Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 260453
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1253 AM EDT SUN JUL 26 2015

.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE MOVING EASTWARD OFF THE MID-ATLANTIC
COAST TONIGHT GIVING WAY TO AN APPROACHING COLD FRONT ON SUNDAY. BY
MONDAY, THIS FRONT WILL DISSIPATE TO OUR SOUTH. HIGH PRESSURE WILL
BUILD EASTWARD INTO THE REGION FOR THE MIDDLE OF THE WEEK BEFORE
ANOTHER COLD FRONT COMES THROUGH THE REGION ON FRIDAY. THE FRONTAL
BOUNDARY LOOKS TO STALL ALONG OR JUST OFF THE EAST COAST NEXT
WEEKEND WITH SEVERAL WAVES OF LOW PRESSURE FORMING ALONG IT.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
LATEST ESTF UPDATE, NOT TOO MANY CHANGES. TEMPERATURES AND DEW
POINTS ARE CLOSE TO EXPECTATIONS. NOT AS PLEASANT OVERNIGHT
AS DEW POINTS ARE HIGHER AND SOME CLOUD DEBRIS IS AROUND. BASED
ON LATEST RADAR TRENDS AND COSPA, WE MADE A SLIGHT TWEAK TO POPS,
ADJUSTING THEM UPWARD IN NORTHWEST NJ. LOOKS LIKE THUNDER SHOULD
REMAIN NORTH OF OUR CWA, SO FOR NOW, SHOWERS.

PREVIOUS UPDATE DISCUSSION...NO MAJOR CHANGES IN THE NEAR TERM.
ADJUSTED TEMPS AND DEW POINTS TO REFLECT CURRENT TRENDS. AGREE
WITH THE PREVIOUS SHIFT THAT ANY PRECIP TONIGHT WILL PROBABLY NOT
BE UNTIL AFTER MIDNIGHT IN OUR AREA, IF EVEN THEN.

PREVIOUS NEAR TERM DISCUSSION...HIGH PRESSURE WILL CONTINUE TO
SLIDE OFF THE COAST TONIGHT PROVIDING A DECENT AMOUNT OF
SUBSIDENCE KEEPING A TIGHT LID ON THE REGION THROUGH AT LEAST A
BETTER PORTION OF THE OVERNIGHT HOURS. OF QUESTION IS WHEN THE
NEXT SHOT OF OVER-RUNNING SHOWERS OCCURS LATE TONIGHT, MOSTLY
ACROSS OUR NORTHERN ZONES WITH A PASSING MID- LEVEL WAVE. HAVE
TRIMMED THE POPS BACK BY SEVERAL HOURS AND DROPPED THEM A CATEGORY
AS THE ELEVATED WARM FRONT REMAINS PRETTY FAR TO OUR NORTH...MORE
OF A STATIONARY BOUNDARY...SO NOT EXPECTING MUCH RAINFALL TONIGHT
AS THE ATMOSPHERE IS STILL RATHER DRY. WILL NOT BE QUITE AS COOL
AS THE PAST FEW MORNINGS WITH THE LOWER DEWPOINTS...AIRMASS
MODIFICATION WILL COMMENCE LATE TONIGHT.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/...
COLD FRONT ACROSS THE UPPER GREAT LAKES SLIDES INTO THE WESTERN PART
OF PENNSYLVANIA BY SUNDAY AFTERNOON BUT IT LOOKS RATHER
DIFFUSE/WASHED OUT. WHAT WE DO SEE AHEAD OF THE WIND SHIFT IS AN
INCREASE IN LOW-LEVEL MOISTURE/INSTABILITY AS PROGGED BY OUR CAMS
AND BETTER/DEEPER SHEAR ASSOCIATED WITH THE NORTHWESTERLY FLOW
ALOFT. EXPECTING AN INCREASE IN SCATTERED COVERAGE FOR AFTERNOON
SHOWERS AND THUNDERSTORMS WITH MORE MUGGY CONDITIONS IN PLACE. WE
KEEP THE SAME TIMING WITH THE HIGHER CHANCES FOR SHOWERS IN PLACE
THOUGH WE TRIED TO BETTER DEFINE THE SOUTHERN EDGE THROUGHOUT THE
DAY. IT IS POSSIBLE THAT SEABREEZE CIRCULATIONS WILL ALSO ALLOW FOR
ISOLATED SHOWERS WELL AHEAD OF ANY SYNOPTIC FORCING. HIGHS WILL
AGAIN BE ABOVE NORMAL.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
SUNDAY NIGHT AND MONDAY: A WEAK COLD FRONT IS LIKELY TO DECAY INTO A
TROUGH OF LOW PRESSURE BY MONDAY. AHEAD OF THIS FEATURE,
TEMPERATURES AND HUMIDITY WILL CONTINUE TO BE ON THE RISE MAKING IT
A MUGGIER NIGHT COMPARED TO THE PREVIOUS FEW NIGHTS. ENOUGH
INSTABILITY MAY BE PRESENT IN CONJUNCTION WITH THE FRONT TO TRIGGER A
FEW TYPICAL SUMMERTIME SCATTERED SHOWERS AND THUNDERSTORMS WITH
DOWNPOURS AND LIGHTNING. SHEAR LOOKS ALMOST NON-EXISTENT FOR
SEVERE CONSIDERATIONS. STILL AN ISOLATED STRONG WIND GUST CAN`T BE
RULED OUT SUNDAY NIGHT OR MONDAY. TEMPERATURES LOOK TO BE AT OR A
HAIR ABOVE MET/MAV/ECMWF MOS WITH HIGHS GETTING CLOSER TO 90. RFC
GUIDANCE APPEARS TO HAVE A GOOD HANDLE ON QPF ACROSS THE REGION.
AS USUAL, SOMEONE WILL SEE LOCALLY HEAVIER RAINFALL WITH THE
THUNDERSTORMS.

