Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 250317
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1117 PM EDT FRI APR 24 2015

.SYNOPSIS...
WEAK HIGH PRESSURE COVERS OUR AREA OVERNIGHT. LOW PRESSURE OVER
SOUTHERN ILLINOIS SATURDAY WILL PASS OFF THE NORTH CAROLINA COAST
SUNDAY. THAT LOW BECOMES PART OF LARGE LOW PRESSURE CIRCULATION
OVER THE MARITIMES EARLY NEXT WEEK PRODUCING A BLUSTERY NORTHWEST
FLOW HERE. LOW PRESSURE SYSTEM OVER THE NORTHERN GULF OF MEXICO
TUESDAY NIGHT EMERGES OFF THE SOUTHEASTERN SEABOARD LATE WEDNESDAY
AND THURSDAY.

&&

.NEAR TERM /THROUGH SATURDAY/...
1116 PM EARLY ESTF: A FEW ADJUSTMENT IN TEMP TRENDS THROUGH 17Z
SATURDAY, DOWN A LITTLE QUICKER TONIGHT AND UP A LITTLE FASTER
SATURDAY MORNING. NO CHANGE FROST/FREEZE BUT TEMPS MAY END UP A
COUPLE DEGREES COLDER THAN PREVIOUSLY FCST, ESPECIALLY SOUTHERN
NJ.

AN IMPRESSIVE 175 KT UPPER-LEVEL JET STREAK THAT WAS CAPTURED ON THE
00Z IAD RAOB WILL PROGRESS TOWARD THE MID-ATLANTIC COAST. ANTICIPATE
SOME JET-INDUCED HIGH CLOUDS TO SPREAD INTO THE AREA AT DAWN
SATURDAY, MAINLY SE PA THROUGH PHILADELPHIA AND SOUTHERN NJ
SOUTHWARD WITH RADIATIONAL CONDS CONTINUING ALONG AND N OF I-78
THROUGH SUNRISE.

AREAS OF WIND DECOUPLING ARE OCCURRING NOW AND SHOULD EXPAND
OVERNIGHT TO PERMIT DECENT RADIATIONAL COOLING IN THE COUNTRYSIDE.

SATURDAY...VARIABLE HIGH CLOUDINESS (MOST OF THE THICKER CLOUDS SE
PA/THROUGH S NJ SOUTHWARD) ASSOCIATED WITH THE SFC LOW HEADING
ESE FROM THE OHIO VALLEY. A NICE DAY WITH MUCH LESS WIND THAN THE
PREVIOUS WED- THU- FRIDAY AFTERNOONS. DAYTIMES TEMPS ARE WARMING
AND WHILE STILL BELOW NORMAL, NOT THE 10 DEGREES OR MORE BELOW
NORMAL OF THURSDAY AND FRIDAY. YOU COULD ALMOST SAY THAT A WEAK
WIND SHIFT BOUNDARY WILL BE FORMING JUST TO OUR NORTH LATE IN THE
DAY WITH WESTERLY WINDS GUSTING TO 15 MPH DURING THE AFTERNOON.


&&

.SHORT TERM /SATURDAY NIGHT/...
SATURDAY NIGHT...THICK HIGH CLOUD ALONG AND SOUTH OF I-78, WITH
THE NORTHERN PORTION OF THE RAIN SHIELD SKIRTING MAYBE THE
SOUTHERNMOST 20 MILES OF OUR CWA, MAINLY TALBOT COUNTY MD AND
SUSSEX COUNTY DE. THIS ASSOCIATED WITH THE LOW REDEVELOPING NEAR
THE NC COAST. WILL DETAIL FURTHER BY THE 330 AM SATURDAY FCST. A
WSHIFT FROM LIGHT WEST TO NORTHEAST PROGRESSES FROM NORTH TO SOUTH
DURING THE NIGHT.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
THE LOW PRESSURE WILL THEN EXIT EAST AND OUT TO SEA THROUGH THE
COURSE OF SUNDAY, BUT THERE COULD BE SOME LEFTOVER PRECIP THAT
LINGERS OVER THE DELMARVA INTO SUNDAY MORNING, AND WE GRADUALLY
DIMINISH POPS TO CHANCE AND THEN LOWER THROUGH THIS PERIOD.
ELSEWHERE THROUGH THE FORECAST AREA, A DRY SUNDAY IS ANTICIPATED
WITH SOME CLOUDS AND GENERALLY LIGHT NORTHERLY WINDS.

