Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 281659
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1259 PM EDT TUE OCT 28 2014

.SYNOPSIS...
HIGH PRESSURE WILL MOVE FARTHER OFFSHORE THIS AFTERNOON. A COLD
FRONT APPROACHES THE AREA OVERNIGHT AND MOVES THROUGH WEDNESDAY.
HIGH PRESSURE WILL BRIEFLY BUILD IN FOR THURSDAY BEFORE AN AREA OF
LOW PRESSURE MOVES OUT OF THE GREAT LAKES REGION AND COMBINES WITH
A DEVELOPING COASTAL LOW OFFSHORE OF THE MID ATLANTIC. HIGH
PRESSURE RETURNS FOR THE END OF THE WEEKEND AND EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THICKER CIRRUS THIS MORNING HAS SLOWED THE MIXING AND RISE IN
TEMPERATURES IN PA AND NJ. MEANWHILE LOWER DELMARVA ALREADY IN THE
LOWER 70S. UPSTREAM CIRRUS DOES NOT LOOK AS THICK AND MODELS
SOUNDINGS ARE FORECASTING LESS MOISTURE. SO WE ARE KEEPING
TEMPERATURES CLOSE TO MAX TEMP PROJECTIONS, JUST MAKING IT LATER IN
THE AFTERNOON. IN DELMARVA, WITH LESS CIRRUS ISSUES TEMPERATURES
ARE ALREADY IN THE LOWER 70S WITH PLENTY OF LOWER TO MID 70S IN
PLACES FARTHER SOUTHWEST. HERE WE ARE FEELING MORE CONFIDENT ABOUT
MAX TEMPS. OTHER THAN ADJUSTMENTS ALREADY MADE TO SKY GRIDS, NO
OTHER BIG CHANGES TO WIND OR DEW POINT FORECASTS.

HIGH PRESSURE HAS MOVED OFF THE SOUTHEAST AND MID-ATLANTIC COAST
EARLY THIS MORNING. MEANWHILE, A SFC LOW WAS LOCATED OVER EXTREME
NORTHEAST LAKE SUPERIOR WITH A COLD FRONT EXTENDING
SOUTHWESTWARD ACROSS THE MIDWEST AND SOUTHERN PLAINS.

THERE ISN`T MUCH EVIDENCE OF A WARM FRONT EAST OF THE APPALACHIANS
ON THE LATEST SFC ANALYSIS DESPITE THE SIGNIFICANT WAA ALOFT. HIGH
CLOUDS AROUND THE PERIPHERY OF THE RIDGE STREAMING IN FROM THE
WEST ARE EXPECTED TO THIN OUT OVER THE MID-ATLANTIC REGION LATER
THIS MORNING AS THE BULK OF THE UPPER-LEVEL MOISTURE SHIFTS
DOWNSTREAM INTO THE NORTHEAST.

AHEAD OF THE MIDWEST COLD FRONT, THE CORE OF THE WARM SECTOR WILL
BECOME ESTABLISHED OVER MID-ATLANTIC STATES THIS AFTERNOON. MAJORITY
OF MODEL GUIDANCE SHOWS 925 MB AND 850 MB TEMPS FOR PHL INCREASING
TO AROUND 21C AND 17C RESPECTIVELY, WHICH IS A +2 SD OCCURRENCE FOR
LATE OCTOBER. ASSUMING FULL MIXING DOWN FROM THE 925 MB WARM NOSE,
TEMPS WOULD REACH THE LOWER TO MID 80S. MAX TEMP FORECAST IS NOT
QUITE THAT WARM (SINCE FULL MIXING NOT EXPECTED OWING TO THE LOW SUN
ANGLE) BUT IS SEVERAL DEGREES ABOVE STAT GUIDANCE. FORECAST HIGHS IN
LOW 80S IN THE DELMARVA AND MID TO UPPER 70S ELSEWHERE MATCHES UP
WELL WITH UPSTREAM OBSERVATIONS YESTERDAY IN THE MIDWEST.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
LOW PRESSURE WILL CONTINUE TO LIFT NORTH OF THE GREAT LAKES TONIGHT
AND TOWARDS JAMES BAY. THE COLD FRONT WITH THIS SYSTEM IS EXPECTED
TO CROSS THE APPALACHIANS THIS EVENING AND SHOULD BE ON THE FRONT
DOOR STEP OF OUR FAR WESTERN ZONES IN EASTERN PA BY DAYBREAK. THE
TREND OF RECENT GUIDANCE WAS TO SLOW DOWN THE PROGRESSION OF THE
FRONT EVER SO SLIGHTLY. FOLLOWED THIS TREND WITH POPS OVERNIGHT,
KEEPING ANY MENTION OF SHOWERS WEST OF THE FALL LINE. POPS FOLLOW
CLOSE SUITE TO THE 21Z/03Z SREF RUNS.

