Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 270820 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 420 AM EDT MON OCT 27 2014 .SYNOPSIS...
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HIGH PRESSURE WILL SETTLE OVERHEAD TODAY BEFORE MOVING OFFSHORE TONIGHT. A WARM FRONT IS WILL PASS THROUGH THE AREA TUESDAY FOLLOWED BY THE PASSAGE OF A COLD FRONT ON WEDNESDAY. HIGH PRESSURE BRIEFLY RETURNS THURSDAY AND THE FIRST PART OF FRIDAY. A COLD FRONT IS EXPECTED TO MOVE THROUGH FRIDAY NIGHT. CANADIAN HIGH PRESSURE BUILDS INTO THE EASTERN UNITED STATES FOR THE WEEKEND.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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SURFACE RIDGING WILL CONTINUE TO EXPAND TOWARDS THE EAST TODAY ENCOMPASSING OUR ENTIRE REGION. LOTS OF SUBSIDENCE WILL OCCUR WHICH WILL KEEP OUR SKIES CLEAR AND DRY WEATHER PREVAILS. THIS WILL LIMIT THE AMOUNT OF VERTICAL MIXING EXPECTED AS THE SUBSIDENCE INVERSION KEEPS A TIGHT LID ON THINGS. COMPARED TO THE PAST COUPLE OF DAYS WE MAY MIX JUST SHY OF 925MB AND THERE IS NOT TOO MUCH MOMENTUM ALOFT TO MIX DOWN. HIGHS TODAY COULD END UP BEING JUST AS WARM AS SUNDAY, IF WE EXPERIENCE OUR FULL MIXING POTENTIAL. FULL SUNSHINE AND A LIGHT WESTERLY FLOW, ADDING IN FOR DOWNSLOPING, COULD PUSH US A BIT HIGHER THAN GUIDANCE IS SUGGESTING SO THIS IS HOW WE TRENDED THE FORECAST. WENT A DEGREE OR TWO ABOVE THE WARMER MAV...MET LOOKED WAY TOO COLD EVERYWHERE TO BE CONSIDERED.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
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RIDGING WILL SLOWLY SLIDE THROUGH TONIGHT ALLOWING FOR FULL DECOUPLING AND GOOD RADIATIONAL COOLING CONDITIONS. CLEAR SKIES AND LIGHT WINDS WILL PREVAIL AS TEMPERATURES DROP QUICKLY AFTER SUNSET. EXPECTING OVERNIGHT LOWS IN THE LOW-40S IN A LOT OF PLACES, WITH MID TO UPPER-30S PROBABLE IN THE PINE BARRENS.
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&& .LONG TERM /TUESDAY THROUGH SUNDAY/...
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ON TUESDAY, THE EASTERN SEABOARD WILL BE ENCOMPASSED IN DEEP S-SWLY FLOW BETWEEN HIGH PRESSURE THAT IS PARKED OFF THE SOUTHEAST COAST AND A COLD FRONT THIS IS APPROACHING FROM THE MIDWEST AND LOWER MISSISSIPPI VALLEY. FORECAST 925 MB TEMPS AROUND 20C AND 850 MB TEMPS AROUND 17C ARE BETWEEN +2 AND +3 SD FOR LATE OCTOBER. REMAINED CONTINUITY AND WAS CLOSE TO THE PREVIOUS FORECASTS FOR MAX TEMPS. FORECAST HIGHS IN THE MID TO UPPER 70S ARE SEVERAL DEGREES WARMER THAN MOS GUIDANCE (WHICH HAS EXHIBITED A RECENT COOL BIAS) BUT SLIGHTLY COOLER THAN PREDICTED VALUES THAT USE FULL MIXING FROM THE 925 MB OR 850 MB LAYER GIVEN HOW LOW THE SUN ANGLE. MAX TEMPS AROUND 80F ARE POSSIBLE, ESPECIALLY IN THE DELMARVA. GED WAS THE ONLY CLIMATE SITE TO RECORD AN 80-DEGREE DAY SO FAR THIS MONTH. THE COLD FRONT IS EXPECTED CROSS THE APPALACHIANS TUESDAY EVENING AND REACH OUR EASTERN PA ZONES BY SUNRISE WEDNESDAY. THE FRONT MAY SLOW DOWN A BIT WEDNESDAY AFTERNOON/EVENING AS IT ADVANCES TOWARD THE COAST AND A WEAK WAVE OF LOW PRESSURE DEVELOPS ALONG THE BOUNDARY. MODELS ARE IN GOOD AGREEMENT WITH THE TIMING OF FROPA, WHICH ADDS CONFIDENCE TO THE FORECAST. WILL CONTINUE TO MENTION SCATTERED SHOWERS WITH THE FROPA LATE TUESDAY NIGHT/WEDNESDAY MORNING IN THE WESTERN ZONES AND WEDNESDAY INTO WEDNESDAY EVENING CLOSER TO THE COAST. HIGH PRESSURE BUILDS IN FROM THE MIDWEST LATE WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. COOLER AIR RETURNS TO THE REGION BUT TEMPS ARE STILL NEAR NORMAL. THE LARGE-SCALE TROUGH STARTS TO AMPLIFY FRIDAY OVER THE EASTERN CONUS AS STRONG SHORTWAVE DISTURBANCE IN THE POLAR JET STREAM DIGS EQUATOR-WARD INTO THE GREAT LAKES. THERE WILL ALSO BE PAC NW ENERGY MOVING INTO THE SOUTHEAST U.S. AS THIS SOUTHERN STREAM SHORTWAVE ROTATES AROUND THE BASE OF THE MAIN TROUGH. MODELS ARE IN GENERAL AGREEMENT WITH THESE TWO SYSTEMS NOT PHASING. SECONDARY CYCLOGENESIS IS EXPECTED TO OCCUR OFF THE NEW ENGLAND COAST AS THE NORTHERN STREAM SYSTEM APPROACHES THE NORTHEAST FRIDAY NIGHT AND SATURDAY. WE MAY SEE A FEW SHOWERS ACROSS THE NORTH FRIDAY NIGHT WITH THE COLD FRONT PASSAGE BUT THE COASTAL LOW WILL NOT DIRECTLY IMPACT OUR REGION. THERMAL PROFILES LOOK TO BE COLD ENOUGH FOR RAIN TO MIX WITH OR EVEN CHANGE TO SNOW/FLURRIES OVER THE POCONOS BY SATURDAY MORNING. THE REMAINDER OF THE WEEKEND IS LOOKING DRY. THE MAIN WX STORY NEXT WEEKEND WILL BE CHILLY TEMPS AS THE COLDEST AIRMASS OF THE SEASON ARRIVES. MAX TEMPS ON SAT WILL LIKELY ONLY BE IN THE 40S AND POSSIBLY EVEN THE 30S IN THE POCONOS. SUNDAY DOES NOT LOOK MUCH WARMER. THERE IS ALSO A POTENTIAL FOR A WIDESPREAD FREEZE ACROSS THE ENTIRE AREA SATURDAY AND SUNDAY NIGHTS, INCLUDING THE PHILLY METRO AND DELMARVA, WHERE A FREEZE HAS YET TO OCCUR THIS FALL. HOWEVER, WE DO NOT ISSUE FROST/FREEZE PRODUCTS AFTER HALLOWEEN UNLESS THERE IS AN ANOMALOUSLY WARM FALL THAT EXTENDS THE END OF THE GROWING SEASON (WHICH WAS NOT THE CASE THIS YEAR).
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&& .AVIATION /08Z MONDAY THROUGH FRIDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY - TONIGHT...VFR. LIGHT WESTERLY WINDS THIS MORNING WILL INCREASE TOWARDS 10 KNOTS THIS AFTERNOON AND THEN VEER TOWARDS THE SOUTH-SOUTHWEST LATE. SURFACE RIDGING SHOULD ALLOW FOR LIGHT AND VARIABLE/CALM WINDS TONIGHT. HIGH CONFIDENCE. OUTLOOK... TUESDAY AND TUESDAY EVENING...VFR. SW WINDS 5-10 KT WITH SLIGHTLY HIGHER GUSTS. TUESDAY OVERNIGHT THROUGH WEDNESDAY EVENING...SCT SHRA MOVE INTO WESTERN TERMINALS LATE TUESDAY NIGHT. SCT SHRA ON WEDNESDAY. TEMPORARY FLIGHT RESTRICTIONS (MAINLY MVFR) IN SHRA. WEDNESDAY OVERNIGHT THROUGH FRIDAY MORNING...VFR. FRIDAY AFTERNOON...VFR. HOWEVER, IF FROPA OCCURS FASTER, SHRA AND MVFR POSSIBLE.
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&& .MARINE...
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TODAY - TONIGHT...SUB-SCA CONDITIONS EXPECTED. WESTERLY WINDS AROUND 15 KNOTS WITH SOME GUSTINESS CLOSE TO 20 KNOTS CAN BE EXPECTED THIS AFTERNOON. SEAS 2 TO 4 FEET, SUBSIDING THROUGHOUT THE DAY. WINDS DECREASE TONIGHT AS HIGH PRESSURE PASSES OVERHEAD. WINDS VEER TOWARDS THE SOUTH EARLY TUESDAY MORNING. HIGH CONFIDENCE. OUTLOOK... TUESDAY AND WEDNESDAY...SW FLOW STRENGTHENS TUESDAY. WINDS AND SEAS INCREASE TO NEAR SCA CRITERIA TUESDAY NIGHT AND WEDNESDAY MORNING. WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...WINDS AND WAVES BELOW SCA CRITERIA. FRIDAY AND FRIDAY NIGHT...SUB SMALL CRAFT ADVISORY CONDITIONS EXPECTED ON FRIDAY. COLD FRONT MOVES THRU LATE. A STRONG NORTHWEST FLOW BEHIND WILL LIKELY PRODUCE SCA WINDS FRIDAY NIGHT.
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...KLEIN NEAR TERM...HEAVENER SHORT TERM...HEAVENER LONG TERM...KLEIN AVIATION...HEAVENER/KLEIN MARINE...HEAVENER/KLEIN

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