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Area Forecast Discussion
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000
FXUS61 KPHI 221953
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
353 PM EDT TUE JUL 22 2014

.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO MOVE EASTWARD TONIGHT ALLOWING FOR A 
BETTER RETURN FLOW TOMORROW AHEAD OF A POTENT COLD FRONT. THE FRONT 
SHOULD MOVE THROUGH LATER ON WEDNESDAY INTO THURSDAY MORNING. HIGH 
PRESSURE WILL FILL IN BEHIND THE DEPARTING FRONT THROUGH THE FIRST 
HALF OF THE WEEKEND BEFORE A COMPLEX SYSTEM APPROACHES SUNDAY 
SPILLING INTO THE NEW WORK WEEK.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
CONDITIONS REMAINED FAIRLY STABLE OVER THE COASTAL PLAIN THIS 
AFTERNOON EVEN WITH THE DEVELOPMENT OF SOME CUMULUS. IT WAS 
MARGINALLY UNSTABLE OVER EASTERN PENNSYLVANIA AND NORTHERN NEW 
JERSEY. THERE WERE ISOLATED LIGHT RAIN SHOWERS IN LANCASTER COUNTY 
AND VICINITY AT MID AFTERNOON. WE WILL MENTION THE POSSIBILITY OF 
ISOLATED SHOWERS FROM BERKS COUNTY AND CHESTER COUNTY UP INTO 
NORTHERN NEW JERSEY UNTIL ABOUT 6 OR 7 O'CLOCK.

THE CUMULUS WILL LIKELY BE ON THE DECREASE THIS EVENING WITH THE 
LOSS OF DAYTIME HEATING. HOWEVER, THE SOUTHERLY SURFACE FLOW WILL 
CONTINUE TO DRAW LOW LEVEL MOISTURE INTO OUR REGION. AS A RESULT, 
THERE MAY BE PATCHY LOW CLOUDS, FOG AND HAZE TOWARD MORNING.

MINIMUM TEMPERATURES SHOULD RANGE FROM THE MIDDLE 60S TO THE LOWER 
70S.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
THE GUIDANCE HAS BEEN FAIRLY CONSISTENT DURING THE PAST SEVERAL DAYS 
REGARDING THE FORECAST FOR WEDNESDAY. TEMPERATURES AT THE 850 HPA 
LEVEL ARE FORECAST TO RISE AROUND 18C OR 19C, SO MAXIMUM 
TEMPERATURES MAINLY IN THE LOWER 90S CONTINUE TO SEEM REASONABLE. 
DEW POINT READINGS SHOULD BE RIGHT AROUND 70 RESULTING IN MAXIMUM 
HEAT INDEX VALUES IN THE MIDDLE AND UPPER 90S. THE WIND IS 
ANTICIPATED TO FAVOR THE SOUTH ON THE COASTAL PLAIN AND THE 
SOUTHWEST INLAND AT SPEEDS AROUND 10 MPH.

INSTABILITY WILL BE ON THE INCREASE THROUGH THE MORNING AND EARLY 
AFTERNOON WITH MIXED LAYER CAPE VALUES EXPECTED TO RISE AROUND 2500 
J/KG IN AREAS ALONG AND TO THE NORTHWEST OF THE INTERSTATE 95 
CORRIDOR. A BIT OF A MID LEVEL CAP MAY PREVENT MUCH ACTIVITY FROM 
DEVELOPING DURING THE EARLY TO MID AFTERNOON. HOWEVER, A LINE OF 
THUNDERSTORMS SHOULD DEVELOP AHEAD OF A COLD FRONT APPROACHING FROM 
THE NORTHWEST. THE CONVECTION WILL LIKELY MOVE INTO OUR NORTHWESTERN 
COUNTIES BY LATE AFTERNOON AND IT SHOULD REACH THE INTERSTATE 95 
CORRIDOR DURING THE EARLY EVENING. THE STORM PREDICTION CENTER 
CONTINUES TO SUGGEST THAT THE GREATEST THREAT OF SEVERE WEATHER 
AHEAD OF THE FRONT WILL BE UP IN NEW ENGLAND. HOWEVER, A FEW STRONG 
STORMS AND ISOLATED SEVERE WEATHER REMAIN POSSIBLE IN OUR AREA.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
COLD FRONT SHOULD BE AT OUR DOORSTEP AT THE START OF THE LONGTERM 
PERIOD THOUGH AS THE CASE DURING THE SUMMER, IT WILL NOT A QUICK PASSAGE. 
UPPER LEVEL SUPPORT WITH THE RIGHT ENTRANCE REGION OF THE JET 
OVERHEAD AND DEEPER TROUGHING NUDGING IN FROM THE WEST COMBINED WITH 
PWATS NEARING 2 INCHES, AGAIN, COULD PRODUCE HEAVY RAIN WITH ANY OF 
THE STORMS. SHEAR VALUES WILL BE RATHER ROBUST, AROUND 25 
KNOTS...BETTER THE FURTHER NORTH YOU GO, SO ORGANIZED CONVECTION 
SEEMS PLAUSIBLE AND THE STORMS WILL BE MOVING. WITH THE DEEPENING 
TROUGH EXPECTED OVERHEAD ON THURSDAY, THE FRONT SHOULD BE SLOW TO 
CLEAR THE REGION SO WE KEEP CHANCE TO LIKELY POPS IN ACROSS THE 
SOUTHERN ZONES THROUGH MOST OF THE AFTERNOON...COULD BE LONG IN THE 
TOOTH.

