Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 291956
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
356 PM EDT MON JUN 29 2015

.SYNOPSIS...
A TROUGH IS EXPECTED TO SLOWLY PROPAGATE EAST THROUGH MID WEEK. AS
IT DOES SO, A WARM FRONT WILL LIFT INTO OUR REGION TOMORROW,
FOLLOWED BY A COLD FRONT LATE WEDNESDAY. THAT FRONT IS EXPECTED TO
STALL JUST SOUTH OF OUR REGION FOR THE REMAINDER OF THE WORK WEEK.
ANOTHER COLD FRONT COULD ARRIVE SATURDAY NIGHT.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
WEAK RIDGE ALOFT GRADUALLY MOVES TO THE EAST TONIGHT AS MID-LEVEL
FLOW BECOMES SOUTHWEST IN RESPONSE TO SHARPENING GRT LAKES TROUGH.
THIS WILL LEAD TO AN INCREASE IN MOISTURE...ESP NORTHWEST OF I-95
WHERE MID-LEVEL CLOUDINESS WILL INCREASE. 12Z/29 MODEL RUNS HAVE
BACKED OFF ON -SHRA OVER THE POCONOS AND LEHIGH VALLEY...AS BEST
LIFT REMAINS TO THE NORTHWEST AND LOW-LEVELS REMAIN DRY WITH HIGH
PRES JUST TO THE NORTHEAST. THUS SCALED BACK ON POPS TONIGHT AND
CONFINED THEM TO THE POCONOS TOWARD DAWN. THE WIND GRADUALLY BACK
FROM THE WEST TO THE SOUTHEAST AS THE WARM FRONT APPROACHES WITH
MIN TEMPS NEAR SEASONAL NORMS.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
INTERESTING DAY SHAPING UP TOMORROW AS S/WV ENERGY TRAVERSING THE
GRT LKS TROUGH LEADS TO SFC LOW DEVELOPMENT OVER LAKE ERIE...AS A
WARM FRONT SLOWLY MOVES THRU REGION. MAIN CONCERN IS CONVECTIVE
POTENTIAL DURING TOMORROW AFTERNOON AND EVENING. THE BEST CHANCES
ARE GENERALLY NW OF I-95...WHERE ML CAPE OF 1.5 KJ AND BULK SHEAR
VALUES OF 30 TO 40 KNOTS COINCIDE. EXPECT CONSIDERABLE CLOUDS OVR
ERN PA AND NRN NJ...WHICH MAY LIMIT SVR POTENTIAL. THE MAIN THREAT
WOULD BE GUSTY WINDS AND SMALL HAIL...W/ INVERTED-V PROFILES AND
FALLING WET BULB ZERO HEIGHTS. THERE IS ALSO A CONSIDERABLE AMOUNT
HELICITY INVOF THE WARM FRONTAL BOUNDARY...SO CANNOT RULE OUT A
SUPERCELL...IF ENOUGH INSTABILITY IS PRESENT.

&&

.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
MODELS CONTINUE TO SHOW A GRADUAL TRANSITION FROM THE MOSTLY
MERIDIONAL PATTERN WE HAVE CURRENTLY TO UPPER LEVEL ZONAL PATTERN
BY NEXT WEEKEND.

TOMORROW NIGHT...THE VORT MAX IN THE LEE OF THE UPPER LEVEL TROUGH
PROPAGATES OVER OUR REGION, BRINGING INCREASING RAIN CHANCES. ONE
FACTOR THAT MAY SLIGHTLY INHIBIT COVERAGE OF CONVECTION WILL BE A
STABILIZING BOUNDARY LAYER RESULTING IN LARGE VALUES OF CIN.
OTHERWISE, MODEST CAPE VALUES FOR ELEVATED PARCELS (AT LAYERS
ABOVE 900 MB) AND BULK SHEAR VALUES OF 20 TO 30 KT, COMBINED WITH
THE UPPER LEVEL SUPPORT SHOULD BE ENOUGH TO SUPPORT SUSTAINED
UPDRAFTS AND A MARGINAL THREAT FOR SMALL HAIL OR GUSTY WINDS.

WEDNESDAY...DEPENDING ON HOW QUICKLY THE SURFACE LOW LIFTS AWAY,
THERE MAY BE A BIT OF A LULL IN THE PRECIP, ESPECIALLY EARLY IN
THE DAY. HOWEVER, GIVEN THE UNCERTAINTY IF A MID LEVEL TROUGH WILL
LIFT OVER THE REGION, KEPT MENTION OF CHANCE POPS THROUGH THE DAY. BY
LATE IN THE DAY, HOWEVER, ATTENTION WILL TURN TO THE NEXT COLD
FRONT DUE TO ARRIVE EITHER WEDNESDAY EVENING OR LATE WEDNESDAY
NIGHT. ISENTROPIC LIFT SHOULD BE SUFFICIENT FOR ANOTHER ROUND OF
SHOWERS AND STORMS WITH THE FRONT.

