FXUS62 KILM 271722
AFDILM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
1222 PM EST FRI NOV 27 2009
.SYNOPSIS...
GUSTY NORTHWEST WINDS WILL USHER IN PLENTY OF DRY AND COLD AIR
AS HIGH PRESSURE BUILDS IN BEHIND COLD FRONT THROUGH TODAY.
DAYTIME WINDS WILL EASE BY SATURDAY AS A DEEP SURFACE LOW OVER NEW
ENGLAND PULLS FARTHER AWAY. TEMPERATURES WILL REBOUND SUNDAY AND
MONDAY AS HIGH PRESSURE PASSES OVERHEAD AND SETTLES OFFSHORE. THE
NEXT CHANCE FOR RAIN WILL BE LATE MONDAY INTO EARLY TUESDAY...AS A
COLD FRONT DROPS SOUTHEAST ACROSS THE AREA. HIGH PRESSURE MAY
BUILD IN BRIEFLY TUESDAY AFTERNOON BEFORE ANOTHER STORM SYSTEM
MOVES INTO THE AREA FROM THE GULF COAST BY WEDNESDAY INTO
THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 10 AM FRIDAY...FOR THE MOST PART JUST AWAITING MOS GUIDANCE TO
SEE IF ANY ADJUSTMENTS TO TEMPS TONIGHT REQUIRED. ETA MOS IS IN AND
APPEARS TO BE WITHIN A DEGREE OF ALL FORECAST POINTS AT THIS TIME. A
GOOD SIGN. WILL WAIT AND SEE IF 12Z GFS MOS CONTINUES THE COOLING
TREND SEEN IN THE 06Z RUN BUT DOUBT ANY BIG CHANGES TO THE CURRENT
FORECAST ARE ON THE HORIZON. IF NOT...THEN NO CHANGES TO THE FREEZE
WARNING ANTICIPATED. -MBB
AS OF 330 AM FRIDAY...FREEZE WARNING IS IN EFFECT FOR ALL COUNTIES
WITH THE EXCEPTION OF THE IMMEDIATE 5 COASTAL COUNTIES.
THE AREA REMAINS UNDER THE INFLUENCE OF CYCLONIC FLOW SFC THRU
ALOFT...AS A NEGATIVELY TILTED UPPER TROF ACROSS THE AREA CLOSES
OFF AND IS THEN PROGGED BY THE MODELS TO LIFT SLOWLY ENE THROUGH
TONIGHT. WITH WNW FLOW SFC THROUGH ALOFT...ANY LEFTOVER MOISTURE
AT ANY LEVEL WILL BE SCOURED OUT DUE TO THE UNIFORM DOWNSLOPE
TRAJECTORY IN THE WIND FIELD. THIS WILL RESULT IN A SUNNY DAY WITH
LIKELY NO CLOUDS TO OBSERVE OTHER THAN THE CU/SC OVER THE OFFSHORE
ATLANTIC WATERS DUE TO THE COLD AIR ADVECTION OVER THE WARMER
SSTS. MAX TEMPS TODAY WILL BE RATHER UNIFORM 50S DEGREE READINGS
ACROSS THE AREA DUE TO THE STRONG CAA. THE TIGHTENED SFC PG WILL
RELAX SOME TONIGHT...ESPECIALLY INLAND AND SW PORTIONS OF THE ILM
CWA DUE TO THE APPROACH OF THE UPPER RIDGE AND GULF COAST HIGH.
HOWEVER...AT THIS POINT NOT STRONG ENOUGH FOR WINDS TO TOTALLY
DECOUPLE. AS A RESULT...HAVE KEPT WINDS AT A MINIMUM OF 5 MPH.
THIS IS EXTREMELY IMPORTANT TO OVERNIGHT LOWS SINCE ALL OTHER
PARAMETERS FAVOR AN EXCELLENT NIGHT FOR RADIATIONAL COOLING.
THINKING IS THE NIGHT-TIME WILL REMAIN MIXED ENOUGH TO PRECLUDE
THAT FROM OCCURRING. OTHERWISE...THE FREEZE WARNING WOULD HAVE
INCLUDED THE COASTAL COUNTIES. WITH DEWPOINTS PROGGED BASICALLY IN
THE 20S...EXCEPT THE IMMEDIATE COAST...THE FREEZE WARNING INSTEAD
OF A FROST ADVISORY WAS CHOSEN. IF CONDITIONS CHANGE FOR THE
COASTAL COUNTIES...IE SFC BASED INVERSION TO DEVELOP AND BECOME
MUCH STRONGER THAN MODELS DICTATE RESULTING IN SFC WINDS
DECOUPLING...THEN A FROST ADV/FREEZE WARN MAY BE NEEDED FOR THE
COAST.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...HIGH PRESSURE WILL MIGRATE EASTWARD THROUGH THE
SHORT TERM PERIOD. LATEST MODEL RUNS CONTINUE TO SHOW A SHORTWAVE
RIDING THROUGH THE SOUTHEAST WITH A BROADER RIDGE OVER THE EAST
COAST. WITH PLENTY OF DRY AIR IN PLACE...EXPECT NOTHING MORE THAN A
FEW CLOUDS POSSIBLE OVERNIGHT SAT INTO EARLY SUN. THIS MAY AFFECT
THE POTENTIAL FOR THE TEMPS TO DROP AS MUCH AS THEY COULD UNDER
CLEAR SKIES...BUT EXPECT TEMPS IN THE 30S ONCE AGAIN OVERNIGHT SAT.
