Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 020111
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
911 PM EDT MON SEP 1 2014

.SYNOPSIS...
SOUTHERLY RETURN FLOW AROUND BERMUDA HIGH PRESSURE WILL RESULT IN
WARM AND MUGGY CONDITIONS INTO TUESDAY. A COLD FRONT IS THEN
EXPECTED TO MOVE ACROSS THE AREA LATE TUESDAY AND EARLY WEDNESDAY.
HIGH PRESSURE WILL BUILD IN BEHIND THIS FRONT BEGINNING WEDNESDAY
AFTERNOON. ANOTHER COLD FRONT COULD APPROACH FROM THE WEST EARLY
SATURDAY BEFORE STALLING NEAR OR JUST SOUTH OF OUR REGION BY
SUNDAY.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
IT MAY BE THE FIRST NIGHT OF METEOROLOGICAL AUTUMN, BUT IT CERTAINLY
FEELS MORE LIKE SUMMER WITH DEWPOINTS LOW TO MID 70S ACROSS MUCH OF
THE AREA. THE MUGGY CONDITIONS TONIGHT ARE A RESULT OF THE S-SWLY
RETURN FLOW AROUND BERMUDA HIGH PRESSURE. MIN TEMPS RANGE FROM THE
MID 60S IN NE PA AND NW NJ TO THE MID 70S IN THE URBAN AND COASTAL
AREAS. PATCHY FOG IS POSSIBLE OVERNIGHT, ESPECIALLY TOWARD DAWN.

00Z OBJECTIVE MESOANALYSIS FROM SPC SHOWS ABOUT 1500-2000 J/KG OF
SBCAPE STILL RESIDING IN THE MID ATLANTIC. DESPITE THE INSTABILITY
AND MOISTURE PRESENT, COVERAGE OF SHOWERS AND STORMS JUST AFTER SUNSET
WAS MINIMAL ACROSS THE CWA DUE TO THE ABSENCE OF ORGANIZED LIFT.
THERE WAS A SMALL CLUSTER OF CONVECTION ENTERING CHESTER/BERKS
COUNTY, A FEW SHOWERS JUST OFFSHORE OF DE AND THAT`S ABOUT IT.
EXPECT THIS LEFTOVER ACTIVITY TO GENERALLY DISSIPATE THIS EVENING
WITH THE LOSS OF DAYTIME HEATING. NONETHELESS, AN ISOLATED SHOWER
CAN STILL NOT BE RULED OUT IN THIS JUICY AIRMASS BUT POPS ARE AROUND
10 PERCENT AND PRECLUDE A MENTION OF PRECIP IN THE WX GRIDS.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
FOR TUESDAY...OVERALL CONDS WILL BE SIMILAR TO LABOR DAY...BUT THE
AIRMASS WILL BE SLIGHTLY WARMER WITH 850MB TEMPS A DEGREES OR TWO
HIGHER. THUS AFTN MAX TEMPS ARE FCST TO REACH 90 OR LOW 90S IN
MANY LOCS...ESP FROM PHL S AND E. SFC DEWPTS ARE FCST TO BE
SLIGHTLY LOWER THAN TODAY...BUT APPARENT TEMPS WILL STILL BE UP IN
THE LOWER TO MID 90S.

A WELL-DEFINED UPPER-LEVEL SHORTWV TROF WILL BE APPROACHING FROM THE
WEST ON TUESDAY...AND THE ASSOCD SFC COLD FRONT SHOULD BE PUSHING
INTO NW PA BY AFTN. MOS GUIDANCE PLUS MODEL UVV/QPF SUGGESTS THAT
THE BULK OF THE FRONTAL PRECIP/CNVTN WILL NOT REACH ERN PA UNTIL
AFTER 00Z WED. HWVR...CANNOT RULE OUT SOME PRE-FRONTAL TROF CONVTN
SO HAVE INCLUDED SLGT-CHC TO CHC POPS INCREASING FROM W TO E FOR
TMRW AFTN.

&&

.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
TUESDAY NIGHT...THE GFS SHOWED A SLIGHTLY SLOWER SOLUTION WITH THE
LATEST RUN, NOW WITH THE COLD FRONT ARRIVING IN SE PA BY LATE
EVENING, THE COASTAL WATERS BY WEDNESDAY MORNING. GIVEN THE RATHER
LATE ARRIVAL OF THE FRONT, INSTABILITY SHOULD BE BE MINIMAL. ALSO,
THE UPPER LEVEL SHORT WAVE TROUGH SHOULD STAY WELL TO THE NORTH OF
THE REGION RESULTING IN LIMITED SYNOPTIC SCALE LIFT.
THUS...DESPITE THE SLIGHT RISK FOR SEVERE STORMS TO OUR WEST,
THINK THE SEVERE THREAT WITHIN OUR REGION WILL BE MINIMAL.

