Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 300342
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1142 PM EDT MON SEP 29 2014

.SYNOPSIS...
LOW PRESSURE OVER THE EASTERN GREAT LAKES TONIGHT WILL MOVE ACROSS
PENNSYLVANIA TUESDAY WHILE A WEAK BACKDOOR COLD FRONT OVER SOUTHERN
NEW ENGLAND SLIDES SOUTHWEST ACROSS THE REGION. THAT LOW PRESSURE
SYSTEM WILL DEVELOP OUT TO SEA WEDNESDAY WITH HIGH PRESSURE IN
EASTERN CANADA RIDGING DOWN INTO THE MID ATLANTIC STATES THURSDAY.
A STRONGER COLD FRONT WILL MOVE EAST ACROSS THE MID ATLANTIC
STATES EARLY SATURDAY. WEAK HIGH PRESSURE FOLLOWS NEXT SUNDAY. A
WARM FRONT APPROACHES THE REGION EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TUESDAY/...
1140 PM UPDATE...RAISED POPS MD/PA BORDER AND MUCH OF SOUTHERN DE
AND EASTERN NJ THROUGH 07Z. TOO MUCH RAIN ON RADAR. THEN THE
CONCERN...SINCE DEWPOINTS ARE MUCH HIGHER THAN MODELED...HOW
EXTENSIVE THE FOG AT SUNRISE TUESDAY. COULD SEE PATCHY DENSE FOG
DEVELOP PORTIONS OF E PA WHERE IT CLEARS BY 09Z AND THEN SEPARATELY
OVER COASTAL SECTIONS.

TUESDAY...A QUIET MORNING EXPECTED...THEN SCT SHOWERS SHOULD
DEVELOP DURING THE MID-LATE AFTN E PA PER INCREASING INSTABILITY
ALOFT AS 500MB TEMPS COOL 2C LATE IN THE DAY STEEPENING MID LVL
LAPSE RATES.

&&

.SHORT TERM /TUESDAY NIGHT/...
TUESDAY NIGHT...COOL POOL ALOFT SLIDES EWD ACROSS THE REGION WITH
500MB TEMPS NEAR -15-16C. BANDS OF SHOWERS MAY BE OCCURRING WITH
SUBTLE LIFT FROM BOTH WEAK BUT DEEP ELY MOIST WINDS NORTH OF I78 AND
THE BACKDOOR COOL FRONT CONVERGENCE ZONE DRIVEN BY THE STRENGTHENING
NE FLOW NE OF THE BACKDOOR CF.

ADDITIONALLY FOG MAY DEVELOP IN THE COOLER BL AIR NE OF THE FRONTAL
BOUNDARY.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
VERY FEW CHANGES IN THE EXTENDED PERIOD FORECAST FROM 12 HOURS
AGO. SEVERAL CHANCES FOR RAIN THROUGH THIS TIME PERIOD BUT AMOUNTS
LOOK LIKE THEY WILL BE ON THE RELATIVELY LIGHT SIDE. TEMPERATURES
FOR THE TIME PERIOD WILL BE SLIGHTLY ABOVE NORMAL EARLY IN THE
PERIOD, THEN TRENDING TO NEAR NORMAL LATE IN THE PERIOD.

HIGH PRESSURE BUILDS INTO THE REGION FOR LATE WEDNESDAY INTO
FRIDAY.

COLD FRONTAL BOUNDARY APPROACHING WITH NEXT UPPER LEVEL SYSTEM
MOVES THROUGH LATE FRIDAY/EARLY SATURDAY BRINGING ANOTHER CHANCE OF
RAIN. HIGHEST POPS THROUGH THE LONG TERM PERIOD ARE ASSOCIATED
WITH THIS SYSTEM.

HIGH PRESSURE BUILDS IN ONCE AGAIN FOR THE REMAINDER OF THE
WEEKEND BEFORE A WARM FRONTAL BOUNDARY APPROACHES FROM THE
SOUTHWEST LATE ON MONDAY, ONCE AGAIN BRINGING A CHANCE OF
PRECIPITATION.

