FXUS62 KILM 071510
AFDILM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
1010 AM EST MON DEC 7 2009
.SYNOPSIS...
LOW PRESSURE OFF THE COAST WILL BRING PLENTY OF CLOUDS TODAY...AND
PERHAPS A FEW SHOWERS OR PATCHY LIGHT DRIZZLE ALONG THE COASTAL
ZONES. WIDESPREAD RAIN IS EXPECTED BY TUESDAY NIGHT...AS A WARM
FRONT LIFTS NORTH ACROSS THE CAROLINAS. BREEZY AND UNSEASONABLY
WARM WEATHER IS EXPECTED WEDNESDAY AHEAD OF AN APPROACHING COLD
FRONT...WHICH WILL PUSH OFF THE COAST WEDNESDAY NIGHT. BELOW NORMAL
TEMPERATURES WILL RETURN BY FRIDAY AND CONTINUE THROUGH THE WEEKEND.
A FAST MOVING LOW PRESSURE SYSTEM MAY BRING A COLD RAIN ON SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 10 AM MONDAY...IMAGES FROM SPACE THIS MORNING SHOWS PLENTIFUL
CLOUD COVER OVERSPREADING THE FORECAST AREA...WITH HIGHER CLOUDS
ALSO APPROACHING THE REGION ASSOCIATED WITH UPSTREAM IMPULSES TRACKING
ACROSS THE LOWER MISSISSIPPI VALLEY. SURFACE ANALYSIS REVEALS A LOW
AMPLITUDE COASTAL TROUGH OFFSHORE OF SOUTH CAROLINA. LOW LEVEL WINDS
ARE CONVERGING ALONG THIS PELAGIC TROUGH AXIS...STRONGEST JUST
OFFSHORE AND SOUTH OF GEORGETOWN SC...WHERE LIGHT SHOWERS WERE
DRIFTING NORTH. THE WEAK ISENTROPIC LIFT OVER INLAND SC ASSOCIATED
WITH THIS FEATURE WAS PRODUCING OCCASIONAL PATCHY LIGHT DRIZZLE. FOR
THE BALANCE OF TODAY...PLENTY CLOUDS ARE EXPECTED WITH
NON-MEASURABLE OR NO PCPN EXPECTED ACROSS OUR COUNTY WARNING AREA.
THE FAVORED AREAS FOR PCPN WILL RESIDE ALONG THE COAST IN CLOSEST
PROXIMITY TO THE CONVERGENT AXIS OFFSHORE. COMBINATION OF THE COOL
HIGH PRESSURE WEDGE ENTRENCHED INLAND AND TENACIOUS CLOUD COVER WILL
TRANSLATE TO BELOW NORMAL MAXIMUM TEMPERATURES THIS AFTERNOON LIKELY
NOT CRACKING THE 60 DEG F MARK.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 3 AM MONDAY...THE 800-POUND GORILLA ON THE WEATHER MAP WILL
BE AN INTENSE LOW PRESSURE SYSTEM LIFTING NORTHEAST FROM THE TX/OK
PANHANDLE INTO THE GREAT LAKES. BROAD MOISTURE FEED FROM THE GULF
OF MEXICO WILL SET UP AHEAD OF THIS LOW...ALONG WITH RESPECTABLE
ISENTROPIC LIFT. LOOK FOR THICKENING AND LOWERING CLOUDS THROUGH
THE DAY ON TUESDAY...AND BREAKING OUT FROM SW TO NE LATE IN THE
DAY. TIMING STILL TRICKY ENOUGH TO LIMIT POPS TO CHANCE IN THE
WESTERN COUNTIES...AND SLIGHT CHANCE FARTHER EAST.
BEST SHOT AT PRECIP WILL BE 00Z-06Z WEDNESDAY AS THE WARM FRONT
LIFTS NORTH ACROSS THE ILM CWA. WILL GO WITH CATEGORICAL POPS
HERE...AND ALSO A NON-DIURNAL TEMP CURVE AS READINGS ONLY DROP A
COUPLE DEGREES FROM TUESDAY HIGHS DURING THE EVENING...AND THEN
SLOWLY RISE THROUGH THE NIGHT.
