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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 100534
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1235 AM EST WED FEB 10 2010

.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM ALOFT WILL MOVE INTO VIRGINIA
WEDNESDAY...PRODUCING VERY WINDY CONDITIONS IN NORTH CAROLINA DURING
THE DAY WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
-- Changed Discussion --
AS OF 930 PM...

LITTLE CHANGE TO FORECAST.
WIDESPREAD RAINS HAVE EXITED THE WESTERN PIEDMONT... AND ANY
FUTURE PRECIPITATION TONIGHT BEHIND THE EXITING RAIN SHIELD WILL
BE BRIEF AND SCATTERED. SLIGHT CHANCE POPS ARE LOCATED NORTH OF
HIGHWAY 64 UNTIL JUST AFTER MIDNIGHT WHERE THE BEST MOISTURE AND
DYNAMICS ARE LOCATED.

MODELS IN GOOD AGREEMENT IN CREATING A DEEP MIXED LAYER BEFORE
DAWN WHICH WILL TAP INCREASING WINDS ALOFT. WITH WINDS AT THE TOP
OF THIS LAYER APPROACHING 35 KNOTS... GUSTS TO 35 MPH EXPECTED AT
THE SURFACE.

IMPRESSIVE COOLING RIDING INTO NORTH CAROLINA ON THESE WINDS.
HOWEVER PRECIPITATION AND MOISTURE WILL EXIT BEFORE TEMPERATURES
FALL ENOUGH ALOFT FOR NONLIQUID PRECIPITATION.

THE TIMING OF FREEZING TEMPERATURES MAY PLAY A POSSIBLE ROLE IN
SLICK SPOTS DEVELOPING NEAR DAWN. MAIN AREA OF CONCERN IS ROUGHLY
ROXBORO TO NORTH OF DURHAM TO ASHEBORO AND POINTS WEST.
TEMPERATURES ALWAYS DIFFICULT IN A STRONG ADVECTION CASE. MODELS
ARE FREQUENTLY TOO COLD WITH NORTHWEST TO WEST FLOW AND DO NOT SEEM
TO FULLY MODEL THE BLOCKING IMPACT OF THE MOUNTAINS. HOWEVER
TAKING THIS INTO ACCOUNT... BELIEVE TEMPERATURES WILL DROP INTO
THE MID 20S IN THE NORTHWEST PIEDMONT BY 9 AM. DEW POINTS ARE
EXPECTED TO FALL INTO THE TEENS BY THIS TIME... AND STRONG DRYING
OF ROADS MAY MAKE BLACK ICE A NON-ISSUE. WILL ONLY MENTION IN THE
WEATHER OUTLOOK PRODUCT AT THIS TIME FOR THE ABOVE OUTLINED AREA.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
AS OF 250 PM TUESDAY...

HIGH WIND WARNING IN EFFECT FOR ALL OF CENTRAL NORTH CAROLINA ON
WEDNESDAY.

MODELS CONTINUE TO ADVERTISE A DEEP MID AND UPPER LEVEL LOW
CROSSING SOUTHERN VA WEDNESDAY...AIDING TO RAPIDLY INTENSIFY
SURFACE LOW OFF THE NORTHERN MID ATLANTIC COAST. 12Z MODELS
CONSISTENT WITH 00Z COUNTERPARTS IN DEPICTING STRATOSPHERIC
INTRUSION INTO THE BOUNDARY WEDNESDAY...HELPING TO MIX VERY STRONG
WINDS TOWARDS THE SURFACE. MODEL SOUNDINGS SUGGEST WINDS 53 TO
58 KNOTS AT THE TOP OF THE MIX LAYER. HAVE NOT SEEN WINDS THIS
STRONG IN A WHILE. WILL LIKELY NOT REALIZE WINDS THIS STRONG AT
THE SURFACE BUT STEEP LOW LEVEL LAPSE RATES SHOULD SUPPORT WIND
GUSTS 40 TO 45 KNOTS...ESPECIALLY ACROSS THE NORTH. TOPSOIL REMAIN
SATURATED WITH LITTLE DRYING ANTICIPATED. THIS SUPPORTS IDEA OF
NUMEROUS DOWNED TREES AND A FEW POWER LINES. THUS...WILL UPGRADED
HIGH WIND WATCH TO A WARNING FOR THE ENTIRE AREA.

