Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 010133
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
933 PM EDT SUN AUG 31 2014

.SYNOPSIS...
HIGH PRESSURE WELL OFF THE EAST COAST WILL MAINTAIN A SOUTHWESTERLY
FLOW OVER THE AREA THROUGH THE FIRST PART OF THE WEEK. A WEAK COLD
FRONT IS THEN EXPECTED TO MOVE ACROSS OUR AREA LATE TUESDAY. HIGH
PRESSURE WILL BUILD IN BEHIND THIS FRONT FOR THE SECOND HALF OF THE
WEEK BEFORE ANOTHER COLD FRONT ARRIVES IN THE REGION THIS WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
SCATTERED SHOWERS AND THUNDERSTORMS CONTINUE ACROSS THE AREA,
ESPECIALLY ACROSS SOUTHERN NEW JERSEY AND THE DELMARVA. THE
STRENGTH OF THE STORMS HAS DIMINISHED AS INSTABILITY IS WANING NOW
THAT NIGHT HAS FALLEN. HOWEVER, AS A COUPLE OF SHORT
WAVES/VORTICITY IMPULSES SLIDE ACROSS THE AREA, THE POTENTIAL FOR
SHOWERS AND THUNDERSTORMS WILL EXIST THROUGH THE NIGHT. THE FIRST
IS SLIDING ACROSS THE NORTHERN HALF OF THE AREA NOW, SO THE
SHOWERS AND THUNDERSTORMS ACROSS MOST OF NEW JERSEY WILL CONTINUE
TO SLIDE OFF THE COAST OVER THE NEXT COUPLE OF HOURS. A SECOND IS
EXPECTED TO SLIDE ACROSS THE SOUTHERN PART OF THE AREA LATER
TONIGHT, WHICH COULD HELP SHOWERS AND THUNDERSTORMS EITHER
CONTINUE OR REDEVELOP ACROSS OUR SOUTHERN AREAS OVERNIGHT. ONCE
BOTH OF THESE PASS TO OUR EAST BY DAYBREAK TOMORROW, WE SHOULD END
UP WITH A BREAK IN SHOWER ACTIVITY.

WITH THE PWATS BEING WELL ABOVE NORMAL, ANY OF THE SHOWERS WILL
BE WATER LADEN AND PRODUCE VERY HEAVY DOWNPOURS. THESE DOWNPOURS
COULD PRODUCE LOCALIZED SMALL STREAM AND POOR DRAINAGE
FLOODING...GOOD THING THE STORM MOTION IS RELATIVELY QUICK.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
SOUPY AIRMASS REMAINS IN PLACE WITH WEAK MID-LEVEL SHORTWAVE MOVING
THROUGH. THE WAVE ALOFT LOOKS TO GET SHEARED OUT AS IT MOVES IN
ALOFT SO IT DOES NOT APPEAR TO BE A GREAT TRIGGER FOR CONTINUED
CONVECTIVE ACTIVITY. THAT BEING SAID, ANY DIFFERENTIAL HEATING THAT
OCCURS COMBINED WITH WEAK SURFACE CONVERGENCE CAN BE THE SPARK
NEEDED TO GET CONVECTION GOING. WE CONTINUE TO HAVE AT LEAST 40-50
PERCENT POPS FOR A MAJORITY OF THE REGION.

TEMPERATURES TOMORROW WILL BE SEVERAL DEGREES ABOVE NORMAL. UPTICKED
THE MAX TEMPERATURES A DEGREE ACROSS THE I-95 CORRIDOR AS ANY BREAKS
IN THE CLOUDS WILL BE ENOUGH FOR SUBSTANTIAL HEATING.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
AT THE BEGINNING OF THIS PERIOD, WE SEE A TRANSITION TO MOSTLY
ZONAL FLOW FROM THE LOWER THROUGH UPPER LEVELS.

TUESDAY...BEFORE MUCH DRY AIR ADVECTION WITH THE ZONAL FLOW CAN
KICK IN THOUGH, WE WILL SEE A RATHER UNCOMFORTABLE DAY WITH HIGHS
IN THE 80S AND 90S, WHILE HEAT INDEX VALUES COULD APPROACH THE MID
AND UPPER 90S IN DELMARVA AND THE I95 CORRIDOR.

TUESDAY NIGHT...MODELS STILL SHOWING THE FRONT ARRIVING DURING
THIS PERIOD, BRINGING SOMEWHAT COOLER, BUT MOSTLY DRIER AIR. STILL
SOME CHANCE FOR SHOWERS AND STORMS AHEAD OF AND WITH THE FRONT,
HOWEVER WITH THE ZONAL FLOW IN PLACE, AND MODEST DRY AIR ADVECTION
OCCURRING AHEAD OF THE FRONT, MOISTURE AVAILABILITY WILL BE
SOMEWHAT QUESTIONABLE.

WEDNESDAY THROUGH FRIDAY...A HIGH BUILDS OVER THE REGION IN THE
WAKE OF THE COLD FRONT. AS A RESULT EXPECT A FEW, NICE, SUMMER
LIKE DAYS WITH HIGHS IN THE 80S.