WARMING TREND WILL BEGIN ON SUN AS HIGH PRESSURE SLIPS OFF SHORE AND
RETURN FLOW SETS UP THROUGH SUNDAY. THIS WILL HELP TO BRING WARMER
AND MOISTER AIR BACK INTO THE AREA. PCP WATER VALUES WILL INCREASE
UP ABOVE A HALF INCH BY SUN AFTN...BUT NOT EXPECTING ANY PCP UNTIL
AFTER THE SHORT TERM PERIOD. OVERALL SHOULD SEE PLENTY OF SUNSHINE
AND WITH AIR MASS MODERATING EXPECT AFTN HIGHS IN THE UPPER 60S AND
OVERNIGHT LOWS SUN NIGHT INTO EARLY MONDAY TO BE SLIGHTLY
WARMER...IN THE 40S WITH LOWER VALUES IN
TRADITIONALLY COOLER PLACES
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 3 AM FRIDAY...HIGH PRESSURE CONTINUES TO SLIP FARTHER OFF
SHORE ON MONDAY AS NEXT STORM SYSTEM APPROACHES FROM THE WEST.
SHOULD SQUEEZE OUT ANOTHER DRY WARM DAY ON MONDAY IN AN INCREASING
SW RETURN FLOW. LOW LEVELS REMAIN VERY DRY AS WINDS HAVE STRONG
WESTERLY COMPONENT TO THEM. TEMPS SHOULD REACH UP NEAR 70. SHOULD
JUST SEE INCREASING HIGH CLOUDS INITIALLY BUT PCP SHOULD HOLD OUT
UNTIL LATER ON MON. BEST CHC OF PCP WILL COME MON NIGHT INTO EARLY
TUES. COLD FRONT SHOULD CLEAR THE COAST TUES WITH HIGH PRESSURE
BUILDING IN BEHIND IT ON TUES. THE FRONT SHOULD GET FAR ENOUGH SOUTH
THAT WE MAY SEE CLEARING BY AFTN ON TUES. A COOLER AIR MASS WILL BE
IN PLACE WITH TEMPS DOWN 5 TO 10 DEGREES FROM THE DAY BEFORE. BOTH
GFS AND ECMWF NOW SHOW BRIEF HIGH PRESSURE BUILDING IN ON TUES...BUT
A LOW PRESSURE SYSTEM MOVES UP FROM THE GULF COAST ON WED BRINGING
PCP BACK INTO THE FORECAST FOR WED. COULD TURN OUT TO BE A DECENT
QPF EVENT ON WED BEFORE LOW TRACKS OFF TO THE NORTHEAST ON THURS
WITH HIGH PRESSURE BUILDING IN BEHIND IT LATE THURS INTO FRI.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
STRONG GRADIENT BETWEEN HIGH PRESSURE OVER THE DEEP SOUTH AND A DEEP
LOW PRESSURE OVER NEW ENGLAND WILL BRING GUSTY WEST NORTHWEST WIND
TO ALL TAF SITES FOR THE NEAR TERM. BY 00Z...WIND DIMINISHES BUT
REMAINS STEADY OUT OF THE WEST AT 6 TO 12 KNOTS. SHOULD
MENTION...VFR AND CLEAR SKIES UNDER THE INFLUENCE OF HIGH PRESSURE.
THE DRY COLUMN AND WIND MIXING DOWN WILL INHIBIT FOG FORMATION.
EXTENDED OUTLOOK...NEXT CHANCE FOR LESS THAN VFR IS MONDAY
AFTERNOON AS COLD FRONT MOVES THROUGH THE AREA.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 10 AM FRIDAY...PERFECT PROGGING THE 12Z WRF IMPLIES THAT NO
CHANGES TO CURRENT FLAGS OR THE FORECAST AS A WHOLE FOR THAT MATTER
WILL BE NEEDED. AN ABATING WIND OVER SOUTHERN ZONES WILL BE UNDERWAY
02Z-06Z WITH THIS TREND SPREADING NORTH BY 12Z. THE OFFSHORE FETCH
HAS OPENED QUITE A RANGE IN NEARSHORE VS OFFSHORE WAVE HEIGHT WITH
THE LARGEST SEAS CONFINED TO THE OUTER REACHES OF THE FORECAST AREA.