MONDAY NIGHT THROUGH THURSDAY: A GRADUAL CONTINUED UPTICK IN HEAT
AND HUMIDITY WITH A STRONG RIDGE ACROSS THE SOUTHERN PLAINS MAKING
ANOTHER CHARGE ACROSS THE REGION WITH RISING HEIGHTS. THIS WILL
RESULT IN A MAINLY DRY PERIOD. FOR ACTUAL HIGH TEMPERATURES, MODELED
925 MB TEMPERATURES RISE FROM AROUND 22C ON TUESDAY TO 25C FOR
WEDNESDAY AND THURSDAY. THIS EQUATES TO HIGH TEMPERATURES STARTING
OFF AROUND 90 ON TUESDAY THEN RISING INTO THE MID 90`S FOR
WEDNESDAY AND THURSDAY. THIS IS ANOTHER POTENTIAL MODELED HEAT
WAVE FOR MOST OF THE REGION. OVERALL, IN THE MODELING WORLD THE
GFS CONTINUES TO RUN SEVERAL DEGREES WARMER THAN THE ECMWF. THE
FORECAST SPLITS THE DIFFERENCE BETWEEN THE TWO AND TAKES INTO
ACCOUNT SOMEWHAT HIGHER CLOUD COVER ON THURSDAY. A COLD FRONTAL
BOUNDARY MAY BE ENOUGH OF A TRIGGER FOR SOME SCATTERED SHOWERS AND
THUNDERSTORMS TO DEVELOP LATE THURSDAY AFTERNOON AS THE 12Z MODEL
GUIDANCE IS A BIT FASTER COMPARED TO THE 00Z RUNS.

THURSDAY NIGHT THROUGH SATURDAY: THE COLD FRONTAL BOUNDARY
APPROACHING THE REGION TO START THIS PERIOD WILL LIKELY SLOW DOWN OR
STALL BY FRIDAY. THIS IS DUE TO MODELED HEIGHT RISES/INCREASED
RIDGING OFF THE EAST COAST. SOME COOLER AIR IS LIKELY TO END THE
POTENTIAL HEAT WAVE BEHIND THE FRONT AS A TROUGH MOVES ACROSS NEW
ENGLAND. WITH THE FRONT NEARBY, SHOWER AND THUNDERSTORM CHANCES (
SLIGHT TO LOW) WILL CONTINUE THROUGHOUT THIS TIMEFRAME. THE
POTENTIAL FOR WAVES OF LOW PRESSURE OR EVEN SOMETHING TROPICAL/
SUB-TROPICAL IN NATURE TO DEVELOP IS ALSO PRESENT ALONG THE FRONT
AT THE END OR JUST BEYOND THE FORECAST PERIOD. HOWEVER,
CONSIDERABLE UNCERTAINTY IS PRESENT THIS FAR OUT IN THE FORECAST.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

06Z TAFS VFR INTO EARLY AFTERNOON, THEN SOME UNCERTAINTY AS
TO EXTENT OF SHOWERS AND THUNDERSTORMS DURING THE LATE
AFTERNOON AND EVENING.

REST OF THE NIGHT...VFR. LIGHT WINDS, SOME CIRRUS CLOUDS
AROUND. NOT EXPECTING FOG AT TERMINALS AS THERE IS
STILL A FAIRLY LARGE TEMPERATURE AND DEW POINT SPREAD. ALTHOUGH
SOME OF THE MORE SMALLER RURAL AIRPORTS MIGHT HAVE PATCHY GROUND
FOG.

