Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 161359
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
959 AM EDT THU APR 16 2015

.SYNOPSIS...
HIGH PRESSURE WILL SHIFT FARTHER OFFSHORE TODAY, THEN WEAK LOW
PRESSURE IS FORECAST TO DEVELOP NEAR THE CAROLINA COAST TONIGHT INTO
FRIDAY BEFORE TRACKING NORTHEASTWARD. A COLD FRONT MOVES THROUGH OUR
AREA LATER SATURDAY BEFORE STALLING TO OUR SOUTH SUNDAY. LOW
PRESSURE MOVING INTO THE AREA DURING MONDAY WILL PULL THE FRONT
NORTHWARD AS A WARM FRONT, THEN THE SYSTEM EXITS TO OUR EAST
TUESDAY. HIGH PRESSURE SHOULD THEN BEGIN BUILDING TOWARD OUR AREA
ON WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SURFACE HIGH PRESSURE CENTERED OVER NEW ENGLAND THIS MORNING WILL
SLIDE TO THE SOUTHEAST AND WILL BE LOCATED OFF THE SOUTHEAST
COAST OF NEW ENGLAND BYLATE THIS AFTERNOON. A SURFACE RIDGE AXIS
IS EXPECTED TO REMAIN ALONG THE LEE OF THE APPALACHIANS THROUGH
THE DAY. MEANWHILE, A MID LEVEL RIDGE AXIS OVERHEAD THIS MORNING
SHOULD MOVE TO OUR EAST DURING THE AFTERNOON.

WE ARE EXPECTING PATCHES OF CIRRUS FROM THE WEST AND SOUTHWEST TO
PASS OVERHEAD THROUGH THE DAY. THE CLOUDS ARE FORECAST TO BE
SUFFICIENTLY THIN ENOUGH TO ALLOW FOR A GOOD DEAL OF SUNSHINE.

A LIGHT EAST WIND THIS MORNING IS ANTICIPATED TO VEER TO THE
SOUTHEAST BY EARLY AFTERNOON HOURS BEFORE SETTLING INTO THE SOUTH
AT MOST LOCATIONS LATER IN THE DAY. THE WIND WILL REMAIN MORE
FROM THE SOUTHEAST ON THE COASTAL PLAIN DUE TO THE EFFECTS OF THE
OCEAN AND DELAWARE BAY.

MAXIMUM TEMPERATURES ARE FORECAST TO BE MOSTLY NEAR 70 DEGREES, WITH
HIGHS IN THE 60S IN THE ELEVATED TERRAIN NORTH AND WEST. HIGHS
WILL BE IN THE UPPER 50S AND LOWER 60S ALONG THE IMMEDIATE COAST
DUE TO ONSHORE FLOW FROM THE STILL COLD OCEAN.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
HIGH CLOUDS ARE FORECAST TO INCREASE AND THICKEN FOR TONIGHT.
MEANWHILE, A DECK OF MID LEVEL CLOUDS SHOULD OVERSPREAD OUR REGION
FROM THE WEST OVERNIGHT. LOWER CLOUDS AND RAIN SHOWERS ARE EXPECTED
TO BEGIN MOVING INTO OUR WESTERN COUNTIES AROUND OR SHORTLY AFTER
MIDNIGHT BASED ON THE LATEST MODEL GUIDANCE. THERE IS AN INCREASING
CHANCE FOR RAIN SHOWERS LATE TONIGHT AS A MID LEVEL SHORT WAVE AND
ITS ASSOCIATED SURFACE COLD FRONT BEGIN TO APPROACH FROM THE WEST
AND NORTHWEST. RAINFALL AMOUNTS BY DAYBREAK ON FRIDAY ARE
ANTICIPATED TO RANGE FROM ONE TO TWO TENTHS OF AN INCH IN OUR
NORTHWESTERN COUNTIES TO PERHAPS A FEW HUNDREDTHS OF AN INCH IN THE
SOUTHEAST.