MONDAY COULD PRESENT A FEW SHOWERS FOR OUR AREA AS AN UPPER
DISTURBANCE/UPPER LOW LINGERS AROUND THE NORTHEAST STATES OR JUST TO
THEIR EAST. MODEL FORECAST SOUNDINGS PREDICT CONVECTIVE TEMPERATURES
TO BE REACHED MONDAY, SO THERE WILL BE INCREASING CLOUDS THROUGH THE
DAY ALONG WITH SOME ISOLATED/SCATTERED SHOWERS EXPECTED AS COOLER
AIR ALOFT ASSOCIATED WITH THE UPPER LOW LINGERS NEARBY.

THE UPPER LOW PULLS AWAY OUT TO SEA INTO TUESDAY, AND WEAK HIGH
PRESSURE FROM THE WEST GRADUALLY BUILDS ACROSS OUR REGION, LASTING
THROUGH THE DAYTIME WEDNESDAY. WE HAVE KEPT A DRY FORECAST THROUGH
THIS PERIOD, WITH RATHER LIGHT NORTHERLY WINDS AND NEAR AVERAGE END
OF APRIL TEMPERATURES. THE TRICKY AND HIGHLY UNCERTAIN PART OF THE
FORECAST THEN INVOLVES THE DEVELOPMENT AND TRACK OF A POTENTIALLY
STRONG COASTAL SYSTEM THAT MAY BEGIN TO AFFECT OUR REGION WEDNESDAY
NIGHT AND LASTING THROUGH THURSDAY TO THURSDAY NIGHT. THERE
CONTINUES TO BE A WIDE RANGE OF SOLUTIONS FROM THE OPERATIONAL
MODELS TO VARIOUS ENSEMBLE DATA REGARDING THE TRACK, EVOLUTION, AND
INTENSIFICATION OF LOW PRESSURE, MOST LIKELY FROM AROUND THE
NORTHERN GULF OF MEXICO REGION WEDNESDAY BEFORE ITS POTENTIAL
EMERGENCE OFF THE EAST COAST THURSDAY. WITH THE GREATER UNCERTAINTY
THROUGH THIS PERIOD, WE LEANED MORE TOWARD WPC GUIDANCE FOR MOST
ELEMENTS, INCLUDING TEMPERATURES, WINDS, AND POPS, WITH ADDITIONAL
COLLABORATION WITH NEIGHBORING OFFICES.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

THROUGH 12Z SATURDAY...VFR CLEAR WITH SCT-BKN CLOUDS AOA 15000 FT
ARRIVING SE PA AND S NJ SOUTHWARD AROUND OR AFTER 09Z. LIGHTNORTH
WIND.

SATURDAY DURING THE DAY...SCT-BKN AOA 15000 FT MAY BRIEFLY THIN
OUR LATE IN THE DAY. LIGHT WEST - NORTHWEST WIND WITH GUSTS TO 15
KT POSSIBLE DURING THE AFTERNOON.

SATURDAY NIGHT...CIGS AOA 10000 FT, ESPECIALLY AFTER 03Z/26. LIGHT
WEST WIND SHIFT NE DURING THE NIGHT AND PLEASE SEE TAFS FOR TIMING
DETAILS AS A WIND SHIFT BOUNDARY SAGS SOUTHWARD.

OUTLOOK...
SATURDAY NIGHT...PRIMARILY VFR CONDITIONS, EXCEPT SOME RAIN AND SUB-
VFR POSSIBLE MAINLY SOUTH OF A KILG/KACY LINE, INCLUDING THE
DELMARVA.

SUNDAY...MAINLY VFR CONDITIONS, AS ANY SUB-VFR IN RAIN TO START
ACROSS SOUTHERN AREAS WILL IMPROVE BACK TO VFR.