SATURDAY THROUGH SUNDAY...THE NEXT COLD FRONT IS SET TO ARRIVE
OVER THE WEEKEND. THOUGH THERE IS SOME QUESTION WITH THE CONTINUED
ZONAL FLOW HOW FAR SOUTH THE FRONT WILL DIG, BOTH THE GFS AND
ECMWF HAVE BEEN CONSISTENT IN SHOWING THE FRONT MOVING SOUTH OF
OUR REGION THROUGH THIS PERIOD.

&&

.AVIATION /01Z MONDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

TONIGHT...MOSTLY VFR TO MVFR. SCATTERED SHOWERS AND A FEW
THUNDERSTORMS POSSIBLE, ESPECIALLY FOR MIV/ACY WHERE THEY ARE
ONGOING AND SHOULD CONTINUE THROUGH MIDNIGHT LOCAL; SO TSRA WERE
CONTINUED IN THE 00Z TAFS. FOR THE REST OF THE TAF SITES, THERE
REMAINS THE POTENTIAL FOR SCATTERED SHOWERS, SO -SHRA/VCSH WERE
INCLUDED FOR THE EARLY PART OF THE NIGHT.

WINDS LIGHTEN AND MAY BECOME VARIABLE AT MANY LOCATIONS, BUT
SHOULD REMAIN MOSTLY SOUTH-SOUTHWESTERLY WHERE THERE IS A
DIRECTION.

NOT ENTIRELY SURE WE WILL SEE WIDESPREAD MVFR CIGS, AS WE MAY END
UP WITH MORE LIGHT FOG OVERNIGHT, ESPECIALLY WERE RAIN FELL.
HOWEVER, WE STILL HAVE A PERIOD OF MVFR CIG AND/OR VSBY OVERNIGHT
AND TOWARD DAYBREAK.

TOMORROW...VFR. ANY STRATUS/FOG MIXES OUT BY LATE MORNING.
ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS ARE POSSIBLE BUT AT
THIS TIME, LOCATION IS A BIG QUESTION, SO ONLY INCLUDED -SHRA IN
THE AFTERNOON TIME PERIOD.

OUTLOOK...
MONDAY NIGHT...COVERAGE OF STORMS DECREASES THROUGH THE EVENING
HOURS. HOWEVER, WITH LOW LEVEL MOISTURE IN PLACE, IFR VISIBILITIES
DUE TO BR COULD LINGER FOR MUCH OF THE NIGHT.

TUESDAY AND TUESDAY NIGHT...CONDITIONS IMPROVING TO VFR EARLY IN THE
DAY. SOME SHOWERS AND THUNDERSTORMS POSSIBLE LATE TUESDAY AFTERNOON
AND TUESDAY EVENING, ALONG WITH AN ABRUPT WIND SHIFT AS A COLD FRONT
MOVES THROUGH THE REGION.

WEDNESDAY THROUGH FRIDAY...GENERALLY VFR CONDITIONS EXPECTED.

&&

.MARINE...
SUB-SCA CONDITIONS EXPECTED TONIGHT AND TOMORROW. SEAS WILL CONTINUE
TO BUILD THROUGH TOMORROW...AROUND 4 FEET. WINDS SHOULD BE LIGHTER
TOMORROW THAN TODAY.

OUTLOOK...
MONDAY NIGHT THROUGH FRIDAY...SEAS AND WINDS ARE EXPECTED TO REMAIN
BELOW SMALL CRAFT ADVISORY CRITERIA. SOME GUSTY WINDS WILL BE
POSSIBLE IN THE VICINITY OF THUNDERSTORMS MONDAY EVENING AND AGAIN
TUESDAY NIGHT.

&&

.HYDROLOGY...
VERY HIGH PWAT AIRMASS IN PLACE TODAY AND TONIGHT. NUMEROUS
MID-LEVEL WAVES/TROUGHS MOVE THROUGH THE REGION TAPPING INTO THE
MOISTURE ALLOWING FOR VERY HEAVY DOWNPOURS, ESPECIALLY IN
CONVECTION. STORM MOTIONS SHOULD BE QUICK ENOUGH FOR MOSTLY POOR
DRAINAGE AND SOME SMALL STREAM FLOODING. THROUGH TOMORROW AFTERNOON,
WHEN MORE SHOWERS AND THUNDERSTORMS ARE POSSIBLE, QPF ACCUMULATIONS
OF AROUND AN INCH ARE POSSIBLE...HIGHER WITHIN SOME STORMS. CURRENT
CONDITIONS ACROSS THE REGION HAVE BEEN DRY SO NOT EXPECTING MUCH IN
THE WAY OF FLASH FLOODING CONCERNS.

&&

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

&&

$$
SYNOPSIS...JOHNSON
NEAR TERM...HEAVENER/ROBERTSON
SHORT TERM...HEAVENER
LONG TERM...JOHNSON
AVIATION...HEAVENER/JOHNSON/ROBERTSON
MARINE...HEAVENER/JOHNSON
HYDROLOGY...HEAVENER




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