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000
FXUS61 KPHI 121347
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
947 AM EDT WED JUN 12 2013

.SYNOPSIS...
WEAK HIGH PRESSURE WILL MOVE ACROSS OUR AREA THROUGH TODAY. MEANWHILE,
LOW PRESSURE OVER THE MIDWEST WILL DEEPEN AND INTENSIFY AS IT
PUSHES EASTWARD, CROSSING OUR AREA ON THURSDAY. HIGH PRESSURE WILL
MOVE INTO THE REGION FROM THE NORTHWEST ON FRIDAY AND SLIDE TO OUR
SOUTH AND EAST OVER THE WEEKEND. ANOTHER LOW PRESSURE SYSTEM WILL
APPROACH FROM THE WEST, PUSHING A WARM FRONT THROUGH THE AREA ON
MONDAY, FOLLOWED BY A COLD FRONT ON TUESDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LOW PRESSURE NEAR COASTAL MAINE WILL SHIFT NORTHEASTWARD THROUGH
THE DAY. THIS WILL ALLOW THE PRESSURE GRADIENT TO RELAX SOME,
HOWEVER IT WILL MAINTAIN A NORTHWESTERLY FLOW. THERE APPEARS TO BE
A WARM FRONT DRAPED FROM THE UPPER OHIO VALLEY INTO THE MID
ATLANTIC, ALTHOUGH IT MAY BE BETTER DEFINED NEAR 850 MB DUE TO
INCOMING WAA AT THIS LEVEL. THIS ENHANCED AREA OF LOW TO MID LEVEL
WAA MAY ALLOW FOR SOME SHOWERS OR THUNDER TO REACH INTO THE
DELMARVA AREA THIS AFTERNOON. THIS WILL MAINLY DEPEND ON UPSTREAM
ACTIVITY AS WE ARE SEEING A DEW POINT GRADIENT SETTING UP NORTH OF
THE WARM FRONT. THE 12Z STERLING, VA RAOB SHOWS ENOUGH INSTABILITY
AND THEREFORE WE MAY NEED TO ADD THUNDER TO OUR SLIGHT CHC/LOW CHC
OF SHOWERS ACROSS OUR FAR SOUTHERN ZONES.

OTHERWISE, BANDS OF CLOUDS MOVING THROUGH IN THE NORTHWEST FLOW
WITH INCOMING WAA. THE HOURLY GRIDS WERE ADJUSTED TO REFLECT LOWER
DEW POINTS UP NORTH ALONG WITH A SLOWER RISE IN TEMPERATURES SO
FAR. THE LAMP/LAV GUIDANCE WAS USED TO ASSIST IN THESE TRENDS THUS
FAR. NO MAJOR CHANGES WERE MADE TO THE HIGH TEMPERATURES ATTM.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
A MID LEVEL RIDGE AXIS FROM THE WEST IS EXPECTED TO REACH OUR
REGION TOWARD DAYBREAK ON THURSDAY. AT THE SAME TIME, A MID LEVEL
TROUGH FROM THE WEST IS FORECAST TO ARRIVE OVER LAKE ERIE AND THE
MIDDLE AND LOWER PARTS OF THE OHIO RIVER VALLEY. CLOUDS WILL BE ON
THE INCREASE TONIGHT IN THE DEVELOPING WARM ADVECTION AHEAD OF THE
APPROACHING TROUGH.

A SURFACE LOW ASSOCIATED WITH THE MID LEVEL TROUGH IS FORECAST TO
BE LOCATED OVER OHIO AROUND DAYBREAK ON THURSDAY WITH A WARM FRONT
EXTENDING TO THE WATERS OFF THE DELMARVA PENINSULA. RAIN SHOWERS
WILL BE ON THE INCREASE IN OUR REGION LATE TONIGHT.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
FLOOD WATCH IN EFFECT THURSDAY THROUGH FRIDAY MORNING.

THURSDAY LOOKS TO BE AN EVENTFUL DAY AROUND THE MIDDLE ATLANTIC.
A STRONG LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MIDWEST AND INTO
CENTRAL PENNSYLVANIA BY THURSDAY AFTERNOON AND THEN CROSS OUR AREA
THURSDAY EVENING INTO FRIDAY. TEMPERATURES ACROSS THE SOUTHERN
HALF OF THE FORECAST AREA WILL RISE WELL INTO THE 80S. NORTH OF
PHILADELPHIA, TEMPERATURES WILL BE A BIT COOLER AS THERE WILL BE A
BIT MORE CLOUD COVER, WITH MAX TEMPS IN THE UPPER 60S (NORTHERN
MOST AREAS) TO THE MID 70S.