WENT ABOVE MOS GUIDANCE FOR MIN TEMP AS SOUTHWESTERLY FLOW IN
PRE-FRONTAL WARM SECTOR AND INCREASING CLOUD COVER LATE SHOULD LIMIT
RADIATIONAL COOLING.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
A COLD FRONT WILL BE MOVING INTO THE AREA AT THE BEGINNING OF THE
DAY WEDNESDAY AND PROGRESS ITS WAY THROUGH THE AREA DURING THE DAY
AND INTO THE EVENING. POPS WILL INCREASE FROM WEST TO EAST THROUGH
THE DAY AS THE FRONT MOVES THROUGH. MODEL GUIDANCE IS IN PRETTY GOOD
AGREEMENT WITH THE PRECIP OCCURRING MOSTLY FROM LATE MORNING THROUGH
THE AFTERNOON HOURS. THERE IS SOME DIFFERENCES IN QPF AMOUNTS, BUT
OVERALL DOES NOT LOOK LIKE A SIGNIFICANT AMOUNT OF RAIN, GENERALLY
ONE-TENTH TO ONE-QUARTER OF AN INCH OR LESS. THE FRONT MOVES
OFFSHORE BY LATE IN THE DAY, AND THE MAIN SHORT WAVE MOVES THROUGH
OVERNIGHT. PRECIP CHANCES WILL DIMINISH FROM WEST TO EAST THROUGH
THE LATE AFTERNOON AND EVENING, AND SHOULD BE ALL OUT OF THE AREA BY
OR SHORTLY AFTER MIDNIGHT.

HIGH PRESSURE IS EXPECTED TO BRIEFLY AFFECT THE AREA THURSDAY INTO
THURSDAY NIGHT. DRY WEATHER AND NEAR NORMAL TEMPERATURES ARE
EXPECTED BEFORE A CHANGE FOR THE UPCOMING WEEKEND.

ON FRIDAY, AND AREA OF LOW PRESSURE WILL BE MOVING OUT OF THE GREAT
LAKES REGION, AND APPROACHING THE AREA, WHILE A COASTAL LOW DEVELOPS
AND STRENGTHENS TO OUR SOUTHEAST. WE DO NOT EXPECT ANY PRECIPITATION
DURING THE DAY AS THE PRECIPITATION TIED TO THE APPROACHING LOW TO
THE NORTHWEST SHOULD STILL BE TO OUR NORTHWEST. HOWEVER, AS WE GO
INTO FRIDAY NIGHT, THE LOW TO THE NORTHWEST IS EXPECTED TO BEGIN
GETTING ABSORBED BY THE COASTAL LOW. AT THE SAME TIME, THE MID/UPPER
TROUGH WILL BE DIVING SOUTHWARD INTO THE AREA AS WELL AND WILL
ALLOW PRECIPITATION TO FILL IN ACROSS THE AREA. THE MID/UPPER TROUGH
WILL SLOWLY SWING ACROSS THE AREA THROUGH SATURDAY, SO THERE COULD
STILL BE SHOWERS ACROSS THE AREA THROUGH THE DAY SATURDAY. THERE IS
SOME COLD AIR ASSOCIATED WITH THE MID/UPPER TROUGH SWINGING ACROSS
THE AREA WITH SUB-ZERO 925/850MB TEMPERATURES LATE FRIDAY NIGHT
THROUGH SATURDAY INTO SATURDAY NIGHT. THERE IS THE POTENTIAL FOR
SOME SNOW TO MIX WITH RAIN, OR EVEN A COMPLETE CHANCE OVER ACROSS
THE HIGHER ELEVATIONS.

WINDS WILL ALSO INCREASE SATURDAY INTO SATURDAY NIGHT AS THE PRESSURE
GRADIENT TIGHTENS SIGNIFICANTLY BETWEEN THE COASTAL LOW AND HIGH
PRESSURE TO THE WEST. THERE IS THE POTENTIAL FOR WINDS TO APPROACH
ADVISORY LEVELS, ESPECIALLY FOR COASTAL AREAS, SO WE WILL KEEP A
MENTION IN THE HWO.

IMPROVING CONDITIONS ARE EXPECTED FOR SUNDAY INTO MONDAY AS HIGH
PRESSURE IS EXPECTED TO BUILD INTO THE REGION FROM THE WEST. THE 00Z
ECMWF IS SLOWER TO MOVE THE COASTAL LOW TO THE NORTHWEST, WHICH
WOULD KEEP THE STRONGER WINDS SLOW TO SUBSIDE AND A CHANCE OF
PRECIP FOR NORTHEASTERN AREAS. HOWEVER, THE THOUGHT IS THIS MAY BE
TO SLOW, SO WE WEAKEN WINDS AND KEEP THE FORECAST DRY SUNDAY
THROUGH MONDAY, ALTHOUGH IT MAY STILL BE A BIT BREEZY.

