FXUS62 KILM 060805
AFDILM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
305 AM EST SUN DEC 6 2009
.SYNOPSIS...
SUNNY AND COOL WEATHER IS ANTICIPATED TODAY AS HIGH PRESSURE PASSES
ACROSS THE AREA. A WEAK COASTAL TROUGH WILL DEVELOP SUNDAY NIGHT
INTO MONDAY...SPREADING CLOUDS INTO THE EASTERN CAROLINAS...AND
PERHAPS A FEW SHOWERS INTO THE COASTAL AREAS. DEEPENING LOW
PRESSURE TRACKING NORTH AND WEST OF THE REGION TUESDAY AND
WEDNESDAY...WILL HELP PUSH A COLD FRONT ACROSS THE EASTERN
CAROLINAS LATE WEDNESDAY. COOL AND DRY CONDITIONS ARE EXPECTED
LATE IN THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM SUNDAY...COLD ADVECTION BEHIND A STORM SYSTEM DEPARTING
THE EAST COAST WILL END LATER THIS MORNING AS THE LOW-LEVEL FLOW
SWINGS FROM NORTHWEST TO NORTHEAST. HIGH PRESSURE WILL BUILD INTO
VIRGINIA AND NORTHERN NORTH CAROLINA DURING THE AFTERNOON. DRY AIR
WILL CONTINUE AT THE LOW LEVELS...BUT CIRRUS WILL INCREASE FROM THE
WEST WELL IN ADVANCE OF A WEAK SHORTWAVE EXPECTED TO CROSS THE AREA
LATE TONIGHT.
SATELLITE THIS MORNING SHOWS A HUGE AREA OF STRATOCUMULUS OVER THE
OCEAN. THESE CLOUDS ARE INDICATIVE OF STRONG LATENT AND SENSIBLE
HEAT FLUX FROM THE OCEAN TO THE ATMOSPHERE. THIS DESTABILIZATION...
COUPLED WITH THE PASSAGE OF THE WEAK UPPER TROUGH LATE TONIGHT WILL
RESULT IN THE DEVELOPMENT OF A COASTAL TROUGH JUST OFF THE GA/SC
COASTLINE. ISENTROPIC ANALYSIS OF MODEL DATA ON THE 290K-295K
SURFACES /4000-6000 FT AGL/ SHOWS THICKENING LOW CLOUDS OVER MUCH OF
THE AREA AND SUFFICIENT DEPTH OF MOISTURE & LIFT FOR SPRINKLES OR
LIGHT RAIN LATE. THE BEST CHANCE FOR MEASURABLE RAIN SHOULD BE ALONG
THE COAST BUT EVEN HERE WE ARE ONLY GOING WITH A 20% POP.
HIGHS TODAY WILL REMAIN QUITE CHILLY EVEN WITH PLENTY OF SUNSHINE.
WE ARE EXPECTING LOWER 50S IN MOST AREAS...ALONG WITH THE COOLER END
OF MOS GUIDANCE. LOWS WILL OCCUR THIS EVENING WHILE RADIATIONAL
COOLING IS STILL FAIR TO GOOD. WE ARE EXPECTING MID TO UPPER
30S...COOLEST IN THE CAPE FEAR AREA AND WEST OF I-95. HOURLY
TEMPERATURE CURVES WILL FLATTEN OUT OVERNIGHT AND MAY EVEN RISE
TOWARD MORNING ALONG THE COAST WITH INCREASING CLOUDS AND LOW-LEVEL
WARM ADVECTION.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY/...
AS OF 3 AM SUNDAY...VERY PROGRESSIVE PATTERN WILL CONTINUE THROUGH
THE PERIOD. COASTAL TROF WILL SHARPEN ON MONDAY AS THE SFC HIGH
MOVES OFF THE DELMARVA COAST. ONSHORE FLOW IS VERY SHALLOW WITH
RESPECTABLE SW FLOW ABOVE IT...SO THIS FEATURE WILL HAVE A HARD
TIME BRINGING MUCH PRECIP ONSHORE BEFORE IT IS CARRIED OFF TO THE
EAST-NORTHEAST MONDAY EVENING. HAVE INCLUDED LOW CHANCE POPS ALONG
THE COAST FOR MONDAY...WITH SLIGHT CHANCES LINGERING INTO THE
EVENING FOR COASTAL NC COUNTIES.
HIGH PRESSURE WILL NOSE IN FROM THE NORTHWEST BRIEFLY MONDAY NIGHT
AND TUESDAY BEFORE THE NEXT SYSTEM REARS ITS HEAD TUE AFTERNOON.
