Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 221637
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1137 AM EST MON DEC 22 2014

.SYNOPSIS...
WEAK LOW PRESSURE WILL CONTINUE TO DEVELOP OFF THE NORTH CAROLINA
COAST THROUGH TODAY, THEN MOVE NORTHWARD AND DISSIPATE OFF THE NEW
JERSEY COAST TUESDAY. ANOTHER AREA OF LOW PRESSURE IS ANTICIPATED
TO DEVELOP OVER THE NORTHWESTERN GULF OF MEXICO TUESDAY AND
STRENGTHEN AS IT LIFTS NORTHWARD AND ACROSS THE EASTERN GREAT LAKES
WEDNESDAY NIGHT. THE LOW IS EXPECTED TO PULL A WARM FRONT THROUGH
OUR REGION WEDNESDAY, FOLLOWED BY A COLD FRONT EARLY THURSDAY. HIGH
PRESSURE BUILDS INTO OUR AREA FOR THURSDAY AND FRIDAY. ANOTHER COLD
FRONT IS THEN EXPECTED TO ARRIVE OVER THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A QUICK UPDATE WAS ISSUED TO RAISE THE HIGH TEMPERATURES SOME
ESPECIALLY FOR SOME LOCALES ALONG AND NORTHWEST OF INTERSTATE 95.
MORE CLOUDS MOVING IN SHOULD SLOW THE RISE FOR THE REST OF THE DAY.
THE POPS WERE ALSO ADJUSTED TO SHOW A SLOWER INCREASE, ESPECIALLY
FARTHER NORTH.

OTHERWISE, AN UPPER-LEVEL TROUGH CONTINUES TO AMPLIFY ACROSS THE
CENTRAL PART OF THE NATION. MEANWHILE, A RIDGE IS SHIFTING OFF THE
EAST COAST. HIGH PRESSURE AT THE SURFACE HOWEVER REMAINS WEDGED DOWN
INTO THE MID ATLANTIC FROM NEW ENGLAND, ALTHOUGH THIS IS FORECAST TO
GRADUALLY WEAKEN AND SHIFT EASTWARD THROUGH TODAY. LOW PRESSURE IS
DEVELOPING OFF THE CAROLINA COAST.

THE RELENTLESS INVERSION IS PRESENT TODAY WITH CLOUDINESS ACROSS A
GOOD PORTION OF THE CWA. THE MOISTURE WILL BE ON THE INCREASE AND AT
FIRST THIS IS IN THE LOWER LEVELS AS SAMPLED BY NEARBY 12Z RAOBS.
THE 12Z UPTON RAOB SHOWS MORE OF A SOUTHEASTERLY LOW-LEVEL FLOW,
WHILE THE STERLING ONE INDICATES THE WINDS VEERING MORE SOUTH OR
SOUTHWEST. THEREFORE THE CLOUD MOTIONS CAN BE SEEN DIFFERING ON THE
VISIBLE SATELLITE IMAGERY LOOP. THE SOUTHEASTERLY FLOW BELOW THE
INVERSION HAS ALLOWED JUST ENOUGH LIFT TO PRODUCE SOME SNOW GRAINS
ACROSS PORTIONS OF NORTHWESTERN NEW JERSEY EARLIER THIS MORNING.
THIS HAS GENERALLY OCCURRED BELOW THE RADAR BEAMS AND WAS RATHER
LIGHT.

