FXUS62 KILM 251432
AFDILM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
932 AM EST FRI DEC 25 2009
.SYNOPSIS...
A STRONG FRONTAL SYSTEM WILL BRING RAIN AND GUSTY WINDS TO THE
EASTERN CAROLINAS TODAY. COLD AND DRY HIGH PRESSURE WILL BUILD
ACROSS THE FORECAST AREA SATURDAY NIGHT THROUGH WEDNESDAY. THE
NEXT STORM SYSTEM MAY AFFECT THE REGION ON THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM FRIDAY...WIND SHIFTS AND TEMPERATURE TRENDS SHOW WARM
FRONT HAS MOVED ASHORE AND IS NOW LIFTING NORTH ACROSS THE
FORECAST AREA. ACCOMPANYING STRATIFORM RAINFALL IS STEADILY
SPREADING NORTHEAST ACROSS THE EASTERN CAROLINAS AND AT THIS POINT
ALL OF OUR SC COUNTIES ARE SEEING AT LEAST DRIZZLE. AT CURRENT
RATE...REMAINDER OF THE FORECAST AREA WILL BE IN A SIMILAR STATE
BY NOON. ANALYSIS OF MORNING SOUNDING DATA SHOWS TODAY WILL BE A
NO CAPE/HIGH HELICITY DAY...STABLE YET VERY STRONGLY SHEARED. MAKE
THAT A VERY HIGH HELICITY DAY FOR THIS AFTERNOON...HAVE NOT SEEN
VALUES THIS HIGH IN QUITE A WHILE. SPC HAS US IN A SIGHT RISK AREA
FOR SEVERE THUNDERSTORMS TODAY DUE TO THIS AND THERE IS AT PRESENT
A TORNADO WATCH JUST TO OUR SOUTH THROUGH NOON TODAY. BUFKIT
SOUNDING DATA SUGGESTS TIMEFRAME FOR GREATEST SEVERE THUNDERSTORM
OR TORNADO THREAT TO BE LATER THIS AFTERNOON AND EVENING AS COLD
FRONT SWEEPS EAST ACROSS THE AREA...BUT AT THIS TIME FEEL
LIKELIHOOD OF SEVERE WX IS LOW. LOOKS LIKE BEST DYNAMICS WILL PASS
TO OUR WEST THIS EVENING.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...
SOUTHWESTERLY CYCLONIC FLOW AROUND DEEP GREAT LAKES VORTEX WILL LAST
THE ENTIRE SHORT TERM PERIOD. LOW LEVEL THERMAL RIDGE IS PUSHED TO
THE EAST BY THIS FEATURE SATURDAY NIGHT BRINGING AN END TO THE ABOVE
CLIMO TEMPS. SPOKES OF VORTICITY BEGIN TO LIFT THROUGH THIS
SOUTHWESTERLY FLOW SUNDAY NIGHT. GUIDANCE IS SHOWING AMPLE MOISTURE
AND LIFT ASSOCIATED WITH THESE SMALL SCALE FEATURES TO SUPPORT SOME
LIGHT PRECIPITATION. GIVEN THE FAIRLY DRY LOW LEVELS AND WEAK COLD
AIR ADVECTION LEADING TO DOWNWARD VERTICAL MOTION BENEATH THE MID
LEVEL LIFT PRECIP SEEMS LESS LIKELY THAN JUST AN INCREASE IN CLOUDS
AT THIS POINT.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 3 AM FRIDAY...ON MONDAY THE FINAL KICKER VORT SWINGS THROUGH
THE TROUGH THAT HAD BEEN IN PLACE OVER THE EASTERN FOR SEVERAL DAYS
PREVIOUS. BEHIND THIS FEATURE WILL COME A BATCH OF RENEWED COLD AIR
ADVECTION PUSHING H850 TEMPS DOWN TO -6 TO -8 DEG C ACCORDING TO
ECMWF BUT ONLY AROUND -2 DEG C ACCORD TO GFS. CAA TAPERS OFF ON
TUESDAY AND H850 TEMPS SHOULD BE WITHIN A FEW DEG OF FREEZING. WILL
UNDERCUT GUIDANCE SOME ON MONDAY AS A COMPROMISE BUT FOLLOW CLOSELY
NEXT FEW DAYS. HIGHS MIRED IN THE 40S FOR MON WITH A RUN AT 50 FOR
THE NEXT FEW. COASTAL TROUGHINESS AND/OR GULF OF MEXICO SYSTEM COULD
BRING INCREASING MOISTURE LOCALLY BY THURSDAY BUT MEASURABLE
RAINFALL WILL PROBABLY BE DELAYED JUST BEYOND THE LONG TERM.
&&
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
AS OF 12Z...WARM FRONT WILL CROSS THE REGION THIS MORNING BRINGING
RAIN AND LOWERING CIGS. RAIN AND POTENTIAL THUNDERSTORMS WILL OCCUR
THIS AFTN IN ADVANCE OF A COLD FROPA THIS EVENING.