THE BASE OF THE TROUGH BEGINS TO FLATTEN OUT BY FRIDAY, THOUGH NOT 
ENTIRELY BECOMING ZONAL. THIS YIELDS SLIGHTLY BELOW NORMAL 
TEMPERATURES AND DECREASED CHANCES FOR CONVECTION GIVEN A DRIER 
AIRMASS IN PLACE. STILL A BIT UNCERTAIN ABOUT THE SATURDAY EVENING 
TIMEFRAME AS SOME OF THE OPERATIONAL GUIDANCE SWINGS A PIECE ENERGY 
THROUGH THE BASE OF THE TROUGH WHICH COULD TOUCH OFF A COUPLE 
STRAY/ISOLATED SHOWERS...BETTER EAST THAN WEST WITH BETTER MOISTURE 
POOLING AND SEABREEZE INTERACTION.

RIDGING BUILDS INTO THE WEST SENDING STRONGER SHORTWAVES OF ENERGY 
INTO THE TROUGH OVERHEAD ALLOWING FOR ANOTHER BOUT OF DEEPER 
TROUGHING. EXPECT UNSETTLED WEATHER THROUGH THE REMAINDER OF THE 
LONGTERM AS A SERIES OF EMBEDDED WAVES PUSHES THROUGH ALOFT TOUCHING 
OFF SHOWERS AND THUNDERSTORMS. 

&&

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

SCATTERED TO BROKEN CLOUDS WITH BASES GENERALLY IN THE 4000 TO 5000 
FOOT RANGE ARE ANTICIPATED FOR THE BALANCE OF THE AFTERNOON. 
ISOLATED RAIN SHOWERS ARE POSSIBLE AROUND KRDG AND KABE. THE CLOUD 
COVER IS FORECAST TO DECREASE DURING THE EVENING HOURS WITH THE LOSS 
OF DAYTIME HEATING.

VFR CONDITIONS ARE ANTICIPATED FOR EARLY TONIGHT. INCREASING LOW 
LEVEL MOISTURE IN THE SOUTHERLY FLOW MAY RESULT IN THE DEVELOPMENT 
OF SOME LOW CLOUDS, HAZE AND FOG FOR LATE TONIGHT INTO EARLY 
WEDNESDAY MORNING.

VFR CONDITIONS ARE EXPECTED FROM MID MORNING ON WEDNESDAY INTO THE 
MID AFTERNOON HOURS. HOWEVER, THUNDERSTORMS OUT AHEAD OF A COLD 
FRONT APPROACHING FROM THE NORTHWEST SHOULD IMPACT OUR REGION DURING 
THE LATE AFTERNOON AND EVENING HOURS.

A SOUTHERLY WIND AROUND 5 TO 10 KNOTS TODAY SHOULD DIMINISH TO 6 
KNOTS OR LESS FOR TONIGHT. A SOUTHWEST TO SOUTH WIND AROUND 10 KNOTS 
IS ANTICIPATED FOR WEDNESDAY.

OUTLOOK...
WEDNESDAY NIGHT AND THURSDAY...MVFR AND IFR CONDITIONS AT TIMES IN 
SHOWERS AND THUNDERSTORMS. PATCHY FOG THU MORNING.

THURSDAY NIGHT THROUGH SATURDAY...MAINLY VFR.

SUNDAY...SUB-VFR POSSIBLE IN SCATTERED SHOWERS AND THUNDERSTORMS.

&&

.MARINE...
HIGH PRESSURE OFF THE COAST AND A COLD FRONT APPROACHING FROM THE 
NORTHWEST SHOULD MAINTAIN A SOUTHERLY FLOW OVER THE COASTAL WATERS 
OF NEW JERSEY AND DELAWARE FOR TONIGHT AND WEDNESDAY. WIND SPEEDS 
WILL FAVOR THE 5 TO 15 KNOT RANGE.

WAVE HEIGHTS ON OUR OCEAN WATERS SHOULD BE 2 TO 4 FEET. WAVES ON 
DELAWARE BAY ARE EXPECTED TO BE 2 FEET OR LESS.

THERE IS A CHANCE OF THUNDERSTORMS LATE ON WEDNESDAY.

OUTLOOK...
THURSDAY THROUGH SUNDAY...HIGH PRESSURE OVERHEAD WILL KEEP SEAS AND 
WINDS BELOW SCA CRITERIA.

&&

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

&&

$$
SYNOPSIS...HEAVENER
NEAR TERM...IOVINO
SHORT TERM...IOVINO
LONG TERM...HEAVENER
AVIATION...IOVINO/HEAVENER
MARINE...IOVINO/HEAVENER






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