Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 271932
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
332 PM EDT WED APR 27 2016

.SYNOPSIS...
A FRONTAL BOUNDARY WILL REMAIN JUST TO OUR SOUTH INTO FRIDAY,
BEFORE GETTING PUSHED INTO THE SOUTHEASTERN STATES DURING FRIDAY
INTO SATURDAY. AN AREA OF LOW PRESSURE WILL TRACK ALONG THIS
BOUNDARY THURSDAY BEFORE SHIFTING OUT TO SEA FRIDAY. HIGH PRESSURE
CENTERED NEAR HUDSON BAY CANADA SATURDAY WILL EXTEND INTO OUR
REGION THROUGH MUCH OF SUNDAY. LOW PRESSURE WILL THEN TRACK ACROSS
OUR AREA MONDAY BEFORE MOVING OFFSHORE MONDAY NIGHT INTO TUESDAY.
A COLD FRONT MAY THEN APPROACH FROM THE NORTHWEST WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
THE BIG QUESTION TONIGHT WILL BE HOW FAR SOUTH THE CLEARING LINE
GETS. NORTH OF THIS CLEARING LINE, EXPECT GOOD RADIATIONAL COOLING
CONDITIONS LEADING TO PATCHY FROST. WHERE THE CLOUDS LINGER, EXPECT
LITTLE DROP OFF IN OVERNIGHT TEMPS, WITH LOWS GENERALLY IN THE MID
TO UPPER 40S.

AT THIS POINT, THINK THAT THE CLEARING LINE WILL NOT GET MUCH
FURTHER SOUTH THAN WHERE IT IS AS OF 3 PM. HOWEVER, IF IT DOES, THE
FROST ADVISORY MAY NEED TO BE EXPANDED.

ACROSS DELMARVA, A FEW LIGHT SHOWERS MAY DEVELOP AS THE ONSHORE
FLOW CONTINUES.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
THE NEXT SHORT WAVE TROUGH APPROACHES THE REGION TOMORROW. MODELS
HAVE TRENDED SLIGHTLY LATER WITH HOW FAST THE TROUGH APPROACHES, AND
THUS LATER WITH THE ONSET OF RAIN. THUS, I ADJUSTED POPS DOWN
THROUGH THE MORNING HOURS (EXCEPT IN DELMARVA WHERE THE ONSHORE
FLOW MAY CONTINUE TO LEAD TO LIGHT PRECIP).

I ALSO TRENDED TEMPS DOWN SLIGHTLY GIVEN TRENDS TODAY. TOMORROW
SHOULD BE SIMILAR EXCEPT THERE SHOULD BE LITTLE IN THE WAY OF
CLEARING BEFORE SUNSET.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
THE SYNOPTIC PATTERN IS FORECAST TO BE COMPRISED OF A STRONG CLOSED
LOW THAT SLOWLY EXITS THE CANADIAN MARITIMES AREA THROUGH FRIDAY.
OUR REGION HOWEVER REMAINS WITHIN A CYCLONIC FLOW REGIME INTO THE
WEEKEND. SOME SHORT WAVES TRAVERSING THE FLOW WILL DRIVE SOME MAINLY
WEAK SURFACE LOWS NEAR OR ACROSS OUR REGION INTO EARLY NEXT WEEK.
THIS INITIALLY OCCURS AS A FRONTAL ZONE IS STALLED JUST TO OUR
SOUTH, BUT THEN GETS PUSHED WELL TO OUR SOUTH FRIDAY INTO SATURDAY.
A MORE NOTABLE FEATURE LOOKS TO ARRIVE EARLY NEXT WEEK AS ENERGY
EJECTS OUT OF THE PLAINS AND ACROSS THE UPPER OHIO VALLEY. THIS
PATTERN WILL TEND TO KEEP OUR WEATHER UNSETTLED AT TIMES AND ON THE
COOLER SIDE. WE USED A MODEL/CONTINUITY BLEND THROUGH SATURDAY, THEN
BLENDED IN THE 12Z WPC GUIDANCE THEREAFTER. SOME ADJUSTMENTS WERE
THEN MADE FOLLOWING ADDITIONAL COLLABORATION WITH OUR NEIGHBORING
OFFICES.

FOR THURSDAY NIGHT AND FRIDAY...A STRONG CLOSED LOW IN THE CANADIAN
MARITIMES AREA WILL GRADUALLY SHIFT EASTWARD. THIS KEEPS CYCLONIC
FLOW OVERALL ACROSS OUR REGION, AND THE CURRENT CLOSED LOW IN THE
PLAINS IS FORECAST TO OPEN UP AND MOVE ACROSS OUR AREA FRIDAY. SOME
GUIDANCE WANTS TO SHARPEN THIS SOME AS IT ARRIVES /AND SOME DIFFER
ON THE TIMING/, HOWEVER OVERALL THE MOISTURE AVAILABILITY MAY BE ON
THE LOWER SIDE. THERE SHOULD STILL BE ENOUGH FORCING TO PROMOTE SOME
SHOWERS DURING THE FIRST HALF OF THURSDAY EVENING AS AN INITIAL WEAK
SURFACE FEATURE EXITS, THEN DURING FRIDAY AS THE PLAINS TROUGH
ARRIVES. AS A RESULT CHC POPS FOR THE AREA WITH THE IDEA FOR AT
LEAST SCATTERED SHOWERS, HOWEVER IT APPEARS RAINFALL AMOUNTS WILL BE
ON THE LIGHT SIDE. GIVEN A NORTHEASTERLY LOW-LEVEL FLOW AND THE
PROSPECTS FOR A LOT OF CLOUD COVER, TEMPERATURES WILL BE ON THE COOL
SIDE.