SOME RAIN WILL OVERSPREAD THE SOUTHERN AREAS THROUGH THE DAY AND
LIFT NORTHWARD WITH TIME. THE TEMPERATURES AT THE SURFACE ARE
WARMING AND THE DEW POINTS CONTINUE TO INCH UPWARD. THERE IS A
CHANCE THAT SOME SLEET MAY MIX WITH ANY RAIN AT THE ONSET OF THE
PRECIPITATION AS THE SOUNDINGS SHOW A DRY LAYER FOR A TIME WITH THE
POTENTIAL FOR SOME EVAPORATIVE COOLING.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
THE COASTAL LOW CONTINUES TO LIFT NORTHWARD THIS EVENING AND
OVERNIGHT TOWARD OUR AREA. THIS WILL CONTINUE TO ALLOW LOW-MID
LEVEL MOISTURE TO SPREAD ACROSS OUR AREA. ADDITIONAL PIECES OF
VORTICITY WILL CONTINUE TO MOVE ACROSS THE AREA WITHIN THE
SOUTHWEST FLOW ALOFT, LEADING TO ENHANCED LOW-MID LEVEL LIFT. THE
BEST LIFT/MOISTURE WILL MOVE FROM SOUTH TO NORTH OVERNIGHT AND
WILL LIKELY AFFECT ALL AREAS AT SOME POINT DURING THE EVENING AND
OVERNIGHT. MOST AREAS WILL WARM ABOVE FREEZING BEFORE THE MAIN
PRECIPITATION MOVES INTO THOSE AREA. HOWEVER, THE NORTHERN THREE
COUNTIES (CARBON/MONROE, PENNSYLVANIA AND SUSSEX, NEW JERSEY) WILL
LIKELY TAKE LONGER TO SCOUR OUT THE COLD AIR. THEREFORE WE EXPECT
A PERIOD OF FREEZING RAIN TO OCCUR ACROSS THESE AREAS LATER THIS
EVENING AND OVERNIGHT. THERE COULD BE SOME SLEET AND/OR SNOW MIX
IN AT THE ONSET OF THE PRECIPITATION, BUT THE MAIN THREAT IS
EXPECTED TO BE FREEZING RAIN. THEREFORE WE HAVE ISSUED A FREEZING
RAIN ADVISORY FOR THESE AREAS FOR THIS EVENING AND INTO THE
OVERNIGHT HOURS. ALL PRECIPITATION IS EXPECTED TO CHANGE OVER TO
ALL RAIN BY DAYBREAK TUESDAY, SO THE ADVISORY WILL END AT 4 AM.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
THE MID LEVEL PATTERN IS EXPECTED TO FEATURE A LOW OVER IOWA WITH
A TROUGH EXTENDING DOWN TO THE SOUTHERN PLAINS ON TUESDAY MORNING.
MEANWHILE, A RIDGE WILL BE LOCATED OVER THE WESTERN NORTH
ATLANTIC. OUR REGION IS FORECAST TO BE UNDER AN INCREASINGLY MOIST
AND RELATIVELY MILD SOUTHWESTERLY FLOW FOR TUESDAY AND WEDNESDAY.

THE INITIAL MID LEVEL LOW IS ANTICIPATED TO LIFT OVER CENTRAL
ONTARIO ON TUESDAY NIGHT WITH ANOTHER LOW DEVELOPING OVER EASTERN
OKLAHOMA AND VICINITY AT THAT TIME. THE SECOND MID LEVEL LOW
SHOULD REACH SOUTHEASTERN ONTARIO LATE ON WEDNESDAY NIGHT AND
QUEBEC ON THURSDAY, WHEN IT SHOULD PULL ITS TROUGH AXIS OVER OUR
REGION. OUR WEATHER IS EXPECTED TO BE RATHER UNSETTLED THROUGH
THAT TIME, WITH PERIODS OF RAIN FROM TUESDAY INTO WEDNESDAY NIGHT,
TAPERING TO RAIN SHOWERS ON THURSDAY MORNING BEFORE ENDING.
FORECAST TEMPERATURE PROFILES FOR THAT PERIOD SUGGEST ALL LIQUID
PRECIPITATION.

A LIGHT SURFACE FLOW FROM THE EAST TO SOUTH QUADRANT IS FORECAST
FOR TUESDAY AND TUESDAY NIGHT. THE WIND IS EXPECTED TO SETTLE INTO
THE SOUTH ON WEDNESDAY AS A WARM FRONT LIFTS THROUGH OUR REGION.
TEMPERATURES ARE ANTICIPATED TO BECOME QUITE MILD ON WEDNESDAY
WITH MAXIMUM READINGS IN THE 50S AND 60S.

AS OUR MID WEEK WEATHER SYSTEM EVOLVES, IT WILL HAVE AMPLE
OPPORTUNITY TO TAP INTO MOISTURE FROM THE GULF OF MEXICO WHICH IT
WILL DRAW IN OUR DIRECTION. A LOW LEVEL JET AROUND 45 TO 55 KNOTS
IS EXPECTED TO DEVELOP OVER THE COASTAL PLAIN. THE STRONGEST OF
THE WINDS SHOULD HAVE A DIFFICULT TIME MIXING TO THE SURFACE.
HOWEVER, SOME GUSTS AROUND 30 OR 35 MPH SEEM POSSIBLE. THE SYSTEM
IS ANTICIPATED TO PULL A COLD FRONT THROUGH OUR REGION EARLY ON
CHRISTMAS MORNING SIGNALING THE BEGINNING OF THE END OF THE RAIN
EVENT AS WELL AS A RETURN TO NEAR SEASONABLE TEMPERATURES FOR THE
BALANCE OF THE WEEK AND INTO THE WEEKEND.

THE MODELS HAVE BEEN TRENDING TOWARD LOWER RAINFALL AMOUNTS FOR
THE MID WEEK EVENT THAN THEY HAD BEEN SHOWING OVER PREVIOUS DAYS.
THE GENERAL CONSENSUS SUGGESTS RAINFALL TOTALS MAINLY IN THE 0.75
TO 1.25 INCH RANGE FOR OUR REGION. WE SHOULD BE ABLE TO HANDLE
THOSE AMOUNTS BASED ON ANTECEDENT CONDITIONS WITH NOT MUCH MORE
THAN SOME LOCALIZED FLOODING IN AREAS OF POOR DRAINAGE.

