Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 142100
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
400 PM EST SUN FEB 14 2016

.SYNOPSIS...
HIGH PRESSURE WILL MOVE OFFSHORE TONIGHT AND DURING MONDAY. LOW
PRESSURE IS FORECAST TO DEVELOP OVER THE LOWER MISSISSIPPI AND
TENNESSEE RIVER VALLEYS ON MONDAY. THE LOW IS EXPECTED TO MOVE
NORTHEASTWARD AND IT SHOULD PASS OVER OR NEAR OUR REGION ON TUESDAY.
A COLD FRONT FROM THE NORTHWEST IS ANTICIPATED TO ARRIVE ON
WEDNESDAY FOLLOWED BY HIGH PRESSURE FOR THURSDAY AND FRIDAY. ANOTHER
COLD FRONT IS EXPECTED TO ARRIVE NEXT WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HIGH PRESSURE WILL SETTLE ACROSS THE AREA TONIGHT AND
THEN MOVE EAST LATE. CLR SKIES AND LIGHT WINDS EARLY WILL RESULT IN
COLD TEMPERATURES FOR MANY AREAS. READINGS WILL NOT BE AS COLD AS
LAST NIGHT, AND WINDS WILL BE LIGHT. LOW TEMPS WILL BE IN THE SINGLE
DIGITS TO LOW TEENS AREA-WIDE. TEMPERATURES WILL BE COLDER EARLY
TONIGHT AND THEN READINGS WILL MODERATE LATER TONIGHT ONCE CLOUDS
BEGIN TO INCREASE. A VERY SMALL CHC FOR SOME SNOW AROUND DAWN
ACROSS THE FAR SW COUNTIES.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
WINTER WEATHER ADVISORIES ARE BEING ISSUED FOR MONDAY.
THE AREAS COVERED BY THE ADVISORIES ARE BASICALLY THE I-95 CORRIDOR
N/W. SNOW WILL OVERSPREAD THAT AREA MONDAY MORNING AND THEN CHANGE
TO RAIN FROM S TO N DURING THE AFTERNOON. LIGHT ACCUMULATIONS OF 1-2
INCHES ARE EXPECTED IN MOST AREAS. A TRANSITION TO SOME SLEET WILL
OCCUR FOR A FEW HOURS BEFORE THE COMPLETE CHANGE TO RAIN. THE RECENT
MODEL RUNS ARE OFFERING LESS QPF...SO WE OPTED TO GO WITH
ADVISORIES. TEMPERATURES WILL TREND UPWARD SLOWLY ALL DAY WITH HIGHS
EXPECTED  LATE AND THEY SHOULD REACH INTO THE UPPER 30S/LOW 40S S/E
AND UPPER 20S/LOW 30S N/W. WINDS WILL BE MOSTLY E OR SE AT AROUND 10
MPH.

&&

.LONG TERM /MONDAY THROUGH SUNDAY/...
THE MAIN CONCERN IS FREEZING RAIN MONDAY NIGHT NORTHWEST OF I-95
AND HEAVY RAINFALL ON TUESDAY WITH RENEWED FLOODING POTENTIAL...

AN ACTIVE PACIFIC JET WILL MAINTAIN A RIDGE ACROSS THE WEST COAST
AND A DOWNSTREAM TROUGH ACROSS THE EAST COAST THROUGH THE MIDDLE
OF THE WEEK, WITH SOME SIGNS OF THIS PATTERN CHANGING THEREAFTER,
AS THE RIDGE MOVES TOWARD THE EAST COAST BY FRIDAY. THE MODELS
ARE STRUGGLING TO RESOLVE SOME OF THE SHORTWAVE ENERGY MOVING
THROUGH THE EAST COAST TROUGH, MOST NOTABLY IN THE MONDAY THRU
WEDNESDAY TIME FRAME. ON MONDAY, A WEAKER LEAD SHORTWAVE MOVES
THROUGH THE OHIO VALLEY DURING THE DAY. THIS IS QUICKLY FOLLOWED
BY A MORE SUBSTANTIAL SHORTWAVE, THE RESULT OF MODEST PHASING OF
THE NORTHERN AND SOUTHERN STREAMS, BECOMING NEGATIVELY TITLED
AS IT MOVES THROUGH THE MID ATLANTIC ON TUESDAY. THIS WILL LEAD
TO CYCLOGENISIS ALONG THE APPLACHIANS, BUT THE MODELS DIFFER ON
HOW THEY HANDLE COMPETING SHORTWAVE ENERGY, WHICH RESULTS IN
DISGREEMENT ON THE EVOLUTION OF THE SURFACE LOW. THERE IS ALSO
SOME DISAGREEENT ON A FAST MOVING CLIPPER SYSTEM IMMEDIATELY
FOLLOWING THIS SYSTEM ON WEDNESDAY. AT THIS TIME, THERE IS A
REPRIEVE WITH RIDGING ACROSS THE REGION ON THURSDAY AND FRIDAY,
BEFORE ANOTHER SYSTEM APPROACHES FOR NEXT WEEKEND.