THURSDAY AND FRIDAY...THE BIG QUESTION ON THESE DAYS WILL BE HOW
FAR SOUTH THE FRONT WILL STALL. LATEST RUNS OF BOTH THE GFS AND
ECMWF HAVE THE FRONT STALLING A BIT FURTHER SOUTH THAN PREVIOUS
RUNS, THUS GIVING OUR REGION ANOTHER LULL IN PRECIP CHANCES.
HOWEVER, STAYED CLOSE TO THE PREVIOUS FORECAST AS I AM NOT
CONFIDENT THIS TREND WILL HOLD GIVEN A FLATTENING TROUGH.

SATURDAY...IN THE WAKE OF ONE FRONT, WE COULD HAVE ANOTHER COLD
FRONT RIGHT ON ITS HEELS. HAVE KEPT THE MENTION OF CHANCE POPS,
BUT AGREE WITH THE PREVIOUS SHIFT THAT IT APPEARS TO BE ONLY A
BRIEF OPPORTUNITY FOR ANY RAIN.

SUNDAY CONTINUES TO LOOK DRY AS WE COULD EVEN HAVE AN UPPER LEVEL
SHORT WAVE RIDGE SLIDING EAST OVER OUR REGION AT THAT TIME.

&&

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

VFR CONDITIONS EXPECTED TO PREVAIL FOR ALL SITES TONIGHT AND INTO
TOMORROW. ALL TAF SITES SHOULD REMAIN DRY TONGIHT...WITH A CHC OF
-SHRA TOMORROW AFTERNOON AND EVENING FOR TERMINALS ALONG AND WEST
OF I-95. WINDS WILL GRADUALLY VEER FROM WEST TO SOUTH-SOUTHEAST
OVERNIGHT...WITH GUSTS TO 20 KNOTS POSSIBLE TOMORROW AFTERNOON.

OUTLOOK...
TUESDAY NIGHT THROUGH WEDNESDAY...MAINLY VFR EXCEPT MVFR OR IFR
CONDITIONS WITH SCATTERED SHOWERS AND STORMS

WEDNESDAY NIGHT...MOSTLY VFR WITH SHOWER CHANCES DECREASING.

THURSDAY THROUGH SATURDAY...MOSTLY VFR EXCEPT MVFR OR IFR WITH
SHOWERS AND THUNDERSTORMS.

&&

.MARINE...
WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SCA CRITERIA TONIGHT
AND TOMORROW.

OUTLOOK...
TUESDAY NIGHT INTO WEDNESDAY...SEAS MAY APPROACH 5 FT, BUT THERE
IS CONSIDERABLE UNCERTAINTY.

THURSDAY THROUGH SATURDAY...WINDS AND SEAS SHOULD REMAIN BELOW SCA
CRITERIA.

&&

.RIP CURRENTS...
SEVERAL RESCUES TOOK PLACE YESTERDAY. BASED ON THIS MORNINGS
SURF ZONE OBSERVATIONS AND FORECAST...THERE IS A MODERATE RISK
OF RIP CURRENTS ALONG THE NJ COAST FOR TODAY. A LOW RISK IS IN
PLACE FOR THE DE COAST.

&&

.CLIMATE...
THE CHART BELOW SHOWS RAINFALL STATISTICS AT OUR FOUR BIG CLIMATE
SITES THRU NOON 6/28. THE COLUMNS ARE BROKEN DOWN BY SITE, "POR"
(HOW FAR RECORDS DATE BACK), 6/27 RAINFALL, JUNE 2015 RAINFALL,
NORMAL JUNE RAINFALL, JUNE 2015 RAINFALL RANKING, AS WELL AS THE
WETTEST JUNE ON RECORD.

SITE    POR     6/27    JUNE         NORMAL    RANK    WETTEST

ILG     1894    2.17    12.46        3.50      2ND     13.66 (2013)
ACY     1874    2.37*    8.04        2.81      2ND      8.45 (1920)
ABE     1922    0.86     7.02        3.86      6TH     10.51 (1938)
PHL     1872    1.34     7.23        3.08     10TH     10.56 (2013)

*ATLANTIC CITY BROKE THEIR DAILY RAINFALL RECORD OF 1.74" IN
1912

AT THIS TIME, IT HAS BEEN THE SECOND WETTEST JUNE ON RECORD IN
BOTH WILMINGTON AND ATLANTIC CITY. WITH ONLY TWO DAYS LEFT IN THE
MONTH, CURRENT FORECASTS DO NOT FAVOR EITHER SITE BREAKING THEIR
ALL-TIME JUNE RAINFALL RECORD. HOWEVER, IT WOULD ONLY TAKE A HEAVY
SHOWER OR THUNDERSTORM TO CLOSE THE GAP, WHICH IS 0.41 INCHES IN
ATLANTIC CITY AND 1.2 INCHES IN WILMINGTON.

&&

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

&&

$$
SYNOPSIS...JOHNSON
NEAR TERM...FRANCK
SHORT TERM...FRANCK
LONG TERM...JOHNSON
AVIATION...FRANCK/JOHNSON
MARINE...FRANCK/JOHNSON
RIP CURRENTS...FRANCK
CLIMATE...FRANCK


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