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Area Forecast Discussion
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000
FXUS61 KPHI 271418
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
918 AM EST TUE JAN 27 2015

.SYNOPSIS...
A STRONG STORM SYSTEM ABOUT 200 MILES OFF THE NEW JERSEY COAST THIS 
MORNING WILL MOVE TOWARD THE GULF OF MAINE THIS AFTERNOON AND 
TONIGHT BEFORE REACHING THE CANADIAN MARITIMES ON WEDNESDAY. HIGH 
PRESSURE BUILDING IN FROM THE OHIO VALLEY WEDNESDAY WILL SETTLE 
OVERHEAD WEDNESDAY NIGHT. A CLIPPER SYSTEM WILL MOVE THROUGH THE 
REGION THURSDAY NIGHT AND FRIDAY MORNING. HIGH PRESSURE RETURNS 
SATURDAY BEFORE ANOTHER LOW PRESSURE SYSTEM MOVES INTO THE EASTERN 
UNITED STATES SUNDAY INTO MONDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LIGHT SNOW CONTINUES OVER A GOOD PORTION OF THE FORECAST AREA THIS
MORNING...ESPECIALLY OVER SOUTHEAST PA AND NEW JERSEY. THE SNOW
THAT IS FALLING IS VERY LIGHT...SO ADDITIONAL ACCUMULATIONS SHOULD
BE LIMITED TO AN INCH OR SO...OR SLIGHTLY HIGHER IN ANY HEAVIER
BANDS THAT MIGHT SET UP. WE WILL CONTINUE WITH THE CURRENT TOTAL
SNOWFALL FORECAST FOR RIGHT NOW WHICH INDICATES THE HIGHER AMOUNTS
IN EASTERN NJ ALONG AND NORTH OF THE I-195 CORRIDOR. WARNINGS AND
ADVISORIES WILL REMAIN IN PLACE TOO. NORTHWEST WINDS WILL CONTINUE TO
GUST IN THE 25 TO 30 MPH RANGE...AND IN THE 30 TO 35 MPH RANGE
ALONG THE COAST. WHILE THESE WINDS WILL BLOW AROUND SNOW ON THE
GROUND...AND THE LIGHT SNOW AS IF FALLS FROM THE CLOUDS...IT WILL
ALSO BRING AN END TO ANY TIDAL FLOODING ISSUES ALONG THE COAST AND
DEL BAY. CLOUDS WILL REMAIN CLOUDY THROUGHOUT MOST OF THE
DAY...BUT THERE COULD BE SOME BRIGHTER SPOTS TOWARD BERKS COUNTY.
HIGH TEMPS AROUND 20 FAR NORTH, UPPER 20S TO AROUND 30 IN THE PHL
METRO AREA...AND MID 30S FAR SOUTH.

WE HAVE ISSUED AN UPDATED PUBLIC INFORMATION STATEMENT CONTAINING
THE LATEST SNOWFALL REPORTS. WE THANK ALL THOSE WHO HAVE GONE OUT
AND MEASURED THEIR SNOW AND REPORTED TO US. IT REALLY HELPS OUR
FORECAST PROCESS.
&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
DEEP LOW PRESSURE WILL CONTINUE TO PULL AWAY TO THE NORTHEAST AS 
HIGH PRESSURE BEGINS TO BUILD OVER THE AREA. THE ONLY MENTION OF 
PRECIP WILL BE SOME LEFTOVER SNOW SHOWERS THIS EVENING ACROSS THE 
SRN POCONOS AND CLOSER TO NYC AREA. SKIES WILL BECOME PARTLY CLOUDY 
TO CLR FROM THE SW TO NE AS THE NIGHT PROGRESSES. LOWS TONIGHT WILL 
BE IN THE TEENS AND LOW 20S OVER MOST AREAS WITH A FEW SINGLE DIGIT 
READINGS OVER THE SRN POCONOS.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
THE COASTAL LOW WILL STEADILY WEAKEN ON WEDNESDAY AS IT LIFTS 
NORTHEASTWARD THROUGH THE CANADIAN MARITIMES. NORTH-NORTHWESTERLY 
FLOW ON THE BACKSIDE OF THE TROUGH WILL GRADUALLY WEAKEN THROUGHOUT 
THE DAY AS HIGH PRESSURE BUILDS IN FROM THE OHIO VALLEY. WEDNESDAY 
WILL BE 5-10F DEGREES BELOW NORMAL. HOWEVER, DID LEAN ON THE WARMER 
SIDE OF GUIDANCE FOR MAX TEMPS UNDER FULL SUNSHINE AND  ADIABATIC 
WARMING FROM A DOWNSLOPING COMPONENT TO THE WINDS AS WELL AS LARGE 
SCALE SUBSIDENCE IN WAKE OF THE EXITING TROUGH. 

