Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 261948
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
348 PM EDT WED AUG 26 2015

.SYNOPSIS...
HIGH PRESSURE ACROSS THE UPPER GREAT LAKES REGION WILL SETTLE ACROSS
THE DELAWARE VALLEY BY FRIDAY AND THEN MOVE OFFSHORE THIS WEEKEND. A
LOW PRESSURE SYSTEM AND FRONT WILL AFFECT THE WEATHER SUNDAY AND
INTO EARLY MONDAY. MORE HIGH PRESSURE BUILDS ACROSS THE AREA NEXT
WEEK.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
A GFS AND WRF-NMMB/NAM BLEND WOULD WORK THE BEST AS
INITIALIZING AT 500MB EASTERN CONUS WHILE THE GFS REMAINS BETTER OUT
WEST. THE SAME COMPROMISE WOULD WORK BEST AS A 925MB INITIALIZATION.
BUT THE GFS ALONE LOOKED BETTER AT 850MB. THE INITIALIZATION DP/DT
CONTINUES TO SHOW MORE RIDGING THAN FORECASTED IN THE WESTERN CONUS,
BUT GENERALLY A FLATTER TROUGH IN THE EASTERN CONUS AND SOUTHEAST
CANADA.

GIVEN THE APPEARANCE OF THE CUMULUS AND CONTINUING CORROBORATION
FROM RECENT HRRR RUNS, WE WILL KEEP THE ISOLATED SPRINKLES OVER
THE FAR NORTHWEST FOR THE NEXT COUPLE OF HOURS.

THE MAINLY CHANNELIZED VORT MAX IS EXPECTED TO REMAIN ACROSS THE
NORTHWEST PART OF OUR CWA INTO THE OVERNIGHT, WITH THE LAST SHORT
WAVE ROUNDING THE BASE OF THE TROF TOWARD MORNING. TENDENCY IS FOR
WINDS TO BE LIGHTER THAN MODEL EXPECTATIONS PRECEDING THESE FEATURES
ON ONE HAND. ON THE OTHER HAND, IT DOES RAISE THE UNCERTAINTY AS TO
LINGERING CLOUDINESS, ESPECIALLY NORTHWEST. VISIBLE SATELLITE IS
SHOWING PLENTY OF CLOUDINESS UPSTREAM AND SOME OF THE MORE HI RES
MODELS DO KEEP LOW LEVEL MOISTURE GOING INTO THE EVENING. BUT, A
TRAPPING INVERSION IS NOT BEING INDICATED. THUS THE FORECAST PLAN
FOR THE NORTHWEST PART OF OUR CWA IS TO AVERAGE PARTLY CLOUDY FOR
TONIGHT WITH A GENERALLY MORE HIGHER CONFIDENT AND CLEARER FORECAST
SOUTHEAST.

BOUNDARY LAYER WINDS ARE PREDICTED TO BE LIGHT ENOUGH FOR
DECOUPLING, ESPECIALLY IN MORE SHELTERED AREAS. GIVEN THE AFTERNOON
DEW POINTS, WE WENT WITH THE STAT GUIDANCE TREND OF LOWERING MINIMUM
TEMPERATURES A BIT IN RURAL/OUTLYING AREAS. HIGHEST CONFIDENCE IS
IN THE SOUTHERN PART OF OUR CWA. CLOUDS MAY MAKE OUR MINS NORTH TOO
LOW.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
WITH THE LAST OF THE SHORT WAVES MOVING OFFSHORE BY EARLY AFTERNOON
THURSDAY, THE TROF FLATTENING AND A HIGH PRESSURE SYSTEM BUILDING
INTO THE EASTERN GREAT LAKES, EVEN MORE OF A CHAMBER OF COMMERCE
LATE AUGUST DAY IS PREDICTED FOR OUR CWA.

THE MODELS DO PASS THE 250MB JET OVER DELMARVA. THEY ARE NOT SHOWING
ANY JET LAYER MOISTURE AT THIS TIME. CUMULUS COVERAGE OVERALL SHOULD
BE LESS THAN TODAY. THE THERMAL TROF PASSES THROUGH AND THE
PREDICTED THERMALS SUGGEST ABOUT A 1F DROP OFF IN MAX TEMPS FROM
TODAY. USING PREDICTED 925MB TEMPS, WE WILL FOLLOW A GFS AND NAM MOS
COMPROMISE. A BRIEF NORTHWEST SURGE BEHIND THE COLD FRONT SHOULD
BECOME LIGHTER AGAIN. ALONG AND NEAR THE COAST AND BAYS, SOME SEA
BREEZE INDUCED WINDS COULD DEVELOP.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
5-WAVE MODEL GUIDANCE SHOWS A BUILDING SOUTHEAST RIDGE THROUGH A
MAJORITY OF THE LONGTERM PERIOD WITH MODERATING TEMPERATURES AND
HUMIDITY.

FRIDAY - SATURDAY...EXPECTING A DRY FORECAST THESE DAYS WITH A WEAK
FRONT NEARING FROM THE NORTHWEST. SOME GUIDANCE IS HINTING AT SHOWER
ACTIVITY ACROSS THE NORTHERN SATURDAY AFTERNOON WITH A BIT OF A
WEAKNESS IN THE PATTERN ALOFT BUT THINKING THAT CONVECTIVE
TEMPERATURES SHOULD BE OUT OF REACH AND THE BETTER FORCING IS STILL
FARTHER TO OUR NORTH AND WEST...WE STAY DRY. BOTH DAYS WE EXPECT
TEMPERATURES IN THE MID-80S WITH DEWPOINTS CLOSE TO 60F.

