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Area Forecast Discussion
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000
FXUS61 KPHI 251037
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
637 AM EDT SAT OCT 25 2014

.SYNOPSIS...
A COLD FRONT OVER THE MIDWEST THIS MORNING WILL MOVE EASTWARD TODAY 
AND THROUGH THE AREA TONIGHT. THE MID-ATLANTIC REGION WILL BE 
SITUATED BETWEEN LOW PRESSURE OVER EASTERN CANADA AND HIGH PRESSURE 
BUILDING IN FROM THE TENNESSEE VALLEY ON SUNDAY. HIGH PRESSURE RIDGES 
INTO THE AREA SUNDAY NIGHT AND MONDAY. A WARM FRONT WILL LIFT NORTH 
OF THE AREA TUESDAY BEFORE A COLD FRONT MOVES THROUGH LATE 
WEDNESDAY. HIGH PRESSURE BRIEFLY RETURNS THURSDAY. LOW PRESSURE MAY 
DEVELOP OVER THE EASTERN UNITED STATES FRIDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HAD TO ADJUST THE HOURLY TEMPERATURES DOWN QUITE A BIT AS MOST
POINTS NOW HAVE COMPLETELY LOST THEIR WINDS AND RADIATED PRETTY
WELL. UPSTREAM OBSERVATIONS INDICATE THAT THE SURFACE RIDGE AXIS
IS JUST TO OUR WEST AT THIS HOUR AND WILL BE MOVING OVERHEAD BY LATE
THIS MORNING. LIGHT AND VARIABLE FLOW WILL BECOME MORE WESTERLY BY
THE AFTERNOON WITH A TIGHTENING SURFACE PRESSURE GRADIENT. AMPLE
SUNSHINE WILL ALLOW FOR DECENT VERTICAL MIXING TODAY, THOUGH NOT
AS STRONG AS IN PAST DAYS...GUSTS UPWARDS OF 20 MPH ARE POSSIBLE
THIS AFTERNOON. A DECK OF STRATOCU IS POSSIBLE BUT GIVEN THE LACK
OF MOISTURE AND JUST REACHING CONVECTIVE TEMPERATURES NOT
EXPECTING ANYTHING WIDESPREAD OR THICK.

TEMPERATURES LOOK TO HAVE ANOTHER CHANCE TO CLIP 70F ACROSS THE 
SOUTHERN HALF OF THE CWA. THE WESTERLY DOWNSLOPING WINDS AND 925MB 
TEMPERATURES CLIMBING TO AROUND 12C WILL MAKE THIS POSSIBLE. WENT A 
COUPLE DEGREES ABOVE GUIDANCE FOR TODAY GIVEN THE ABOVE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
GUSTS SHOULD DROP OFF BY LATER THIS EVENING AND WINDS BACK TOWARDS 
THE SOUTHWEST JUST A BIT AHEAD OF AN APPROACHING WEAK COLD FRONT. 
THE FRONT SHOULD BLAST THROUGH THE REGION BY SUNDAY MORNING WITH JUST 
A FEW PASSING CLOUDS EXPECTED. THE COLUMN WILL REMAIN DRY ENOUGH AND 
THERE IS NOT MUCH FORCING ASSOCIATED WITH THE FRONT OVER OUR REGION, 
SO WE KEEP IT DRY. GOOD COLD AIR ADVECTION ALOFT WILL ALLOW FOR 
BETTER MIXING TONIGHT AND COUPLED WITH THE TIGHTER PRESSURE GRADIENT 
WE KEEP STRONGER WESTERLY WINDS THROUGH THE OVERNIGHT HOURS. WITH 
THAT BEING SAID, USED THE WARMER MAV GUIDANCE FOR LOWS TONIGHT.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
A VERTICALLY-STACKED LOW WILL BE POSITIONED OVER EASTERN CANADA 
WHILE HIGH PRESSURE IS CENTERED JUST WEST OF THE CENTRAL 
APPALACHIANS. A TIGHT PRESSURE GRADIENT BETWEEN THESE TWO SYSTEMS 
WILL RESIDE OVER THE MID-ATLANTIC REGION, THUS SUNDAY WILL BE A 
BREEZY DAY. 00Z NAM/GFS BUFKIT SOUNDINGS SHOW THE POTENTIAL FOR 
FREQUENT GUSTS 25 TO 30 MPH WITH OCCASIONALLY HIGHER GUSTS TO 35 
MPH. POST-FRONTAL CAA EXPECTED TO BE TRANSIENT, BECOMING NEUTRAL 
DURING THE AFTERNOON. THEREFORE, TEMPS SHOULD BE ABLE TO REACH CLIMO 
(MID 60S) IN MOST PLACES. 

