN NORTHWEST OF OUR REGION UNTIL VERY LATE IN THE DAY. THUS EVEN IF STORMS DEVELOP DURING THE DAY (POSSIBLE WITH HELP FROM REMNANT OUTFLOW BOUNDARIES OF LAST NIGHT/S CONVECTION AND A WEAK PRE FRONTAL TROUGH IN THE REGION), COVERAGE SHOULD BE LIMITED UNTIL THE UPPER LEVEL TROUGH AND COLD FRONT APPROACH THE REGION LATER. AS FOR SEVERE THREAT...AS PREVIOUSLY MENTIONED IT WILL BE QUITE UNSTABLE WITH ML CAPE VALUES NEAR OR ABOVE 1000 J/KG. INTERESTINGLY, THE NAM HAS EVEN HIGHER CAPE VALUES OVER THE REGION THIS AFTERNOON, BUT THIS SEEMS TO BE A RESULT OF THE NAM BRINGING CONSIDERABLY MORE MOISTURE INTO THE REGION THAN ANY OTHER MODEL. AND GIVEN HOW MUCH OF AN OUTLIER IT IS, FORECAST FAVORS THE GFS. EVEN WITH THE HIGHER CAPE VALUES THOUGH, BULK SHEAR VALUES SHOULD REMAIN BELOW 30 KT THROUGH THE DAY.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
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AS THE UPPER LEVEL TROUGH AND COLD FRONT APPROACH THE REGION, SHOULD SEE CONSIDERABLY MORE COVERAGE OF THUNDERSTORMS THROUGH THE EVENING INTO OVERNIGHT HOURS. INSTABILITY SHOULD DECREASE THROUGH THIS TIME. HOWEVER, 0-6KM BULK SHEAR VALUES SHOULD INCREASE TO NEAR 40KT IN THE VICINITY OF THE APPROACHING FRONT, WHICH SHOULD INCLUDE MUCH OF THE AREA NORTH AND WEST OF THE I95 CORRIDOR. AS SUCH, THE SEVERE THREAT, PRIMARILY FOR STRONG WINDS WILL CONTINUE FOR SOME OF THE REGION THROUGH THE EVENING HOURS, POSSIBLY CONTINUING FOR A FEW HOURS AFTER MIDNIGHT. AS FOR THE HEAVY RAIN THREAT, MODELS CONTINUE TO SHOW PWAT VALUES NEAR OR JUST BELOW 2 INCHES (WITH THE EXCEPTION OF THE NAM WHICH SHOWS EVEN HIGHER PWAT VALUES, BUT AS MENTIONED EARLIER, THIS WAS THE WET OUTLIER). HOWEVER, FAST STORM MOTIONS SHOULD MEAN THAT ANY FLOODING THREAT WILL BE LIMITED TO POOR DRAINAGE AREAS. WITH HIGHER DEW POINTS LINGERING IN THE REGION AS THE COLD FRONT DRIFTS EAST, COULD SEE FOG DEVELOPMENT LATE TONIGHT, IN AREAS WHERE STORMS CLEAR OUT BY LATE EVENING.
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&& .LONG TERM /WEDNESDAY THROUGH MONDAY/...
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AT THE START OF THE EXTENDD PD, A CDFNT WILL BE WORKING ITS WAY ACRS THE REGION. THERE WILL BE PRECIP CHCS WITH THE FRONT BUT IT LOOKS LIKE THE BEST CHCS WILL BE OVER SRN AND ERN AREAS ON WED. BEHIND THE FRONT, HIGH PRES OVER THE OH VLY WILL MOVE INTO THE AREA AND WILL BE THE DOMINANT WX FEATURE THRU THE FIRST PART OF THE WEEKEND. SOME DIURNAL PRECIP CAN NOT BE RULED OUT ON THU, MAINLY S AND E AS THE FRONT IS NEARBY BUT MOST LOCATIONS WILL REMAIN DRY. FRI LOOKS DRY AND AGAIN A DIURNAL SHOWER OR TSTM CAN NOT BE RULED OUT ON SAT. BY SUN, S TO SWLY FLOW WILL BEGIN TO INCREASE IN ADVANCE OF THE NEXT FRONT. LOW PRES IN SERN CAN ON SUN WILL MOVE EWD AND ITS ATTEND CDFNT WILL TRIGGER SOME SHWRS ANT TSRA AHEAD OF IT ON SUN. THERE IS A BETTER CHC OF PRECIP AS THE FRONT GETS CLOSER SUN NIGHT INTO MON. FOR NOW, WILL JUST CARRY CHC POPS AS THERE ARE SOME USUAL TIMING DIFFS WITH THE FRONT. TEMPS WILL BE NEAR OR SLIGHTLY ABV NRML THRU THE PD.