FOR MONDAY NIGHT, THE MAIN ISSUE WILL BE FREEZING RAIN TO THE
NORTHWEST OF I-95 WHERE A WINTER WEATHER ADVISORY IS IN EFFECT.
WE EXPECT HEAVIER RAIN ON TUESDAY WITH THE POTENTIAL FOR SOME
URBAN AND SMALL STREAM FLOODING...SEE THE SEPERATE HYDROLOGY
SECTION. TEMPERATURES WILL BE WELL ABOVE NORMAL...AND FOG IS
ALSO POSSIBLE WHERE WE HAVE SNOW COVER. THERE WILL ALSO BE A
GUSTY SOUTH-SOUTHEAST WIND WHICH WILL LEAD TO HIGHER WATER
LEVELS ALONG THE COAST...SEE THE SEPERATE TIDES/COASTAL
FLOODING SECTION.

FOR WEDNESDAY...THERE IS THE POTENTIAL FOR SOME LIGHT PRECIP
WITH A FAST MOVING CLIPPER SYSTEM...BUT THERE IS STILL A LOT
OF UNCERTAINTY AS TO WHETHER IT MAKES IT TO OUR AREA. BOTH
THURSDAY AND FRIDAY ARE EXPECTED TO FEATURE FAIR WEATHER...
WITH THE NEXT CHANCE OF PRECIP WITH THE APPROACH OF A COLD
FRONT NEXT WEEKEND.

&&

.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

HIGH PRESSURE ACROSS THE AREA THIS EVENING MOVES EAST OVERNIGHT. VFR
CONDITIONS OVERNIGHT WITH CLR SKIES EARLY THEN THICKENING BKN-OVC BY
DAWN. NW WINDS AROUND 10 KNOTS LATE THIS AFTERNOON THEN LIGHT
VARIABLE OVERNIGHT. WINDS WILL BECOME E OR SE AROUND 5 KTS BY DAWN.

MONDAY...DETERIORATING CONDITIONS WITH MVFR CIGS/VSBYS AND SNOW BY
MID/LATE MORNING. THERE IS SOME CHC FOR SNOW TO ARRIVE EARLIER
(MAINLY KPHL AND SOUTH)...BUT CONFID IN THIS IS LOW ATTM. IFR
CONDITIONS OVERSPREADING AREA WITH SN/SLEET MOVING SW TO NE THROUGH
THE LATE MORNING AND AFTERNOON.

OUTLOOK...

MONDAY NIGHT...IFR CONDITIONS EXPECTED.

TUESDAY...IFR CONDITIONS. LOW LEVEL WIND SHEAR IS POSSIBLE,
MAINLY IN THE MORNING.

TUESDAY NIGHT THROUGH FRIDAY...MAINLY VFR.

&&

.MARINE...
HIGH PRESSURE WILL CREST OVER THE WATER TONIGHT AND THEN
MOVE EAST. THE WINDS AND SEAS WILL CONTINUE THE DIMINISHING TREND
THAT BEGAN EARLIER THIS AFTERNOON. WE WILL TAKE THE SCA FLAG DOWN
WITH THE 330 PM ISSUANCE. SUB-SCA CONDITIONS EXPECTED OVERNIGHT AND
MUCH OF MONDAY. WINDS WILL INCREASE FROM THE SE MONDAY AFTERNOON.
SNOW THEN RAIN EXPECTED LATER MONDAY.

OUTLOOK...

TUESDAY THRU WEDNESDAY...A SMALL CRAFT ADVISORY IS LIKELY AND
THERE IS THE POTENTIAL FOR GALE FORCE GUSTS AS WELL.

THURSDAY AND FRIDAY...SUB SCA CONDITIONS EXPECTED.

&&

.HYDROLOGY...
WE CONTINUE TO BE CONCERNED ABOUT THE POTENTIAL FOR FLOODING ON
TUESDAY WITH THE EXPECTED ARRIVAL OF A PERIOD OF MODERATE TO HEAVY
RAINFALL FROM LATE MONDAY NIGHT INTO EARLY TUESDAY AFTERNOON.
LIQUID PRECIPITATION TOTALS ARE FORECAST TO FAVOR THE 1.5 TO 2.0
INCH RANGE IN MUCH OF EASTERN PENNSYLVANIA AND NORTHERN NEW JERSEY.
WHILE THE PRECIPITATION SHOULD FALL AS SNOW AND ICE DURING MONDAY
AND PART OF MONDAY NIGHT, WARMING TEMPERATURES AND THE ARRIVAL OF
THE MODERATE TO HEAVY RAINFALL WILL CAUSE MUCH OF THE SNOW AND ICE
TO MELT. SMALL STREAMS ARE ALREADY RUNNING A BIT HIGH, SO THE
RAINFALL AND RUNOFF FROM THE MELTED SNOW AND ICE COULD CAUSE SOME
SMALL STREAM FLOODING. ALSO, THE RAINFALL ALONG WITH THE POTENTIAL
THAT STORM DRAINS WILL BE BLOCKED BY SNOW, ICE AND DEBRIS COULD
RESULT IN FLOODING OF ROADWAYS AND AREAS OF POOR DRAINAGE.