GULF MOISTURE FEED STARTS TO DEVELOP AHEAD OF DEEPENING LOW
PRESSURE...AND WILL BE SUFFICIENT TO SPREAD LOW CHANCES FOR PRECIP
INTO THE WESTERN PORTION OF THE ILM CWA. HOWEVER AM INCLINED TO
THINK THAT EVEN THESE SMALL POPS ARE A BIT ON THE GENEROUS
SIDE...WITH THE MORE SUBSTANTIAL PRECIP ACCOMPANYING THE WARM
FRONT TUE NIGHT.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 3 AM SUNDAY...PRECIP IS A PRETTY GOOD BET ON TUESDAY NIGHT
AS A WARM FRONT LIFTS NORTH ACROSS THE CAROLINAS AHEAD OF
DEEPENING LOW PRESSURE THAT WILL MOVE INTO THE OHIO VALLEY.
WEDNESDAY POPS ARE STARTING TO LOOK A BIT IFFY NOW AS IT APPEARS A
DRY SLOT WILL COME INTO PLAY IN THE WARM SECTOR. WILL KEEP HIGH
CHANCE OR LOW LIKELY POPS...AND CARRY THE MENTION OF THUNDER AS
THIS SYSTEM WILL BE DYNAMIC ENOUGH THAT ONLY MINIMAL INSTABILITY
WILL BE NECESSARY. WEDNESDAY NIGHT IS A POTENTIAL BUST AS IT IS
UNCERTAIN HOW CLEANLY THE COLD FRONT GETS THROUGH. COULD HANG UP
CLOSE ENOUGH TO WARRANT KEEPING SLIGHT CHANCE POPS. BETWEEN A
BREEZY NIGHT AND COLD ADVECTION THAT HANGS BACK... EXPECT THE
UNSEASONABLY MILD CONDITIONS TO CONTINUE INTO EARLY THU.
MINIMAL RISE IN TEMPS ON THURSDAY IN THE POST-FRONTAL NW FLOW.
COOL AND DRY HIGH PRESSURE WILL FOLLOW...BUT IT IS PROGRESSIVE
ENOUGH THAT SATURDAY COULD SEE YET ANOTHER COASTAL TROF.
&&
.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
AS OF 06Z...HIGH PRESSURE BUILDING ACROSS THE REGION EARLY THIS
MORNING WILL DRY OUT THE ATMOSPHERIC COLUMN AND CREATE GENERALLY VFR
CONDITIONS AT ALL TERMINALS. GUSTY NW WINDS WILL EASE AS THE
GRADIENT RELAXES AND TURN TO THE NE LATER TODAY AS THE HIGH SLIDES
UP TO THE NORTH.
STRATUS /BASES 1700-2200 FT AGL/ IS DEVELOPING ALONG THE LEADING
EDGE OF A COLD SURGE THIS MORNING...AND THIS IS DEPICTED WELL ON
11U-3.9U MICRON SATELLITE. MODELS HAVE NOT DEVELOPED THIS FEATURE
WELL...SO HAVE MOSTLY USED UPSTREAM OBS AND SATELLITE INTERPRETATION
TO TIME MVFR CIGS AT THE TERMINALS. THE LOWEST CIGS ARE OCCURRING
ALONG THE NOSE OF THIS SURGE...AND SKC HAS DEVELOPED BEHIND IT.
EXPECT THE COASTAL TERMINALS TO GO TO SKC IN THE NEXT FEW HOURS AND
REMAIN SO UNTIL SOME HIGH LEVEL CI STARTS TO FILTER IN TOMORROW.
EVEN WITH CLEARING SKIES AROUND DAYBREAK DO NOT EXPECT ANY FOG
DEVELOPMENT AS WINDS WILL STAY ELEVATED ENOUGH TO CONTINUE MIXING.
AS THE HIGH PRESSURE MOVES OFF TO THE NORTH LATER TODAY WINDS WILL
VEER TO THE NE AND BE AROUND 10 KT AT ALL TERMINALS. INTERESTING
FEATURE TONIGHT AS A WEAK TROUGH TRIES TO DEVELOP AND MOVE ONSHORE.
WITH SOME ENHANCED CONVERGENCE ALONG THIS FEATURE COULD SEE SOME LOW
CLOUDS AND SHOWERS DEVELOPING MONDAY AT ILM/MYR/CRE. SINCE THIS IS
BEYOND THE END OF THIS TAF PERIOD HAVE JUST INTRODUCED SOME BKN 4K
FOOT CIGS TO REFLECT THIS POTENTIAL...AND WILL LET FUTURE TAFS
ADDRESS THIS MORE COMPLETELY.
