National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS61 KPHI 312210
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
610 PM EDT THU JUL 31 2014

.SYNOPSIS...
WEAK HIGH PRESSURE WILL REMAIN ACROSS THE REGION TONIGHT AND INTO
EARLY FRIDAY. SEVERAL WEAK DISTURBANCES AND A COASTAL FRONT WILL
AFFECT THE AREA THIS WEEKEND. HIGH PRESSURE WILL BUILD ACROSS THE
AREA EARLY NEXT WEEK. ANOTHER DISTURBANCE WILL MOVE TOWARD THE
AREA TOWARD THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
A COUPLE OF TRULY ISOLATED SHOWERS AND THUNDERSTORMS STILL
WORKING THEIR WAY ACROSS THE NORTHWESTERN PART OF OUR CWA AND WE
WILL KEEP THE LOW CHANCE INTO EARLY THIS EVENING. A COUPLE OF SEA
BREEZE LOCATIONS HAVE TEMPS DROPPING SLIGHTLY FASTER THAN
ANTICIPATED AND SLIGHT ADJUSTMENTS WERE MADE THERE. OTHERWISE FORECAST
REMAINS ON/CLOSE TO SCHEDULE. ANY ADJUSTMENTS IF NEEDED ON THE
TOWARD MORNING SHOWERS WILL BE DONE WITH THE NEXT ESTF UPDATE ONCE
COSPA/HRRR HAS BETTER TEMPORAL COVERAGE.

THIS EVENING SHOULD BE A DRY ONE, EXCEPT FOR THE SLIGHT
POSSIBILITY OF A PASSING SHOWER OR THUNDERSTORM NORTHWEST. POPS
WERE LOWERED BASED ON RADAR/SATELLITE TRENDS. ANOTHER COOL AND
COMFORTABLE NIGHT IS IN STORE FOR MOST OF US, WITH THE EXCEPTION
BEING DELAWARE AND SOUTH JERSEY WHERE HUMIDITY WILL BE NUDGING
EVER SO SLIGHTLY HIGHER. SOME LOW CLOUDS AND BRIEF LOCALIZED FOG
IS POSSIBLE TOWARDS SUNRISE AS WELL. STAYED CLOSE TO THE MAV/MET
ON TEMPERATURES TONIGHT AND ADJUSTED THE EVENING TEMPERATURES
SLIGHTLY BASED ON THE LATEST METAR OBS AND INCORPORATED THE LATEST
LAMP/LAV GUIDANCE. CLOUDS WILL BE ON THE INCREASE AHEAD OF THE
NEXT SYSTEM BY SUNRISE.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
ANOTHER SHORTWAVE TO OUR WEST WILL CAUSE A SOUTHEASTERLY FLOW TO
DEVELOP OVER THE REGION AND AN OFFSHORE FRONT TO BACK AND MOVE
CLOSER TO THE COAST. AS A RESULT, MOISTURE WILL BE ON THE RISE ON
FRIDAY, BOTH AT THE SURFACE AND AT MID-LEVELS. IT WILL FEEL MUGGY
AGAIN JUST IN TIME FOR AUGUST. ALTHOUGH THE ONSHORE FLOW WILL LESSEN
ANY INSTABILITY THAT DEVELOPS, SHOWERS AND ISOLATED THUNDERSTORMS
WILL STILL BE POSSIBLE IN THE AFTERNOON FRIDAY WITH THE GREATEST
THREAT IN THE WESTERN PARTS OF THE REGION WHERE THE SOUTHEAST FLOW
WILL HAVE A LESSER IMPACT ON INSTABILITY. CAPE VALUES ARE EXPECTED
TO BE NEAR 1000 J/KG IN THE WESTERN PART OF THE REGION, AND AROUND
500-800 J/KG ELSEWHERE. THIS WILL LIMIT THE THREAT FOR STRONG
THUNDERSTORMS BUT WILL STILL ENOUGH TO HAVE THUNDER IN THE GRIDS.
WENT A TOUCH COOLER THAN THE MAV/MET FOR TEMPERATURES BASED ON THE
LIKELIHOOD OF CLOUDS AND SPOTTY SHOWERS. NOT SOLD ON THE WETNESS OF
THE NAM/SREF IN TERMS OF QPF, SO WENT RATHER LIGHT WITH THIS
ELEMENT. DUE TO THE SPOTTY NATURE OF ANY SHOWERS IN THE AFTERNOON
WENT FAIRLY LOW WITH CHANCE POPS AND SLOWER TIMING ON ANY RAIN WHEN
COMPARED TO THE NAM/GFS MORE IN LINE WITH THE RGEM/ECMWF.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
AN UNSETTLED PERIOD EXPECTED THIS WEEKEND INTO EARLY
MONDAY...BEFORE AN IMPROVING PICTURE NEXT WEEK.