WILL STAY ON THE COOL SIDE OF MOS GUIDANCE DUE TO STRONG LOW
LEVEL COLD AIR ADVECTION...OFFSET SOMEWHAT BY DOWNSLOPE
COMPONENT/ADIABATIC WARMING. HIGHS MID 30S NORTH TO LOWER 40S
SOUTH. TEMPERATURES COMBINED WITH WINDS WILL PRODUCE WIND CHILLS
IN THE 20S.

WEDNESDAY NIGHT...WINDS WILL SLOWLY SUBSIDE BUT REMAIN BLUSTERY.
SKIES WILL REMAIN CLEAR TO PARTLY CLOUDY. IN SPITE OF
MIXING...850MB THERMAL TROUGH IMMEDIATELY NORTHWEST OF FORECAST
AREA. LEANED TOWARD THE COOL END OF MOS BUT COULD SEE MINIMUM
TEMPERATURES 2 TO 3 DEGREES COOLER IF LIGHTER WINDS OCCUR.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
AS OF 300 PM TUESDAY...

THE EXTENDED FORECAST WILL CONTINUE TO FEATURE TEMPERATURES BELOW
NORMAL. CURRENTLY...NO DAY IN THE EXTENDED FORECAST SHOWS A HIGH OR
LOW AT OR ABOVE NORMAL.  THURSDAY THROUGH FRIDAY...SURFACE WINDS
SHOULD STILL BE GUSTY INTO THE DAY THURSDAY...ESPECIALLY AFTER
DIURNAL MIXING TAKES PLACE...WITH 925 MILLIBAR WINDS NEAR 40 KNOT
AROUND 12Z THURSDAY...DIMINISHING TO 30 KNOT LATE IN THE DAY. DID
NOT FORECAST WINDS REALLY HIGH YET...TO 40 MPH...AS BUFR SOUNDINGS
AND 925 MILLIBAR WINDS SHOW A FAIRLY RAPID DECREASE IN GUST
POTENTIAL BETWEEN 12Z AND 18Z... BUT TRENDS WILL HAVE TO BE
MONITORED AS THE GRADIENT REMAINS TIGHT THROUGHOUT MUCH OF THE
DAY. WINDS WILL DIMINISH THURSDAY NIGHT AND BE MARKEDLY LOWER
FRIDAY AS 925 MILLIBAR WINDS FALL TO 10-15 KNOT FOR MUCH OF THE
DAY.

1000-850MB THICKNESSES REMAIN COOL...SHOWING HIGHS ONLY IN THE UPPER
30S IN THE TRIAD THURSDAY AND IN THE LOWER 40S IN THE SAME LOCATION
FRIDAY. ELSEWHERE...THIS SHOULD TRANSLATE TO HIGHS IN THE LOWER TO
MID 40S. MIXING ON THE GFS IS BETTER FRIDAY COMPARED TO THE NAM...
BUT DEGREE OF HIGH CLOUDS AHEAD OF THE NEXT LOW PRESSURE SYSTEM TO
AFFECT THE SOUTHEAST IS MUCH MORE PRONOUNCED ON THE GFS...WITH ITS
UPPER-LEVEL MOISTURE...COMPARED TO THE NAM. THERE COULD ALSO BE A
FEW HIGH CLOUDS IN THE STRONG WINDS ALOFT EARLY THURSDAY...MAINLY
CENTRAL AND WEST...AND 300MB WINDS ARE FORECAST TO EXCEED 150 KNOT
THURSDAY.

THE MODEL TRENDS FROM THE ECMWF HAVE FORECAST LATE-WEEK LOW PRESSURE
OVER THE SOUTHEAST FARTHER NORTH...WHILE THE GFS HAS TRENDED DRIER
AND FARTHER SOUTH. THE GFS OVERALL HAS TRENDED WEAKER WITH THE GULF
LOW AND STRONGER WITH SURFACE HIGH PRESSURE FOR LATE IN THE
WEEK...AND RELATIVE TO THE ECMWF...THE GFS IS STRONGER WITH THE HIGH
AND WEAKER WITH THE LOW. QPF WITH THE GFS IS ZERO OVER CENTRAL NORTH
CAROLINA...WHILE THE FARTHER NORTH ECMWF SHOWS LIGHT PRECIPITATION
JUST BARELY REACHING THE SOUTH TIER OF CENTRAL NORTH CAROLINA
COUNTIES LATE FRIDAY NIGHT INTO EARLY SATURDAY. FOR WHAT IT IS
WORTH...THE DGEX IS WELL SOUTH...CLOSER TO THE GFS IN TRACK BUT
STRONGER WITH LOW PRESSURE...KEEPING PRECIPITATION SOUTH OF CENTRAL
NORTH CAROLINA. WHILE THE SYSTEM BEARS WATCHING...AS ANY
PRECIPITATION THAT OCCURS WITH THIS WOULD BE IN THE FORM OF LIGHT
SNOW BASED ON COLD THICKNESSES...BASED ON THE CURRENT CONSENSUS
TRACK OF LOW PRESSURE WILL CONTINUE A DRY FORECAST.