MONDAY...MAINLY VFR CONDITIONS; ALTHOUGH, SOME ISOLATED SHOWERS ARE
POSSIBLE. GUSTY NORTH TO NORTHWEST WINDS, WITH GUSTS TO 20 KNOTS.

TUESDAY AND WEDNESDAY...MAINLY VFR EXPECTED; ALTHOUGH, CONDITIONS
MAY DETERIORATE LATE WEDNESDAY NIGHT DEPENDING ON THE TIMING AND
TRACK OF A POSSIBLE COASTAL LOW PRESSURE.

&&

.MARINE...
WINDS HAVE GRADUALLY DIMINISHED OVER THE PAST COUPLE OF HOURS THIS
EVENING. SCA CONDITIONS NO LONGER BEING OBSERVED IN THE DELAWARE
BAY, WHERE THE SCA WAS ALLOWED TO EXPIRE EARLIER. ON THE OCEAN
WATERS, SCA CONDITIONS EXPECTED TO LINGER INTO THE EARLY MORNING
HOURS. SUB-SCA CONDITIONS ARE EXPECTED DURING THE DAY SATURDAY AND
ALSO SATURDAY NIGHT. WINDS SATURDAY NORTHWEST AND THEN LIGHT WEST
WINDS SATURDAY NIGHT SHIFT NE WITH GUSTS TO 15 KT AS A WIND SHIFT
BOUNDARY SAGS SOUTH THROUGH THE WATERS.

OUTLOOK...
SUNDAY...SUB-ADVISORY CONDITIONS ARE EXPECTED AT THIS TIME. AN
AREA OF LOW PRESSURE IS FORECAST TO PASS BY TO OUR SOUTH, BUT IT
SHOULD NOT BE CLOSE ENOUGH TO RAISE WINDS OR SEAS TO SCA LEVELS.

MONDAY...CONTINUED MAINLY SUB-SCA CONDITIONS; ALTHOUGH, SOME WIND
GUSTS TO AROUND 20 KNOTS PLUS ARE POSSIBLE.

TUESDAY AND WEDNESDAY...MOSTLY SUB-ADVISORY CONDITIONS THROUGH THIS
PERIOD; ALTHOUGH, SOME HIGHER WINDS AND SEAS MAY BEGIN TO OCCUR LATE
WEDNESDAY NIGHT DEPENDING ON THE TIMING AND TRACK OF POSSIBLE
COASTAL LOW PRESSURE. LOW CONFIDENCE.

&&

.FIRE WEATHER...
DRY CONDITIONS ARE EXPECTED ONCE AGAIN SATURDAY, WITH MINIMUM RH
VALUES ONCE AGAIN RANGING FROM 20 TO 30 PERCENT. HOWEVER, WINDS
WILL BE CONSIDERABLY LIGHTER TOMORROW, WITH WIND GUSTS GENERALLY
NEAR OR BELOW 15 MPH THROUGH THE DAY TOMORROW.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...FREEZE WARNING FROM 2 AM TO 8 AM EDT SATURDAY FOR PAZ060>062-
     101>106.
     FROST ADVISORY FROM 2 AM TO 8 AM EDT SATURDAY FOR PAZ070-071.
NJ...FREEZE WARNING FROM 2 AM TO 8 AM EDT SATURDAY FOR NJZ001-
     007>010-012-013-015>022-027.
     FROST ADVISORY FROM 2 AM TO 8 AM EDT SATURDAY FOR NJZ014-
     023>026.
DE...FROST ADVISORY FROM 2 AM TO 8 AM EDT SATURDAY FOR DEZ001>004.
MD...FREEZE WARNING FROM 2 AM TO 8 AM EDT SATURDAY FOR MDZ008.
     FROST ADVISORY FROM 2 AM TO 8 AM EDT SATURDAY FOR MDZ012-015-
     019-020.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT SATURDAY FOR ANZ450>455.

&&

$$
SYNOPSIS...KLINE/DRAG 1116
NEAR TERM...DRAG/KLEIN 1116
SHORT TERM...DRAG/JOHNSON 1116
LONG TERM...KLINE
AVIATION...DRAG/JOHNSON/KLEIN/KLINE 1116
MARINE...DRAG/JOHNSON/KLINE 1116
FIRE WEATHER...1116



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