A SOUTHERLY WIND AROUND 5 TO 10 MPH IS EXPECTED FOR TONIGHT. THE
SOUTHERLY SURFACE FLOW ALONG WITH THE CLOUD COVER SHOULD PREVENT
TEMPERATURES FROM FALLING BELOW THE LOWER AND MIDDLE 50S AT MOST
LOCATIONS.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
THE SYNOPTIC SETUP IS COMPRISED OF AN INITIAL BROAD TROUGH FROM THE
GREAT LAKES TO THE NORTHEAST FRIDAY, WHICH THEN AMPLIFIES SATURDAY
ACROSS THE NORTHEAST. AS THIS OCCURS, A CLOSED LOW ACROSS THE
CENTRAL ROCKIES DROPS EAST-SOUTHEAST EVENTUALLY EJECTING ACROSS THE
PLAINS INTO SUNDAY. THIS FEATURE BUILDS RIDGING DOWNSTREAM, WHICH
SHOULD SAVE MUCH OF OUR WEEKEND. THE CLOSED LOW LOOKS TO GET
ABSORBED INTO A LARGE SCALE TROUGH FROM THE MIDWEST AS IT UNDERGOES
AMPLIFICATION EASTWARD THROUGH EARLY NEXT WEEK. THE MODEL GUIDANCE
HAS COME INTO BETTER AGREEMENT ON THE SYNOPTIC PATTERN, WHICH
INCREASES OUR CONFIDENCE REGARDING THE DETAILS. IT APPEARS THAT
WHILE SOME WET WEATHER MOVES THROUGH FRIDAY, THE MAIN PRECIPITATION
EVENT /POTENTIALLY HEAVY RAIN/ IS SCHEDULED FOR MONDAY. WE USED A
MODEL BLEND FOR FRIDAY INTO SUNDAY, THEN BLENDED IN THE 00Z WPC
GUIDANCE WITH CONTINUITY. SOME ADJUSTMENTS WERE THEN MADE FOLLOWING
ADDITIONAL COLLABORATION WITH OUR NEIGHBORING OFFICES.

FOR FRIDAY AND SATURDAY...A COLD FRONT WILL WORK ITS WAY ACROSS THE
AREA DURING FRIDAY. THERE APPEARS TO BE A SMALL WINDOW OF
OPPORTUNITY FOR INCREASED MOISTURE AHEAD OF THIS FRONT, AS A NARROW
CORRIDOR OF AROUND AN INCH OF PW AIR ADVECTS ACROSS THE AREA. THE
BETTER CHC OF SHOWERS LOOKS TO BE FROM ABOUT INTERSTATE 95 ON NORTH
AND WEST, WITH THE POTENTIAL FOR SHOWERS TO WEAKEN AS THEY TRACK
FARTHER EAST. SOME OF THE MODEL FORECAST SOUNDINGS DEVELOP SOME
INSTABILITY DURING FRIDAY, ALTHOUGH THE LIFT MAY NOT BE STRONG
ENOUGH TO PROMOTE THUNDER. GIVEN SOME CONFLICTING SIGNALS, WE DID
NOT INCLUDE THUNDER ATTM. THE ACTUAL FRONT MAY FALL APART AS IT
SHIFTS ACROSS OUR AREA DURING FRIDAY. A POTENT SHORT WAVE IS THEN
FORECAST TO DROP DOWN ACROSS NEW ENGLAND DURING SATURDAY WITH LOW
PRESSURE AT THE SURFACE. AN ASSOCIATED COLD FRONT IS FORECAST TO
MOVE THROUGH OUR AREA DURING SATURDAY THEN STALL, HOWEVER THIS
FEATURE LOOKS MOISTURE STARVED ACROSS OUR REGION. AS A RESULT, WE
WILL MAINTAIN A DRY SATURDAY. PLENTY OF WARMTH IS FORECAST TO ADVECT
IN AHEAD OF THIS FRONT, WHICH MAY BE ENHANCED SOME BY A WEST-
NORTHWEST WIND COMPONENT /DOWNSLOPING INTO THE COASTAL PLAIN/. HIGH
TEMPERATURES FOR SATURDAY WERE INCREASED SOME AS A RESULT.

