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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPHI 162332
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
732 PM EDT THU MAY 16 2013

.SYNOPSIS...
A COLD FRONT WILL PUSH TO OUR SOUTH TONIGHT 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.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
THE LATEST LAPS SOUNDING ARE SHOWING SFC BASED CAPES HAVE DROPPED
25 TO 50 PERCENT FROM LAST HOUR AND ARE BELOW 500J IN NEARLY EVERY
LOCATION AND WHERE THEY ARE NOT, ITS SHOWING CIN. MESOSCALE MODELS
OVERDID CONVECTIVE POTENTIAL BETWEEN 21-00Z AND USED THEIR NULL
AREAS AS PRETTY MUCH A GUARANTEE AFTER 00Z. THE WESTERLY FLOW THAT
IS SHOWING UP IN THE LAPS SOUNDINGS IS NOT VERY CONDUCIVE FOR
STORM RELATIVE INFLOW AS ARE THE DEVELOPING WAVE CLOUDS WEST OF
CHESAPEAKE BAY. SO WORST CASE SCENARIO IS AN ISOLATED SHOWER OR
THUNDERSTORM DELMARVA WHICH ATTM COVERAGE LOOKS TOO LOW TO WARRANT
CONTINUING MENTION IN THE GRIDS. WE WILL UPDATE AS NEEDED.

TEMPERATURE AND DEW POINTS DID NOT NEED MUCH OF AN ADJUSTMENT.

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 AT LEAST INTO THE EVENING HOURS. THE SECONDARY
FRONT MAY MIX THINGS A BIT AND TURN THE REST OF THE NIGHT INTO A
MILDLY ADVECTIVE ONE.

&&

.SHORT TERM /6 AM FRIDAY THROUGH 6 AM FRIDAY/...
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.

&&

.LONG TERM /FRIDAY THROUGH THURSDAY/...
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 AIRMASS 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.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

THE 00Z TAFS CARRY A VFR FORECAST. ANY LEFTOVER CONVECTION NOT
EXPECTED TO AFFECT THE TERMINALS EARLY AND EVEN THE AMOUNT OF
CLOUDINESS OVERALL APPEARS MINUSCULE. WITH DRIER AIR MOVING INTO
THE AREA, NO FOG IS ANTICIPATED TOWARD MORNING. WINDS SHOULD VEER
FROM THE WEST TOWARD THE NORTH OVERNIGHT (SOME TAFS 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
IN THE TAFS. 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.
-- End Changed Discussion --

&&

.MARINE...
WE WILL LET THE SCA FOR HAZARDOUS SEAS EXPIRE AS SEAS ARE TRENDING
DOWNWARD AT BUOY 65. WINDS AND SEAS OVER ALL WATERS ARE NOW BELOW
ADVISORY CRITERIA THROUGH FRIDAY.

LIGHT WINDS THROUGH THIS EVENING 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.

&&

.FIRE WEATHER...
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.

&&

.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