FXUS62 KILM 101412
AFDILM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
912 AM EST THU DEC 10 2009
.SYNOPSIS...
A COLD FRONT WILL MOVE WELL OFFSHORE THIS MORNING. CHILLY HIGH
PRESSURE WILL BUILD INTO THE REGION THROUGH EARLY SATURDAY. A
COLD RAIN MAY DEVELOP LATE SATURDAY INTO SUNDAY AS LOW PRESSURE
FORMS OFFSHORE OF NORTHERN FLORIDA SATURDAY NIGHT AND TRACKS
NORTH ALONG THE CAROLINA COASTAL WATERS. ANOTHER COLD FRONT IS
EXPECTED TO CROSS THE AREA LATE TUESDAY INTO WEDNESDAY OF NEXT
WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 9 AM THURSDAY...COLD FRONT HAS FINALLY MOVED OFFSHORE AND
AIR MASS CHANGE IS QUITE EVIDENT...WITH DEW POINTS HAVING CRASHED
DOWN INTO THE 20S. COLD AIR ADVECTION NOW SETTING UP IN EARNEST
AND TEMPERATURES HAVE ACTUALLY DECREASED OVER THE PAST HOUR...NOW
RANGING FROM THE UPPER 40S INLAND TO THE MID 50S AT THE COAST.
STILL CLOUDY OVER THE FORECAST AREA AS FRONT IS A SLOW
MOVER...UPPER FLOW IS NEARLY PARALLEL TO ORIENTATION OF FRONT SO
PUSH IS NOT STRONG. HOWEVER...HIGH PRESSURE BUILDING IN WILL
FINALLY PUSH FRONT AND ASSOCIATED CLOUDS WELL OFFSHORE LATER
TODAY. WILL LIKELY SEE SUN BREAK OUT THIS AFTERNOON AS THIS
OCCURS. THIS MAY HELP BRING TEMPS BACK UP INTO THE UPPER 50S BUT
IT WILL BE A TOUGH CLIMB AND MAY HAVE TO REVISE THE TEMPERATURE
CURVE FOR TODAY. PATCHY LIGHT RADAR ECHOS ALONG THE COAST SUGGEST
REMNANT SPRINKLES...HOWEVER DP DEPRESSIONS ARE SO WIDE DO NOT
THINK ANYTHING IS REACHING THE GROUND. DRY AND COLD OVERNIGHT WITH
FREEZING TEMPERATURES MOST EVERYWHERE EXCEPT AT THE BEACHES.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...STRONG 1033MB SURFACE HIGH BUILDING OVER THE
REGION AS MID LEVEL FLOW REMAINS ZONAL. FORECAST SOUNDINGS SHOW A
DEEP NEARLY ISOTHERMAL LAYER NEAR FREEZING FROM H700 TO H925MB AND A
MIXED LAYER BELOW. THIS WILL BE COLD ENOUGH TO KEEP HIGHS IN THE
UPPER 40S DESPITE A FAIR AMOUNT OF SUNSHINE. A VERY CHILLY NIGHT ON
TAP FRIDAY NIGHT WITH LOWS IN THE LOW TO MID 20S AS CLOUD COVER
REMAINS MINIMAL. COASTAL TROUGHING BEGINS TO DEVELOP ON
SATURDAY...FAIRLY QUICKLY BY EVENING...AS THE SURFACE COLD WEDGE
HOLDS. CLOUD COVER INCREASES IN THE WARM AIR ADVECTION. TIMING THE
ONSET OF THE RAIN IS TOUGH AS THE ANTECEDENT AIR MASS WILL BE
EXTREMELY DRY. MOST MEASURABLE RAIN LOOKS TO HOLD OFF TIL SATURDAY
EVENING OVER SOUTHERN ZONES AND PROBABLY SATURDAY NIGHT ELSEWHERE.
THIS SLOWER TIMING SHOULD PRECLUDE ANY P-TYPE ISSUES THAT A FASTER
SOLUTION WOULD IMPLY WERE THE PRECIP TO ARRIVE SATURDAY MORNING.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 3 AM THURSDAY...TEMPS RETURN TO MILD IN BROAD MID LEVEL WSW
FLOW. RAIN SHOULD WIND DOWN FAIRLY QUICKLY AS OFFSHORE WAVE MOVES
AWAY TO THE NORTHEAST ALTHOUGH SOME TIMING DIFFERENCES STILL EVIDENT
IN GUIDANCE. MONDAY THROUGH TUESDAY WILL BRING A CONTINUATION OF
SLIGHTLY WARM WEATHER AS NORTHERN AND SOUTHERN BRANCH FEATURES
ATTEMPT TO PHASE IN THE PLAINS MONDAY NIGHT. THESE FEATURES WILL
DRIVE A COLD FRONT THROUGH THE REGION ON TUESDAY. WITH A LITTLE
MOISTURE FLUX AHEAD OF THE BOUNDARY RAIN CHANCES SEEM FAIR. WHETHER
OR NOT THE TWO FEATURES PHASE WILL DETERMINE HOW MUCH OF THE ARCTIC
AIR BEHIND THE BOUNDARY IS DRIVEN INTO THE SOUTHEASTERN U.S.
