-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPHI 170422
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1222 AM EDT FRI MAY 17 2013

.SYNOPSIS...
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A COLD FRONT WILL PUSH TO OUR SOUTH OVERNIGHT AND STALL TO OUR
SOUTH THROUGH THE UPCOMING WEEKEND. THE FRONTAL BOUNDARY IS
EXPECTED TO RETURN NORTHWARD AS A WARM FRONT LATE MONDAY INTO
TUESDAY. ANOTHER FRONTAL SYSTEM IS EXPECTED TO APPROACH THE AREA
FROM THE WEST AND MOVE THROUGH THE AREA DURING THE MIDDLE TO LATE
PART OF NEXT WEEK.
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&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
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BASICALLY DEBRIS AND BLOW-OFF CLOUDINESS FROM CONVECTION WILL
REMAIN ACROSS OUR SOUTHERN COUNTIES OVERNIGHT WITH A MAINLY CLEAR
SKY TO THE NORTH. DEW POINTS HAVE DROPPED PRECIPITOUSLY BEHIND THE
COLD FRONT IN EASTERN PA AND FAR NW NJ AND THIS SHOULD TRANSLATE
SOUTHEAST AS THE FRONT CLEARS THE REST OF OUR CWA OVERNIGHT.
HOURLY TEMPS AND DEW POINTS ARE GOING TO HAVE A BUMPY RIDE
DOWNWARD AS THERE IS SOME WIND ABOVE THE BOUNDARY LAYER THAT MAY
MIX FROM TIME TO TIME.

TEMPERATURES ARE A GUIDANCE/CONTINUITY BLEND. UP NORTH, THERE MAY
BE SOME RADIATING WITH LOWER DEW POINTS ALREADY IN PLACE AND WINDS
EXPECTED TO GO LIGHT. THE SECONDARY FRONT MAY MIX THINGS A BIT
AND TURN THE REST OF THE NIGHT INTO A MILDLY ADVECTIVE ONE.
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&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TODAY/...
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OUR FORECAST IS THAT THE SURFACE HIGH RIDGING DOWN FROM CENTRAL
CANADA AND SOME LOCAL MID LEVEL RIDGING TO OUR WEST (AHEAD OF A
SLOW MOVING SYSTEM THAT WAS THE CLOSED LOW RESPONSIBLE FOR THE
SPLIT FLOW EARLIER IN THE WEEK) WILL CARVE OUT A DRY DAY FOR THE
ENTIRE FORECAST AREA. THERE SHOULD BE A DECENT AMOUNT OF SUNSHINE,
ALTHOUGH SOME HIGH CLOUDINESS MAY BEGIN TO INVADE FROM THE SOUTH
AND WEST DURING THE COURSE OF THE DAY. WINDS SHOULD BE RATHER
LIGHT AS HIGH PRESSURE MOVES OVER US. TEMPERATURES ARE A
GUIDANCE/CONTINUITY BLEND IN LINE WITH H925 TEMPERATURES, AND ARE
FORECAST TO BE A BIT ABOVE NORMAL. THE CAVEAT IS THAT WE EXPECT A
SEA BREEZE TO DEVELOP DURING THE COURSE OF THE DAY.
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&&

.LONG TERM /TONIGHT THROUGH THURSDAY/...
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THE COLD FRONT WILL REMAIN STALLED TO OUR SOUTH FOR THE UPCOMING
WEEKEND. FRIDAY NIGHT INTO SATURDAY, HIGH PRESSURE WILL NOSE DOWN
ACROSS OUR AREA FROM THE NORTH, KEEPING THE FRONT TO OUR SOUTH AND
KEEPING OUR AREA IN MORE OF AN EASTERLY/SOUTHEASTERLY FLOW. SOME
GUIDANCE IS TRYING TO BRING SOME LIGHT QPF ACROSS THE AREA AS
EARLY AS FRIDAY NIGHT, BUT WE WILL KEEP FRIDAY NIGHT DRY. AS WE
MOVE INTO THE WEEKEND, A SLOW MOVING SHORT WAVE WILL BE SLIDING
ACROSS THE OHIO RIVER VALLEY AND TOWARD THE EAST COAST. THIS WILL
PUSH SEVERAL WEAK DISTURBANCES ACROSS THE AREA THROUGH THE
WEEKEND, WHICH MAY HELP CREATE SOME SHOWER ACTIVITY. THE AIR MASS
SHOULD BE FAIRLY STABLE, SO WE ARE NOT EXPECTING THUNDERSTORMS AT
THIS TIME. WITH THE EASTERLY/SOUTHEASTERLY FLOW, TEMPERATURES ARE
NOT EXPECTED TO WARM SIGNIFICANTLY EITHER.

AS THE HIGH PRESSURE REMAINS TO OUR NORTHEAST AND SLOWLY BUILDS
OUT TO SEA MONDAY INTO TUESDAY, MOISTURE WILL CONTINUE TO PUSH
ACROSS THE AREA THROUGH EARLY NEXT WEEK. THE FRONTAL BOUNDARY TO
OUR SOUTH IS EXPECTED TO BEGIN PUSHING BACK NORTHWARD AS A WARM
FRONT AS WELL, AND MAY MOVE THROUGH THE AREA BY MONDAY NIGHT INTO
TUESDAY. WE COULD CONTINUE TO SEE SOME PRECIPITATION ACROSS THE
AREA AHEAD OF THE WARM FRONTAL BOUNDARY AS SEVERAL WEAK
DISTURBANCES MOVE ACROSS THE AREA IN THE WESTERLY FLOW ALOFT.