HIGH CONFIDENCE IN CHARACTERISTICS OF EVENT TODAY...WITH LOW
CONFIDENCE IN TIMING. LARGE AREA OF STRATIFORM RAIN JUST TO THE SW
OF FLO THIS MORNING...AND THIS WILL SPREAD ACROSS THE AREA
THROUGH THE AFTN. ONCE RAIN BEGINS VSBYS AND CIGS WILL QUICKLY DROP
TO MVFR...WITH IFR CIGS DEVELOPING A SHORT TIME AFTER. AS IS TYPICAL
IN THESE OVERRUNNING SITUATIONS THE COLUMN SATURATES FROM TOP DOWN
AND IFR CIGS DEVELOP FREQUENTLY...SO AM FAIRLY CONFIDENT IN IFR
TODAY. WINDS WILL INCREASE THROUGH THE AFTN AS A STRONG 850MB JET OF
50 TO 60 KTS MOVES OVERHEAD. STRENGTH OF SURFACE WINDS WILL DEPEND
GREATLY ON LEVEL OF MIXING...BUT EXPECT SEVERAL HOURS OF 20 TO 30 KT
GUSTS AS THE WINDS VEER TO THE SOUTH THROUGH THE AFTN.
RAIN TYPE WILL BECOME MORE CONVECTIVE THIS AFTN AS COLD FRONT
APPROACHES. WITH SIGNIFICANT SHEAR DUE TO THE LLJ SOME
THUNDERSTORMS...POTENTIALLY SEVERE...ARE POSSIBLE FOR A SHORT
DURATION THIS AFTN. VERY LOW CONFIDENCE IN THIS PART OF THE FORECAST
BUT ANY THUNDER WILL LIKELY OCCUR AFTER NEXT TAF ISSUANCE SO THERE
IS SOME TIME TO UPDATE. FOR NOW HAVE VCTS WITH 1K FOOT CB IN THE
TAFS TO REFLECT POTENTIAL. ONCE COLD FRONT COMES THROUGH THIS
EVENING WINDS WILL BEGIN TO DECREASE AND SHOULD EASE SIGNIFICANTLY
TONIGHT. HAVE INTRODUCED LLWS ONLY AT ILM DUE TO THEIR PROXIMITY TO
THE LLJ AS IT PULLS AWAY TONIGHT. GUIDANCE SPLIT ON CLEARING
TONIGHT...BUT WITH SIGNIFICANT LL MOISTURE THINK THERE IS A GOOD
CHANCE FOR IFR STRATUS AT ALL THE TERMINALS TOWARD THE END OF THIS
TAF PERIOD.
EXTENDED OUTLOOK...VFR SUNDAY. SLIGHT POTENTIAL FOR MVFR CIGS WITH
LOW PRESSURE TROUGH MONDAY. VFR TUESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM FRIDAY...WARM FRONT HAS MOVED ASHORE AND GRADIENT
REMAINS TIGHT ACROSS THE COASTAL WATERS THIS MORNING. THIS WILL BE
THE RULE DURING THE DAYTIME HOURS...WITH STRONG WINDS AND HIGH SEAS
PERSISTING UNTIL TONIGHT. WINDS WILL SHIFT AND BECOME OFFSHORE
WHILE DECREASING OVERNIGHT AS COLD FRONT MOVES ACROSS THE WATERS.
WILL LET SMALL CRAFT ADVISORY RIDE THROUGH THE NEAR TERM AS SEAS
WILL BE SLOW TO SUBSIDE BELOW 6 FT.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...
WEST TO NORTHWEST WINDS THROUGH THE PERIOD AS HIGH PRESSURE BUILDS
IN FROM THE WEST BEHIND COLD FRONT. THE PROLONGED OFFSHORE FLOW WILL
OPEN UP A RANGE IN SEAS FROM NEARSHORE TO OFFSHORE...GENERALLY
AVERAGING 3 TO 5 FT FOR SATURDAY AND SUBSIDING TO 2 TO 4 FT ON
SUNDAY IN A SHORT PERIOD WIND WAVE DOMINATED SEA STATE.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 3 AM FRIDAY...
UPPER LEVEL DISTURBANCE SWINGS THROUGH ON MONDAY BRINGING A
FORTIFIED SURGE OF COLD AIR. NW WINDS WILL INCREASE AS HIGHER
PRESSURES AGAIN BEGIN TO BUILD ACROSS THE WATERS. ADVISORIES NOT
ANTICIPATED AT THIS TIME BUT CAUTIONARY HEADLINES NOT OUT OF THE
QUESTION. BOTH WINDS AND SEAS WILL ABATE ON TUESDAY AS GRADIENT
DECREASES.
&&
.HYDROLOGY...
ALL RIVERS IN THE RIVER DISTRICT ARE BELOW FLOOD STAGE.
THE WACCAMAW RIVER AT CONWAY IS CURRENTLY AT ACTION STAGE AND
FORECAST TO HOLD STEADY DURING THE PERIOD.
A CLOSE WATCH IS WARRANTED FOR THE GREAT PEE DEE AT PEE DEE...NOW A
HAIR BELOW ACTION STAGE OF 18 FEET AND FORECAST TO HOLD STEADY UNTIL
THE AM...THEN SLOWLY RECEDE. THE LITTLE PEE DEE AT GALIVANTS FERRY
IS ABOVE ACTION STAGE BUT FORECAST TO HOLD STEADY THROUGH THE
FORECAST PERIOD.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EST SATURDAY FOR AMZ250-252-
254-256.
&&
$$
SYNOPSIS...REK
NEAR TERM...III
SHORT TERM...MBB
LONG TERM...MBB