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&& .AVIATION /07Z TUESDAY THROUGH SATURDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDITIONS SHOULD CONTINUE THROUGH AT LEAST 18Z. AFTER THAT, THERE WILL BE INCREASING CHANCES FOR TSRA. CHANCES SHOULD INCREASE FROM WEST TO EAST LATE IN THE AFTERNOON. AT THIS TIME, IT SEEMS LIKELY THAT KABE AND KRDG WILL BE AFFECTED BY TSRA. THOUGH THE EXACT TIMING IS UNCERTAIN (GFS SHOWED A LATER TREND WITH THE LAST RUN), AT THIS POINT WOULD EXPECT THE PRIME PERIOD FOR TSRA TO BE BETWEEN 22 AND 03Z. FOR KPHL, KTTN, KPNE, AND KILG, IT IS A LITTLE LESS CERTAIN IF THEY WILL BE IMPACTED BY TSRA, BUT IF THEY ARE, IT SHOULD BE A FEW HOURS LATER, GENERALLY BETWEEN 00 AND 05Z. KMIV AND KACY ARE THE LEAST LIKELY TO SEE ANY TSRA, THOUGH IT IS NOT OUT OF THE QUESTION. WITH ANY STORMS THAT DEVELOP, MVFR AND BRIEF IFR CONDITIONS, VRB AND STRONG WINDS, AND SMALL HAIL WILL BE POSSIBLE. ONCE THE STORMS MOVE THROUGH, LIKELY BY 06Z, THE NEXT CONCERN WILL BE THE DEVELOPMENT OF BR. PATCHY BR IS POSSIBLE ACROSS THE REGION, PRIMARILY BETWEEN 06 AND 12Z. OUTLOOK... WED...MAINLY VFR. MVFR AND IFR CONDITIONS POSSIBLE UNDER ANY TSRA THAT DEVELOP IN THE AFTN/EVE. THE THREAT FOR STORMS WILL BE FURTHER SOUTHEAST THAN THOSE OF TUESDAY EVENING, THIS TIME FAVORING KMIV AND KACY. MDT CONFIDENCE. THU THRU FRI...GENERALLY VFR, A SMALL RISK OF TSRA ON THU, WITH MVFR PSBL. MDT TO HIGH CONFIDENCE. SAT...MVFR/IFR MAY BE PSBL EARLY OTHERWISE VFR. LOW CONFIDENCE ON MVFR/IFR OTHERWISE HIGH CONFIDENCE.
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&& .MARINE...
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EXPECT WINDS AND SEAS TO INCREASE EARLY THIS AFTERNOON BACK TO SMALL CRAFT ADVISORY CONDITIONS FOR THE OCEAN WATERS. AT THIS TIME, DO NOT EXPECT SMALL CRAFT ADVISORY ON THE DE BAY AS THE WIND DIRECTION (SOUTHERLY OR SOUTHWESTERLY) IS UNFAVORABLE FOR A BIG IMPACT TO THE BAY. CHANCES FOR STORMS WILL INCREASE LATE TODAY INTO TONIGHT, AND UNDER ANY STORMS THAT DEVELOP GUSTY WINDS ABOVE SMW CRITERIA WILL BE POSSIBLE. OUTLOOK... WED...SCA WILL CONTINUE, MAINLY FOR SEAS IN THE MRNG AND PSBLY INTO THE AFTN, BEFORE SEAS SUBSIDE. THERE IS A RISK FOR STRONG GUSTY WINDS WITH ANY STORMS THAT DEVELOP WEDNESDAY AFTERNOON OR NIGHT FROM THE S NJ COAST SOUTHWARD THROUGH THE DE WATERS. THU THRU SAT...NO MARINE HEADLINES ANTICIPATED.
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&& .PHI WATCHES/WARNINGS/ADVISORIES...
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PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE.
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&& $$ SYNOPSIS...NIERENBERG NEAR TERM...JOHNSON SHORT TERM...JOHNSON LONG TERM...NIERENBERG AVIATION...JOHNSON/NIERENBERG MARINE...JOHNSON/NIERENBERG

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