Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 080418
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1218 AM EDT WED JUL 8 2015

.SYNOPSIS...
A COLD FRONT IN NORTHWEST PENNSYLVANIA WILL SAG SLOWLY SOUTHEAST
TODAY, REACHING SOUTHERN SECTIONS OF PENNSYLVANIA AND NEW JERSEY
BEFORE STALLING WEDNESDAY NIGHT. TWO AREAS OF LOW PRESSURE WILL
MOVE EAST ALONG THE FRONT AND OFF THE NEW JERSEY COAST, ONE EARLY
THURSDAY AND THEN ANOTHER EARLY FRIDAY. THEREAFTER THE FRONT SLIPS
SLOWLY SOUTH OF THE DELMARVA DURING FRIDAY. HIGH PRESSURE WILL
BRIEFLY MOVE INTO THE REGION FOR THE WEEKEND, BEFORE A WARM FRONT
MOVES TO OUR NORTH ON MONDAY. A TROUGH LOOKS TO PERSIST OVER OUR
AREA THROUGH MOST OF NEXT WEEK, AS A RESULT OF A DOMINANT RIDGE
OVER THE MIDWEST.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
1122 PM ESTF: SHOWERS DISSIPATING AS THEY MOVE EAST FROM CENTRAL PA
AND ADJUSTED POPS/TEMPS DOWN SLIGHTLY BEFORE THE SCHEDULED 1230 AM
ESTF.

A FAIR, WARM AND HUMID SUMMER NIGHT...MIN TEMPS 6 TO 12 DEGREES ABOVE
NORMAL. STILL A CHANCE OF SHOWERS EARLY TODAY FOR THE POCONOS INTO
NW NJ...DEPENDING ON ANY SHOWERS THAT CAN REMAIN ACTIVE IN THEIR
EWD TREK FROM THE 0330Z PIT-UNV AREA. PWAT INCREASES OVERNIGHT REACHING
2 INCHES ALONG AND W OF I-95 BY 12Z WEDNESDAY. INSTABILITY ALOFT
ALSO INCREASES EARLY TODAY.

TODAY-WEDNESDAY...A COOL FRONT IS FORECAST TO EXTEND FROM THE
CATSKILLS ACROSS NORTHEASTERN PENNSYLVANIA TO AROUND PITTSBURGH
EARLY ON WEDNESDAY MORNING. THE BOUNDARY IS EXPECTED TO SINK
SLOWLY INTO OUR NORTHWESTERN COUNTIES AS THE AFTERNOON PROGRESSES.

SHOWERS EITHER ON GOING AT DAYBREAK NEAR AND NORTH OF I-80 OR REDEVELOP
DURING THE MIDDAY/AFTERNOON HOURS OVER E PA AND N OR CENTRAL NJ.

PWAT 2.25 INCHES DURING THE AFTN AND EVENING ALONG AND SE OF I-95!
YET MLCAPE NOT IMPRESSIVE...ABOUT 800J. 0-6KM BULK SHEAR DECREASES
DURING THE DAY WITH WLY CONVECTIVE STEERING FLOW APPEARING TO
SLOW TO 15 TO 20 KT BY THIS WED EVENING, AND NEARLY PARALLEL TO
THE SLOW MOVING FRONT. THIS COULD MEAN NARROW SWATH OF LARGE
RAINFALLS, IF TRAINING CAN OCCUR OR REOCCUR, ESPECIALLY DELMARVA
OR SE PA AND S NJ.

MAXIMUM TEMPERATURES ARE DEPENDENT ON REMAINING SUNSHINE HEATING
AND ONSET OF SHOWERS AT ANY LOCATION. FOR NOW, WITH ABOUT 18C AT
850 TO START THE DAY AND STILL 16-17C AT 18Z...THINK WE SHOULD
NUDGE 90 IN PHL AROUND 17Z BEFORE ANY FURTHER RISE IN TEMPS IS
PROBLEMATIC WITH THICKENING CLOUD COVER AND DEVELOPMENT OF
SHOWERS. DEWPOINTS AT TIME OF MAX TEMP SHOULD BE LOW ENOUGH TO
PREVENT HEAT INDICES FROM RISING TO ADVISORY THRESHOLD. STILL A
HOT AND HUMID DAY VCNTY I-95 SEWD, ESPECIALLY WITH LESS WIND THAN
TUE AFTN.

FCST MAX TEMPS FOR WEDNESDAY.., NOT YER DECIDED ON WEIGHTING THE
VARIOUS OPERATIONAL GUIDANCES.

