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000
FXUS61 KPHI 180725
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
325 AM EDT FRI APR 18 2014

.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO EXTEND ACROSS THE EASTERN SEABOARD
THROUGH TODAY. THE HIGH WILL RETREAT AS A WEAKENING FRONTAL BOUNDARY
MOVES ACROSS THE AREA TONIGHT INTO SATURDAY MORNING. HIGH PRESSURE
REESTABLISHES ITSELF ACROSS EASTERN CANADA OVER THE WEEKEND AND
BUILDS SOUTHWARD ALONG THE EASTERN SEABOARD SUNDAY INTO MONDAY.
ANOTHER FRONTAL BOUNDARY IS EXPECTED TO AFFECT THE AREA NEXT
TUESDAY, FOLLOWED BRIEFLY BY HIGH PRESSURE WEDNESDAY NIGHT INTO
THURSDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
230 AM ESTF...DROPPED THE REMAINING FROST HEADLINE IN SE PA.

EARLY THIS MORNING...MOSTLY CLOUDY WITH A FEW BREAKS IN THE OVC.
TEMPS MOSTLY 35 TO 40. ISO FREEZING TEMPS KSMQ TO KMPO SHOULD BE
WARMING SEVERAL DEGREES DURING THESE PREDAWN HOURS.

A LIGHT NE-E WIND CONTINUES.

ELY MARINE LAYER OF HIGH RH SATURATING JUST BELOW THE INVERSION
AROUND 2200-2400 FT. NOT NEARLY AS COLD AS THURSDAY MORNING WHEN A
RECORD LOW WAS SET AT ALLENTOWN PA.

TODAY...FCST BASIS IS MOSTLY NAM 3RLY TEMPS AND MAX T DURING THE
DAY AND THE HIGHER OF THE NCEP 3 HRLY MOS DEWPOINTS. 50 50 BLENDED
SFC SUSTAINED WINDS.

LOW CLOUDS RECEDE EWD AS THE BL WARMS BUT LOW CLOUDS SHOULD
DOMINATE MOST OF THIS FRIDAY MORNING. THEN CONSIDERABLE HIGH CLOUD
DURING THE AFTN. E WIND G NEAR 15 KT BECOMING S-SE LATE IN THE
DAY. MAX TEMPS NEAR 5 PM THIS AFTN IN THE INTERIOR AS THE LOW
CLOUDS DISSIPATE DURING THE AFTN AND TEMPS MAY RISE 5 DEGREES BETWEEN
2P AND 5P VCNTY PHILADELPHIA.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
TONIGHT...FCST BASIS IS A 50 50 BLEND OF THE 00Z/18 NCEP MOS
GUIDANCE WITH THE COLDER OF THE LOW TEMPS NEAR 10Z/SAT.

CONSIDERABLE MOSTLY HIGH CLOUD WITH A SMIDGE OF CFP CLOUD NEAR
4000 FT TOWARD DAWN SATURDAY. LIGHT SE-S WIND DURING THE EVENING
TURN W OR NW LATE AT NIGHT.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
WE EXPECT DRY WEATHER TO BUILD IN ACROSS THE AREA SATURDAY BEHIND
THE WEAKENING FRONTAL BOUNDARY THAT WILL CROSS THE AREA EARLY
SATURDAY MORNING AS HIGH PRESSURE BEGINS TO BUILD SOUTHWARD OUT OF
CANADA. THE HIGH SHOULD SUPPRESS THE LOW TO OUR SOUTH OFF THE
SOUTHEAST COAST WHICH SHOULD PREVENT ANY PRECIPITATION FROM REACHING
OUR AREA.

THIS HIGH WILL REESTABLISH ITSELF ACROSS EASTERN CANADA AND BUILD
SOUTHWARD ALONG THE EASTERN SEABOARD SUNDAY AND MONDAY. THIS WILL
CONTINUE TO PROVIDE DRY WEATHER OVER THE WEEKEND INTO MONDAY OF NEXT
WEEK. WITH SLIGHT RIDGING ALOFT TAKING PLACE, TEMPERATURES WILL
RETURN CLOSER TO NORMAL OVER THE WEEKEND INTO EARLY NEXT WEEK.
SUNDAY WILL LIKELY BE THE COOLEST DAY WHEN THICKNESSES AND 925 MB
TEMPERATURES ARE AT THEIR LOWEST.