RADIATIONAL COOLING SHOULD BE STRONG WITH CLEAR SKIES AND CALM WINDS 
OVERNIGHT AS THE CENTER OF HIGH PRESSURE SHIFTS DIRECTLY OVERHEAD. 
GIVEN HOW DRY THE AIRMASS IS, THERE IS THE POTENTIAL FOR TEMPS TO 
BOTTOM OUT IN THE TEENS FOR THE I-95 URBAN CORRIDOR, ALONG THE COAST 
AND IN THE DELMARVA AND SINGLE DIGITS ELSEWHERE. MIN TEMP FORECAST 
WAS A BLEND BETWEEN PREVIOUS FORECAST (WHICH WAS THE COLDER THAN ANY 
00Z GUIDANCE) AND THE 00Z NAM.

AN ALBERTA CLIPPER IS FORECAST TO TRACK EASTWARD ACROSS THE UPPER 
MIDWEST/GREAT LAKES ON THURSDAY BEFORE MOVING THROUGH THE NORTHEAST 
STATES ON FRIDAY. ISENTROPIC LIFT AHEAD OF THE ATTENDANT COLD FRONT 
AND DPVA WITH THE UPPER SHORTWAVE TROUGH WILL SPREAD INTO 
NORTHEASTERN PA LATE IN DAY THURSDAY AND THE REMAINDER OF THE CWA 
THURSDAY NIGHT. A PERIOD OF LIGHT SNOW IS LIKELY DURING THIS TIME 
WITH THE HIGHEST POPS OVER EASTERN PA AND NORTHERN NJ. THIS SYSTEM 
WILL HAVE A BIT MORE MOISTURE (PWAT APPROACH 0.6 INCHES) TO WORK 
WITH THAN WHAT TYPICALLY ACCOMPANIES CLIPPERS AS IT IS ABLE TO TAP 
INTO LIMITED GULF OF MEXICO MOISTURE. GIVEN THE PROGRESSIVE NATURE 
OF THE LOW IS AND THE FACT THAT IT IS NOT FORECAST TO STRENGTHEN 
UNTIL IT REACHES THE GULF OF MAINE, SNOWFALL AMOUNTS SHOULD BE 
LIGHT: 1-3 INCHES IN THE POCONOS AND EXTREME NW NJ, LESS THAN AN 
INCH FARTHER SOUTH AND EAST.

STRONG CAA BEHIND THE COLD FRONT ON FRIDAY. MAX TEMPS IN THE 30S ARE 
FORECAST TO OCCUR IN THE AM WITH TEMPS FALLING THROUGHOUT THE 
AFTERNOON. BRISK NW WINDS HAVE THE POTENTIAL TO GUST 30-40 MPH 
ASSUMING DEEP MIXING IS REALIZED ON LAND. ADDITIONAL SNOW SHOWERS 
ARE POSSIBLE IN THE POCONOS.

DAYS 4.5-7 OF THE FORECAST WAS BASED ON THE 05Z/27 WPC ELEMENTS
OF TT/TD/WIND/SKY/POP. WE ADJUSTED THE WPC TEMPS MUCH HIGHER SUN
NIGHT AND A BIT HIGHER MONDAY PER NEW 00Z/27 MODE GUIDANCE
SUGGESTING LOW PRESSURE AND PRECIPITATION IN THIS TIME FRAME.

FRI NIGHT...VERY COLD WITH WIND CHILL ADVISORY POTENTIAL. NW FLOW 
BEHIND THE DEPARTING AREA OF LOW PRESSURE SHOULD STILL HAVE GUSTY 
WINDS WITH IT THROUGH THE NIGHT.  

SATURDAY...FAIR AND VERY COLD. AVERAGE TEMPS ABOUT 15 DEGREES BELOW 
NORMAL. 

SUNDAY...MODERATING WITH INCREASING CLOUDS DURING THE DAY AND PCPN 
OF SOME SORT EXPECTED AT NIGHT. HIGHLY VARIABLE SET OF SOLUTIONS AND 
CONFIDENCE ON TEMPS/PTYPE IS WELL BELOW AVERAGE. 

MONDAY...MAYBE SOME LEFT OVER PCPN, ESPECIALLY DURING THE MORNING 
THEN DRYING OUT AND TURNING COLDER.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, 
KMIV, KACY AND SURROUNDING AREAS.