FOR SUNDAY THROUGH TUESDAY...HIGH PRESSURE AT THE SURFACE SHOULD
BUILD IN BRIEFLY FOR SUNDAY AS A FRONT IS STALLED TO OUR SOUTH. AS
ENERGY EJECTS EASTWARD FROM A CLOSED LOW AND ALSO FROM THE MIDWEST,
A COMPLEX SYSTEM SHOULD EVOLVE AND CONSOLIDATE EASTWARD WITH TIME.
WE KEPT SUNDAY DURING THE DAY DRY DUE TO THE PRESENCE OF HIGH
PRESSURE WITH MUCH OF THE LIFT HANGING BACK TO THE SOUTHWEST, THEN
WAA AND MOISTURE ADVECTION BEGINS TO OVERTAKE THE AREA AT NIGHT WITH
THE NORTHWARD MOVEMENT OF A WARM FRONT. THIS MAY ALLOW FOR SOME
SHOWERS TO ARRIVE LATE, ALTHOUGH IT STILL LOOKS LIKE THE MORE
UNSETTLED TIME FRAME IS DURING MONDAY. THE MODEL GUIDANCE APPEARS TO
BE IN BETTER AGREEMENT WITH THE SYNOPTIC SETUP, THEREFORE AN AREA OF
RAIN SHOULD OVERSPREAD THE REGION ON MONDAY. AN AREA OF PW AIR OF
1.0-1.5 INCHES IS FORECAST TO SURGE ACROSS THE CWA, THEREFORE THE
RAIN COULD BE HEAVY AT TIMES. THE FORECAST SOUNDINGS INDICATE
GENERALLY A DEEP SATURATED PROFILE WHICH TENDS TO LIMIT THE
INSTABILITY. THE STEADIEST RAIN TAPERS TO SHOWERS WHICH SHOULD BE
SHIFTING TO OUR NORTHEAST AND EAST MONDAY NIGHT AS A COLD FRONT
ARRIVES.

LOW PRESSURE AND A COLD FRONT SHOULD BE EXITING TO OUR EAST TUESDAY
MORNING, WITH ANY SHOWERS ENDING. AN UPPER-LEVEL TROUGH THOUGH IS
FORECAST TO LINGER FROM THE GREAT LAKES TO THE NORTHEAST, AND WITH A
SURFACE TROUGH POTENTIALLY EXTENDING NEARBY SOME SHOWERS MAY PERSIST
TUESDAY ESPECIALLY ACROSS THE NORTHERN ZONES.

FOR WEDNESDAY...THE PRESENCE OF AN UPPER-LEVEL TROUGH FROM THE
MIDWEST TO NEW ENGLAND WILL MAINTAIN SOME CYCLONIC FLOW ACROSS OUR
AREA. WHILE WEAK HIGH PRESSURE BUILDS TOWARD OUR AREA FROM THE
SOUTHWEST, A COLD FRONT MAY ORGANIZE ACROSS THE GREAT LAKES. WE MAY
HAVE ENOUGH LIFT WITHIN THE CYCLONIC FLOW COMBINED WITH DAYTIME
HEATING TO PROMOTE A FEW SHOWERS MAINLY ACROSS THE NORTH. FOR NOW,
WE WENT WITH MAINLY SOME SLIGHT CHC POPS ACROSS THE NORTHWEST
ZONES.

&&

.AVIATION /14Z THURSDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

VFR CONDITIONS WITH JUST SOME HIGH CLOUDINESS ARE FORECAST FOR
TODAY. AN EAST WIND AT 5 TO 10 KNOTS THIS MORNING IS EXPECTED TO
VEER TO THE SOUTHEAST AND SOUTH DURING THE AFTERNOON. SPEEDS MAY
REACH 10 TO 14 KNOTS FROM THE SOUTH SOUTHEAST AT KILG DUE TO THE
FUNNELING EFFECT UP DELAWARE BAY.

