FXUS62 KILM 250038
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
738 PM EST THU DEC 24 2009

.SYNOPSIS...
LOW PRESSURE WILL DEVELOP OVER THE DEEP SOUTH TONIGHT...AND BRING
WARMER TEMPERATURES AND SOAKING RAINS AS IT LIFTS NORTHEAST ACROSS
THE CAROLINAS FRIDAY AND FRIDAY NIGHT. HIGH PRESSURE WILL BUILD
FROM THE NORTHWEST BEGINNING SATURDAY...WITH COLD TEMPERATURES
RETURNING SUNDAY THROUGH WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 3 PM THURSDAY...HIGH PRESSURE CONTINUES TO NOSE DOWN INTO
THE AREA ALTHOUGH PRESSURES HAVE STABILIZED AND MODELS ARE
ADVERTISING PRESSURES TO FALL FROM THIS POINT ON. THE LOWER
TROPOSPHERE REMAINS MOISTURE CHALLENGED VIA VISIBLE SATELLITE
LOOPS AND SURFACE OBSERVATIONS SHOWING DEWPOINTS IN THE LOWER 30S
AND EVEN A SMALL AREA OF UPPER 20S IN OUR NORTHEASTERN COUNTIES.
WITH THIS TREND AND CONSIDERING THE MODELS HAVE BEEN TRENDING
SLOWER WITH THE PROGRESSION OF THE COLD FRONT ASSOCIATED WITH THE
POWERFUL CYCLONE ACROSS THE CENTRAL UNITED STATES...HAVE
DRAMATICALLY SCALED BACK POPS AND CLOUD COVER FOR THE FIRST 12
HOURS OF THE NEAR TERM. THE LONG ADVERTISED COASTAL TROUGH HAS YET
TO MATERIALIZE AND CONSIDERING THE MOISTURE PROFILES...THE MAIN
FRONT WHICH IS SLATED TO ARRIVE LATER FRIDAY WILL...MOST LIKELY BE
THE FORCING MECHANISM FOR MEASURABLE RAIN. OVERNIGHT LOWS WILL
CHALLENGING AND WILL BE AT THE MERCY OF LOW LEVEL WARM ADVECTION
WHICH WILL COINCIDE WITH THE INCREASE IN CLOUD COVER. OVERALL THE
COOLER MAV NUMBERS SEEM THE BEST BET...REACHED EARLY WITH WARMING
TEMPERATURES AFTER 0800/0900 UTC.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
AS OF 3 PM THURSDAY...MAIN CHALLENGE WILL BE THE QUESTION OF
SEVERE WEATHER AS LOW PRESSURE MOVES OUT OF THE DEEP SOUTH AND
CROSSES THE CAROLINAS ON AN INLAND TRACK ON FRIDAY. THIS WILL BE
A VERY DYNAMIC STORM SYSTEM WITH DIFLUENCE ALOFT...AND STRONG LOW-
LEVEL JETTING WITH 850MB WINDS PROGGED TO INCREASE TO 55-60
KT...PROVIDING STRONG DEEP-LAYER DIRECTIONAL AND SPEED SHEAR. SPC
DAY 2 OUTLOOK HAS THE ILM CWA AT THE NORTHERN END OF A SLIGHT RISK
AREA. BIGGEST NEGATIVE FOR SEVERE WEATHER IS THE LACK OF
INSTABILITY...AS CAPE IS NEGLIGIBLE AND LIFTED INDICES BARELY GO
NEGATIVE IF AT ALL. FOR NOW WILL JUST MENTION THE SLIGHT RISK IN
THE HWO...AS I BELIEVE THAT EVEN THUNDER WILL BE DIFFICULT TO COME
BY.

MINOR TIMING DIFFERENCES BETWEEN THE MODELS RAISE AN INTERESTING
QUESTION OF HOW DEEP INTO FRI EVENING POPS WILL NEED TO BE
CARRIED. GFS HAS THE LOW-LEVEL JET EXITING TO THE NORTHEAST BY
00Z...WHILE THE NAM IS A FEW HOURS SLOWER. FOR NOW WILL TAPER FRI
EVENING POPS FROM HIGH CHANCE ALONG THE NC COAST TO SLIGHT CHANCE
IN THE WESTERN ZONES...ROUGHLY SPLITTING THE DIFFERENCE. HOWEVER
WE DID LEAN TOWARD THE WARMER NAM MOS GUIDANCE FOR MIN TEMPS AS
THE GFS SEEMS A BIT TOO BULLISH WITH THE COLD AIR.  

