FXUS62 KILM 300251
AFDILM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
950 PM EST SUN NOV 29 2009
.SYNOPSIS...
HIGH PRESSURE WILL SLIP OFFSHORE OVERNIGHT WHILE A COLD FRONT
APPROACHES FROM THE NORTHWEST. THE FRONT WILL MOVE THROUGH THE
AREA MONDAY NIGHT...BRINGING A CHANCE OF SHOWERS LATE MONDAY
AFTERNOON THROUGH THE EVENING. LOW PRESSURE EMERGING FROM THE GULF
OF MEXICO COULD BRING MORE SIGNIFICANT RAINFALL TO THE EASTERN
CAROLINAS WEDNESDAY. BUILDING HIGH PRESSURE IS EXPECTED TO OFFER
UP COOLER BUT DRIER WEATHER ACROSS THE REGION LATE IN THE WEEK
HEADING INTO THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 9 PM SUNDAY...A COLD FRONT IN THE OHIO VALLEY WILL MOVE
SOUTHEAST THROUGH THE NIGHT...REACHING THE APPALACHIAN MOUNTAINS BY
DAYBREAK. HIGH PRESSURE IS WELL OFF THE COAST AND THE PRESSURE
GRADIENT BETWEEN THESE TWO WEATHER SYSTEMS IS PRODUCING A DECENT
GRADIENT OVER THE EASTERN CAROLINAS. ALTHOUGH WINDS AT THE SURFACE
ARE GENERALLY LESS THAN 10 MPH...1000 FT WINDS ARE AROUND 30 MPH AND
WILL HELP TO KEEP THE BOUNDARY LAYER MIXED. CIRRUS CLOUDS WILL VARY
FROM SCATTERED TO OCCASIONALLY BROKEN THROUGH THE NIGHT AND WILL
ALSO HELP IMPEDE EFFICIENT RADIATIONAL COOLING. WE HAVE MADE
SUBSTANTIAL UPWARD REVISIONS TO LOW TEMPERATURE FORECASTS ACROSS
COASTAL NORTH CAROLINA WHERE THESE BOUNDARY LAYER WINDS ARE
STRONGEST...LOWER 50S FOR WILMINGTON WITH MID TO UPPER 50S ALONG THE
BRUNSWICK/NEW HANOVER COUNTY BEACHES. FOR AREAS NEAR AND SOUTH OF A
LINE FROM FLORENCE TO MARION TO MYRTLE BEACH WEAKER LOW LEVEL WINDS
ARE ALLOWING A STRONGER SURFACE INVERSION TO DEVELOP AND LOWS SHOULD
BOTTOM OUT NEAR PREVIOUS FORECASTS...GENERALLY IN THE MID 40S.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 300 PM SUNDAY...MONDAY WEATHER HIGHLIGHTS FEATURE A PROGRESSIVE
COLD FRONTAL PASSAGE REACHING THE FAR INTERIOR AROUND 7 PM AND
EXITING THE COAST BY MIDNIGHT. THE BULK OF GULF MOISTURE TAP
CURRENTLY BEING DRAWN NORTHWARD WILL BE EXPENDED AS DECENT RAINFALLS
ACROSS AREAS WEST OF THE APPALACHIANS DURING THE DAY
MONDAY...YIELDING ONLY ABOUT A TENTH OF AN INCH AT BEST PER THE
LATEST CONSENSUS AMONG MODELS FIELDS. NOT REALLY UNREASONABLE SINCE
A DRY AIR MASS WILL BE ACCELERATING THE FRONT ACROSS THE
MID-ATLANTIC QUITE SWIFTLY WITH A PUNCH OF MUCH DRIER NORTH WIND
FLOW INTO THE REGION EARLY TUESDAY.