EXTENDED OUTLOOK...POSSIBLE IFR CIGS AND MVFR VSBYS MONDAY IN
SCATTERED SHOWERS. MORE IFR POSSIBLE TUESDAY NIGHT AND WEDNESDAY
WITH RAIN.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM SUNDAY...STRONG LOW PRESSURE IS MOVING OUT INTO THE OPEN
ATLANTIC OFF THE NEW ENGLAND COAST. BLUSTERY NORTH WINDS EARLY THIS
MORNING WILL TURN NORTHEASTERLY AND DIMINISH THIS AFTERNOON AS HIGH
PRESSURE BUILDS INTO VIRGINIA AND NORTHERN NORTH CAROLINA. A COASTAL
TROUGH IS EXPECTED TO DEVELOP TONIGHT ALONG THE GEORGIA AND SOUTH
CAROLINA COAST. NORTHEAST WINDS WILL CONTINUE FOR OUR FORECAST
AREA...WITH THE PRIMARY IMPACT FROM THE TROUGH BEING AN INCREASE IN
CLOUDS AND RAIN CHANCES LATE.
BUOYS AT 3 AM ARE SHOWING SEAS HAVE DIMINISHED BELOW 6 FT AND WINDS
HAVE FALLEN TO 20 KNOTS OR LESS WITHIN 20 MILES OF SHORE. THE SMALL
CRAFT ADVISORY IS NO LONGER NEEDED. SEAS SHOULD REMAIN GENERALLY 4
FT OR LESS THROUGH TONIGHT.
SHORT TERM /MONDAY THROUGH TUESDAY/...
AS OF 3 AM SUNDAY...FOR THE MOST PART EXPECT NORTH OR NORTHEAST
FLOW THROUGH THE PERIOD. MAIN SOURCE OF UNCERTAINTY ON MONDAY IS A
COASTAL TROF...WHICH WILL EDGE VERY CLOSE TO SHORE IN THE
AFTERNOON. COULD SEE A PERIOD OF EAST OR SOUTHEAST...OR EVEN
VARIABLE WINDS IN THE NC WATERS THAT WILL BE CLOSEST TO THE TROF.
NORTHERLY GRADIENT IS REINFORCED MONDAY NIGHT AS HIGH PRESSURE
NOSES IN FROM THE NW AND PUSHES THE COASTAL TROF OUT OF THE
PICTURE. WILL SEE WINDS GENERALLY FROM THE NE AROUND 15 KT HEADING
INTO TUESDAY...WITH PERHAPS A SLIGHT VEERING LATE IN THE DAY AS
THE WARM FRONT TAKES SHAPE TO OUR SOUTH AND WEST. SEAS GENERALLY
2-3 FT THRU THE PERIOD.
LONG TERM /TUESDAY NIGHT THROUGH THURSDAY/...
AS OF 3 AM SUNDAY...EXPECT DETERIORATING CONDITIONS TUE NIGHT AND
WED AS A COMPLEX STORM SYSTEM AFFECTS THE CAROLINAS. INCREASING
EAST WINDS TUESDAY EVENING WILL VEER TO SW OVERNIGHT AS A WARM
FRONT LIFTS NORTH ACROSS THE AREA. LOW-LEVEL JET WILL INCREASE TO
50-55 KT WHICH WILL BE ENOUGH TO GET SOLID SCA WINDS FOR SEVERAL
HOURS LATE TUESDAY NIGHT AND WEDNESDAY MORNING. SOUTHWESTERLY
TRAJECTORY WILL PROVIDE A FAIRLY PERSISTENT AND LONG
FETCH...ALLOWING SEAS TO BUILD TO 6-8 FT BY WED AFTERNOON OVER ALL
BUT THE NEARSHORE WATERS...AND UP TO 10 FT FARTHER OUT ALONG
FRYING PAN SHOALS.
LOW-LEVEL JET IS SHUNTED OFFSHORE BY WEDNESDAY EVENING...BUT WITH
STRONG LOW PRESSURE TO OUR NORTH AND THE HIGH STILL DIVING FOR THE
LOWER MISSISSIPPI VALLEY...WINDS WILL REMAIN FAIRLY FRISKY OUT OF
THE WEST. THUS SEAS WILL NOT SUBSIDE BELOW ADVISORY THRESHOLDS
UNTIL THURSDAY MORNING ALONG FRYING PAN SHOALS...BUT 2-4 FT
ELSEWHERE BY THAT POINT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...TRA
SHORT TERM...RAS
LONG TERM...RAS
AVIATION...TRA/JW