A FRONT/INVERTED TROUGH WILL LINGER ALONG THE EAST COAST THIS
WEEKEND WHILE UPPER HEIGHTS BEGIN TO BUILD. THE UPPER HIGH ACROSS
THE OCEAN WILL BEGIN TO BUILD BACK ACROSS THE AREA LATE THIS
WEEKEND INTO NEXT WEEK. THIS WILL BRING AN ONSHORE FLOW WITH
ABUNDANT MOISTURE THIS WEEKEND. SCT SHOWERS AND TSTMS WILL BE IN
THE FCST FOR FRI NIGHT AND THRU THE WEEKEND. TEMPERATURES WILL
HOLD TO MOSTLY NORMAL OR A BIT BELOW NORMAL WITH ALL THE EXTRA
CLOUDINESS. IT WILL BE A RATHER HUMID PERIOD HOWEVER.

BY MONDAY...THE BUILDING HIGH WILL CAUSE THE ONSHORE FLOW TO
WEAKEN AND THE MEAN FLOW ALOFT WILL SWITCH TO MOVE WRLY/SWLY. THIS
WILL ALLOW DRIER AIR TO ARRIVE...BUT ALSO WARMER TEMPERATURES.
HIGHS TUE-THU WILL MOSTLY BE IN THE MID/UPPER 80S ACROSS THE SRN
AREAS AND LOW/MID 80S NORTH. THESE TEMPERATURES ARE AT OR A BIT
ABOVE NORMAL. SCT SHOWERS EARLY MONDAY...THEN A MOSTLY DRY FCST
FOR NEXT WEEK.

&&

.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

GENERAL SOUTHERLY WINDS TONIGHT BEFORE BECOMING VARIABLE. LOW
CLOUDS/PATCHY FOG ARE POSSIBLE TONIGHT AND SHOWING UP ON SOME
BUFKIT SOUNDINGS. KEPT TAFS MORE OPTIMISTIC ATTM AS GFS/NAM
GUIDANCE IS MIXED ON THIS WITH THE NAM HITTING HARDER. CLIMATOLOGY
SUGGESTS A 40% OF MVFR CONDITIONS AS WELL, GIVING SOME CONFIDENCE
TO LOWERING CEILINGS/VISIBILITIES BUT KEEPING VFR. BROUGHT IN A
GRADUAL OVERCAST TOMORROW FROM SOUTH TO NORTH AT ABOUT 10,000 FEET
LOWERING IT AT PHL BY 15Z. SHOWERS WE`RE NOT ADDED TO THE TAFS FOR
TOMORROW GIVEN THE HIGHEST CHANCE IS AFTER 18Z.

OUTLOOK...
FRI NIGHT THRU SUN NIGHT...LOWER CIGS EXPECTED AT TIMES WITH ON
      ONSHORE FLOW. SCT SHOWERS/TSTMS AT TIMES WITH LOWER VSBYS.
MON THRU TUE...MOSTLY VFR WITH SCT SHOWERS.

&&

.MARINE...
SEAS AND WINDS ARE EXPECTED TO REMAIN BELOW SCA CRITERIA ATTM. SEAS ARE
LIKELY TO BE AROUND THREE FEET AND WINDS LESS THAN 10 KNOTS.

OUTLOOK...
FRI NIGHT THRU TUESDAY ...SUB- SCA CONDITIONS EXPECTED THROUGH
THE PERIOD. SCT TSTMS WILL CREATE LOCALLY HIGHER WINDS AND SEAS.

&&

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

&&

$$
SYNOPSIS...O`HARA/99
NEAR TERM...GAINES/GIGI/VIVOLA
SHORT TERM...GAINES
LONG TERM...O`HARA
AVIATION...GAINES/O`HARA
MARINE...GAINES/O`HARA