AFTER THE WARM FRONT MOVES THROUGH, TUESDAY AND WEDNESDAY OF NEXT
WEEK LOOK TO BE THE WARMEST DAYS. WE DID NOT GO AS HIGH AS WHAT
THE 850 MB ECMWF/GFS TEMPS WOULD FORECAST FOR SURFACE MAXES, BUT
WE SHOULD BE ABLE TO REACH AT LEAST THE LOW 80S FOR MUCH OF THE
AREA. WE WILL KEEP A CHANCE OF SHOWERS/THUNDERSTORMS IN THE
FORECAST TUESDAY/WEDNESDAY AS WE SHOULD BE IN THE WARM SECTOR
AHEAD OF THE NEXT APPROACHING FRONTAL SYSTEM. ANY SHORT WAVES/VORT
MAXES COULD HELP CREATE SHOWERS/THUNDERSTORMS WITH THE AVAILABLE
INSTABILITY.

THE LATEST GFS/ECMWF VARY ON THEIR TIMING OF THE NEXT FRONTAL
SYSTEM. THE GFS BRINGS THE FRONT THROUGH WEDNESDAY NIGHT INTO
THURSDAY, WHILE THE ECMWF BRINGS IT THROUGH THURSDAY NIGHT INTO
FRIDAY. BEING SO FAR OUT, WE WILL KEEP A CHANCE OF SHOWERS IN THE
FORECAST THROUGH THURSDAY NIGHT FOR NOW.
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&&

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

THE 00Z TAFS CARRY A VFR FORECAST WITH NO CIGS. WITH DRIER AIR
MOVING INTO THE AREA, NO FOG IS ANTICIPATED TOWARD MORNING. WINDS
SHOULD VEER FROM THE WEST TOWARD THE NORTH OVERNIGHT (SOME TAF
SITES ARE SHOWING AN AVERAGE DIRECTION FOR THE FORECAST PERIOD).
SPEEDS ARE EXPECTED TO BE LESS THAN 10 KNOTS.

ON FRIDAY THE CONVECTIVE TEMPERATURE IS EXPECTED TO BE TOO HIGH
FOR CUMULIFORM BASED CLOUDS TO FORM AND ONLY CIRRUS IS MENTIONED.
NORTH WINDS SHOULD AVERAGE CLOSE TO 10 KTS. WE ARE EXPECTING SEA
AND BAY BREEZE FRONTS TO FORM DURING THE AFTERNOON AND MOVE
WESTWARD REACHING KACY IN THE MIDDLE OF THE AFTERNOON AND KPHL
LATE IN THE DAY.

OUTLOOK...
FRIDAY NIGHT...MOSTLY VFR.

SATURDAY-SATURDAY NIGHT...MAINLY VFR WITH LOWERING CLOUDS. A
SLIGHT CHANCE OF SHOWERS AND SOUTH TO SOUTHEAST WINDS AROUND 5
KNOTS.

SUNDAY-SUNDAY NIGHT...GENERALLY VFR EXPECTED, POSSIBLE MVFR CIGS,
ESPECIALLY WITH ANY SHOWERS.

MONDAY-TUESDAY...GENERALLY VFR, POSSIBLE MVFR CIGS/VSBYS,
ESPECIALLY WITH ANY SHOWERS/THUNDERSTORMS.
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&&

.MARINE...
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LIGHT WEST WINDS ARE EXPECTED TO BECOME NORTHERLY AND PICK UP
SOME AS A SECONDARY COLD FRONT DROPS ACROSS THE COASTAL WATERS OF
NEW JERSEY AND DELAWARE. FORECAST PRESSURE RISES SUPPORT A
MODERATE BUT NOT ADVISORY LEVEL WIND. WINDS SHOULD DIMINISH AGAIN
ON FRIDAY. THE WINDS MAY BECOME ONSHORE NEAR LAND.

OUTLOOK...
CONDITIONS SHOULD REMAIN BELOW ADVISORY LEVELS THROUGH SATURDAY.
HOWEVER, WINDS MAY RETURN CLOSE TO ADVISORY LEVELS STARTING
SATURDAY NIGHT INTO SUNDAY AS THE PRESSURE GRADIENT TIGHTENS
ACROSS THE WATERS AS HIGH PRESSURE PUSHES OFF THE NORTHEAST COAST.
WITH THE EASTERLY/SOUTHEASTERLY FLOW, SEAS MAY RETURN TO SMALL
CRAFT ADVISORY LEVELS DUE TO THE LONG FETCH STARTING SUNDAY AND
CONTINUING INTO TUESDAY.
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&&

.FIRE WEATHER...
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WE WILL MENTION IN THE FIRE WEATHER FORECAST THAN MINIMUM
RELATIVE HUMIDITY LEVELS WILL DROP TO OR BELOW 30 PERCENT ON
FRIDAY AFTERNOON FOR MUCH OF THE FORECAST AREA. WINDS AND FINE
FUELS ARE NOT A CONCERN.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...ROBERTSON
NEAR TERM...DELISI/GIGI
SHORT TERM...DELISI
LONG TERM...ROBERTSON
AVIATION...GIGI/ROBERTSON
MARINE...DELISI/GIGI/ROBERTSON
FIRE WEATHER...DELISI