-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 260858 CCA
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
325 AM EST THU FEB 26 2015

.SYNOPSIS...LOW PRESSURE WILL TRACK OFF OF THE NORTH CAROLINA COAST
THIS MORNING. COLD CANADIAN HIGH PRESSURE WILL FOLLOW THE STORM
FRIDAY INTO SATURDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 325 AM THURSDAY...

...MAJOR WINTER STORM WINDING DOWN...

PLAN TO MAINTAIN WINTER STORM WARNING FOR A LARGE PART OF CENTRAL NC
EARLY THIS MORNING AS MAJOR WINTER STORM GRADUALLY PULLS AWAY FROM
OUR REGION. WILL ALSO MAINTAIN THE ADVISORY FOR THE FAR SOUTH AND SE
COUNTIES AS TEMPS THERE WILL REMAIN CLOSE TO FREEZING WITH A SMALL POTENTIAL
FOR A LIGHT ICE ACCRUAL ON EXPOSED OBJECTS.

MAIN AXIS OF HEAVY WET SNOW HAS FALLEN FROM THE WESTERN PIEDMONT
INTO THE NORTHERN PIEDMONT WITH AMOUNTS IN THE 6-8 INCH RANGE COMMON
FROM ASHEBORO TO NORTH RALEIGH TO ROXBORO. 06Z GSO SOUNDING DEPICTS
A DEEP ISOTHERMAL LAYER. WITH THIS TEMP PROFILE...EXPECT SNOW DURING
PERIODS OF HEAVIER PRECIP INTENSITY AND A MIX OF SNOW/SLEET/FREEZING
RAIN DURING LIGHTER PRECIP INTENSITY. THE DUAL POL CORRELATION
COEFFICIENT PRODUCT (CC)WAS HELPFUL OVERNIGHT DEPICTING THE SNOW/MIX
PHASED REGIONS VERY WELL.

LATEST WATER VAPOR IMAGERY DEPICTS DRIER AIR ALOFT ADVANCING NEWD
INTO CENTRAL NC. WITH LOSS OF MOISTURE IN THE FAVORED ICE NUCLEATION
GROWTH ZONE...EXPECT CHARACTER OF PRECIP TO BECOME MORE
RAIN/FREEZING RAIN VERSUS SNOW FOR MOST LOCATIONS EXCEPT FOR THE VA
BORDER COUNTIES WHERE SNOW/SLEET MAY OCCUR UP TO OR JUST PAST
DAYBREAK. THUS CURRENT RADAR TREND OF PRECIP BECOMING
LIGHTER/SPOTTIER WILL CONTINUE THROUGH 12Z. AFTER 12Z...SHOULD SEE
PRECIP DIMINISH/END FROM THE SW.

WHILE NOT EXPECTING ICE ACCRUAL AMOUNTS OF ANY SIGNIFICANCE...WHAT
ICE THAT DOES ACCRUAL COUPLED WITH HEAVY WET SNOW WILL LIKELY LEAD
TO MORE POWER OUTAGES (PER DUKE PROGRESS ENERGY ALREADY OVER 50000
WITHOUT POWER IN THE RALEIGH-DURHAM AREA).

EXPECT BULK OF LIGHT PRECIP TO DIMINISH/END IN THE 14Z-17Z TIME
FRAME WITH MOSTLY CLOUDY TO OVERCAST SKIES TO PERSIST THROUGH THE
REST OF THE DAY. AFTERNOON TEMPS SHOULD RECOVER 3-4 DEGREES FROM
CURRENT LEVELS...WHICH WILL ALLOW FOR SOME MELTING.

THIS MELTING WILL LIKELY RE-FREEZE LATE TONIGHT LEADING TO
WIDESPREAD BLACK ICE CONDITIONS. ONCE CURRENT SET OF
ADVISORY/WARNING EXPIRES...ANOTHER ADVISORY FOR BLACK ICE MAY BE
NECESSARY FOR LATE TONIGHT-EARLY FRI MORNING. MIN TEMPS OVERNIGHT 20-
25.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
AS OF 325 AM THURSDAY...

FRIDAY AND FRIDAY NIGHT: ANOTHER WEAK S/W DISTURBANCE IS EXPECTED TO
MOVE ACROSS THE REGION IN THE WEST-SOUTHWESTERLY MID LEVEL FLOW.
HOWEVER... WITH PW`S LESS THAN THREE TENTHS OF AN INCH OR SO EXPECT
WE WILL SEE LITTLE IF ANY PRECIP. WILL KEEP MENTION OF FLURRIES IN
THE FORECAST FOR LATE FRIDAY AFTERNOON INTO THE EVENING ACROSS THE
PIEDMONT... AS THE LATEST GFS BUFR SOUNDINGS CONTINUE TO SHOW SOME
SATURATION UP CLOSE TO -10C ACROSS WESTERN AND NORTHERN PORTIONS OF
CENTRAL NC... WITH STEEP LOW LEVEL LAPSE RATES. CANT RULE OUT A VERY
BRIEF LIGHT SNOW SHOWER OR TWO, BUT FEEL NOTHING WILL BE MEASURABLE.
EXPECT HIGH TEMPS FRIDAY WILL BE IN THE MID TO UPPER 30S NORTH TO
NEAR 40 SOUTH.

