Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 301628
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1228 PM EDT SUN AUG 30 2015

.SYNOPSIS...
A WEAKENING COLD FRONT WILL ARRIVE TONIGHT, OTHERWISE HIGH
PRESSURE WILL REMAIN MOSTLY CENTERED NEAR THE MID ATLANTIC REGION
THROUGH MUCH OF THIS WEEK. HOWEVER, A WEAK COLD FRONT MAY SLIDE
INTO OUR REGION ON THURSDAY. AN OFFSHORE LOW AND HIGH PRESSURE TO
OUR NORTHEAST MAY PROVIDE SOME COOLER CONDITIONS FOR NEXT WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A SHORT WAVE TROUGH WILL ARRIVE INTO THE NORTHEAST LATER TODAY, AND
AS IT DOES IT SHOULD TEND TO WEAKEN. A WEAK COLD FRONT AT THE
SURFACE IS TIED TO THIS FEATURE, AND WITH SOME MOISTURE ON THE
INCREASE SOME ADDITIONAL SHOWERS AND A THUNDERSTORM ARE EXPECTED TO
DEVELOP TO OUR WEST. THERE IS SOME INSTABILITY DURING THE DAY, WITH
THIS PROBABLY BEST ACROSS THE WESTERN ZONES. HOWEVER, THE FORECAST
SOUNDINGS MOSTLY SHOW A SKINNY CAPE PROFILE WHICH TENDS TO KEEP
UPDRAFTS ON THE WEAKER SIDE. THE BULK OF THE LIFT ASSOCIATED WITH
THE TROUGH AXIS IS FORECAST TO BE TO OUR WEST DURING PEAK HEATING
WITH THE ACTUAL SHORT WAVE AND THE RIGHT ENTRANCE REGION OF AN UPPER-
LEVEL JET. HOWEVER, TERRAIN INFLUENCES ALONG WITH WEAK SURFACE
CONVERGENCE COULD BE ENOUGH AND THEREFORE WE KEPT A SLIGHT CHC POP
ACROSS THE NORTHWESTERN ZONES. THIS WAS DELAYED A BIT THOUGH GIVEN
SLOWER CUMULUS DEVELOPMENT THUS FAR. HIGH LEVEL CLOUDINESS IS
STREAMING NORTHWARD FROM MARYLAND AND DELAWARE.

IT WILL BE RATHER WARM TO HOT ACROSS MUCH OF THE CWA THIS AFTERNOON,
HOWEVER DEW POINTS MAY LOWER A LITTLE BIT BY LATE DAY IN SOME AREAS
DUE TO SIGNIFICANT HEATING OF THE BOUNDARY LAYER. THE PRESSURE
GRADIENT IS NOT FORECAST TO BE ALL THAT TIGHT, THEREFORE LIGHT
ENOUGH FLOW WILL RESULT IN A SEA BREEZE ONCE AGAIN THROUGH THIS
AFTERNOON.

THE HOURLY GRIDS WERE ADJUSTED BASED ON THE LATEST OBSERVATIONS,
THEN THE LAMP/LAV GUIDANCE WAS BLENDED IN TO ASSIST. NO MAJOR
CHANGES WERE MADE TO THE HIGH TEMPERATURES ATTM.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
ANY ISOLD SHWRS OR TSTMS WILL COME TO AN END AND THEN
EXPECT JUST A PCLDY SKY WITH GRADUALLY INCREASING DEW PTS, AS THE
HIGH REMAINS THE DOMINANT WX FEATURE AS WE CLOSE OUT AUGUST AND
METEOROLOGICAL SUMMER.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
SOME SHIFTS IN TRACKS AND TIMING WITH THE LATEST MODEL RUNS, BUT
THE MAIN STORY REMAINS THE HIGH SLIDING OVER THE REGION FOR MUCH
OF THE WORK WEEK.

MONDAY THROUGH WEDNESDAY...MAY SEE A FEW LINGERING SHOWERS OR
THUNDERSTORMS MONDAY MORNING AS AN UPPER LEVEL SHORT WAVE TROUGH
MOVES FURTHER AWAY FROM THE REGION, BUT OTHERWISE PRECIPITATION
CHANCES THROUGH THIS PERIOD ARE VERY SLIM. SHOULD SEE A MODEST
WARMING TREND FROM MONDAY INTO TUESDAY AS THE RIDGE AXIS SLIDES
OVERHEAD, THUS LEADING TO INCREASING 1000-500 MB THICKNESSES FOR
THE REGION. EVEN WITH THIS HIGH AMPLITUDE RIDGE THOUGH, HIGHS
SHOULD STAY WELL BELOW RECORDS, AND HEAT INDEX VALUES SHOULD STAY
IN THE LOWER TO MID 90S.