FOR SATURDAY AND SUNDAY...AS ADDITIONAL ENERGY AMPLIFIES SOME FROM
THE PLAINS TOWARD THE OHIO VALLEY INTO SUNDAY, HIGH PRESSURE AT THE
SURFACE CENTERED NEAR HUDSON BAY WILL WEDGE DOWN INTO OUR AREA. THIS
WILL RESULT IN A CONTINUATION OF AN ONSHORE FLOW IN THE LOWER
LEVELS. THE AMOUNT OF CLOUD COVER AT LEAST FOR SATURDAY AND TO START
SUNDAY WILL DEPEND ON HOW MUCH DRY AIR GETS PUSH SOUTHWARD ALONG
WITH SUBSIDENCE. LOW PRESSURE THEN MIGRATING FROM THE CENTRAL PLAINS
TO THE UPPER OHIO VALLEY SUNDAY WILL PUSH A WARM FRONT TOWARD OUR
AREA SUNDAY NIGHT. SOME WAA AND ISENTROPIC LIFT SHOULD BE ENOUGH TO
PRODUCE SOME SHOWERS STARTING MAINLY SUNDAY AFTERNOON AND ESPECIALLY
AT NIGHT. THERE COULD END UP BEING ENOUGH OVERRUNNING TO RESULT IN A
PERIOD OF STEADIER RAIN. FOR NOW, MAINTAINED AS SHOWERS.

FOR MONDAY THROUGH WEDNESDAY...AN UPPER-LEVEL TROUGH IS FORECAST TO
AMPLIFY INTO THE EAST MONDAY ALLOWING SURFACE LOW PRESSURE TO SHIFT
OFFSHORE. WHILE SOME SHOWERS ARE POSSIBLE MONDAY, A DRYING TREND IS
CURRENTLY FORECAST WITH A COLD FRONT OFFSHORE. ANOTHER COLD FRONT
THOUGH MAY APPROACH THE AREA LATER WEDNESDAY IN ASSOCIATION WITH AN
UPPER-LEVEL TROUGH, ALLOWING FOR AT LEAST SOME TEMPERATURE
MODERATION AHEAD OF IT.

&&

.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

EXPECT CEILINGS TO GENERALLY STAY BELOW 5000 FT AGL THROUGH THE
OVERNIGHT HOURS. HOWEVER, AT THIS POINT, EXPECT THAT CEILINGS WILL
BE MOSTLY VFR OVERNIGHT. THERE IS A CHANCE THAT LOCALIZED MVFR
CEILINGS COULD DEVELOP, BUT I DON`T HAVE ENOUGH CONFIDENCE TO
INCLUDE IN ANY TAF AT THIS TIME. CEILINGS AND VISIBILITIES WILL ONCE
AGAIN LOWER AFTER 18Z TOMORROW AS THE NEXT ROUND OF SHOWERS MOVES
INTO THE REGION.

WINDS SHOULD BE MOSTLY LIGHT AND VARIABLE THROUGH AT LEAST 12Z.
AFTER 12Z, EXPECT WINDS TO SETTLE OUT OF THE NORTHEAST OR EAST, BUT
REMAIN NEAR 10 KT.

OUTLOOK...
THURSDAY NIGHT...MVFR TO POSSIBLY IFR ALONG WITH SOME SHOWERS AND
LOCAL FOG.

FRIDAY...MVFR CONDITIONS WITH SOME SHOWERS, WHICH SHOULD IMPROVE TO
VFR AT NIGHT.

SATURDAY AND SUNDAY...VFR CEILINGS WHICH MAY THIN OUT FOR A TIME
FROM THE NORTH SATURDAY, THEN CLOUDS INCREASE AND LOWER DURING
SUNDAY WITH SHOWERS LATER SUNDAY.

MONDAY...SUB-VFR CONDITIONS POSSIBLE WITH SHOWERS OR A PERIOD OF
RAIN.

&&

.MARINE...
WINDS AND SEAS SHOULD REMAIN BELOW SCA CRITERIA TONIGHT AND
TOMORROW. A FEW GUSTS NEAR OR ABOVE 20 KT WILL BE POSSIBLE TOMORROW
MORNING AND SEAS WILL SUBSEQUENTLY INCREASE AS WELL.

OUTLOOK...
THURSDAY NIGHT THROUGH SATURDAY...NORTHEASTERLY WINDS INCREASE WITH
GUSTS TO 25 KNOTS POSSIBLE, THEN DIMINISH SOME DURING SATURDAY. SEAS
ARE ANTICIPATED TO BUILD INTO THE 3-6 FOOT RANGE /LOWEST IN DELAWARE
BAY/ BEFORE SUBSIDING SOME DURING SATURDAY AND SATURDAY NIGHT.

SUNDAY AND MONDAY...NORTHEASTERLY WINDS INCREASE AGAIN ESPECIALLY
MONDAY WITH GUSTS POTENTIALLY NEARING 25 KNOTS. THIS WOULD ALLOW
SEAS TO ALSO BUILD TO AROUND 5 FEET ON THE ATLANTIC COASTAL
WATERS.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...FROST ADVISORY FROM 4 AM TO 8 AM EDT THURSDAY FOR PAZ062.
NJ...FROST ADVISORY FROM 4 AM TO 8 AM EDT THURSDAY FOR NJZ001-
     007>010.
DE...NONE.
MD...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...GORSE
NEAR TERM...JOHNSON
SHORT TERM...JOHNSON
LONG TERM...GORSE
AVIATION...GORSE/JOHNSON
MARINE...GORSE/JOHNSON



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