WEDNESDAY SHOULD SEE BREEZY AND UNSEASONABLY WARM CONDITIONS IN A
PRONOUNCED DRY SLOT AHEAD OF THE COLD FRONT. FAIRLY JUICY BOUNDARY
LAYER WITH DEWPOINTS IN THE 60S...BUT INSTABILITY IS MARGINAL AT
BEST. HIGH CHANCE POPS WITH A PRE-FRONTAL TROF WEDNESDAY
AFTERNOON...AND WILL MENTION ISOLATED THUNDER.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 3 AM MONDAY...LOW-CONFIDENCE FORECAST ESPECIALLY FROM FRIDAY
ONWARD AS THERE IS SOME DISAGREEMENT AMONG THE MODELS. THIS IS NOT
ENTIRELY UNEXPECTED IN SUCH A PROGRESSIVE PATTERN...WHERE TIMING
OF FEATURES IS DIFFICULT AND CAN MAKE A HUGE DIFFERENCE.
EXPECT ABOVE NORMAL TEMPS TO CONTINUE THROUGH THURSDAY WITH BREEZY
POST-FRONTAL CONDITIONS ON WED NIGHT...AND DOWN SLOPE NW FLOW ON
THU...BOTH PROPPING UP TEMPERATURES. HIGH PRESSURE BUILDS TO OUR
NORTH ON FRIDAY...TURNING THE GRADIENT MORE NORTHEASTERLY AND
BRINGING IN COLDER AIR FOR THE WEEKEND.
DECENT AGREEMENT BETWEEN GFS AND ECMWF THAT FRIDAY WILL BE QUITE
CHILLY...WITH TEMPS JUST GETTING INTO THE 50S. MIGHT NEED TO LOWER
THIS FORECAST A BIT MORE...BUT WILL ONLY TREND FOR NOW UNTIL
CONFIDENCE IS HIGHER. FAST-MOVING SOUTHERN STREAM SYSTEM WILL
MERIT HIGH CHANCE POPS ON SATURDAY...AND WHILE IT LOOKS LIKE A
COLD RAIN THIS FAR SOUTH THE QUESTION REMAINS HOW COLD. LATEST RUN
OF THE GFS CAME IN WITH HIGHS IN THE 40S BOTH SAT AND SUN...BUT
THE ECMWF SUGGESTS WE WILL BE QUITE A BIT MILDER. THEREFORE DID
NOT CHANGE THE GOING TEMP FORECAST.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
AS OF 12Z TERMINALS ARE VFR. 11U-3.9U SATELLITE IMAGES INDICATE
EXTENSIVE STRATO-CU CEILINGS DEVELOPING AND SPREADING NORTHEAST THIS
MORNING. THESE CEILINGS ARE ALREADY AT THE FLO/LBT TERMINALS...AND WILL
SPREAD ACROSS THE COASTAL TERMINALS THROUGH THE EARLY MORNING
HOURS. CEILINGS WILL BE 4K-5K INITIALLY...BUT WILL HAVE THE
POTENTIAL TO LOWER TO 3K-3.5K LATER THIS MORNING AND AFTERNOON.
THERE IS A SLIGHT CHANCE OF MVFR CEILINGS LATE THIS MORNING AND
THIS AFTERNOON BUT HAVE LEFT OUT OF TAFS ATTM SINCE IT IS NOT
EXPECTED TO BE PERSISTENT. RADAR CURRENTLY INDICATES VERY LIGHT
RAIN SOUTH AND SOUTHWEST OF MYR MOVING TO THE NORTH. DO NOT EXPECT
PRECIPITATION TO BECOME HEAVY ENOUGH TO LOWER VISIBILITIES TODAY.
MOST LIKELY THE COASTAL TERMINALS WILL EXPERIENCE BRIEF PERIODS OF
VERY LIGHT RAIN THROUGH THE DAY. WINDS WILL BE LIGHT NORTHEAST TO
EAST AT 3-7 KNOTS THROUGH THE DAY AT ALL TERMINALS.