SURFACE HIGH PRESSURE OVER THE MID MS RIVER VALLEY AND OHIO VALLEY
ON FRIDAY EVENING WILL BUILD EAST AND SOUTHWARD OVERNIGHT INTO
CENTRAL NC. THIS YIELD LOW TEMPS BY SATURDAY MORNING IN THE TEENS TO
LOWER 20S ACROSS THE AREA.

SATURDAY: SURFACE HIGH PRESSURE WILL EXTEND INTO OUR REGION FROM THE
NORTH ON SATURDAY... WITH POSSIBLY SOME HIGH CLOUDS INCREASING LATE
IN THE DAY IN THE WEST TO WEST-SOUTHWESTERLY MID LEVEL FLOW IN
ADVANCE OF THE NEXT SYSTEM. THIS WILL YIELD HIGH TEMPS AGAIN WELL
BELOW NORMAL... WITH AFTERNOON LOW LEVEL THICKNESS VALUES SOME 50+
METERS BELOW NORMAL. EXPECT HIGH TEMPS TO BE IN THE 30S.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 1200 PM WEDNESDAY...

THE LONG-TERM SATURDAY NIGHT THROUGH WEDNESDAY IS CATEGORIZED BY
SOME UNCERTAINTY IN PRECIPITATION TIMING AND TYPE...WITH AT LEAST
MODEST CONFIDENCE IN MUCH WARMER TEMPERATURES DEVELOPING BY THE END
OF THIS PERIOD THAN WHAT HAS BEEN OCCURRING RECENTLY. DRYING IS
FORECAST FOR SATURDAY NIGHT...WITH A MID-LEVEL SHORTWAVE MOVING INTO
THE CAROLINAS BY SUNDAY NIGHT. AS HEIGHTS ALOFT RISE LATE IN THE
WEEKEND AND EARLY NEXT WEEK...THE 06Z GFS IN PARTICULAR AND POSSIBLY
EVEN THE 12Z GFS SEEMS TO HAVE ISSUES WITH FEEDBACK SUCH THAT THE
ECMWF IS PREFERRED OVERALL. IT SHOULD BE COLD TO START SUNDAY
MORNING AS CLOUDS INCREASE...BUT THE GFS AND ECMWF TREND OF A LATER
ARRIVAL OF MID-LEVEL VORTICITY AND OVERALL MOISTURE INCREASE SHOULD
RESULT IN PRECIPITATION BEING IN THE FORM OF LIQUID BY THE TIME ANY
WOULD ARRIVE LATER IN THE DAY. PARTIAL THICKNESSES AND MODEL
SOUNDINGS CURRENTLY SUPPORT THIS...AND WILL HAVE A CHANCE OF
AFTERNOON RAIN SUNDAY PRIMARILY TOWARD THE YADKIN RIVER FOLLOWED BY
CHANCES OF RAIN OVERNIGHT...WITH SURFACE TEMPERATURES REMAINING
ABOVE FREEZING AND MODEL SOUNDINGS SHOWING WARMING ALOFT AS 1000-
850MB THICKNESSES RISE AROUND 20M DURING THE NIGHT...SUGGESTING THE
POTENTIAL FOR LOW TEMPERATURES EARLY SUNDAY NIGHT FOLLOWED BY STEADY
OR A SLOW RISE IN READINGS LATE.