SUNDAY - MONDAY...THE AFOREMENTIONED COLD FRONT GETS CLOSER BUT WITH
IT DOESN`T REALLY PACK A PUNCH BUT WE CONTINUE THE SLIGHT CHANCE
WITH SOMEWHAT BETTER INSTABILITY. HIGH PRESSURE SLIDES OFF THE COAST
AND ALLOWS FOR BETTER AIRMASS MODIFICATION SO WE WILL SEE AN
INCREASE IN HUMIDITY AND INSTABILITY. HIGHS BOTH DAYS APPROACH, IF
NOT EXCEED, 90F.

TUESDAY - WEDNESDAY...NO APPRECIABLE RAIN EXPECTED EITHER DAY WITH
SOUTHEAST RIDGE AXIS OVERHEAD. CONTINUED HEAT AND HUMIDITY INCREASE
IS EXPECTED BUT IT DOES APPEAR THAT THE CORE OF THE WARMEST 925MB
TEMPERATURES STAYS TO THE SOUTH AND WEST OF THE REGION. NONE-THE-
LESS 90F IS NOT OUT OF THE QUESTION EACH AFTERNOON.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE,
KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS.

18Z TAFS WERE VFR.

REST OF THIS AFTERNOON...A HIGH BASED CUMULUS DECK, BECOMING A CIG
AT TIMES AT THE NORTHWEST TERMINALS AND AIRPORTS. WEST WINDS WILL BE
CLOSE TO 10 KNOTS. THE SEA BREEZE FRONT IS EXPECTED TO REMAIN NEAR
THE IMMEDIATE NJ AND DE COAST AND NOT MAKE IT INLAND OR TO KACY.

TONIGHT...THE CUMULUS CLOUDS SHOULD DISSIPATE, ESPECIALLY I95
CORRIDOR SOUTHEAST. WINDS WILL BE LIGHT FROM THE NORTHWEST AND MORE
SHELTERED AIRPORTS/TERMINALS MAY GO CALM FOR A WHILE. NO VSBY
RESTRICTIONS AT THE TERMINALS. LATE TONIGHT ANOTHER UPPER AIR
DISTURBANCE MIGHT BRING SOME MID LEVEL CLOUDS ACROSS THE AREA AGAIN.
HIGHEST CONFIDENCE NORTHWEST AIRPORTS AND TERMINALS.

THURSDAY...A NEAR CARBON COPY OF TODAY. SOME HIGH BASED CUMULUS
CLOUDS SHOULD DEVELOP AGAIN, PROBABLY LESS OVERALL COVERAGE THAN
TODAY. NORTHWEST WINDS SHOULD AVERAGE 5 TO 10 KNOTS. A SEA BREEZE
FRONT DURING THE AFTERNOON MIGHT MAKE MORE OF AN INLAND INTRUSION.

OUTLOOK...

THURSDAY NIGHT THRU SATURDAY NIGHT...MOSTLY VFR. PATCHY FOG PSBL
DURING THE PREDAWN HOURS.

SUNDAY - MONDAY...MOSTLY VFR. SHOWERS POSSIBLE WITH LOWER
CONDITIONS.

&&

.MARINE...
SUB SMALL CRAFT ADVISORY CONDITIONS WILL CONTINUE TONIGHT AND
THURSDAY.

SEA BREEZE INDUCED CIRCULATIONS LATE THIS AFTERNOON INTO THIS
EVENING SHOULD BECOME A PREVAILING WEST TO NORTHWEST FLOW AGAIN
TONIGHT. MESOSCALE MODELS HAVE THE STRONGEST (POSSIBLY EXCEEDING 15
KNOTS) SOUTHERLY FLOW EARLY OFF THE OCEAN AND ATLANTIC COUNTY COASTS
WITH LESS VARIATION IN SPEEDS WITH THE NORTHWEST FLOW OVERNIGHT.

AS THE OVERALL PRESSURE GRADIENT WEAKENS AGAIN DURING THE DAY ON
THURSDAY, A MORE VARIABLE SEA BREEZE INDUCED WIND FLOW SHOULD
DEVELOP AGAIN ON THE OCEAN WATERS. WE ARE NOT AS CERTAIN ABOUT AN UP
(SOUTHEASTERLY WINDS) THE DELAWARE BAY FLOW OCCURRING.  SUSTAINED
WIND SPEEDS THURSDAY SHOULD REMAIN AT 15 KNOTS OR LESS.

OUTLOOK...

SUB-SCA CONDITIONS THRU THE PERIOD. SEAS WILL BUILD TO AROUND 4 FT
ON THE OCEAN SAT NIGHT INTO SUNDAY. WIDELY SCT SHOWERS/TSTMS
POSSIBLE SUN.

&&

.RIP CURRENTS...
WE WILL CONTINUE THE MODERATE RISK FOR THE FORMATION OF DANGEROUS
RIP CURRENT ALONG THE NJ BEACHES FOR THE REST OF THE DAY. A MORE
FAVORABLE WIND FLOW FOR STRONGER RIP CURRENTS IS STARTING TO
DEVELOP.

&&

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

&&

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


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