MUCH OF TUESDAY WILL BE FAIR AS HIGH PRESSURE MOVES GENERALLY EAST
ACROSS THE REGION...BUT SOUTHERN STREAM CYCLOGENESIS EMERGING FROM
THE NORTH CENTRAL GULF OF MEXICO WILL CHANGE FAIR OVER TO INCREASING
CLOUDY AND EVENTUALLY WET...AS WARM ADVECTION OVER-RUNNING GRADUALLY
SERVES TO SATURATE THE ATMOSPHERE INTO DAYBREAK WEDNESDAY. MODEL
TIMING MAY SHIFT WITH TIMING OF STRATIFORM RAINFALL ONSET OVER THE
FORECAST AREA AND RIGHT NOW WILL INTRODUCE A CHANCE OF RAIN AFTER
MIDNIGHT TUESDAY NIGHT...INCREASING POPS IN TIME SW TO NE OVER THE
REGION.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 300 PM SUNDAY...A LOW PRESSURE SYSTEM OVER GULF COAST EARLY
WED WILL TRACK UP THE APPALACHIANS THROUGH WED. THIS WILL BRING RAIN
TO THE AREA ON WED. HIGHEST QPF AMTS SHOULD BE TO THE WEST WHERE
BEST LIFT WILL OCCUR BUT OVERALL RAIN WILL OVERSPREAD THE AREA
THROUGH THE MORNING ON WED. A LITTLE TRICKIER FOR COASTAL SECTIONS
WHICH MAY GET INTO WARM SECTOR EARLIER ON. ONCE WARM FRONT LIFTS
NORTH BY AFTERNOON EXPECT MORE CONVECTIVE TYPE PCP THROUGH THE
EVENING IN WARM SECTOR AHEAD OF COLD FRONT. SHOULD TAP INTO BOTH
GULF AND ATLANTIC MOISTURE WITH LLJ UP TO 40-50 KTS BY WED AFTN. PCP
WATER VALUES WILL INCREASE FROM NEAR A HALF INCH EARLY WED UP NEAR 2
INCHES BY WED EVENING WITH MOISTURE POOLING AHEAD OF COLD FRONT.
SHOULD TURN OUT TO BE A DECENT QPF EVENT ON WED BEFORE LOW TRACKS
OFF TO THE NORTHEAST ON THURS. LOOKS LIKE COASTAL CAROLINAS WILL BE
IN DRYING OUT BY THURS MORNING WITH JUST SOME LINGERING PCP IN THE
EARLY MORNING TAPERING OFF AND CLEARING THROUGH THE DAY BEHIND COLD
FRONT. COLD FRONT SHOULD BLOW THROUGH ON THURS MORNING WITH HIGH
PRESSURE BUILDING IN BEHIND IT LATE THURS INTO FRI. PCP WATER VALUES
DROP TO LESS THAN A HALF INCH BY THURS AFTN AND THEN LESS THAN A
QUARTER OF AN INCH BY FRI MORNING IN COLD AND DRY GUSTY W-NW FLOW.
AS FOR TEMPS PLENTY OF WAA ON WED IN THE WARM MOIST FLOW COMING UP
FROM THE GULF. THIS WILL HELP TO PUSH TEMPS INTO THE 60S EVEN WITH
CLOUDS AND RAIN HOLDING THEM DOWN A BIT. TEMPS WILL HOLD UP THROUGH
WED NIGHT WITH CLOUDS AND PCP AND STILL PLENTY OF WARM AIR STREAMING
IN AHEAD OF COLD FRONT. ONCE FRONT PUSHES THROUGH ON THURS CLEARING
AND DRYING WILL OCCUR WITH COOLER AIR MOVING IN. THEREFORE THURS
WILL BE THE TRANSITIONAL DAY AND DEPENDING ON EXACT TIMING OF COLD
FRONT SHOULD SEE TEMPS START TO DROP BEHIND IT. LOOKS LIKE LOW LEVEL
THICKNESSES WILL RISE UP NEAR 1380M WED EVENING WITH 850 TEMPS UP
NEAR 12-13C....BUT BY A HUGE DOWNWARD TREND WILL BEGIN ON THURS WITH
THICKNESSES DOWN NEAR 1290 BY FRI MORNING. SHOULD SEE SOME OF THE
COLDEST AIR OF THE SEASON WITH 850 TEMPS DOWN BELOW -5 C. THEREFORE
ONCE FRONT MOVES THROUGH CAA WILL FOLLOW IN FORCE. TEMPS ON FRI
SHOULD NOT MAKE IT OUT OF THE LOWER 50S AND TEMPS OVERNIGHT FRI
NIGHT SHOULD BE BELOW FREEZING MOST PLACES. BEST CAA WILL SHUT OFF
ON FRI BUT VERY GOOD RADIATIONAL COOLING CONDITIONS WILL PERSIST
THROUGH THE WEEKEND AS HIGH PRESSURE MIGRATES EASTWARD. THEREFORE
EXPECT TEMPS TO PERSIST BELOW NORMAL...50S DURING THE DAY AND 30S
OVERNIGHT.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
AS OF 00Z...HIGH PRESSURE OFFSHORE KEEPING VFR CONDITIONS AT ALL THE
TERMINALS TONIGHT WITH LIGHT S/SW WINDS. HIGH LEVEL CI WILL AGAIN
FILTER IN ALOFT ASSOCIATED WITH A COLD FRONT THAT WILL APPROACH THE
AREA TOMORROW NIGHT AND MAY BRING SOME LIGHT SHOWERS TO THE INLAND
TERMINALS BEFORE 00Z WEDNESDAY.