&&

.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

18Z TAFS VFR THRU THIS EVENING, UNCERTAIN ABOUT MVFR/IFR
CONDITIONS TOWARD WEDNESDAY MORNING AND A CHANCE OF SHOWERS LATER
WEDNESDAY. WE ADDED LLWS FOR KABE AND KRDG.

FOR THIS AFTERNOON VFR CIRRUS WITH SOUTH TO SOUTHWEST WINDS
AVERAGING CLOSE TO 10 KNOTS. A SLIGHT BACKING OF THE WIND DIRECTION
TOWARD EVENING.

THIS EVENING INTO THE OVERNIGHT. CONTINUED MAINLY CIRRUS BASED VFR
CIGS. VERY LIGHT WINDS FROM THE SOUTH IF NOT CALM. A LOW LEVEL JET
IS PREDICTED TO PASS ACROSS OUR NORTHWEST TERMINALS AND AIRPORTS.
SINCE THE COMBINATION OF MOST LIKELY CALM WINDS AND LOCATION OF
THE LLJ, WE DID ADD A LLWS PERIOD AT KABE AND KRDG AND WILL
MONITOR FOR THE REST OF THE TERMINALS.

LATE TONIGHT WE DID BRING MOST TERMINALS DOWN TO MVFR CONDITIONS
MAINLY DUE TO FOG AND ALSO SOME STRATUS AND STRATOCU AND SOME OF
THE MORE INLAND TERMINALS. CONFIDENCE THOUGH IS NOT HIGH AS IT
DEPENDS UPON HOW THICK THE CIRRUS WILL BE.

ON WEDNESDAY MORNING, VFR CONDITIONS PREDICTED TO RETURN AS A COLD
FRONT STARTS MOVING THROUGH THE AREA. WINDS ARE FORECAST TO BECOME
WEST. SHOWERS ARE POSSIBLE AT THE MORE INLAND TERMINALS WITH THEM
POSSIBLY REACHING THE INTERSTATE 95 CORRIDOR AIRPORTS BY THE END
OF THE TAF FCST PERIOD. WITH THE 30HR TAF AT KPHL WE DO SHOW A
WINDOW OF MAINLY VFR SHOWERS DURING THE AFTERNOON.


OUTLOOK...
WEDNESDAY NIGHT-FRIDAY...MOSTLY VFR.

FRIDAY NIGHT-SATURDAY...GENERALLY VFR, WITH MVFR CONDITIONS
POSSIBLE WITH SHOWERS. SNOW SHOWERS POSSIBLE ACROSS NORTHEAST
PENNSYLVANIA AND NORTHWEST NEW JERSEY. STRONG, GUSTY WINDS
SATURDAY INTO SATURDAY NIGHT.

&&

.MARINE...
SWLY WINDS WILL STRENGTHEN TODAY TO 10-20 KT. THE GRADIENT TIGHTENS
A BIT MORE TONIGHT. WARM AIR ATOP THE COOLER OCEAN WATERS DO NOT
PROVIDE A PARTICULARLY FAVORABLE MIXING SETUP BUT OCCASIONAL GUSTS
TO 25 KT ARE POSSIBLE OVER THE COASTAL WATERS LATE. USING WAVEWATCH
GUIDANCE, SEAS WILL INCREASE TO 4-5 FT OVERNIGHT. A SCA WAS ISSUED
FOR THE ATLANTIC ZONES STARTING AT MIDNIGHT TONIGHT.

OUTLOOK...
WEDNESDAY...SMALL CRAFT REMAINS IN EFFECT THROUGH MIDDAY
WEDNESDAY, THEN SEAS ARE EXPECTED TO SUBSIDE.

WEDNESDAY NIGHT-FRIDAY...SUB-SMALL CRAFT ADVISORY CONDITIONS EXPECTED.

FRIDAY NIGHT-SATURDAY...INCREASING WINDS OVERNIGHT INTO SATURDAY
AND SATURDAY NIGHT AS A COASTAL LOW STRENGTHENS. AT LEAST SMALL
CRAFT CONDITIONS EXPECTED, WITH GALE FORCE WINDS POSSIBLE.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT
     WEDNESDAY FOR ANZ450>455.

&&

$$
SYNOPSIS...ROBERTSON
NEAR TERM...GIGI/KLEIN
SHORT TERM...KLEIN
LONG TERM...ROBERTSON
AVIATION...GIGI/ROBERTSON
MARINE...KLEIN/ROBERTSON






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