THE HIGH WILL WEAKEN AND RETREAT MONDAY NIGHT AHEAD OF AN
APPROACHING STORM SYSTEM. AN AREA OF LOW PRESSURE IS FORECAST TO
MOVE OUT OF THE GREAT LAKES REGION AND STRENGTHEN AS IT MOVES INTO
NEW ENGLAND TUESDAY INTO TUESDAY NIGHT. AS THIS OCCURS, A COLD
FRONT WILL SWEEP THROUGH THE AREA LATE TUESDAY INTO TUESDAY NIGHT,
WHICH WILL BRING THE NEXT CHANCE OF PRECIPITATION ACROSS THE AREA.
THEREFORE WE MAINTAIN CHANCE POPS ACROSS THE AREA DURING THIS TIME
PERIOD.

THIS LOW IS EXPECTED TO SLOWLY PULL TO OUR NORTHEAST THROUGH
WEDNESDAY AND THURSDAY AS HIGH PRESSURE BEGINS TO BUILD SOUTHWARD
OUT OF CANADA ONCE AGAIN. WEDNESDAY AND THURSDAY ARE EXPECTED TO BE
DRY, BUT SHOULD BE QUITE GUSTY WITH THE TIGHTENING PRESSURE
GRADIENT. WINDS COULD EASILY GUST 25-30 MPH, IF NOT HIGHER.

&&

.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

THROUGH 12Z...CIGS 2000-2500 FT. LIGHT EAST WIND.

AFTER 12Z...THE MVFR CIG IS EXPECTED TO DISSIPATE RAPIDLY EASTWARD
LATE THIS MORNING OR MIDDAY WITH A VFR CIRRUS DECK ABOVE IT DURING
THE AFTERNOON. SYNOPTIC SCALE WINDS OVERALL SHOULD BE LIGHTER
(GENERALLY AN EASTWARD COMPONENT) THAN THURSDAY AND A SEA BREEZE
FRONT MAY FORM DURING THE AFTERNOON AS THE WIND TENDS TO TURN SE-S.

TONIGHT...VFR CIRRUS WITH CHC OF A SCT-BKN DECK NEAR 4000 FT TOWARD
10Z SATURDAY ASSOCIATED WITH A WEAK COLD FRONTAL PASSAGE (CFP).

OUTLOOK...
SATURDAY-MONDAY NIGHT...MOSTLY VFR. GUSTY N-NW WINDS 15-20 KNOTS
SATURDAY.

TUESDAY...MVFR CONDITIONS POSSIBLE WITH SHOWERS WITH A FRONTAL
PASSAGE.

&&

.MARINE...
SEAS 9 FT AT 44009 AT 2 AM.

GFS WW4 GUIDANCE HAS BEEN TOO LOW BY A FOOT OR 2 ON THE ATLANTIC
WATERS AND SO HAVE RAISED THAT GUIDANCE THRU THIS FRIDAY EVENING.

SCA CONTINUES OPEN ATLC WATERS...MAINLY FOR SEAS AND HAVE CONVERTED
THAT SCA HEADLINE TO SCA FOR HAZARDOUS SEAS HERE AT THE 3 AM ISSUANCE.

DE BAY WATERS NO HEADLINE THRU TONIGHT. E-NE WIND G 15 KT AND SEAS
LESS THAN 3 FT TODAY. WINDS AND SEAS DIMINISH/SUBSIDE TONIGHT. THE
WIND TURN S TOWARD SUNSET FRIDAY THEN SHIFT TO W OR NW TOWARD DAWN
SATURDAY.

OUTLOOK...
SATURDAY...SUB-SMALL CRAFT ADVISORY CRITERIA EXPECTED, THOUGH
WINDS MAY GUST NEAR 20 KNOTS.

SATURDAY NIGHT-SUNDAY NIGHT...WINDS AND SEAS INCREASING TO SMALL CRAFT
ADVISORY CRITERIA OVERNIGHT SATURDAY AND CONTINUE INTO SUNDAY. SEAS
MAY REMAIN ELEVATED INTO SUNDAY NIGHT.

MONDAY-MONDAY NIGHT...A RETURN TO SUB-SMALL CRAFT ADVISORY CRITERIA.

TUESDAY...FRONTAL PASSAGE EXPECTED WITH NEAR ADVISORY CONDITIONS.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 AM EDT
     SATURDAY FOR ANZ450>455.

&&

$$
SYNOPSIS...ROBERTSON
NEAR TERM...DRAG
SHORT TERM...DRAG
LONG TERM...ROBERTSON
AVIATION...DRAG/ROBERTSON
MARINE...DRAG/ROBERTSON