BEAUTIFUL EVENING WITH ONLY FEW 25K FOOT CI AT THE TERMINALS.
THIS CIRRUS WILL SLOWLY INCREASE IN COVERAGE BECOMING BKN TO OVC BY
TMRW AFTN. A COLD FRONT APPROACHING FROM THE WEST WILL BEGIN TO
LOWER CIGS BY LATE TMRW...BUT NOTHING BELOW VFR EXPECTED THROUGH THE
TAF PERIOD. TIMING THE FROPA IS BIGGEST CHALLENGE THIS FORECAST
PERIOD...BUT EXPECT SOME LIGHT SHOWERS AT LBT/FLO BY 00Z WEDNESDAY.
ILM/CRE/MYR SHOULD REMAIN DRY THROUGH THE TAF PERIOD...BUT HAVE PUT
VCSH AFTER 23Z IN THESE TAFS TO REFLECT APPROACHING FRONT. ANY RAIN
THAT FALLS WILL BE LIGHT AND SHOULD NOT REDUCE VSBYS BELOW VFR. ONLY
OTHER CONCERN TOMORROW WILL BE GUSTY W/SW WINDS AHEAD OF THE FROPA.
WITH TIGHTENED GRADIENT NEAR THE FRONT...AND ANOTHER DAY OF DEEP
MIXING...EXPECT 20 KT GUSTS AT ALL THE TERMINALS SHORTLY AFTER
SUNRISE AND THROUGH THE AFTN. WINDS WILL DECREASE TOMORROW NIGHT
ONCE MIXING SUBSIDES...BUT WILL REMAIN AROUND 10 KT AS FRONT
APPROACHES.
WAS A LITTLE CONCERNED ABOUT FOG TONIGHT SINCE THE SOUTHERLY FLOW
HAS INCREASED LOW LEVEL MOISTURE AT THE TERMINALS. HOWEVER...WINDS
LOOK TO STAY JUST HIGH ENOUGH TO KEEP ANY FOG MIXED OUT THROUGH THE
NIGHT. CANNOT RULE OUT SOME LIGHT GROUND FOG AT THE USUAL
TERMINALS...CRE/LBT/FLO...BUT HAVE NOT PUT ANYTHING IN THE TAFS
SINCE CHANCE OF REDUCED VSBYS DUE TO FOG IS VERY LOW.
EXTENDED OUTLOOK...POSSIBLE IFR WITH RAIN LATE MONDAY NIGHT INTO
TUESDAY. MORE IFR POSSIBLE WITH A LOW PRESSURE SYSTEM WEDNESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 9 PM SUNDAY...HIGH PRESSURE WELL OFFSHORE IS GIVING WAY TO A
COLD FRONT APPROACHING FROM THE NORTHWEST. THIS FRONT IS STILL IN
THE OHIO VALLEY AND WILL NOT CROSS THE APPALACHIANS UNTIL DAYBREAK.