THURSDAY...A BIT MORE UNCERTAINTY IN THIS PERIOD, SPECIFICALLY
WITH THE EVOLUTION OF THE WEAK COLD FRONT. SOME MODELS ARE NOW
STALLING THIS FRONT WELL NORTH OF THE REGION, OR SHOWING THE
TEMPERATURE GRADIENT ALMOST DISAPPEAR COMPLETELY BY THE TIME IT
REACHES OUR REGION. FOR NOW THOUGH, HAVE STAYED CLOSE TO THE
PREVIOUS FORECAST FOR BOTH TEMPERATURES AND PRECIPITATION CHANCES,
AS THE UPPER LEVEL SHORT WAVE TROUGH COULD PROVIDE ENOUGH LIFT AND
FOCUS FOR CONVECTION EVEN WITHOUT THE FRONT, AND STILL THINK THERE
IS A CHANCE THE FRONT WILL REACH THE AREA GIVEN THAT THE MODELS
TEND TO UNDERESTIMATE HOW FAR SOUTH FRONTS WILL PROPAGATE IN THE
TRANSITION SEASONS.

FRIDAY THROUGH SATURDAY...STAYED RELATIVELY CLOSE TO THE PREVIOUS
FORECAST AS THERE ARE SOME LARGE DIFFERENCES AMONG THE LONG RANGE
MODELS IN THIS PERIOD. THE GFS SHOWS STEADY ON SHORE FLOW AS A
SURFACE HIGH DEVELOPS TO OUR NORTHWEST. MEANWHILE, THE ECMWF SHOWS
A VERTICALLY STACKED, AND NEARLY STATIONARY, LOW TO OUR SOUTHEAST.
EITHER SOLUTION THOUGH DOES LOOK TO BRING A COOLING TREND THROUGH
THE WEEKEND.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

THIS AFTERNOON...VFR WITH SOME CUMULUS DEVELOPING AROUND 5000 FEET,
ALONG WITH HIGH LEVEL CLOUDS MOVING THROUGH. SOUTHWESTERLY WINDS UP
TO 10 KNOTS, WHICH SHOULD TURN MORE SOUTHERLY AT KACY AND PERHAPS
KILG DUE TO A SEA/BAY BREEZE. AN ISOLATED SHOWER OR THUNDERSTORM
MAY APPROACH THE KABE TO KRDG AREAS TOWARD EVENING.

TONIGHT...VFR OVERALL. A WEAKENING COLD FRONT SHOULD ALLOW A SHOWER
OR THUNDERSTORM TO ARRIVE MAINLY NEAR THE KABE AND KRDG AREAS THIS
EVENING, HOWEVER COVERAGE IS EXPECTED TO BE RATHER LOW.
SOUTHWESTERLY WINDS 5-10 KNOTS, BECOMING LIGHT AND VARIABLE AT MANY
OF THE TERMINALS.

OUTLOOK...
MONDAY THROUGH WEDNESDAY...VFR CONDITIONS EXPECTED THOUGH
LOCALIZED MVFR CONDITIONS WITH FOG POSSIBLE EACH MORNING.

THURSDAY...MOSTLY VFR CONDITIONS. ISOLATED THUNDERSTORMS
POSSIBLE.

&&

.MARINE...
NO MARINE FLAGS ARE ANTICIPATED THRU THE NR AND SHORT TERM
PDS. SEAS WILL GENLY BE IN THE 2 TO 3 FT RANGE. WIND WILL GENLY
BE SW IN THE 10 TO 15 KT RANGE WITH GUSTS AS HIGH AS 20 KT.

OUTLOOK...
MONDAY THROUGH THURSDAY...WINDS AND SEAS SHOULD STAY WELL BELOW
SMALL CRAFT ADVISORY CRITERIA. WATER TEMPERATURES ARE ABOVE
NORMAL.

&&

.RIP CURRENTS...
A LONG PERIOD EAST TO SOUTHEAST SWELL, 10-11 SECONDS, CONTINUES TO
ROLL IN ALONG THE COAST. THIS COMBINED WITH WINDS TURNING MORE
SOUTHERLY AND INCREASING SOME THROUGH THE DAY WILL RESULT IN TRICKY
CONDITIONS AT TIMES WITHIN THE SURF ZONE ESPECIALLY DURING TIDE
CHANGES. AS A RESULT THERE IS A MODERATE RISK FOR THE DEVELOPMENT OF
DANGEROUS RIP CURRENTS THROUGH THIS EVENING ALONG THE NEW JERSEY
SHORE AND THE DELAWARE BEACHES.

&&

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

&&

$$
SYNOPSIS...GORSE/JOHNSON
NEAR TERM...GORSE
SHORT TERM...NIERENBERG
LONG TERM...JOHNSON
AVIATION...GORSE/JOHNSON
MARINE...JOHNSON/NIERENBERG
RIP CURRENTS...GORSE



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