&&
.AVIATION /14Z THURSDAY THROUGH MONDAY/...
AS OF 12Z...TERMINALS ARE VFR AND EXPECTED TO REMAIN VFR THROUGHOUT
THE TAF PERIOD.
AN UPPER TROUGH IS SLOWLY PROGRESSING TO THE EAST. SPRINKLES NEAR
THE COASTAL TERMINALS AT TAF ISSUANCE TIME WILL QUICKLY DISSIPATE.
THE MAIN AREA OF PRECIPITATION JUST EAST OF THE COASTAL TERMINALS
WILL CONTINUE TO MOVE FURTHER OFFSHORE THROUGH THE MORNING HOURS AS
THE UPPER TROUGH SLIDES EAST. MID-LEVEL CEILINGS...MAINLY AT THE
COASTAL TERMINALS WILL BECOME SCATTERED BY MID MORNING AS DRIER
AIR BUILDS IN...AND BY AFTERNOON...JUST SCATTERED TO BROKEN HIGH
LEVEL CIRRUS IS EXPECTED.
WEST TO WEST NORTHWEST WINDS WILL GUST TO 20-25 KNOTS THIS MORNING.
BY AFTERNOON WIND GUSTS WILL DECREASE TO 15-20 KNOTS...THEN BY
LATE AFTERNOON WILL DECREASE TO 4 TO 7 KNOTS AS A LOW LEVEL
INVERSION SETS UP. OVERNIGHT CLEAR SKIES AND LIGHT NORTHWEST WINDS
EXPECTED AT ALL TERMINALS. ATTM DO NOT EXPECT FOG DEVELOPMENT DUE TO
SURFACE WIND SPEEDS.
EXTENDED OUTLOOK...CHANCE IFR SATURDAY NIGHT INTO SUNDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 9 AM THURSDAY...GUSTY WINDS WILL KEEP SMALL CRAFT ADVISORY
IN EFFECT UNTIL NOON. AS WINDS ARE OFFSHORE SEAS WILL BE LIMITED
TO AROUND 4 OR 5 FT TODAY AND THAT WILL BE FOUND WELL OFFSHORE.
STRONG COLD FRONT HAS ONLY RECENTLY MOVED ACROSS THE WATERS AND A
COLD SURGE IS NOW IN PROGRESS. EXPECT THIS WILL KEEP WINDS IN THE
20 KT RANGE TODAY...AND BETWEEN 15 AND 20 OVERNIGHT.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...A LIGHT NORTHERLY GRADIENT WIND TO START THE
PERIOD AS STRONG HIGH PRESSURE BUILDS IN FROM THE WEST. NEAR SHORE
SEAS USUALLY VERY SMALL IN SUCH A FLOW REGIME BUT COULD STILL RUN UP
TO 4 FT TOWARDS OUTSIDE EDGE OF FCST AREA. AS THE DAY WEARS ON
HOWEVER THE GRADIENT WILL SLACKEN SIGNIFICANTLY AND THE SEAS WILL
FOLLOW SUIT...FALLING TO AROUND 2 FT. A COASTAL TROUGH WILL DEVELOP
WELL TO THE SOUTH EARLY SATURDAY AND THEN STRENGTHEN CONSIDERABLY
SATURDAY AFTERNOON AND EVENING. THE VEER TO NORTHEAST WILL BE
ACCOMPANIED BY AN INCREASE IN SPEEDS. THIS WILL MEAN NOT TO MUCH OF
A CHANGE IN WAVE HEIGHT THROUGH MIDDAY SATURDAY. WAVES THEN BUILD
SATURDAY AFTERNOON AND QUITE STRONGLY IN THE EVENING AND
OVERNIGHT...REACHING INTO THE SMALL CRAFT ADVISORY REALM.
LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 3 AM THURSDAY...WEAK EXITING STORM SYSTEM BRINGING
NORTHEASTERLY WINDS THAT WILL DECREASE AS THE LOW PULLS AWAY. THE
LONG TERM WILL THUS INITIALIZE WITH SMALL CRAFT ADVISORY BUT THE
FLAG WILL BE ABLE TO BE LOWERED SUNDAY OR SUNDAY NIGHT AS BOTH
WIND AND WAVES SUBSIDE...THE FORMER MORE QUICKLY THAN THE LATTER.
PRESSURE GRADIENT TURNS PRETTY WEAK MONDAY ESPECIALLY BY DECEMBER
STANDARDS.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL NOON EST TODAY FOR AMZ250-252-254-
256.
&&
$$
SYNOPSIS...REK
NEAR TERM...REK
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...MRR
MARINE...ALL