DURING THE REST OF THE EXTENDED PERIOD...WHILE THE FORECAST WILL
STILL BE DRY...THERE IS SOME CONCERN ABOUT A MODERATELY-STRONG
SHORTWAVE OR TWO IN THE NORTHWEST FLOW THAT WILL MOVE ACROSS CENTRAL
NORTH CAROLINA. THE GFS SUPPORTS TWO OF THESE...ONE BEHIND THE
SOUTHEAST LOW LATE FRIDAY NIGHT AND EARLY SATURDAY...AND ANOTHER
SUNDAY NIGHT INTO EARLY MONDAY. THE ECMWF IS MORE SUPPORTIVE OF THE
LATTER...AND IT APPEARS LIKELY THAT IN SOME PART OF THIS PERIOD...
WITH THE PERSISTENCE OF THE UPPER LOW PRESSURE OVER SOUTHEAST CANADA
AND A RIDGE IN THE WEST WITH THE GENERAL NORTHWEST FLOW RIGHT
THROUGH THE MID-ATLANTIC AND CAROLINAS...AT LEAST ONE MODESTLY
STRONG SHORTWAVE WILL MOVE OVER OR NEAR CENTRAL NORTH CAROLINA. ANY
PRECIPITATION SHOULD BE LIGHT...BUT GIVEN THE COLD AIR THAT WILL BE
IN PLACE...ANY PRECIPITATION WOULD ALMOST CERTAINLY BE FROZEN
PARTICULARLY IF THE TIMING IS AT NIGHT. WILL REFRAIN FROM
INTRODUCING A SLIGHT CHANCE OR CHANCE OF SNOW SHOWERS WITH A
NOCTURNAL TIMING OUT TO THE SIXTH OR SEVENTH DAY...BUT WILL INCREASE
CLOUD COVER FOR A COUPLE OF PERIODS WHERE THE CONSENSUS SUPPORTS AT
LEAST A WAVE MOVING OVER OR NEAR THE AREA.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
AS OF 1230 AM WEDNESDAY...

THE WIDESPREAD LIFR/IFR CONDITIONS...ASSOCIATED WITH A STABLE COLD
AIR DAMMING WEDGE AND A STRENGTHENING AREA OF LOW PRESSURE ALONG THE
NORTH CAROLINA COAST...WILL QUICKLY SCOUR OUT BY 08Z TO 10Z AS A
STRONG COLD FRONT PUSHES THROUGH THE AREA.

THEREAFTER...THE PRIMARY AVIATION CONCERN WILL BE VERY STRONG
CROSSWINDS OF RUNWAYS ORIENTED SW TO NE AS SUSTAINED WEST/NW WINDS
OF 25-30 KNOTS... WITH FREQUENT GUSTS TO 40-45 KNOTS ARE EXPECTED BY
MID/LATE MORNING. SPORADIC GUSTS UP TO 50 KNOTS WILL BE POSSIBLE AT
THE INT/GSO/RDU/RWI TAF SITES...PARTICULARLY IN THE 17-21Z PERIOD
WED AFTERNOON.

00Z THURSDAY THROUGH SUNDAY:
STRONG NORTHWEST WINDS WILL GRADUALLY SUBSIDE WEDNESDAY NIGHT. VFR
CONDITIONS ARE EXPECTED THURSDAY THROUGH SUNDAY. -VINCENT
-- End Changed Discussion --

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING FROM 6 AM TO 9 PM EST WEDNESDAY FOR
NCZ007>011-021>028-038>043-073>078-083>086-088-089.

&&

$$

SHORT TERM...WSS
LONG TERM...DJF
AVIATION...CBL/VINCENT