THIS IS A POTENT SYSTEM. THERE IS PLENTY OF MID LEVEL ENERGY THAT
WILL MOVE THROUGH THE AREA, ALONG WITH PLENTY OF MOISTURE, GOOD
LOW-LEVEL SHEAR, GOOD SURFACE HEATING AND INSTABILITY TO BOOT.
CAPE VALUES ARE IN THE 1500-2200 J/KG RANGE, MAINLY FROM
TRENTON/READING AND SOUTH.

THE STORM PREDICTION CENTER HAS PLACED THESE AREAS IN A MODERATE
RISK FOR SEVERE WEATHER, WITH THE REMAINING AREA IN SLIGHT RISK.
SUPERCELLULAR STRUCTURES WILL DEVELOP, PRODUCING MAINLY DAMAGING
WINDS BUT THERE IS THE POTENTIAL FOR LARGE HAIL AND ISOLATED
TORNADOES AS WELL. IT WILL DEFINITELY BE A `KEEP AN EYE TO THE
SKY` KIND OF DAY ACROSS THE SOUTHERN 2/3RDS OF OUR FORECAST AREA.

WITH PRECIPITABLE WATER VALUES RISING UP TO 2 INCHES, HEAVY RAIN
WILL ONCE AGAIN BE A THREAT. WE HAVE ISSUED A FLOOD WATCH FOR THE
AREAS AT GREATEST RISK AND FOR THOSE AREAS WHICH HAVE ALREADY SEEN
UP TO 6 INCHES OR SO OF RAIN OVER THE PAST SEVERAL DAYS. MORE
INFORMATION IN THE HYDROLOGY SECTION BELOW.

THE LOW STARTS TO PUSH OFFSHORE AND TO THE EAST LATE THURSDAY
NIGHT INTO FRIDAY. THE HEAVIEST RAINS LOOK TO FALL DURING THE DAY
ON THURSDAY AND THEN START TO DECREASE IN COVERAGE AND INTENSITY
AS THE LOW PULLS AWAY. SOME LINGERING SHOWERS ON FRIDAY SHOULD
DECREASE THROUGH THE DAY AND WE DRY OUT BY FRIDAY
AFTERNOON/EVENING.

HIGH PRESSURE WILL THEN BUILD INTO THE AREA FOR THE WEEKEND. A
NICE, MOSTLY DRY, WEEKEND WILL BE ON TAP WITH TEMPERATURES IN THE
UPPER 70S TO THE LOWER 80S ACROSS MUCH OF THE REGION.

THE NEXT SYSTEM WILL START TO APPROACH FROM WEST LATE IN THE
WEEKEND WITH A WARM FRONT PUSHING NORTHWARD THROUGH MONDAY.
SHOWERS AND THUNDERSTORMS WILL ONCE AGAIN BE POSSIBLE ON MONDAY
AND THE CHANCES WILL CONTINUE THROUGH TUESDAY AS THE COLD FRONT
THEN PUSHES THROUGH THE AREA. MOISTURE WILL START TO INCREASE ONCE
AGAIN IN THE SOUTHWESTERLY FLOW AHEAD OF THIS NEXT SYSTEM AND
PRECIPITABLE WATER VALUES WILL BE IN THE 1.5-2.0 INCH RANGE. WITH
THE VERY WET CONDITIONS ACROSS THE REGION, WE WILL NEED TO KEEP AN
EYE ON THIS AS WE COULD ONCE AGAIN HAVE FLOODING CONCERNS. THE
SOUTHWESTERLY FLOW WILL ALSO BRING IN SOME WARMER AIR AND
TEMPERATURES WILL RISE INTO THE 80S FOR THE BEGINNING OF THE WEEK.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

TODAY...OVERALL VFR. SOME MVFR BASES AROUND, HOWEVER THESE SHOULD
LIFT WITH ADDITIONAL HEATING. OTHERWISE, AREAS OF MID TO HIGH
CLOUDS AROUND WITH SOME CUMULUS DEVELOPMENT. NORTHWEST WINDS
AROUND 10 KNOTS, HOWEVER SOME LOCAL GUSTS TO NEAR 20 KNOTS WILL
OCCUR THROUGH ABOUT EARLY AFTERNOON. THERE IS A CHANCE FOR A FEW
SHOWERS OR A THUNDERSTORM THIS AFTERNOON SOUTHWEST OF KILG.