THE PRESSURE GRADIENT WILL WEAKEN SUNDAY NIGHT AS THE LOW LIFTS INTO 
THE CANADIAN MARITIME WHILE HIGH PRESSURE BUILDS TOWARD THE MIDDLE 
ATLANTIC. STILL NOT CERTAIN ON FULL DECOUPLING, SO WENT CONSERVATIVE 
WITH MIN TEMPS IN THE MID/UPPER 30S NORTHEAST PA/NORTHWEST NJ AND 
LOW/MID 40S FROM I-95 EAST. 

HIGH PRESSURE SHIFTS OFF THE SOUTHEAST COAST EARLY IN THE WEEK. 
SOUTH-SOUTHWEST RETURN FLOW AROUND THE HIGH ON LATE MONDAY WILL 
STRENGTHEN TUESDAY AS A WARM FRONT ADVANCES NORTHWARD THRU THE 
REGION AND A COLD FRONT APPROACHES FROM THE MIDWEST STATES. TUESDAY 
AND WEDNESDAY LOOKS TO BE THE WARMEST DAYS OF THE PERIOD (MAX TEMPS 
NEAR 70F) WITH THE WARM SECTOR ESTABLISHED IN THE REGION.

LOW PRESSURE WILL CUT WELL TO OUR NORTHWEST AS IT TRACKS FROM THE 
GREAT LAKES TOWARD HUDSON BAY MIDWEEK. THE ATTENDANT COLD FRONT WILL 
PROGRESS INTO THE AREA DURING THIS TIME. DIFFERENCES IN TIMING OF 
FROPA HAVE NARROWED WITH THE LATEST MODEL GUIDANCE. THE COLD FRONT 
WILL MOST LIKELY MOVE THRU WEDNESDAY AFTERNOON INTO WEDNESDAY EVE. 
SHOWERS ARE POSSIBLE WITH THE FRONT. WENT SLIGHTLY HIGHER WITH POPS 
THAN PREVIOUS FORECAST BUT STILL LIMITED TO AROUND 30 PERCENT WITH 
LIMIT MOISTURE/LIFT ALONG THE FRONT.

DRY CONDITIONS AND SEASONABLE TEMPS EXPECTED BEHIND THE FRONT 
THURSDAY WITH WEAK HIGH PRESSURE BUILDING IN FROM THE TN VALLEY. 

THE DETAILS FOR THE END OF THE WEEK STILL NEED TO BE DETERMINED BUT 
MODELS SIGNALING TOWARD THE AMPLIFICATION OF A LONGWAVE TROUGH OVER
THE EASTERN CONUS ON FRIDAY. INCREASING CLOUDS ARE LIKELY WITH
PERHAPS SHOWERS RETURNING TO OUR AREA.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, 
KMIV, KACY AND SURROUNDING AREAS.

NO CHANGE WITH THE 12Z TAFS, ADDED AN EXTRA GROUP FOR PHL TO BRING
IN THE STRONG NORTHWEST GUSTS SUNDAY MORNING.

TODAY - TONIGHT...VFR. WESTERLY WINDS GUSTING TO 20 KNOTS THIS 
AFTERNOON DECREASE THIS EVENING. WINDS BACK TOWARDS THE SOUTHWEST 
AHEAD OF APPROACHING DRY COLD FRONT. WINDS VEER TO THE WEST AGAIN 
BEHIND THE FRONT. HIGH CONFIDENCE.

OUTLOOK...
SUNDAY...VFR. BREEZY W-NW WINDS 15-20 KT WILL GUST UP TO 30 KT. 

SUNDAY NIGHT THROUGH TUESDAY NIGHT...VFR. LIGHT NW WINDS GENERALLY 
AOB 10 KT THRU MONDAY, BECOMING SLY TUESDAY.

WEDNESDAY AND WEDNESDAY NIGHT...GENERALLY VFR ALTHOUGH A BRIEF 
PERIOD OF MVFR AND SHRA POSSIBLE WITH COLD FROPA.