&&

.SHORT TERM /WEDNESDAY NIGHT/...
WEDNESDAY NIGHT...EVENING CONVECTION PROBABLY DIES OUT THOUGH THERE
IS A CHANCE OF RENEWED SHOWERS/TSTMS TO OUR WEST ADVANCING INTO
OUR AREA OVERNIGHT. THE SFC COOL FRONT SAGS DOWN TO NEAR PHILADELPHIA
AND ATLANTIC CITY BY DAWN THURSDAY. HUMID. PWAT LOWERS .3 TO .4
INCHES OVERNIGHT BUT STILL A JUICY 1.5 TO 2 INCHES S OF I-78 AT
DAYBREAK THURSDAY.

THIS FCST AT 330 AM WILL PROBABLY BE A 50 50 BLEND OF THE 00Z/8
NAM/GFS MOS GUIDANCE.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
HEMISPHERIC WAVE GUIDANCE SHOWS DEEP SOUTHWESTERLY FLOW ACROSS THE
EASTERN HALF OF THE U.S. AT THE START OF THE LONGTERM PERIOD. BY THE
WEEKEND THE WAVELENGTH ACROSS THE CONTIGUOUS U.S. BECOMES LONGER
ALLOWING THE SOUTHEAST RIDGING TO RETROGRADE TOWARDS THE CENTRAL
U.S. THIS SETS UP A PSEUDO-HIGH LATITUDE OMEGA BLOCK, WITH OUR
REGION ON THE PERIPHERY OF AN EAST COAST TROUGH. THIS PATTERN LOOKS
TO REMAIN IN PLACE, WHILE LIFTING AND WEAKENING A BIT, GOING INTO
NEXT WORK WEEK, ADDING TO OUR DAILY CHANCES FOR SHOWERS AND
THUNDERSTORMS.

THURSDAY  - FRIDAY NIGHT...THE SLOW SAGGING COLD FRONT THAT
BEGINS TO CROSS THE REGION ON WEDNESDAY LOOKS TO MAKE IT AS FAR
SOUTH AS DELMARVA ON THURSDAY AND REMAIN NEARLY IN PLACE THROUGH
FRIDAY. MULTIPLE WAVES MOVE ALONG THIS BOUNDARY AS IT PRESSES
SOUTHWARD ADDING TO THE INCREASED CHANCES FOR SCATTERED SHOWERS
AND EMBEDDED THUNDER. GUIDANCE TRIES TO ADVECT IN MORE INSTABILITY
FROM THE SOUTH ON THURSDAY AHEAD OF THE FRONT BUT THE TIMING
DOESN`T LOOK LIKE IT OVERLAPS THE FRONTAL PASSAGE. THAT BEING SAID
PWATS WILL STILL BE WELL ABOVE NORMAL, POSSIBLY 2+ INCHES GIVING
US MORE LOCALIZED FLOODING ISSUES...SAME AS IT EVER WAS. WE
CONTINUE WITH THE HEAVY RAIN WORDING IN THE FORECAST THURSDAY
NIGHT INTO FRIDAY MORNING, BUT CONFINE IT TO OUR NORTHERN
HALF...BETTER LIFT/DYNAMICS AND SOME ELEVATED INSTABILITY TO WORK
WITH. AFTER WHAT COULD BE A GREAT LAKES MCS PASSAGE FRIDAY MORNING
ACROSS OUR NORTH, THE FRONT CONTINUES TO SAG SOUTHWARD DURING THE
DAY WITH ISOLATED SHOWERS AND THUNDERSTORMS POSSIBLE ACROSS
DELMARVA...DRYING OUT BEHIND THE FRONT ACROSS THE NORTH. IT SHOULD
BE NOTED THAT FFG ACROSS THE NORTHERN ZONES IS RUNNING QUITE LOW
WITH A LOT OF AREAS ONLY NEEDING 1.5 INCHES IN AN HOUR TO CAUSE
ISSUES...SOMETHING TO WATCH.

SATURDAY...THE AFOREMENTIONED FRONT SHOULD BE FARTHER TO OUR SOUTH
THIS WEEKEND WHILE LARGE SCALE SUBSIDENCE TAKES OVER...THE LONGWAVE
RIDGING RETROGRADING ALL THE WHILE. WE STILL EXPECT SATURDAY TO BE
RAIN FREE BUT THERE COULD BE LINGERING MID-LEVEL ENERGY MOVING BY TO
OUR SOUTHWEST THAT MAY TOUCH OFF A FEW ISOLATED TO SCATTERED SHOWERS
IN OUR EXTREME SOUTHWEST ZONES...HAVE TIME TO BETTER DEFINE THESE
CHANCES IF ANY.