TONIGHT...THE WINDS WILL BECOME LIGHT AND VARIABLE DURING THE
EVENING AT MOST OF THE TERMINALS, ALTHOUGH TEND TO TURN TO THE EAST
AND SOUTHEAST LATE TONIGHT AS A WARM FRONT BEGINS TO APPROACH FROM
THE SOUTH. THE CLOUDS WILL BE ON THE INCREASE WITH LOWERING BASES
AS SHOWERS SPREAD INTO OUR REGION MAINLY LATE. OVERALL, VFR IS
ANTICIPATED FOR MOST OF THE NIGHT UNLESS HEAVIER RAIN DEVELOPS.
THE THUNDER POTENTIAL LOOKS LOW ENOUGH AT THIS TIME AND SOMEWHAT
UNCERTAIN, THEREFORE IT WAS NOT INCLUDED.

OUTLOOK...
THURSDAY AND THURSDAY NIGHT...MVFR/IFR CONDITIONS POSSIBLE IN
SHOWERS AND THUNDERSTORMS. SOME THUNDERSTORMS MAY PRODUCE GUSTY
WINDS.

FRIDAY...IMPROVING CONDITIONS TO VFR BY FRIDAY AFTERNOON/EVENING.
SHOWERS POSSIBLE THROUGH THE AFTERNOON.

SATURDAY...MAINLY VFR CONDITIONS EXPECTED.

SUNDAY...MAINLY VFR CONDITIONS EXPECTED. SHOWERS POSSIBLE, MAINLY
IN THE AFTERNOON AND EVENING.

&&

.MARINE...
A NORTHWEST FLOW IS EXPECTED TODAY AS LOW PRESSURE NEAR NOVA
SCOTIA PULLS FARTHER AWAY FROM OUR REGION. A WARM FRONT IS
EXPECTED TO APPROACH FROM THE SOUTH TONIGHT. WIND SPEEDS AND WAVE
HEIGHTS WILL REMAIN BELOW THE SMALL CRAFT ADVISORY CRITERIA FOR
TODAY AND TONIGHT.

OUTLOOK...
THURSDAY WILL START OFF WITH SUB ADVISORY CONDITIONS ACROSS THE
BUT AS A STRONG LOW PRESSURE SYSTEM STARTS TO APPROACH AND THEN
CROSS THE REGION, WE WILL START TO SEE WINDS PICK UP BY THURSDAY
AFTERNOON. WITH THE GRADIENT TIGHTENING UP, A SMALL CRAFT ADVISORY
WILL NEEDED. GALE FORCE GUSTS WILL BE POSSIBLE IN THE STRONG
NORTHWEST FLOW BEHIND THE DEPARTING LOW LATE THURSDAY NIGHT AND
FRIDAY ON THE OCEAN WATERS.

SEAS WILL ALSO RISE ABOVE 5 FEET ON THURSDAY AFTERNOON/EVENING
AND WILL START TO SUBSIDE BELOW 5 FEET ON FRIDAY.

IN ADDITION, SHOWERS AND THUNDERSTORMS WILL AFFECT THE WATERS ON
THURSDAY. THESE STORMS MAY PRODUCE GUSTY WINDS ALONG WITH HEAVY
RAIN.

SUB ADVISORY CONDITIONS WILL RETURN FOR THE WEEKEND.

&&

.HYDROLOGY...
A FLOOD WATCH IS IN EFFECT FOR THURSDAY THROUGH FRIDAY MORNING.

PRECIPITABLE WATER VALUES WILL ONCE AGAIN RISE TO AROUND 2 INCHES
ON THURSDAY AND WE WILL SEE YET ANOTHER DAY OF FLOOD AND FLASH
FLOOD POTENTIAL ACROSS THE REGION.

