Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 070150
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
950 PM EDT WED MAY 6 2015

.SYNOPSIS...
HIGH PRESSURE WILL BUILD ACROSS OUR AREA THROUGH THURSDAY. THE HIGH
WILL THEN BUILD TO OUR EAST FRIDAY AND THROUGH THE WEEKEND, LEADING
TO A RETURN FLOW ACROSS OUR REGION. LOW PRESSURE IS FORECAST TO LIFT
THROUGH THE GREAT LAKES REGION EARLY NEXT WEEK AND TOWARD THE
NORTHEAST BY WEDNESDAY, PULLING A COLD FRONT TO THE EAST COAST
AROUND TUESDAY.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
THE WATER VAPOR IMAGERY SHOWS FAST WEST-NORTHWEST FLOW ALOFT ACROSS
THE NORTHEAST, ALTHOUGH RIDGING IS STARTING TO BUILD MORE JUST TO
OUR WEST. MEANWHILE, A SURFACE FRONT IS DRAPED JUST TO OUR SOUTH AND
SOUTHWEST WITH A LOW-LEVEL MARINE AIRMASS OVER OUR AREA AND
CONTINUING TO SPREAD WESTWARD, THUS MORE STABILITY.

SOME WEAK LIFT NORTH OF THE AFOREMENTIONED FRONT HAS HELPED TO
SUSTAIN SOME LIGHT SHOWERS OR SPRINKLES FOR PARTS OF THE AREA,
HOWEVER THESE CONTINUE TO DWINDLE AS THEY TRACK SOUTHEASTWARD. SOME
NEW DEVELOPMENT HAS BEEN OCCURRING IN THE HARRISBURG TO LANCASTER
CORRIDOR, HOWEVER EVEN THESE ARE WEAKENING WITH A SOUTHEASTERN
EXTENT. ANY LINGERING SHOWER/SPRINKLES WILL DISSIPATE TOWARD
MIDNIGHT, HOWEVER SOME LINGERING WEAK LIFT AND LOW-LEVEL CONVERGENCE
CLOSER TO THE FRONT MAY PRODUCE A FEW MORE SHOWERS OVERNIGHT OR
TOWARD DAYBREAK. THIS IS OF LOWER CONFIDENCE AS ANY LIFT GENERALLY
LOOKS RATHER WEAK AND DISORGANIZED. THEREFORE, WE CONTINUED TO
ADVERTISE A DRY OVERNIGHT.

A RIBBON OF CLOUDINESS REMAINS AROUND THE CENTRAL PART OF THE CWA,
WITH LESS UP NORTH AND ACROSS PORTIONS OF THE DELMARVA. THE LOW-
LEVEL DRY AIR SHOULD HELP KEEP LESS CLOUDS ACROSS THE FAR NORTH,
MEANWHILE FARTHER SOUTH THERE IS A CIRRUS CANOPY FROM THE
DISORGANIZED SYSTEM OFF THE SOUTHEAST COAST.

THE HOURLY GRIDS WERE ADJUSTED WITH THE LATEST OBSERVATIONS /WHICH
INCLUDED A BIT FASTER TEMPERATURE DROP THUS FAR ACROSS THE EASTERN
ZONES/, AND THEN THE LAMP/LAV GUIDANCE WAS BLENDED IN TO ASSIST
THROUGH THE EVENING. NO MAJOR CHANGES WERE MADE TO THE LOW
TEMPERATURES ATTM.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
THURSDAY...RIGHT NOW THINK IT SHOULD OVERALL AVERAGE PARTLY CLOUDY
WITH CONSIDERABLE CONVECTIVELY DRIVEN MIDDAY CLOUD COVER. 50 50
BLENDED 12Z/6 NCEP MOS GUIDANCE TEMPS/DEWS/WINDS.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
HIGH PRESSURE BUILDS OFFSHORE OF THE EAST COAST THURSDAY NIGHT INTO
FRIDAY, AND OUR AREA WILL REMAIN ON THE WESTERN SIDE OF THE HIGH
THROUGH THE UPCOMING WEEKEND. MEANWHILE, RIDGING ALOFT BUILDS OVER
THE AREA, WHICH WILL ALLOW TEMPERATURES TO REMAIN WARM THROUGH THE
UPCOMING WEEKEND. TEMPERATURES THROUGH SUNDAY WILL REMAIN CLOSE TO
10 DEGREES ABOVE NORMAL EACH DAY. MOSTLY DRY WEATHER IS EXPECTED AS
THERE IS NO STRONG, DISCERNIBLE SHORT WAVE/VORTICITY IMPULSES
FORECAST TO TRAVERSE THE AREA AROUND THE RIDGE ALOFT. HOWEVER,
WITH RETURN FLOW IN PLACE AND THE WARM, MOISTENING LOW LEVELS,
THERE IS BE SOME DAYTIME INSTABILITY. THIS COULD LEAD TO SOME
DIURNAL, INSTABILITY INDUCED SHOWERS/THUNDERSTORMS, ESPECIALLY
SATURDAY AND SUNDAY. WE HAVE SLIGHT CHANCE/CHANCE
SHOWERS/THUNDERSTORMS POSSIBLE OVER THE WEEKEND. WITH THE ADDED
LOW LEVEL MOISTURE AND STABLE AIR OVERNIGHT, THERE IS THE
POSSIBILITY OF OVERNIGHT/EARLY MORNING FOG DEVELOPMENT EACH NIGHT
FROM FRIDAY NIGHT THROUGH SUNDAY NIGHT.

