Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KPHI 300142
AFDPHI

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

.SYNOPSIS...
A TROUGH IS EXPECTED TO SLOWLY MOVE EAST THROUGH MID WEEK. AS IT
DOES SO, A WARM FRONT WILL LIFT INTO OUR REGION TUESDAY, FOLLOWED
BY A SLOW MOVING COLD FRONTAL PASSAGE LATE WEDNESDAY OR THURSDAY.
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/...
930 PM ESTF: LITTLE CHANGE TO THE SMALL GLIDE SLOPE CHANGES
APPLIED IN THE 630 PM UPDATE. TEMPS FALLING STEADILY UNDER CLEAR
SKY LIGHT WIND RADIATIONAL COOLING CONDITIONS LATE THIS EVENING
BEFORE LEVELING WITH THE APPROACHING MID DECK CLOUD LAYER NOW
CROSSING THE APPALACHIANS AT 9 PM. SPRINKLES POSSIBLE FROM THE
MID DECK CLOUD COVER IN E PA AFTER 08Z/30. MONROE COUNTY MIGHT
SEE A SPRINKLE HERE AROUND 10 PM BUT ITS POSSIBLE THIS RADAR
RETURN IS VIRGA.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
INTERESTING DAY SHAPING UP TOMORROW AS S/WV ENERGY TRAVERSING THE
GREAT LAKES 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 NEAR 1000J AND BULK SHEAR
VALUES OF 30 TO 40 KNOTS COINCIDE. EXPECT CONSIDERABLE CLOUDS OVR
ERN PA AND NRN NJ...WHICH MAY LIMIT SVR POTENTIAL. SOME MODEL
GUIDANCE SUGGESTS IT MIGHT BE PARTLY SUNNY INSTEAD OF MO CLOUDY.
THE MAIN THREAT FROM TSTMS 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.

HWO: ADDED STRONG TSTM THREAT TO THE DELMARVA AND S NJ WHERE THE
RECENT MULTI MODEL GUIDANCE LOOKS LIKE ITS CONCENTRATING GREATER
AND DEEPER INSTABILITY VIA KI/TT/SWI AND MLCAPE PROJECTIONS,
ESPECIALLY AFTER 00Z/01.

&&

.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 /02Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

OVERNIGHT...VFR CLEAR THEN CIGS AOA 7000 FT INVADING FROM WEST TO
EAST. LIGHT SW TO S WIND. PLEASE SEE TAF FOR DETAILS.

TUESDAY...SCT-BKN AOA 5000 FT. S WIND GUST 15-20 KT DURING THE AFTN.
SCT SHOWERS E PA DURING THE MORNING THEN TSTMS EXPECTED TO DEVELOP
AND ROLL NEWD TUE AFTN. STRONGEST STORMS KRDG TO THE DELMARVA
WHERE THEY SHOULD PRODUCE A FEW GUSTS 30-40 KT.

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 TUESDAY.

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...
TUESDAY: LOW RISK DE BUT MDT RISK NJ. USED 3 FT 8 SEC AND A SE
WIND 12 KT. LOCAL AP GAVE LOW RISK EVERYWHERE BUT WITH FULL MOON
JULY 1, RAISED THE RISK JUST INTO THE MDT RANGE FOR NJ.

TIDE WILL BE TURNING AROUND AND COMING IN DURING THE AFTERNOON SO
THAT MAY LOWER THE RISK SLIGHTLY?.

WHAT WE DO KNOW IS THAT SSTS LOOK LIKE THEY ARE RUNNING 2 TO 4F
DEGREES ABOVE NORMAL WITH VERY LITTLE UPWELLING PRESENT...VERY
UNIFORM SST FROM NORTH TO SOUTH ALONG OUR MID ATLANTIC COASTS.

THERE MAY BE A LITTLE MORE SUNSHINE THAN CURRENTLY FORECAST AND
ANY TSTMS SHOULD BE DELAYED TIL AROUND 5P OR AFTER.

SAFEST SWIMMING IS TO BE FOUND IN THE PRESENCE OF LIFEGUARDS.
JETTY, PIER AND GROYNE (GROIN) SWIMMING IS RISKY AND FRAUGHT WITH
GREATER DANGERS ASSOCIATED WITH RECURRENT RIP CURRENTS THERE.

&&

.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 ONE DAY 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...DRAG 942P
SHORT TERM...DRAG/FRANCK
LONG TERM...JOHNSON
AVIATION...DRAG/JOHNSON
MARINE...FRANCK/JOHNSON
RIP CURRENTS...
CLIMATE...



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.