THE MODERATE TO HEAVY RAINFALL SHOULD IMPACT PARTS OF NORTHEASTERN
MARYLAND, DELAWARE AND SOUTHERN AND CENTRAL NEW JERSEY, AS WELL.
HOWEVER, LIQUID PRECIPITATION AMOUNTS ARE FORECAST TO BE A BIT LOWER
THERE, PERHAPS IN THE 0.75 TO 1.25 INCH RANGE. NEVERTHELESS, SOME
SMALL STREAM AND POOR DRAINAGE AREA FLOODING IS POSSIBLE.

DEPENDING UPON THE ACTUAL RAINFALL AMOUNTS AND HOW THE RUNOFF
REACTS, FLOODING MAY LINGER INTO TUESDAY NIGHT AND WEDNESDAY WITH
NOTICEABLE RISES POSSIBLE ON SOME OF THE MAIN STEM RIVERS.

&&

.TIDES/COASTAL FLOODING...
AFTER EXPERIENCING LOW WATER LEVELS ALONG THE TIDAL DELAWARE RIVER
LAST NIGHT AND EARLIER TODAY, WATER LEVELS ARE EXPECTED TO RETURN
CLOSER TO NORMAL WITH THE NEXT LOW TIDE LATER TONIGHT AS NORTHWEST
WINDS SUBSIDE AND ACTUALLY BECOME MORE SOUTHEASTERLY DURING THE
OVERNIGHT.

THE MOON WILL BE AT ITS FIRST QUARTER PHASE EARLY IN THE NEW WEEK,
SO ASTRONOMICAL TIDES WILL BE LOW. THE SOUTHEASTERLY ONSHORE FLOW IS
EXPECTED TO BE RELATIVELY SHORT LIVED, GENERALLY LASTING ONLY FOR
MONDAY, AND MODEL GUIDANCE CONTINUES TO INDICATE THE POTENTIAL FOR
EVEN MINOR TIDAL FLOODING ALONG THE COASTS OF NEW JERSEY AND
DELAWARE TO BE LOW WITH THE UPCOMING WEATHER SYSTEM MONDAY INTO
TUESDAY.

THE DEVELOPMENT OF A MODERATE SOUTHERLY FLOW FOR MONDAY NIGHT INTO
TUESDAY SHOULD PUSH WATER UP CHESAPEAKE BAY AND UP DELAWARE BAY AND
INTO THE TIDAL DELAWARE RIVER. HOWEVER, MOST OF THE AVAILABLE
GUIDANCE, INCLUDING ETSS/DBOFS/CBOFS, SUGGESTS THAT NO FLOODING WILL
OCCUR. THE ONLY OUTLIER CONTINUES TO BE THE ESTOFS MODEL WHICH
SUGGESTS MINOR FLOODING ON UPPER CHESAPEAKE BAY. WE WILL CONTINUE TO
MONITOR THE LATEST INCOMING DATA AS WE GET CLOSER TO THIS EVENT.

&&

.CLIMATE...
EVEN WITH A VERY STRONG BLAST OF COLD AIR WE DID NOT SEE
ANY RECORD LOWS ACROSS THE REGION THIS MORNING. ALSO, PHILADELPHIA,
ATLANTIC CITY AND WILMINGTON WILL ALL HAVE HIGH TEMPERATURES WARMER
THAN THE RECORD LOW MAXIMUM TEMPERATURE FOR FEBRUARY 14TH. THE
RECORD LOW MAXIMUM TEMPERATURE AT ALLENTOWN TODAY IS 14 DEGREES
WHICH IS ONE DEGREE BELOW THE CURRENT FORECAST HIGH OF 15.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER WEATHER ADVISORY FROM 9 AM MONDAY TO 2 AM EST TUESDAY
     FOR PAZ054-055-061-062-105-106.
     WINTER WEATHER ADVISORY FROM 6 AM MONDAY TO 2 AM EST TUESDAY
     FOR PAZ060-070-071-101>104.
NJ...WINTER WEATHER ADVISORY FROM 9 AM MONDAY TO 2 AM EST TUESDAY
     FOR NJZ001-007>010-012-015.
DE...WINTER WEATHER ADVISORY FROM 6 AM MONDAY TO 2 AM EST TUESDAY
     FOR DEZ001.
MD...WINTER WEATHER ADVISORY FROM 6 AM MONDAY TO 2 AM EST TUESDAY
     FOR MDZ008.
MARINE...NONE.

&&

$$
SYNOPSIS...FRANCK/IOVINO
NEAR TERM...O`HARA
SHORT TERM...O`HARA
LONG TERM...FRANCK
AVIATION...FRANCK/O`HARA
MARINE...FRANCK/O`HARA
HYDROLOGY...KLINE/IOVINO
TIDES/COASTAL FLOODING...KLINE/IOVINO
CLIMATE...GAINES


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