AS WE MOVE INTO MONDAY, A BACKDOOR TYPE FRONT TRIES TO SAG SOUTHWARD
FROM THE NORTH, WHILE THE RIDGE ALOFT BEGINS TO BREAK DOWN AND MOVE
EASTWARD. THE FRONT MAY NOT MAKE IT INTO OUR AREA, BUT WILL REMAIN
INSTABILITY ACROSS THE AREA. IF ANY VORTICITY IMPULSES ARE ABLE TO
SLIDE ACROSS THE AREA IN THE SOUTHWEST FLOW ALOFT, THE WOULD HELP
ENHANCE OUR SHOWER/THUNDERSTORM POTENTIAL. SO WE WILL CONTINUE WITH
LOW END CHANCE POPS FOR MONDAY.

AN BROAD AREA OF LOW PRESSURE IS FORECAST TO MOVE OUT OF THE GREAT
LAKES MONDAY NIGHT, AND INTO THE NORTHEAST US/SOUTHEASTERN CANADA
THROUGH TUESDAY. AS IT DOES SO, IT WILL PULL A COLD FRONT ACROSS THE
AREA. SHOWERS AND THUNDERSTORMS CHANCES INCREASE FROM MONDAY NIGHT
INTO TUESDAY/TUESDAY NIGHT. THE MOST LIKELY PERIOD OF
SHOWERS/THUNDERSTORMS WOULD BE WITH THE FRONTAL PASSAGE WHICH IS
CURRENTLY EXPECTED DURING THE DAY TUESDAY.

AN AREA OF LOW PRESSURE OFF THE SOUTHEAST COAST IS FORECAST TO
MEANDER NEAR THE CAROLINA COASTS THROUGH THE UPCOMING WEEKEND. BY
THE TIME IT STARTS TO MOVE NORTHWARD, IT SHOULD GET CAUGHT UP IN
THE SOUTHWEST FLOW ALOFT AND BEGIN MOVING OFFSHORE EARLY NEXT
WEEK. FOR NOW IT IS EXPECTED TO REMAIN FAR ENOUGH TO OUR SOUTH,
BUT WE`LL NEED TO WATCH THE FORECAST OVER THE NEXT SEVERAL DAYS.

&&

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

OVERNIGHT...VFR WITH A CEILING AT OR ABOVE 4000 FEET, WHICH MAY
SCATTER OUT FOR SOME AREAS ESPECIALLY LATE. NORTHEASTERLY WINDS
AROUND 5 KNOTS, POSSIBLY TURNING LOCALLY LIGHT SOUTHEAST.

THURSDAY...VFR WITH CLOUD BASES /A CEILING AT TIMES ESPECIALLY IN
THE MORNING/ AT OR ABOVE 4000 FEET. EASTERLY WINDS 4-8 KNOTS TURNING
SOUTH-SOUTHEAST THEN SOUTHWEST DURING THE AFTERNOON /REMAINING MORE
SOUTHEAST MAINLY AT KILG, KACY AND KMIV DUE TO BAY/SEA BREEZE
INFLUENCE/.

OUTLOOK...
THURSDAY NIGHT-FRIDAY NIGHT...GENERALLY VFR EXPECTED.

SATURDAY-MONDAY...GENERALLY VFR DURING THE DAY. ISOLATED/SCATTERED
SHOWERS/THUNDERSTORMS EACH AFTERNOON. FOG/STRATUS POSSIBLE
OVERNIGHT/EARLY MORNING WITH REDUCED CIGS/VSBYS.

&&

.MARINE...
WINDS AND SEAS SHOULD REMAIN BELOW SCA CRITERIA THROUGH THURSDAY.
NORTHEAST /LOCALLY SOUTHEAST/ THIS EVENING, THEN LIGHT EAST-
NORTHEAST OVERNIGHT AND TURNING SOUTHEAST ON THURSDAY. SEAS
GENERALLY AOB 2 FEET.

OUTLOOK...
THURSDAY NIGHT-MONDAY...SUB-SMALL CRAFT ADVISORY CONDITIONS
CONTINUE TO BE EXPECTED THROUGH THE WEEKEND. WINDS MAY GUST AROUND
20 KNOTS SATURDAY-MONDAY, WITH SEAS BUILDING TO 4 FEET.

&&

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

&&

$$
SYNOPSIS...GORSE/ROBERTSON
NEAR TERM...GORSE
SHORT TERM...DRAG
LONG TERM...ROBERTSON
AVIATION...GORSE/ROBERTSON
MARINE...DRAG/ROBERTSON


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