WRAPAROUND SNOW FROM THE COASTAL STORM CONTINUES TO EXPAND TO THE 
SOUTH AND WEST ACROSS THE AREA EARLY THIS MORNING. THE TERMINALS ARE 
LOCATED ON THE WESTERN PERIPHERY, WHERE LIFT IS WEAKER AND SNOW IS 
LIGHTER. HAVE HIGHLIGHTED A 3-4 HOUR TEMPO GROUP EARLY THIS MORNING 
FOR IFR VSBYS AT TTN/PNE/PHL/ACY AND MVFR FARTHER SOUTH AND WEST. 
THIS SHIELD OF SNOW MAY LINGER OVER THE TERMINALS THROUGH ABOUT 18Z 
BUT VSBYS SHOULD GRADUALLY IMPROVE AFTER 15Z AS THE INTENSITY OF THE 
SNOW TAPERS OFF. N-NW WINDS 15-20 KT WILL GUST UP TO 25 KT TODAY. 
BLSN MAY REDUCE VSBYS LOCALLY AT THE TERMINALS BUT WAS NOT AS 
PESSIMISTIC WITH THE VSBYS SINCE THERE IS ONLY A FRACTION OF SNOW ON 
THE GROUND AS PREVIOUSLY ANTICIPATED.

VFR LATE THIS AFTN AND TONIGHT. WINDS RELAX A BIT OVERNIGHT.

OUTLOOK...
WEDNESDAY AND WEDNESDAY NIGHT...PRIMARILY VFR. NW WINDS 10-15 KT IN 
THE DAY, BECOMING CALM AT NIGHT.

THURSDAY INTO FRIDAY MORNING...VFR TO FOR MUCH OF THURSDAY. LIGHT 
SNOW WILL LIKELY SPREAD INTO THE AREA FROM WEST TO EAST THURSDAY 
NIGHT BUT MAY REACH ABE/RDG BY LATE AFTERNOON. MVFR/IFR RESTRICTIONS 
POSSIBLE WITH THE SNOW. HIGHEST CONFIDENCE IS AT NORTHERN TERMINALS.
 
FRIDAY AFTERNOON...VFR WITH BLUSTERY NW WIND GUSTING TO 30 KT.

FRI NIGHT...VFR.  GUSTY NW WINDS.

SATURDAY...VFR.

&&

.MARINE...
STORM WARNINGS CHANGED TO GALE WARNINGS FOR NJ WATERS. 

DEEP LOW PRESSURE EAST OF THE WATERS WILL CONTINUE TO MOVE NORTHEAST 
TODAY. STRONG WINDS WILL CONTINUE TODAY WITH GALE GUSTS EXPECTED AT 
LEAST THE FIRST PART OF TODAY. WINDS WILL PROBABLY DROP BACK BELOW 
GALE STRENGTH LATER...BUT THE DAY SHIFT CAN MAKE THAT CALL LATER. 
SIGNIFICANT SEAS WILL CONTINUE TODAY THEN SUBSIDE TONIGHT. 

OUTLOOK...
WEDNESDAY...SCA LIKELY WITH FREEZING SPRAY.

WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...NO MARINE HEADLINES ARE 
ANTICIPATED. SOME FREEZING SPRAY POSSIBLE WEDNESDAY NIGHT.

FRIDAY- NEAR GALE-FORCE GUSTS BEHIND A CLIPPER SYSTEM.

FRI NIGHT: POSSIBLE LEFTOVER NW GALE FORCE WIND GUSTS.

SATURDAY...SCA CONDITIONS POSSIBLE.

&&

.TIDES/COASTAL FLOODING...
THE OVERNIGHT HIGH TIDE ALONG THE NJ/DEL SHORE AND DEL BAY PRODUCED
MINOR TIDAL FLOODING, BUT NOTHING TOO SERIOUS. WITH A WELL-
ESTABLISHED NORTHWEST FLOW OVER THE REGION, NO ADDITIONAL TIDAL
ISSUES ARE EXPECTED WITH SUBSEQUENT HIGH TIDE CYCLES. 

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR PAZ055-062-
     071-103>106.
NJ...WINTER STORM WARNING UNTIL 3 PM EST THIS AFTERNOON FOR NJZ001-
     007>010-012>015-020-025-026.
     WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR NJZ018-019-
     027.
DE...NONE.
MD...NONE.
MARINE...GALE WARNING UNTIL 6 PM EST THIS EVENING FOR ANZ430-431-
     450>455.

&&

$$
SYNOPSIS...KLEIN
NEAR TERM...MIKETTA
SHORT TERM...O'HARA
LONG TERM...DRAG/KLEIN
AVIATION...DRAG/FRANCK/KLEIN
MARINE...DRAG/KLEIN
TIDES/COASTAL FLOODING...MIKETTA








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