WEDNESDAY AND THURSDAY...THOUGH THERE WON`T BE SIGNIFICANT COLD
AIR ADVECTION BEHIND THE FRONT, THERE WILL BE CONSIDERABLE DRY AIR
ADVECTION, ALBEIT SHORT LIVED. THUS, WHILE HIGHS WILL STILL BE
ABOVE NORMAL, IT WILL FEEL A BIT MORE PLEASANT WITH HEAT INDEX
VALUES NEAR AIR TEMPERATURES.

FRIDAY INTO SUNDAY...AS THE SURFACE HIGH SLIDES OFF SHORE FRIDAY,
THE REGION WILL ONCE AGAIN SEE LOW LEVEL MOIST FLOW AHEAD OF THE
NEXT COLD FRONT. THE COLD FRONT IS SET TO ARRIVE SATURDAY...THOUGH
THERE HAS BEEN POOR RUN TO RUN CONSISTENCY ON THE TIMING OF THE
FRONT. AN ADDED COMPLICATION IS THAT BOTH THE GFS AND ECMWF
CONTINUE TO SHOW THE FRONT STALLING, EITHER OVER OUR REGION OR
JUST SOUTH OF THE REGION. DEPENDING ON HOW FAR NORTH IT STALLS,
THE REGION COULD BE UNDER MOIST ON SHORE/UPSLOPE FLOW THROUGH
EARLY NEXT WEEK. FOR NOW, HAVE STAYED CLOSE TO THE PREVIOUS
FORECAST CONSIDERING THE UNCERTAINTY.

&&

.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

VFR CONDITIONS THIS EVE. SWLY WIND UNDER 10 KT THIS EVE, NEARLY CALM
OVERNIGHT. PATCHY RADIATIONAL FOG MAY DEVELOP BETWEEN 08-12Z. LATEST
GUIDANCE USED FOR THE 00Z TAFS DID NOT PROVIDE OVERWHELMING SUPPORT
FOR VSBYS RESTRICTIONS LOWER THAN MVFR. HOWEVER, WITH SUCH A MUGGY
AIRMASS IN PLACE, TEMPORARY IFR POSSIBLE TOWARD DAYBREAK TUESDAY
MORNING AT THE FOG-PRONE TERMINALS SUCH AS RDG/MIV/ABE IF BREAKS IN
THE CLOUD COVER PERSIST LONG ENOUGH.

S-SW WINDS INCREASE DURING THE DAY TUE AS THE PRESSURE GRADIENT
INCREASES AHEAD OF A COLD FRONT THAT IS APPROACHING FROM THE WEST.
CHANCES FOR SHRA/TSRA DELAYED UNTIL LATE IN THE DAY TUE WITH
ARRIVAL OF FRONT NOT EXPECTED UNTIL TUE NGT. THIS FAR OUT, INCLUDED
A PROB30 GROUP FOR SHRA IN THE 00Z TAFS STARTING AFTER 20Z FOR
ONLY THE WESTERN TERMINALS (RDG/ABE).

OUTLOOK...
TUESDAY NIGHT...THUNDERSTORMS AND AN ABRUPT WIND SHIFT POSSIBLE
WITH A COLD FRONT THAT WILL MOVE THROUGH OVERNIGHT. MVFR CEILINGS
AND VISIBILITIES AS LOW AS IFR WILL BE POSSIBLE WITH ANY
THUNDERSTORMS. OTHERWISE VFR CONDITIONS EXPECTED.

WEDNESDAY THROUGH FRIDAY...VFR CONDITIONS EXPECTED.

FRIDAY NIGHT INTO SATURDAY...AS A COLD FRONT MOVES IN FROM THE
WEST...IFR CONDITIONS AND THUNDERSTORMS POSSIBLE.

&&

.MARINE...
SUB SCA CONDS ARE EXPECTED THROUGH TUESDAY. SW WINDS WILL CONTINUE
AROUND THE SUMMERTIME BERMUDA WITH AT 10 TO 15 KT OR SO. SEAS WILL
BE IN THE 2 TO 4 FT RANGE OVER THE COASTAL WATERS. CHANCES FOR
SHOWERS AND TSTMS LATE IN THE AFTN TUE AS A COLD FRONT APPROACHES
FROM THE WEST.

OUTLOOK...
TUESDAY NIGHT...THOUGH SEAS SHOULD REMAIN BELOW SMALL CRAFT
ADVISORY CRITERIA, GUSTY WINDS WILL BE POSSIBLE IN THE VICINITY OF
ANY STORMS THAT DEVELOP WITH THE COLD FRONT.

WEDNESDAY THROUGH FRIDAY...WINDS AND SEAS ARE EXPECTED TO REMAIN
BELOW SCA CRITERIA.

FRIDAY NIGHT INTO SATURDAY...SEAS SHOULD REMAIN JUST BELOW SCA
CRITERIA. GUSTY WINDS WILL BE POSSIBLE IN THE VICINITY OF
ANY STORMS THAT DEVELOP.

&&

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

&&

$$
SYNOPSIS...JOHNSON/KLEIN
NEAR TERM...KLEIN
SHORT TERM...AMC
LONG TERM...JOHNSON
AVIATION...AMC/JOHNSON/KLEIN
MARINE...AMC/JOHNSON/KLEIN






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