Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 192157
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
557 PM EDT SAT JUL 19 2014

.SYNOPSIS...
HIGH PRESSURE CENTERED NEAR NOVA SCOTIA WILL DRIFT NORTHEASTWARD
THROUGH TONIGHT. MEANWHILE, WEAK LOW PRESSURE OFF THE NORTH CAROLINA
COAST WILL MOVE TO THE NORTHEAST AND OUT TO SEA ON SUNDAY. ANOTHER
AREA OF HIGH PRESSURE IS EXPECTED TO ESTABLISH ITSELF OVER OUR
REGION FOR MONDAY THROUGH WEDNESDAY. A COLD FRONT IS THEN
ANTICIPATED TO ARRIVE THURSDAY WITH HIGH PRESSURE FOLLOWING FOR
FRIDAY AND SATURDAY.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
OUR AREA IS MAINLY BETWEEN A WEAKENING UPPER-LEVEL TROUGH TO THE
WEST AND A SURFACE LOW TO OUR SOUTHEAST. THE MODEL GUIDANCE
INDICATES A DOUBLE UPPER-LEVEL JET STRUCTURE WITH OUR REGION WITHIN
THE RIGHT ENTRANCE REGION OF THE FARTHER NORTHWEST JET SEGMENT. THE
OTHER JET ENTRANCE REGION IS GENERALLY OFFSHORE AND IS PROBABLY
ASSISTING IN SHOWER DEVELOPMENT THERE ALONG WITH THE WEAK SURFACE
LOW. OVERALL, THE FORCING IS WEAK AND THEREFORE ANY SPRINKLES OR
LIGHT SHOWERS SHOULD BE LIMITED IF THEY OCCUR AWAY FROM THE COAST.
THERE ARE SHOWERS TO OUR WEST AND SOUTHWEST AND SOME OF THEM COULD
MAKE A RUN AT OUR WESTERN ZONES BEFORE WEAKENING. WE WILL CONTINUE
TO MENTION SOME SPRINKLES OR SLIGHT CHC TO LOW CHC POPS ESPECIALLY
CLOSER TO THE COAST FOR AWHILE.

OTHERWISE, THE UPPER-LEVEL JETS ARE PROVIDING A DECENT AMOUNT OF
CLOUD COVER ALTHOUGH THERE IS A GAP BETWEEN THE TWO AFOREMENTIONED
SYSTEMS. THIS WILL RESULT IN LESS CLOUDS FOR A TIME AWAY FROM THE
COAST BUT OVERALL THE CLOUDS SHOULD WIN OUT THROUGH THE OVERNIGHT.
THERE IS AN ONSHORE FLOW AND WITH THE ONSET OF BOUNDARY LAYER
COOLING, SOME LOW CLOUDS COULD DEVELOP ESPECIALLY CLOSER TO THE
COAST. DEPENDING ON THE THICKNESS OF THE CLOUD COVER, PATCHY FOG
COULD DEVELOP LATE.

THE HOURLY GRIDS WERE ADJUSTED WITH THE LATEST OBSERVATIONS, THEN
THE LAMP/LAV GUIDANCE WAS BLENDED IN TO ASSIST. NO MAJOR CHANGES
WERE MADE ATTM OTHER THAN SOME ADJUSTMENTS TO THE POPS.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
THERE WAS GOOD AGREEMENT FOR MOST WEATHER ELEMENTS IN THIS
FORECAST PERIOD. USING THE 925 MB TEMPERATURES AS REFERENCE WOULD
YIELD A HIGH OF 83 AT PHL TOMORROW WHILE THE MODELED TWO METER
TEMPERATURES WERE AROUND 80. COMPONENTS OF THE MAV AND MET WERE
USED TO GET IN THIS RANGE. THE OVERALL FLOW WILL CONTINUE TO BE
FROM THE EAST TO SOUTHEAST AS WELL. IN TERMS OF POPS AND CLOUD
COVER, SOME WEAK SHORTWAVES MAY PASS THROUGH THE REGION BUT APPEAR
TO HAVE LIMITED MOISTURE ASSOCIATED WITH THEM. AS A RESULT, MOSTLY
CLOUDY SKIES ARE STILL EXPECTED BUT HAVE KEPT THE FORECAST DRY.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
A MID LEVEL TROUGH IS FORECAST TO BE LOCATED OVER THE
NORTHEASTERN STATES ON SUNDAY EVENING. THE TROUGH IS EXPECTED TO
CONTINUE LIFTING NORTHEASTWARD WITH RIDGING BUILDING OVERHEAD FROM
THE WEST AND SOUTH FOR MONDAY AND TUESDAY. WE ARE ANTICIPATING A
FAIR AMOUNT OF MID LEVEL CLOUDINESS ALONG WITH SOME STRATOCUMULUS
FOR SUNDAY NIGHT INTO MONDAY MORNING, THEN A GENERAL DECREASE IN
CLOUD COVER.

CONDITIONS ARE EXPECTED TO REMAIN MARGINALLY STABLE FOR MONDAY
AND TUESDAY WITH JUST A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS
ON TUESDAY AFTERNOON, MAINLY ON THE NORTHWESTERN EDGE OF OUR
FORECAST AREA FROM BERKS COUNTY INTO THE LEHIGH VALLEY AND THE
POCONOS.