WE ARE EXPECTING CLOUDS TO INCREASE AND LOWER FOR TONIGHT WITH
MAINLY VFR CONDITIONS. LIGHT RAIN SHOWERS ARE FORECAST TO SPREAD
INTO OUR REGION FROM THE WEST AFTER 0400Z. CONDITIONS MAY LOWER INTO
THE MVFR RANGE AROUND KRDG AND KABE AFTER 0800Z. THE WIND IS
ANTICIPATED TO FAVOR THE SOUTH FOR TONIGHT AROUND 5 TO 10 KNOTS.

OUTLOOK...
FRIDAY...MVFR CONDITIONS AT TIMES WITH SOME SHOWERS ESPECIALLY FROM
ABOUT KPHL ON NORTH AND WESTWARD, OTHERWISE VFR.

SATURDAY AND SUNDAY...OVERALL VFR WITH A DRY COLD FRONTAL PASSAGE
DURING SATURDAY. THE CLOUDS SHOULD INCREASE SUNDAY AND THEN LOWER TO
MVFR SUNDAY NIGHT WITH THE ARRIVAL OF OUR NEXT SYSTEM.

MONDAY...MVFR/IFR WITH PERIODS OF RAIN.

&&

.MARINE...
HIGH PRESSURE IS FORECAST TO DROP SOUTHEASTWARD ACROSS NEW ENGLAND
TODAY BEFORE MOVING OUT TO SEA TONIGHT. THE WIND DIRECTION IS
EXPECTED TO VEER FROM NORTH AND NORTHEAST THIS MORNING TO SOUTHEAST
AND SOUTH FOR THIS AFTERNOON AND TONIGHT. WIND SPEEDS AND WAVE
HEIGHTS WILL REMAIN BELOW THE SMALL CRAFT ADVISORY CRITERIA FOR
TODAY AND TONIGHT.

OUTLOOK...
FRIDAY AND SATURDAY...THE CONDITIONS ARE ANTICIPATED TO BE BELOW
SMALL CRAFT ADVISORY CRITERIA AS A COUPLE OF WEAK COLD FRONTS MOVE
THROUGH.

SUNDAY AND MONDAY...THE WINDS MAY BECOME MARGINAL FOR A SMALL CRAFT
ADVISORY LATER SUNDAY NIGHT AND MONDAY, HOWEVER THE SEAS ARE
EXPECTED TO BUILD TO AROUND 5 SUNDAY NIGHT AND MONDAY AS AN ONSHORE
FLOW STRENGTHENS AHEAD OF LOW PRESSURE AND A COLD FRONT.

&&

.FIRE WEATHER...
MINIMUM RELATIVE HUMIDITY VALUES ARE FORECAST TO DROP INTO THE 20 TO
30 PERCENT RANGE IN MUCH OF EASTERN PENNSYLVANIA AND NEW JERSEY
DURING THE AFTERNOON. MINIMUM RELATIVE HUMIDITY VALUES MAY REACH
ONLY THE 30 TO 35 PERCENT RANGE IN MUCH OF DELAWARE AND NORTHEASTERN
MARYLAND. THE 10-HOUR FUEL MOISTURE LEVELS APPEAR TO BE MOSTLY IN
THE 7 TO 13 PERCENT RANGE IN OUR REGION EARLY THIS MORNING AND THEY
SHOULD FALL MAINLY TO LESS THAN 10 PERCENT DURING THE DAY.

WHILE BOTH THE LOW RELATIVE HUMIDITY VALUES AND THE DRY FINE FUELS
PRESENT A FIRE WEATHER CONCERN, SUSTAINED WIND SPEEDS ARE FORECAST
TO REMAIN MOSTLY LESS THAN 12 MPH WITH GUSTS NOT ANTICIPATED TO
REACH MORE THAN 16 OR 18 MPH. AS A RESULT, THE POTENTIAL FOR RAPID
WILDFIRE SPREAD SHOULD BE LIMITED.

&&

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

&&

$$
SYNOPSIS...GORSE
NEAR TERM...AMC/IOVINO
SHORT TERM...IOVINO
LONG TERM...GORSE
AVIATION...GORSE/IOVINO
MARINE...GORSE/IOVINO
FIRE WEATHER...IOVINO


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