COLD ADVECTION HOLDS OFF FOR MOST OF SATURDAY...SO EXPECT QUITE A
MILD DAY WITH TEMPS GETTING INTO THE 60S ACROSS MUCH OF THE ILM
CWA. CHILLIER AIR MASS FINALLY STARTS TO GET IN HERE SAT NIGHT
WITH TEMPS BACK TO THE LOW SIDE OF CLIMO...BASICALLY SPLITTING THE
DIFFERENCE BETWEEN MOS GUIDANCE NUMBERS.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 3 PM THURSDAY...DEEP-LAYER CYCLONE WILL PIVOT TOWARDS THE SRN 
GREAT LAKES REGION ON SUNDAY...THEN OPEN UP AND LIFT OUT BEGINNING 
SUNDAY NIGHT. GFS AND TO A LESSER EXTENT THE ECMWF ARE SUGGESTING 
SOME GULF MOISTURE WILL BE PICKED UP IN SW FLOW AND STREAM OVER THE 
EASTERN CAROLINAS SUNDAY/SUNDAY NIGHT. 24/12Z MEX GUIDANCE HAS 
RAMPED UP POPS SIGNIFICANTLY OVER PREVIOUS RUNS DURING THIS TIME 
FRAME...SO THINK AT LEAST A LOW CHANCE POP IS WARRANTED AT THIS TIME.

SHORTWAVE WILL PUSH OFF THE COAST MONDAY AFTERNOON...AND COLD HIGH 
PRESSURE WILL BUILD IN THROUGH MIDWEEK. MODELS AGREE IN THE 
DEVELOPMENT OF A COASTAL TROUGH WEDNESDAY...WITH A SURFACE LOW 
EITHER RIDING UP FROM THE GULF OR DEVELOPING OFF THE SC COAST BY 
THURSDAY. EITHER SCENARIO WILL LEAD TO INCREASED CHANCE FOR A RAIN 
EVENT LATE IN THE WEEK.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
AS OF 00Z...BIG CHANGES COMING. CLEAR...CRISP DAYS LEAVE AS HIGH 
PRESSURE WEDGE RECEDES AND ANOTHER STRONG LOW PRESSURE MOVES THROUGH 
THE EASTERN HALF OF THE US. THIS TIME THE LOW MOVES UP THE WEST SIDE 
OF THE APPALACHIAN MOUNTAINS...CURRENTLY MOVING THROUGH ARKANSAS. 
THE ASSOCIATED FRONTS WILL AFFECT THE TERMINALS WITH INCREASED 
CLOUDINESS...RAIN AND BREEZY EASTERLY WINDS.

VFR FOR ALL TERMINALS TO START. SC TAF SITES BECOME MVFR BY 04Z WITH 
CEILING BELOW 3000 FEET. LBT/ILM FOLLOW SUIT BY 08Z. AS THE WARM 
FRONT APPROACHES...RAIN BEGINS BY 10Z AT FLO AND SLOWLY ENGULFS THE 
TERMINAL AREA WITH CEILINGS LOWERING TO 2000 FEET AND VISIBILITY 
DROPS TO MVFR RANGE. FLO/LBT IFR WITH CEILINGS BY 14Z. CONFIDENCE 
DROPS LATE IN THE PERIOD AS TO WHEN WARM FRONT MOVES THROUGH THE 
TERMINAL AREA...AROUND 20Z. SHOWERS WILL THEN MOVE INTO THE AREA 
WITH THE POSSIBILITY OF A THUNDERSTORM...NOT ENOUGH CONFIDENCE TO 
ADD TO TAFS WITH HIGH SHEAR BUT LOW CAPE...WILL ADDRESS IN NEXT SET. 
WIND CONTINUES GUSTY THROUGH THE PERIOD FROM THE EAST 10 TO 20 KNOTS 
WITH GUSTS TO 25 KNOTS. WIND VEERS MORE SOUTHERLY AND LESS BREEZY 
LATE IN THE PERIOD.