INCREASING SOUTHWEST FLOW AHEAD OF THE FRONT WILL INCREASE WIND
SPEEDS FROM THE CURRENT 10 KNOTS TO 15-20 KNOTS BY DAYBREAK...WITH A
CONSUMMATE INCREASE IN SEA HEIGHTS AS WELL. WINDS/SEAS ARE CURRENTLY
RUNNING WELL BELOW PREVIOUS FORECASTS...ONLY 12 KNOTS AND 2 FT AT
FRYING PAN SHOALS BUOY. AN INCREASE IN WINDS AND SEAS IS STILL
EXPECTED BUT DELAYED 4-6 HOURS FROM PREVIOUS THINKING.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 300 PM SUNDAY...MONDAY MORNING WILL LIKELY BE GREETED WITH
15-20 KNOT WINDS ACROSS THE WATERS WITH 2 TO 4 FOOT SEAS IN A
MODERATE SW CHOP...WITH HIGHEST SEAS MOVING ACROSS THE OUTER WATERS.
BY MONDAY AFTERNOON AS THE COLD FRONT NEARS...WINDS WILL APPROACH 20
KNOTS WITH GUSTS TO 25 KNOTS NOT TOO FAR FETCHED FROM MID AFTERNOON
MONDAY THROUGH MONDAY NIGHT IN COLD AIR ADVECTION GUSTS. THE
FREQUENCY OF THE GUSTS MAY REQUIRE AN ADVISORY...BUT RIGHT NOW OUT
TO THE 3RD PERIOD...WE WILL AWAIT ANOTHER MODEL RUN TO PIN DOWN
TIMING/EXTENT/DEGREE OF THE WIND SPEEDS PRIOR TO AND AFTER FRONTAL
PASSAGE. THUS FOR NOW NO HEADLINES BUT WILL ADVERTISE A FEW GUSTS TO
25 KNOTS AND CAP SEA HEIGHTS OFFSHORE AT AROUND 5 FEET. THE NEW WAVE
GROWTH WILL RESULT IN DOMINANT WAVE PERIODS AROUND 6 SECONDS AT THE
PEAK OF SEA HEIGHTS LATE MONDAY...PRODUCING MODERATELY STEEP SEAS.
LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 300 PM SUNDAY...HIGH PRESSURE WILL MIGRATE FARTHER OFF SHORE
WHILE A LOW PRESSURE SYSTEM TRACKS UP FROM THE GULF COAST ON WED.
THIS WILL LEAD TO A TIGHTENED ON SHORE GRADIENT FLOW THROUGH THE
DAY. WINDS WILL VEER AROUND THROUGH WED FROM E-SE TO SE-S BY EVENING
AND SHOULD INCREASE WELL ABOVE SCA CRITERIA BY LATE WED. WNA MODEL
HAS BEEN CONSISTENTLY FORECASTING 10 TO 12 FT SEAS IN OUTER WATERS
ESPECIALLY OUT NEAR FRYING PAN SHOALS BY WED EVENING. SHOULD SEE A
RAPID INCREASE IN WINDS AND SEAS THROUGH THE DAY ON WED WITH SCA
CONDITIONS PERSISTING FROM WED AFTN THROUGH MUCH OF THURS UNTIL COLD
FRONT PASSES BY THURS AFTN.
AS LOW PRESSURE SYSTEM MOVES OFF TO THE NORTHEAST AND COLD FRONT
SWEEPS THROUGH BY THURS AFTN WINDS WILL BECOME MORE OFF SHORE AND
GRADIENT WILL WEAKEN. THEREFORE WINDS AND SEAS WILL DECREASE LATE
THURSDAY THROUGH FRI BUT DECENT COLD SURGE WILL KEEP WINDS AND SEAS
UP AT LEAST THROUGH THURS NIGHT INTO EARLY FRIDAY. NORTHWEST WINDS
WILL BEGIN TO SLOWLY VEER AROUND HEADING INTO THE WEEKEND AND WILL
WEAKEN AS HIGH PRESSURE MIGRATES EASTWARD. BY FRI SEAS WILL BE DOWN
TO 2 TO 4 FT AND WILL CONTINUE TO DECREASE THROUGH MUCH OF THE
WEEKEND.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...MJC
SHORT TERM..MJC
LONG TERM...RGZ
AVIATION....JDW