SUNDAY - TUESDAY...WARM FRONT PASSAGE, FROM WHAT WAS ONCE THE COLD
FRONT EARLIER IN THE PERIOD, MOVES BACK TOWARDS THE NORTH ON SUNDAY
NIGHT INTO MONDAY. COLD FRONT THEN NEARS FROM THE NORTHWEST LATE
ON MONDAY INTO TUESDAY AS TROUGHING TAKES BACK OVER AGAIN.
NORTHWEST FLOW ALOFT LOOKS TO PREVAIL AS CENTRAL U.S. RIDGING
AMPLIFIES. THIS MAY SEND SEVERAL SHORTWAVES THROUGH THE REGION
FROM LATE MONDAY ONWARD...NORTHERN PLAINS MCS SEASON.

&&

.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

OVERNIGHT...VFR HIGH CIGS DEVELOP. VSBY MAY LOWER TO 4-6 MI IN HAZE
FOG IN A FEW LOCATIONS. LIGHT S-SW WIND. CHANCE OF SHOWERS TOWARD
DAWN NEAR AND N OF I-80 (SHOWERS SEEN ON RADAR OVER W AND CENTRAL
PA AT 0330Z).

WEDNESDAY...VFR CIGS . BRIEF IFR CONDITIONS IN MAINLY AFTERNOON EVENING
SHOWERS AND SCT TSTMS, ESPECIALLY KPHL SOUTH. GRADIENT S-SW WIND GUST
15 KT, POSSIBLY 20 KT AT 15Z, BUT SOMEWHAT DECREASING GUSTINESS DURING
THE AFTERNOON EXCEPT NEAR TSTMS WHERE GUSTS 30-40 KT POSSIBLE.

WEDNESDAY NIGHT...VFR CIGS WITH MVFR VSBY POSSIBLE. CHANCE OF SHOWERS.

OUTLOOK...

THURSDAY...POTENTIAL MVFR AND IFR RESTRICTIONS IN SHOWERS AND
THUNDERSTORMS, HIGHEST CHANCES EACH AFTERNOON AND EVENING. WEST-
SOUTHWEST WIND GUSTS AT OR UNDER 20 KNOTS.

FRIDAY - SATURDAY NIGHT...VFR. WINDS AT OR UNDER 10 KNOTS, MAINLY
NORTHERLY.

SUNDAY...MOSTLY VFR. SOME SCATTERED SHOWERS AND EMBEDDED THUNDER
POSSIBLE.

&&

.MARINE...
NO MARINE HAZARDS FORESEEN ATTM THROUGH WEDNESDAY NIGHT, EXCEPTING
THE POSSIBILITY OF MWS OR SMW`S FOR CONVECTIVE GUSTS 25-35 KT
LATE THIS AFTN/EVENING, ESPECIALLY DELAWARE WATERS AND SOUTH OF
LITTLE EGG INLET NJ (KACY).

OTHERWISE GRADIENT SSW WIND GUSTS 15-20 KT THIS MORNING MAY DECREASE
LATE TODAY FROM NORTH TO SOUTH IN NJ WITH THE APPROACHING COLD FRONT
THEN WINDS ALONG THE NJ COAST SHOULD BECOME SOME SORT OF NLY COMPONENT
OVERNIGHT WEDNESDAY.

OUTLOOK...

SUB-SCA WINDS AND SEAS EXPECTED. ANY WIND GUSTS LOOK TO REMAIN
BELOW 20 KNOTS, MORE NORTHERLY THROUGH SATURDAY NIGHT. SEAS
AROUND FOUR FEET ON WEDNESDAY AND THURSDAY. THE HIGHEST CHANCE OF
THUNDERSTORMS IS WEDNESDAY AFTERNOON AND EVENING THEN AGAIN LATER
THURSDAY.

&&

.RIP CURRENTS...
4 FT 6 SECOND WITH A 190 DEGREE WIND AT 12 KT OFFERS LOW RISK FOR
BOTH THE NJ AND DE COASTS TODAY. OUTGOING AFTERNOON TIDES WILL
LOCALLY ENHANCE THE RIP CURRENTS BUT THE LACK OF MUCH LONG PERIOD
INCOMING SWELL KEEPS THE RISK GENERALLY LOW. THUNDERSTORMS MAY
IMPACT BEACH ACTIVITIES MID OR LATE AFTERNOON, ESPECIALLY S NJ.

&&

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

&&

$$
SYNOPSIS... DRAG 1218
NEAR TERM...DRAG/IOVINO/JOHNSON 1218
SHORT TERM...DRAG/IOVINO/JOHNSON
LONG TERM...GAINES/HEAVENER
AVIATION...DRAG/IOVINO/HEAVENER/JOHNSON 1218
MARINE...DRAG/IOVINO/HEAVENER/JOHNSON 1218
RIP CURRENTS...1218


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