RAINFALL AMOUNTS OF 1 TO 3 INCHES OF RAIN ARE EXPECTED ACROSS THE
AREA WITH SOME LOCALLY HIGHER AMOUNTS. MOST AREAS ALONG THE I-95
CORRIDOR HAVE ALREADY SEEN 4 TO 6 INCHES OF RAIN OVER THE PAST
WEEK. WITH THE WET ANTECEDENT CONDITIONS, ANY ADDITIONAL RAINFALL
THIS WEEK WILL MORE THAN LIKELY BECOME RUNOFF AS THE GROUND WILL
BE UNABLE TO SOAK UP MUCH MORE. WITH THE RIVERS, CREEKS AND
STREAMS ALREADY RUNNING HIGH AND WITHOUT MUCH TIME FOR THEM TO
SUBSIDE ENOUGH IN ADVANCE OF THIS SYSTEM, THERE IS THE POTENTIAL
FOR MORE FLOODING TO OCCUR.

THE LATEST GUIDANCE BRINGS THE LOW PRESSURE SYSTEM DIRECTLY
ACROSS OUR REGION ON THURSDAY AFTERNOON/EVENING. THE HEAVIEST
RAINFALL IS CURRENTLY FORECAST TO FALL ACROSS EASTERN PENNSYLVANIA
AND THE NORTHERN HALF OF NEW JERSEY AS THE SYSTEM MOVES THROUGH.
IN ADDITION, THE POTENTIAL FOR STRONG TO SEVERE THUNDERSTORMS WILL
EXIST ACROSS THE REMAINING AREAS, WITH THE POTENTIAL FOR HEAVY
RAINFALL TO OCCUR THERE AS WELL.

&&

.RIP CURRENTS...
A WEST NORTHWEST FLOW WOULD USUALLY RESULT IN A LOW RISK OF RIP
CURRENTS ALONG OUR COAST. HOWEVER, THE CONTINUING EAST TO
SOUTHEAST SWELL WAS CAUSING A MODERATE RISK ALONG MUCH OF THE NEW
JERSEY SHORE. AS A RESULT, A MODERATE RISK FOR DANGEROUS RIP
CURRENTS IS IN EFFECT INTO TONIGHT FOR NEW JERSEY. BASED ON LOCAL
GUIDANCE, A LOW RISK IS CARRIED FOR THE DELAWARE BEACHES.

&&

.CLIMATE...
JUNE RECORD MONTHLY RAINFALL...

PHL...10.06 INCHES IN 1938. AS OF 1 AM 6.79 INCHES...RANKED 10TH.
ILG....9.90 INCHES IN 2003. AS OF 1 AM 7.13 INCHES...RANKED 7TH.
ACY....8.45 INCHES IN 1920. AS OF 1 AM 4.07 INCHES...NOT TOP 10.

THURSDAY JUNE 13TH DAILY RECORD RAINFALL...

ACY...1.29 INCHES IN 1953.
PHL...2.21 INCHES IN 1982.
ILG...2.41 INCHES IN 1982.
ABE...2.93 INCHES IN 1942.

RAINFALL THIS MONTH IN OUR AREA, THROUGH THE 10TH, IS ABOUT 200-400
PERCENT OF NORMAL WITH 5 TO 7 INCHES COMMON ALONG THE I-95 CORRIDOR.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...FLOOD WATCH FROM THURSDAY MORNING THROUGH LATE THURSDAY NIGHT
     FOR PAZ054-055-060>062-070-071-101>106.
NJ...FLOOD WATCH FROM THURSDAY MORNING THROUGH LATE THURSDAY NIGHT
     FOR NJZ001-007>010-012>020-026-027.
DE...FLOOD WATCH FROM THURSDAY MORNING THROUGH LATE THURSDAY NIGHT
     FOR DEZ001.
MD...FLOOD WATCH FROM THURSDAY MORNING THROUGH LATE THURSDAY NIGHT
     FOR MDZ008.
MARINE...NONE.

&&

$$
SYNOPSIS...MEOLA
NEAR TERM...GORSE
SHORT TERM...IOVINO
LONG TERM...MEOLA
AVIATION...GORSE/MEOLA
MARINE...IOVINO/MEOLA
HYDROLOGY...MEOLA
RIP CURRENTS...IOVINO
CLIMATE...DRAG