USE WPC GUIDANCE PREDOMINATELY FOR DAYS 4 THOUGH 7. FOR TUE NIGHT
INTO THU, USED A 50/50 BLEND OF PREVIOUS FORECAST AND ADJUSTED GFS
MAV MOS

&&

.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

THROUGH 12Z...AREAS OF LIGHT RAIN SHOWERS FROM MID LVL DECK OF CIGS
AOA 6000 FT WITH A CLEARING TREND EXPECTED E PA OVERNIGHT. LIGHT
SOUTH WIND WITH HIGHER THAN MODELED DEWPOINTS SHOULD FACILITATE
THE DEVELOPMENT OF 1-3 MI FOG PATCHES AND POTENTIAL BRIEF LIFR
CONDS IN ST/FOG NEAR 11Z BOTH VCNTY KRDG/KABE BUT ALSO ELSEWHERE
WHERE IT RAINED THIS PAST MONDAY AFTERNOON/EVENING.

AFTER 12Z TUESDAY...AFTER ANY LEFTOVER IFR ST/FOG BURNS OFF BY
14Z....SCT CLOUDS AOA 5000 FT BECOME BKN MID-LATE AFTN WITH A
POSSIBLE SHOWER VCNTY KRDG/KABE. LIGHT SOUTH WIND TURNING E.

TUESDAY NIGHT...WIND BECOMING NE AT 5-15 KT AND A DECK OF IFR
ST/FOG SHOULD DEVELOP BEHIND THE BACKDOOR COLD FRONT CURRENTLY
MOVING SW FROM SOUTHERN NEW ENGLAND. CHC OF SHOWERS...MAINLY N OF
KPHL.

OUTLOOK...

WEDNESDAY...MAINLY VFR CIGS WITH POSSIBLE MVFR CONDS IN SHOWERS
KABE/KRDG/KTTN DURING THE MORNING. E/NE WINDS GUST 15 KNOTS.

THURSDAY...POSSIBLE MVFR FOG EARLY OTHERWISE VFR SCT-BKN CLOUDS
AOA 4000 FT. N-NW WIND GUST 15 KT.

FRIDAY...VFR CIGS EXCEPT POSSIBLE MVFR CONDS IN ST/FOG EARLY FRIDAY
MORNING AND THEN AGAIN FRIDAY NIGHT IN SHOWERS NEAR A COLD FRONT.
E-SE WIND BECOMING S OR SW LATE AT NIGHT.

SATURDAY...VFR CONDITIONS EXPECTED.

&&

.MARINE...
SEAS THIS EVENING ARE AROUND TWO FEET ACROSS THE REGION. WINDS WILL
BE LIGHT THROUGH TONIGHT AS WELL. TOMORROW WE WILL GRADUALLY SEE
SEAS BUILD AND WINDS INCREASE OUT OF NORTHEAST. SEAS MAY REACH FOUR
FEET TUESDAY AFTERNOON WITH SOME WIND GUSTS AROUND 20 KNOTS AS WELL.
CONDITIONS BELOW SCA CRITERIA FOR THIS PERIOD.

TUESDAY NIGHT...NE WIND 10-20 KT WITH ATLC SEAS NEAR 4 FT. NO HEADLINE
ANTICIPATED ATTM.

OUTLOOK...

WEDNESDAY THROUGH WEDNESDAY NIGHT: NE FLOW WEDNESDAY AND WEDNESDAY
NIGHT SHOULD INCREASE TO SCA CRITERIA ALONG THE NNJ COAST AND THEN
POSSIBLY SOUTHWARD TO THE ENTIRE ATLC COAST LATER WEDNESDAY OR
WEDNESDAY NIGHT. DELAWARE BAY MAY NOT SEE WIND GUSTS ABOVE 22 KT
WITH ANY SCA HEADLINE THERE NOT LIKELY. HAVE HELD OFF ON ISSUING
ANY FORMAL HEADLINES ON THIS FORECAST UPDATE AS CONDITIONS WILL
JUST MEET LOWER END SCA CRITERIA AND CONFIDENCE IS NOT YET HIGH.

THURSDAY...SMALL CHANCE OF SCA SEAS ON THE ATLANTIC WATERS FROM NE
SWELLS GENERATED BY AN OFFSHORE LOW.

FRIDAY...WIND BECOMING SOUTH BY NIGHT. SMALL CHANCE OF AN SCA AT
NIGHT.

SATURDAY...SCA CONDITIONS POSSIBLE EARLY WITH COLD FRONT PASSAGE,
THEN IMPROVING CONDITIONS EXPECTED.

&&

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

&&

$$
SYNOPSIS...DRAG/SZATKOWSKI
NEAR TERM...DRAG 1141
SHORT TERM...DRAG
LONG TERM...SZATKOWSKI
AVIATION...DRAG/SZATKOWSKI
MARINE...DRAG/GAINES/SZATKOWSKI/HEAVENER





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