AS SUCH AS SOON AS THE WIND WINDS DOWN AT THE TIMES JUST MENTIONED
THE SEAS TOO WILL DROP...THAT IS...THERE WILL NOT BE THE LAG IN
DIMINISHING SEAS THAT WOULD HAVE BEEN EXPERIENCED WITH A STRONG
ONSHORE FLOW. -MBB
AS OF 330 AM FRIDAY...SMALL CRAFT ADVISORY TO CONTINUE ACROSS ALL
WATERS INTO TONIGHT. RATHER LARGE AMPLITUDE NEGATIVELY TILT UPPER
TROF ACROSS EAST COAST THIS MORNING TO CLOSE OFF ACROSS NEW ENGLAND
AND LIFT SLOWLY ENE. INTENSIFIED SFC LOW IS PROGGED OFF NEW ENGLAND
WITH ITS EXPANSIVE CIRCULATION TO EXTEND ACROSS THE AREA
WATERS...AND IN COMBO WITH THE APPROACH OF THE SFC HIGH FROM THE
GULF COAST STATES. THIS WILL RESULT IN A TIGHTENED SFC PG ACROSS THE
AREA THIS MORNING THAT WILL CONTINUE WELL INTO TONIGHT. CYCLONIC
CIRCULATION THRU THE ATMOSPHERE WILL RESULT IN GUSTY WEST TO
NORTHWEST WINDS AND A LOCALLY PRODUCED RANGE OF VERY SHORT PERIOD
WIND DRIVEN SEAS DUE TO THE OFFSHORE TRAJECTORY IN THE WINDS FIELD.
DIMINISHING AND SUBSIDING TRENDS WILL OCCUR TONIGHT FIRST ACROSS THE
SOUTHERNMOST WATERS BEFORE FINALLY REACHING THE NORTHERNMOST WATERS
LATE. THIS A RESULT OF THE UPPER TROF/CLOSED LOW LIFTING TO THE ENE
AND THE AREA BECOMING UNDER THE ANTICYCLONIC INFLUENCES OF THE
APPROACH OF THE GULF COAST SFC HIGH AND EVENTUAL UPPER RIDGE. THE
NAM WAS THE MODEL OF CHOICE FOR WIND USAGE...WITH TWEAKS OF
ADDITIONAL MPH ADDED DUE TO OBSERVATIONS AND TRENDS OVER THE WATERS
DURING AND AFTER THE CFP. WAVEWATCH3 PREFERRED OVER LOCALLY PRODUCED
SWAN DUE 2 ITS HIGHER SEAS OUTPUT INITIALLY EVENTHOUGH GFS WAS NOT
ILLUSTRATING THE HIGHER WIND FIELD LOCALLY.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...AS HIGH PRESSURE MIGRATES EASTWARD THROUGH
SAT...GRADIENT WILL WEAKEN AND CAA WILL SHUT OFF AND THEREFORE WINDS
AND SEAS WILL DIMINISH. SEAS SHOULD DROP BELOW 3 FT BY SAT AFTN AND
WILL ONLY INCREASE SLIGHTLY STARTING SUN AFTN AS HIGH PRESSURE SLIPS
OFF SHORE AND RETURN FLOW SETS UP. SW WINDS WILL INCREASE UP TO 10
TO 15 KTS OVERNIGHT SUN INTO EARLY MON AND THEREFORE SEAS WILL
INCREASE UP TO 2 TO 4 FT.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 3 AM FRIDAY...HIGH PRESSURE WILL SHIFT FARTHER OFF SHORE AS
STORM SYSTEM APPROACHES FROM THE WEST. WINDS WILL INCREASE UP TO 15
TO 20 KTS BY MON AFTN IN THIS TIGHTENED GRADIENT FLOW. SEAS JUST
STARTING TO RISE BY LATE SUN AND THEN INCREASING THROUGH MON WITH
TIGHTENED GRADIENT FLOW AHEAD OF APPROACHING FRONTAL SYSTEM. SHOULD
REACH JUST NEAR SCA CRITERIA IN OUTER WATERS MON NIGHT BEFORE FROPA
HEADING INTO TUES MORNING. THE OFF SHORE FLOW BEHIND FRONT SHOULD
ALLOW SEAS TO DECREASE ESPECIALLY NEAR SHORE THROUGH TUES.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...FREEZE WARNING FROM 1 AM TO 8 AM EST SATURDAY FOR SCZ017-023-
024-032-033-039.
NC...FREEZE WARNING FROM 1 AM TO 8 AM EST SATURDAY FOR NCZ087-096-
099.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST SATURDAY FOR AMZ252-254-
256.
SMALL CRAFT ADVISORY UNTIL 7 AM EST SATURDAY FOR AMZ250.
&&
$$
SYNOPSIS...RGZ
NEAR TERM...DCH
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...MDC