LOWER STRATO-CU CEILINGS WILL SCATTERED OUT THIS EVENING AT FLO/LBT
LEAVING SCATTERED TO BROKEN CEILINGS AT 10K OVERNIGHT. STRATO-CU
CEILINGS AROUND 4K WITH SCATTERED CLOUDS 1K-2K WILL PERSIST AT THE
COASTAL TERMINALS THROUGH THE NIGHT. WINDS WILL CONTINUE
LIGHT/VARIABLE OR LIGHT NORTHEAST LESS THAN 5 KNOTS THROUGH THE
NIGHTTIME HOURS.
EXTENDED OUTLOOK...IFR POSSIBLE TUESDAY NIGHT AND WEDNESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 10 AM MONDAY...A MODERATE NE WIND FLOW CURRENTLY OVER THE
WATERS WILL EASE UP A BIT BY AFTERNOON...AS A COASTAL TROUGH
OFFSHORE OF SC WEAKENS AND SFC HIGH PRESSURE INLAND BEGINS TO LIFT
NORTH. EXPECT GENERALLY A 3-4 FOOT RANGE OF SEA HEIGHTS TODAY WITH
2 FOOT SEAS NEAR SHORE SOUTH OF CAPE FEAR BUT NORTH OF MURRELLS
INLET. DOMINANT WAVE PERIODS WILL RUN BETWEEN 5 AND 7 SECONDS WHICH
SHOULD MAKE NAVIGATION QUITE MANAGEABLE...WITH WAVES EXHIBITING NON
HAZARDOUS STEEPNESS FOR THE RESPECTIVE HEIGHTS. VISIBILITIES MAY BE
REDUCED AT TIMES TO 4NM DUE TO PATCHY DRIZZLE AND MIST...SPREADING
NORTHEAST FROM SC THIS MORNING TO THE NC WATERS BY THIS AFTERNOON.
SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 3 AM MONDAY...EXPECT A STEADY DETERIORATION OF MARINE
CONDITIONS TUESDAY INTO TUESDAY NIGHT. LIGHT NE WINDS WILL
INCREASE AND VEER TO THE EAST DURING THE DAY...THEN REALLY CRANK
UP OUT OF THE SOUTH-SOUTHWEST AFTER MIDNIGHT AS WE BREAK INTO THE
WARM SECTOR. HEALTHY LOW-LEVEL JET /55+ KT AT 900MB/ WILL SUPPORT
25 TO OCCASIONALLY 30 KT WINDS ON WEDNESDAY. EXPECT SEAS TO BREACH
ADVISORY CRITERIA AROUND MIDNIGHT TUESDAY NIGHT... AND BUILD AS
HIGH AS 10 FT WED AFTERNOON ALONG FRYING PAN SHOALS. WILL DEFER
ONE MORE SHIFT ON ACTUALLY HOISTING THE SCA AS THIS IS STILL A
LATE 4TH PERIOD EVENT.
LONG TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AS OF 3 AM MONDAY...COLD FRONT SHOULD BE NEAR THE COAST TO BEGIN
THE PERIOD...WITH AT LEAST MARGINAL SMALL CRAFT WINDS AND SEAS.
WINDS SHOULD ABATE BY DAYBREAK THU...WITH SEAS SUBSIDING IN THE
OFFSHORE FLOW AS WELL. THE LAST AREA TO SEE IMPROVING CONDITIONS
WILL BE ALONG FRYING PAN SHOALS...WHERE THE WESTERLY WIND
DIRECTION WED NIGHT WILL MAINTAIN A MUCH LONGER FETCH.
MORE PRONOUNCED IMPROVEMENT IS EXPECTED THU/THU NIGHT AS WINDS
DIMINISH FURTHER AND VEER TO A MORE PURE OFFSHORE TRAJECTORY. LOOK
FOR MODEST NE WINDS ON FRIDAY...WITH SEAS ALSO CLEANLY BELOW
ADVISORY CRITERIA.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...MJC
SHORT TERM..RAS
LONG TERM...RAS
AVIATION....MRR