THE MODEL GUIDANCE CONTINUES TO DIFFER ON THE HANDLING OF THE MID
LEVEL SHORT WAVE AND THE ACCOMPANYING COLD FRONT FOR THE COMING
WEEKEND. WE WILL KEEP THE MENTION OF A SLIGHT CHANCE OF SNOW
SHOWERS AND RAIN SHOWERS FOR THE TIME BEING WITH THE HOPE THAT THE
MODELS WILL COME INTO BETTER AGREEMENT DURING THEIR SUBSEQUENT
RUNS.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

THIS AFTERNOON...VFR/MVFR CEILINGS, WITH THE LOWEST CEILINGS MAINLY
NORTH OF THE KPHL AREA FOR AWHILE. AS MOISTURE INCREASES, THE
CEILINGS ARE ANTICIPATED TO LOWER INTO THIS EVENING. SOME RAIN IS
ANTICIPATED LATER TODAY FROM SOUTH TO NORTH, WITH AREAS MAINLY
SOUTH AND EAST OF KPHL HAVING THE BEST CHANCE. SOME MVFR
VISIBILITIES SHOULD OCCUR AT TIMES MAINLY DURING THE RAIN.
LIGHT/VARIABLE WINDS BECOMING NORTHEAST OR EAST-NORTHEAST 5-8
KNOTS.

TONIGHT...MVFR CEILINGS ARE ANTICIPATED TO LOWER TO IFR/LIFR WITH
LIGHT RAIN OR DRIZZLE. NORTHEAST WINDS GENERALLY AROUND 5 KNOTS.

OUTLOOK...
TUESDAY...CONDITIONS POSSIBLY LOWERING INTO THE MVFR CATEGORY
WITH A CHANCE OF LIGHT RAIN.

TUESDAY NIGHT...MVFR AND IFR CONDITIONS ANTICIPATED WITH RAIN
LIKELY.

WEDNESDAY AND WEDNESDAY NIGHT...MVFR AND IFR CONDITIONS WITH RAIN
LIKELY. THE RAIN MAY BE HEAVY AT TIMES.

THURSDAY...CONDITIONS IMPROVING TO VFR WITH A GUSTY WEST WIND.

THURSDAY NIGHT AND FRIDAY...MAINLY VFR.

&&

.MARINE...
CONDITIONS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY
LEVELS TODAY AS HIGH PRESSURE TO OUR NORTH BEGINS TO RETREAT. AS A
COASTAL LOW APPROACHES THE AREA THIS EVENING AND OVERNIGHT, WINDS
MAY BEGIN TO INCREASE AND COULD GUST TO AROUND 20 KNOTS. SEAS
AROUND 1-2 FEET THIS MORNING WILL INCREASE LATER TODAY AND
ESPECIALLY OVERNIGHT AS THE COASTAL LOW APPROACHES AND SEAS MAY
BEGIN TO APPROACH 4 FEET.

OUTLOOK...
TUESDAY AND TUESDAY NIGHT...WAVE HEIGHTS ON OUR OCEAN WATERS MAY
BUILD TO 5 FEET IN A DEVELOPING EAST TO SOUTH FLOW.

WEDNESDAY...SOUTHERLY WIND GUSTS IN EXCESS OF 25 KNOTS ARE
EXPECTED. WAVE HEIGHTS ON OUR OCEAN WATERS MAY BUILD TO 6 TO 9
FEET.

WEDNESDAY NIGHT...A SOUTH WIND BECOMING WEST. WIND GUSTS IN
EXCESS OF 25 KNOTS ARE EXPECTED. WAVE HEIGHTS ON OUR OCEAN WATERS
MAY BE 6 TO 9 FEET.

THURSDAY...WESTERLY WIND GUSTS IN EXCESS OF 25 KNOTS ARE
EXPECTED. LOCALIZED GALE FORCE GUSTS ARE POSSIBLE. WAVE HEIGHTS ON
OUR OCEAN WATERS MAY BE TO 5 TO 7 FEET.

THURSDAY NIGHT...WIND GUSTS AND WAVE HEIGHTS ARE FORECAST TO FALL
GRADUALLY BELOW THE SMALL CRAFT ADVISORY CRITERIA.

FRIDAY...NO MARINE HEADLINES ARE ANTICIPATED.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...FREEZING RAIN ADVISORY FROM 6 PM THIS EVENING TO 4 AM EST
     TUESDAY FOR PAZ054-055.
NJ...FREEZING RAIN ADVISORY FROM 6 PM THIS EVENING TO 4 AM EST
     TUESDAY FOR NJZ001.
DE...NONE.
MD...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...GORSE/IOVINO
NEAR TERM...GORSE
SHORT TERM...ROBERTSON
LONG TERM...IOVINO
AVIATION...GORSE/IOVINO
MARINE...IOVINO/ROBERTSON




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