HIGH TEMPERATURES SHOULD BE MAINLY IN THE MIDDLE 80S ON MONDAY
AND IN THE UPPER 80S ON TUESDAY WITH AN INCREASE IN HUMIDITY AS
THE SURFACE FLOW VEERS FROM THE NORTHEAST AND EAST TO THE SOUTH.

IT CONTINUES TO APPEARS AS THOUGH WEDNESDAY WILL BE THE HOTTEST
DAY OF THE NEW WEEK. A PIECE OF THE HOT AIR FROM THE GREAT PLAINS
IS FORECAST TO DRIFT EASTWARD AND IT SHOULD AFFECT OUR REGION AT
THAT TIME. TEMPERATURES AT THE 850 HPA LEVEL ARE FORECAST TO RISE
AROUND 18C OR 19C. THE INCREASE IN HUMIDITY SHOULD PREVENT
TEMPERATURES FROM RISING TO THEIR DRY ADIABATIC POTENTIAL. WE WILL
CONTINUE TO PREDICT MAXIMUM TEMPERATURES MOSTLY IN THE LOWER 90S.
IT NO LONGER LOOKS AS THOUGH WE WILL REACH HEAT INDEX VALUES OF
100 FROM THE URBAN CORRIDOR SOUTHEASTWARD. PEAK HEAT INDEX VALUES
ARE NOW FORECAST TO BE MOSTLY IN THE MIDDLE 90S, SO THE MENTION
WILL BE REMOVED FROM THE HAZARDOUS WEATHER OUTLOOK PRODUCT.

WE WILL MENTION A CHANCE OF THUNDERSTORMS MOVING INTO OUR REGION
FROM THE NORTHWEST ON WEDNESDAY. HOWEVER, A BIT OF A CAP MAY
PREVENT THE ACTIVITY FROM BECOMING WIDESPREAD AT THAT TIME.

THE GUIDANCE IS COMING TOGETHER WITH A COLD FRONTAL PASSAGE ON
THURSDAY. WE WILL MENTION A CHANCE OF SHOWERS AND THUNDERSTORMS
FOR WEDNESDAY NIGHT INTO THURSDAY AHEAD OF AND WITH THE BOUNDARY.

ALSO, WE ARE SEEING A TREND TOWARD CONSENSUS ON DRY AIR BUILDING
INTO OUR REGION FROM THE NORTHWEST FOR FRIDAY AND SATURDAY.
DAYTIME HIGHS ARE ANTICIPATED TO RETURN TO THE MIDDLE 80S AT MOST
LOCATIONS.

&&

.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

TONIGHT...A CEILING MOSTLY AT OR ABOVE 10000 FEET, HOWEVER AN
ONSHORE FLOW COULD ALLOW FOR SOME MVFR CEILINGS TO DEVELOP MAINLY
SOUTH AND EAST OF KPHL. LOCALIZED MVFR FOG CANNOT BE RULED OUT LATE
ESPECIALLY IF CLOUDS THIN LONG ENOUGH, HOWEVER THE CHC AND
CONFIDENCE IS LOW AND THEREFORE NOT INCLUDED AT THIS TIME. ANY
ISOLATED LIGHT SHOWER OR BRIEF SPRINKLES ARE EXPECTED TO HAVE NO
IMPACT. EASTERLY WINDS BECOMING NORTHEAST LESS THAN 10 KNOTS.

SUNDAY...LOCALIZED MVFR CEILINGS POSSIBLE TO START, OTHERWISE A VFR
CEILING. NORTHEAST WINDS BECOMING SOUTHEASTERLY IN THE AFTERNOON
NEAR 10 KNOTS.

OUTLOOK...
SUNDAY NIGHT THROUGH TUESDAY...MAINLY VFR.

TUESDAY NIGHT AND WEDNESDAY...MAINLY VFR. POSSIBLE LATE NIGHT AND
EARLY MORNING MVFR OR IFR CONDITIONS IN LOW CLOUDS, FOG AND HAZE.
A CHANCE OF AFTERNOON THUNDERSTORMS.

WEDNESDAY NIGHT AND THURSDAY...MVFR AND IFR CONDITIONS AT TIMES
IN SHOWERS AND THUNDERSTORMS.

&&

.MARINE...
SEAS AND WINDS ARE EXPECTED TO REMAIN BELOW SCA CRITERIA. SEAS
AROUND FOUR FEET ARE LIKELY TOMORROW ON THE OCEAN WITH AN EASTERLY
FLOW. WIND GUSTS AROUND 20 KNOTS ARE POSSIBLE ON THE OCEAN SUNDAY
AFTERNOON.

OUTLOOK...
SUNDAY NIGHT THROUGH THURSDAY...NO MARINE HEADLINES ARE
ANTICIPATED.

&&

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

&&

$$
SYNOPSIS...GORSE/IOVINO
NEAR TERM...GORSE
SHORT TERM...GAINES
LONG TERM...IOVINO
AVIATION...GORSE/IOVINO
MARINE...GAINES/IOVINO




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