THIS MORNING...VFR. LIGHT SOUTH TO SOUTHWEST WINDS DEVELOPING.

THIS AFTERNOON...VFR WITH STRONGER SOUTH TO SOUTHWEST WINDS
AVERAGING CLOSER TO 10 KNOTS. IF THERE IS A SEA BREEZE FRONT,
ITS TOUGH TO DECIPHER IT AS THE GENERAL FLOW WILL BE EITHER
SOUTH OR SOUTHWEST. SCATTERED SHOWERS AND THUNDERSTORMS SHOULD
START FORMING IN THE NORTHWEST PART OF OUR AREA. BECAUSE OF
THUNDERSTORM EXTENT UNCERTAINTY, THE TEMPO GROUP AT KABE AND KRDG
IS CARRYING MVFR CONDITIONS IN SHOWERS, MIGHT UPGRADE TO THUNDER
WITH 12Z TAFS.

THIS EVENING...VFR CIG EXPECTED. SOUTH WINDS WILL BECOME
LIGHTER. SHOWERS AND THUNDERSTORMS SHOULD SPREAD FARTHER TO
THE SOUTHEAST. BECAUSE INSTABILITY WILL BE DECREASING, TERMINALS
EITHER HAVE SHOWERS OR VCSH. WE KEPT KACY AND KMIV PCPN FREE
AS ANY PRECIPITATION THAT WOULD MAKE IT THERE SHOULD BE AFTER
06Z.


OUTLOOK...
SUNDAY OVERNIGHT THROUGH MONDAY NIGHT: VFR, ISOLATED TO SCATTERED
SHOWERS THUNDERSTORMS, PARTICULARLY MONDAY MAY BRIEFLY REDUCE
VISIBILITIES AND CEILINGS. WINDS AT OR UNDER UNDER 10 KNOTS
OUTSIDE OF THUNDERSTORMS.

TUESDAY THROUGH THURSDAY: VFR, ISOLATED TO SCATTERED THUNDERSTORMS
POSSIBLE THURSDAY AFTERNOON. WINDS AT OR UNDER 10 KNOTS OUTSIDE
OF THUNDERSTORMS.

&&

.MARINE...
SUB-SCA CONDITIONS EXPECTED TONIGHT AND TOMORROW WITH HIGH PRESSURE
CONTINUING TO SLIDE OFF THE COAST TONIGHT. EAST-SOUTHEAST WINDS VEER
MORE TOWARDS THE SOUTH-SOUTHWEST BY SUNDAY AFTERNOON AS A WARM FRONT
LIFTS THROUGH. WINDS INCREASE BEHIND THE FRONT AND SEAS INCREASE A
TAD BUT SHOULD REMAIN LESS THAN 4 FEET WITH SOME GUSTS UPWARDS OF 20
KNOTS.OUTLOOK...

OUTLOOK: SEAS AND WINDS LOOK TO REMAIN BELOW
SCA CRITERIA THROUGH THURSDAY. ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS ARE POSSIBLE SUNDAY EVENING THEN AGAIN MONDAY
AFTERNOON/NIGHT AND THURSDAY AFTERNOON/EVENING WITH THE POTENTIAL
FOR LIGHTNING A STRONG WIND GUST OR TWO. SEAS OVERALL FOUR FEET OR
LESS WITH WIND GUSTS 20 KNOTS OR LESS OUTSIDE OF THUNDERSTORMS.

BUOY 44009...
WATER TEMPERATURE HAS NOT BEEN REPORTED BY BUOY 44009 SINCE JULY
22ND. WE`VE BEEN INFORMED BY THE NDBC THAT THE FAILED SENSOR WILL
UNFORTUNATELY REMAIN OUT OF SERVICE UNTIL IT IS REPAIRED OR
REPLACED SOMETIME NEXT YEAR.

&&

.RIP CURRENTS...
WITH THE LONG PERIOD (11-12 SECOND) 1 TO 2 FOOT EASTERLY SWELL
CONTINUING INTO TOMORROW...EXPECT THE MODERATE RISK OF DANGEROUS
RIP CURRENTS TO ALSO CONTINUE TOMORROW.

&&

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

&&

$$
SYNOPSIS...GAINES
NEAR TERM...GIGI/HEAVENER/JOHNSON
SHORT TERM...HEAVENER
LONG TERM...GAINES
AVIATION...GAINES/HEAVENER/JOHNSON/O`HARA
MARINE...GAINES/HEAVENER/O`HARA
RIP CURRENTS...



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