Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 190924
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
424 AM EST FRI DEC 19 2014

.SYNOPSIS...
HIGH PRESSURE OVER THE NORTHERN GREAT LAKES WILL MOVE INTO THE OHIO
VALLEY THIS MORNING. LOW PRESSURE IS EXPECTED TO FORM OVER THE GULF
STATES LATE TONIGHT AND TRACK ACROSS GEORGIA SATURDAY. A STRONG LOW
PRESSURE SYSTEM AND COLD FRONT MAY MOVE THROUGH THE EASTERN SEABOARD ON
CHRISTMAS EVE.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SURFACE HIGH CONTINUES TO SLIDE CLOSER TO THE REGION TODAY. HOWEVER,
LIKE LAST WEEK, THERE APPEARS TO BE ABUNDANT MOISTURE BELOW THE
INVERSION, SO DESPITE THE SYNOPTIC SCALE SUBSIDENCE, SHOULD STILL
SEE QUITE A BIT OF CLOUD COVER. WITH LITTLE CHANGE IN THE AIR MASS,
EXPECT HIGHS NEAR MAX TEMPS YESTERDAY WHICH ARE NEAR OR JUST BELOW
NORMALS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
THE BIGGEST CHANGE TONIGHT FROM THE LAST FEW NIGHTS IS THAT WITH THE
HIGH INCHING CLOSER AND THUS THE PRESSURE GRADIENT ACROSS THE REGION
DECREASING, WINDS SHOULD BE LIGHT. THOUGH WE WOULD TYPICALLY EXPECT
TO SEE CLEARING SKIES IN THIS PATTERN, WITH THE LOW LEVEL MOISTURE
LIKELY STILL IN PLACE, COULD STILL SEE QUITE A BIT OF CLOUD COVER,
ESPECIALLY OVER THE NORTHERN HALF OF THE REGION.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
MID-LEVEL FLOW THE NEXT COUPLE OF DAYS IS RATHER FLAT THOUGH A
CHANGE TO THAT PATTERN APPEARS LIKELY BY THE END OF THE WEEKEND. A
DEEP TROUGH EMERGES ACROSS THE CENTRAL U.S. BY TUESDAY AS MULTIPLE
PACIFIC NORTHWEST WAVES ROUND THE BASE OF THE TROUGH AND ACROSS OUR
REGION...WE ARE HEADING FOR A VERY UNSETTLED PERIOD BY EARLY NEXT
WEEK.

SATURDAY - SUNDAY...LOOKS MOSTLY DRY BOTH DAYS WITH HIGH PRESSURE
ANCHORED TO OUR NORTHEAST. THERE IS SOME NORTHERN STREAM ENERGY TO
CONTEND WITH LATE SATURDAY NIGHT WITH THE HELP OF A WEAK INVERTED
TROUGH OFFSHORE. THIS COMBINATION COULD TOUCH OFF A FEW SHOWERS AS
ALONG THE NORTHEASTERN NEW JERSEY COAST BUT WILL BE OF LITTLE
CONSEQUENCE. ONSHORE FLOW WILL HELP TO KEEP AMPLE LOW-LEVEL MOISTURE
STREAMING INTO THE REGION, UNDER THE SUBSIDENCE INVERSION. SATURDAY
COULD BE THE SUNNIER DAY THAN SUNDAY, BUT EACH DAY THE CONVECTIVE
TEMPERATURES LOOK TO BE REACHED SO IT MAY BE SHORT LIVED.

MONDAY - TUESDAY...ONCE THE AFOREMENTIONED SYSTEM ABOVE DEPARTS
ANOTHER, BETTER DEFINED SYSTEM MOVES OFF THE CAROLINA COAST AND OUT
TO SEA ON TUESDAY. WEAK BAROCLINIC ZONE OFF THE MID-ATLANTIC COAST
WILL ALLOW FOR AMPLE MOISTURE TO ADVECT IN FROM THE SOUTH. AS THE
WAVE OF LOW PRESSURE MOVES BY IT WILL TAP INTO THE MOISTURE FEED
ALLOWING FOR BETTER CHANCES OF PRECIPITATION. CONTINUED ONSHORE FLOW
AHEAD OF THE SYSTEM WILL ALLOW FOR A WARMING LOW-LEVEL THERMAL
PROFILE SO ANY PRECIPITATION WILL BE LIQUID WITH SOME MIXING
POSSIBLE IN THE FAR NORTHWESTERN ZONES. IT IS ENTIRELY POSSIBLE THAT
A WEAK CAD SETUP OCCURS LATE MONDAY NIGHT WITH A NORTHERLY BOUNDARY
LAYER AGEOSTROPHIC WIND COMPONENT. MODELS HAVE BEEN KNOWN TO WARM
THE SURFACE LAYER TOO FAST WITH A RATHER LARGE NEW ENGLAND HIGH
PRESSURE IN PLACE, OR THEY PUSH THE HIGH OUT FASTER ALLOWING A
SOUTHEAST RETURN FLOW. EITHER WAY IT COULD BE A MESSY TUESDAY
MORNING COMMUTE ACROSS OUR NORTHWEST ZONES. SYSTEM MOVES OFF TOWARDS
THE NORTHEAST ON TUESDAY, WITH RAIN STILL ONGOING, BUT WE ARE
GEARING UP FOR THE BIGGER EVENT ON CHRISTMAS EVE.