&&

.MARINE...
TODAY...SUB-SCA EXPECTED. GUSTS ACROSS OUR SOUTHERN WATERS MAY COME 
CLOSE TO SCA THIS MORNING BUT DROP OFF THROUGH THE DAY. SEAS WILL 
REMAIN 3 TO 4 FEET AND DECREASE BY THIS EVENING. HIGH CONFIDENCE.

TONIGHT...SCA CONDITIONS EXPECTED, POSSIBLE BRIEF GALES RIGHT BEHIND 
COLD FRONT PASSAGE...MAINLY SOUTHERN WATERS. WESTERLY WINDS INCREASE 
TO 20 TO 25 KNOTS LATER TONIGHT AS A COLD FRONT MOVES THROUGH THE 
WATERS. THERE IS A LOW-END CHANCE OF A FEW GALE GUSTS BUT NOT 
CONFIDENT...HIGH END SCA GUSTS EXPECTED. HIGH CONFIDENCE ON SCA, LOW 
ON GALES.

OUTLOOK...
SUNDAY AND SUNDAY NIGHT...HIGH END SCA SUNDAY WITH W-NW GUSTING TO 
30 KT. STILL CANNOT RULE OUT THE POSSIBILITY FOR GALES BUT SETUP NOT 
PARTICULARLY FAVORABLE FOR DEEP MIXING AS CAA ALOFT CEASES RATHER 
QUICKLY IN THE MORNING. SCA EXTENDED INTO SUNDAY EVE FOR THE WATERS, 
ENDING SOUTH TO NORTH OVERNIGHT FOR THE COASTAL ATLANTIC ZONES AS 
THE PRESSURE GRADIENT GRADUALLY WEAKENS. 

MONDAY AND MONDAY NIGHT...LIGHT WINDS AND CALM SEAS.

TUESDAY AND WEDNESDAY...SOUTHWEST WINDS INCREASE AHEAD OF A COLD 
FRONT. HAVE CAPPED GUSTS AT 20 KT OWING TO STABLE MIXING PROFILES.

&&

.FIRE WEATHER...
BREEZY AND DRY CONDITIONS EXPECTED ON SUNDAY BEHIND A COLD FRONT. 
SUSTAINED NW WINDS NEAR 20 MPH ARE EXPECTED. 00Z NAM/GFS BUFKIT 
SOUNDINGS SHOW THE POTENTIAL FOR FREQUENT GUSTS OF 25 TO 30 MPH WITH 
OCCASIONALLY HIGHER GUSTS TO 35 MPH. THE POST-FRONTAL CAA PATTERN IS 
BRIEF, BECOMING NEUTRAL DURING THE AFTERNOON. CURRENT FORECAST 
REFLECTS MIN RHS SUNDAY AFTERNOON IN THE LOW TO MID 30S EVEN AFTER 
LEANING TOWARD A DRIER (I.E., LOWER DEWPOINTS) SOLUTION WITH 
DOWNSLOPING W-NW FLOW OFF THE HIGHER TERRAIN. ADDITIONALLY, HEATING 
MAY BE LIMITED SOMEWHAT BY STRATOCU OFF THE GREAT LAKES, ESPECIALLY 
OVER THE NORTHWEST HALF OF THE CWA WHICH MAY PREVENT RHS FROM 
FALLING CRITICAL THRESHOLDS. AN ENHANCED THREAT FOR THE SPREAD OF 
WILDFIRES MAY EXIST ON SUNDAY WITH THE ABOVE METEOROLOGICAL FACTORS 
AND WITH FORECAST FUEL MOISTURE BELOW 10 PERCENT BUT CONFIDENCE NOT 
NEARLY HIGH ENOUGH TO ISSUE A FIRE WEATHER WATCH.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 2 AM EDT MONDAY 
     FOR ANZ452>455.
     SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 AM EDT MONDAY 
     FOR ANZ450-451.
     SMALL CRAFT ADVISORY FROM 8 AM TO 9 PM EDT SUNDAY FOR ANZ430-
     431.

&&

$$
SYNOPSIS...KLEIN
NEAR TERM...HEAVENER
SHORT TERM...HEAVENER
LONG TERM...KLEIN
AVIATION...HEAVENER/KLEIN
MARINE...HEAVENER/KLEIN
FIRE WEATHER...






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