EXTENDED OUTLOOK...MEDIUM CONFIDENCE FOR DRY AIR TO QUICKLY REPLACE 
MOIST AIR MASS FOR VFR SATURDAY. SUNDAY A DIFFERENT STORY WITH MOIST 
AIR BACK BRINGING POSSIBLE IFR CONDITIONS...AND BACK TO VFR MONDAY
AND TUESDAY.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 PM THURSDAY...WINDS AND SEAS CONTINUE ON THE UPTREND THIS 
AFTERNOON WITH 41013 REPORTING 21 KNOTS THE PAST COUPLE OF HOURS AND 
SEAS UP TO ALMOST SIX FEET. 41110 IS ECLIPSING FIVE FEET AS WELL. 
WINDS WILL CONTINUE IN A RANGE OF 20-25 KNOTS FOR THE OVERNIGHT 
HOURS AND VEER TO THE EAST AND FINALLY SOUTHEAST BY MORNING AS THE 
WEDGE BREAKS. SWAN INITIALIZED THE SEAS ALMOST PERFECT AND SEE NO 
REASON TO DEVIATE FROM THESE VALUES THROUGH THE NEAR TERM. BY EARLY 
FRIDAY MORNING WE SHOULD SEE A SOLID 6-8 FEET IN THE COASTAL ZONES 
WITH SOME 10 FOOTERS POSSIBLE FOR 41013. SMALL CRAFT CONDITIONS 
CONTINUE FOR ALL WATERS.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 PM THURSDAY...MAIN CHALLENGE IS HOW STRONG THE WINDS WILL
GET ON FRIDAY WITH THE LOW-LEVEL JET TRANSLATING ACROSS THE
WATERS. WINDS AT 850MB WILL CRANK UP TO 55-60 KT FRI
AFTERNOON...BUT STABILITY WILL LIMIT SFC WINDS TO A SOLID 25 KT. A
FEW GALE FORCE GUSTS WILL BE QUITE LIKELY...BUT NOT WITH THE
PERSISTENCE OR FREQUENCY TO MERIT A WARNING. THESE WINDS WILL BE
ENOUGH TO DEVELOP SEAS AS HIGH AS 8-10 FT AWAY FROM SHORE. THIS IS
SLIGHTLY UNDER THE SWAN OUTPUT...WHICH SEEMS TO DEVELOP SEAS TOO
FAST EVEN IN THIS ONSHORE FLOW REGIME.

BY FRI EVENING THE LOW-LEVEL JET SHIFTS NORTH AND EAST OF THE
WATERS...ALLOWING WINDS TO VEER TO WESTERLY AND DIMINISH
SUBSTANTIALLY. OFFSHORE TRAJECTORY WILL KNOCK SEAS DOWN FAIRLY
QUICKLY. EXPECT TO FALL BELOW SCA THRESHOLDS SOMETIME AFTER
MIDNIGHT...BUT WILL KEEP STATUS QUO WITH THE ADVISORY GOING THRU
6AM SAT.  

BENIGN W-NW WINDS AND SUBSIDING SEAS EXPECTED SAT AND SAT NIGHT AS
HIGH PRESSURE AND AN INITIALLY MILD AIR MASS SPREAD IN. 

LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 3 PM THURSDAY...WEAK SURFACE HIGH IS EXPECTED TO BE OVER SE GA 
EARLY SUNDAY WITH A RATHER WEAK GRADIENT OVER THE CAROLINA COASTAL 
WATERS. RESULT WILL BE NW FLOW 10 KT...PERHAPS BECOMING VARIABLE 
LATE SUNDAY AS THE HIGH FADES. STRONGER HIGH PRESSURE WILL BUILD IN 
FROM THE WEST BEGINNING SUNDAY NIGHT. NW FLOW WILL INCREASE TO 
AROUND 20 KT BY EARLY MONDAY...THEN DIMINISH AND BECOME MORE 
NORTHERLY BY TUESDAY AFTN AS THE HIGH CENTER SHIFTS TOWARD THE 
MID-ATLANTIC REGION.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST SATURDAY FOR AMZ250-252-
     254-256.

&&

$$
NEAR TERM...SHK
SHORT TERM...RAS
LONG TERM...CRM
AVIATION...MDC