WEDNESDAY...STILL WATCHING A LARGE LOW PRESSURE FORM TO OUR WEST AND
TRACK INTO THE GREAT LAKES REGION ON WEDNESDAY. THIS WOULD KEEP OUR
REGION UNDER A WARMING THERMAL PROFILE WITH A LOT OF MOISTURE TO
WORK WITH...AN ALL LIQUID EVENT IS EXPECTED AT THIS POINT. GUIDANCE
CONTINUES TO SHOW A WEAKER SECONDARY DEVELOPMENT ALONG A TRIPLE
POINT OVER OUR REGION DURING THE DAY. THIS WOULD HELP TO INTENSIFY
RAINFALL AMOUNTS AND ENHANCE THE LOW-LEVEL PRESSURE GRADIENT. HEAVY
RAIN WITH STRONG WINDS ARE EXPECTED SO IT IS ENTIRELY POSSIBLE WE
ARE LOOKING AT ANOTHER MULTIPLE HEADLINE EVENT. COASTAL FLOODING
COULD ALSO BECOME AN ISSUE WITH THE STRONGER ONSHORE WINDS DURING
WEDNESDAY`S HIGH TIDE. HAVE GONE WITH CATEGORICAL POPS FOR THAIS
TIMEFRAME. WE WILL CONTINUE TO HAVE WORDING IN THE HWO FOR THIS
EVENT. LOOKS LIKE RUDOLPH AND THE OTHER REINDEER WILL HAVE THEIR
WORK CUT OUT FOR THEM THIS CHRISTMAS EVE.

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

MOSTLY VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD. THERE
SHOULD BE PERSISTENT CLOUDS BETWEEN 3000 AND 5000 FT AGL FOR MUCH OF
THE DAY, SO COULD SEE LOCALIZED MVFR CEILINGS RIGHT AT 3000 FT, BUT
MOSTLY CEILINGS SHOULD BE BETWEEN 3500 AND 4000 FT. NORTHWESTERLY
WINDS MAY GUST AT TIMES TO 20KT THROUGH EARLY THIS AFTERNOON, BUT BY
TONIGHT SHOULD BE LESS THAN 10KT.

OUTLOOK...
SATURDAY - SUNDAY...VFR. NORTH-NORTHEAST WINDS EXPECTED. CIGS COULD BE
LOWERING THROUGHOUT THE DAY

MONDAY - TUESDAY...SUB-VFR EXPECTED WITH SCATTERED RAIN/SNOW
SHOWERS, BECOMING ALL RAIN BY TUESDAY.

&&

.MARINE...
WINDS AND SEAS SHOULD STAY BELOW SCA CRITERIA. HOWEVER, GUSTS NEAR
OR JUST ABOVE 20KT WILL BE POSSIBLE THROUGH THIS EVENING.

OUTLOOK...
SATURDAY - SUNDAY...SUB-SCA EXPECTED FOR THE MOST PART. SEAS REMAIN
AROUND 3 TO 4 FEET.  CONFIDENCE: AVERAGE TO SLIGHTLY BELOW AVERAGE.

MONDAY - TUESDAY...SCA CONDITIONS SHOULD PRESENT THEMSELVES LATER ON MONDAY
UNDER A STRENGTHENING EASTERLY FLOW AND BUILDING SEAS. CONFIDENCE:
AVERAGE.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...GIGI
NEAR TERM...JOHNSON
SHORT TERM...JOHNSON
LONG TERM...HEAVENER
AVIATION...HEAVENER/JOHNSON
MARINE...HEAVENER/JOHNSON





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