A BRIEF WARMUP OCCURS MONDAY AHEAD OF A COLD FRONT THAT MOVES
THROUGH CENTRAL NORTH CAROLINA LATER IN THE DAY AND AT NIGHT. STRONG
HIGH PRESSURE BUILDS IN BEHIND THE COLD FRONT...AND THE PATTERN
WOULD SUGGEST PRETTY CHILLY TEMPERATURES ONCE AGAIN WITH THE 1000-
850MB THICKNESSES SUGGESTING LOWS A LITTLE BELOW FREEZING. MOS
GUIDANCE LOWS ARE AT LEAST ONE IF NOT MORE CATEGORIES ABOVE THIS...
SO FOR NOW WILL SIMPLY UNDERCUT GUIDANCE WITH OVERNIGHT LOWS AT OR
SLIGHTLY ABOVE FREEZING. CONDITIONS SHOULD DRY BRIEFLY BEHIND THE
FRONT AS HIGH PRESSURE BUILDS IN...THEN UNCERTAINTY INCREASES AS THE
GFS AND THE ECMWF SUGGEST MOISTURE RETURNING TO CENTRAL NORTH
CAROLINA AS THE GULF OPENS BY TUESDAY INTO TUESDAY NIGHT. IF
PRECIPITATION WOULD RETURN TO CENTRAL NORTH CAROLINA QUICKLY ENOUGH
ON TUESDAY...PRECIPITATION TYPE CONCERNS WOULD EXIST DUE TO CHILLY
THICKNESSES TO START THE DAY. BY 00Z WEDNESDAY ON THE 12Z GFS...AND
FOR THE MOST PART ON THE 00Z ECMWF...THICKNESSES ARE WARM ENOUGH FOR
RAIN AND BASED ON THE WARM-AIR ADVECTION AT THE TIME WOULD
ANTICIPATE ANOTHER POTENTIAL NON-DIURNAL TEMPERATURE SCENARIO AS ANY
COLD-AIR DAMMING ERODES. BASED ON THE PATTERN WILL ONLY NOTE A
SLIGHT CHANCE OF RAIN OR SNOW EARLY ON THE SIXTH DAY IN THE WESTERN
PIEDMONT WITH A CHANCE OF JUST ALL RAIN THROUGHOUT CENTRAL NORTH
CAROLINA BY TUESDAY AFTERNOON. 1000-850MB THICKNESSES ON THE 12Z GFS
AND 00Z ECMWF ARE QUITE WARM WEDNESDAY...APPROACHING 1380M ON THE
LATEST GFS AND ONLY SLIGHTLY COOLER ON THE 00Z ECMWF...SUCH THAT...
WITH SHOWERY CONDITIONS IN A MOIST AIR MASS AND A SOUTHWEST FLOW
ALOFT...HIGH TEMPERATURES COULD POSSIBLY REACH THE 60S THROUGHOUT
CENTRAL NORTH CAROLINA WITH SOME TEMPERATURES PUSHING 70F ESPECIALLY
OVER PARTS OF THE SANDHILLS AND SOUTHERN COASTAL PLAIN.

&&


.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 100 AM THURSDAY...

PRIMARY AVIATION CONCERNS NEXT 24 HRS: IFR/LIFR CIGS THROUGH 21Z-23Z
THU... AND MAINLY IFR VSBYS WITHIN WINTRY PRECIP THROUGH 11Z-13Z.

VERY POOR AVIATION CONDITIONS WILL DOMINATE THROUGH TONIGHT. LOW
PRESSURE SYSTEM NOW OVER NRN FL WILL TRACK NE THROUGH MID MORNING...
REACHING JUST OFF CAPE HATTERAS AROUND 13Z. BANDS OF MOSTLY WINTRY
PRECIP (MAINLY SNOW AT INT/GSO/RDU/RWI AND A RAIN/SNOW MIX AT FAY)
WILL PERSIST UNTIL AROUND DAYBREAK. SNOW MAY BE HEAVY AT TIMES AT
INT/GSO/RDU/RWI... DROPPING VSBYS OCCASIONALLY TO LIFR EARLY THIS
MORNING. PRECIP WILL TAPER OFF AROUND 11Z (PLUS OR MINUS AN HOUR OR
SO) AT INT/GSO/FAY AND CLOSER TO 12Z-13Z AT RDU/RWI. CIGS WILL
REMAIN PRIMARILY IFR UNTIL LATE THIS AFTERNOON. UNCERTAINTY GROWS
AFTER 23Z BUT WE KEEP VERY HIGH MOISTURE (HIGH RH VALUES) NEAR THE
GROUND... SUGGESTING THAT AS WINDS GO LIGHT/VARIABLE WE`LL SEE
DEVELOPMENT OF LOW STRATUS AND/OR SUB-VFR FOG THIS EVENING/TONIGHT
IN THE 00Z-06Z TIME FRAME. RUNWAYS ESPECIALLY AT INT/GSO/RDU/RWI ARE
LIKELY TO REMAIN TREACHEROUS THROUGH AND BEYOND THE TAF VALID PERIOD.

LOOKING BEYOND 06Z EARLY FRI MORNING: SUB-VFR CIGS/VSBYS ARE LIKELY
TO PERSIST THROUGH 12Z FRI AT ALL SITES EXCEPT GSO/INT WHERE CIGS
MAY TREND TO VFR IN THE PREDAWN HOURS. MVFR CIGS ARE EXPECTED
THROUGH FRI... THEN CONDITIONS SHOULD TREND TO VFR FRI NIGHT...
EXCEPT AT GSO/INT WHERE REDEVELOPMENT OF SUB-VFR CIGS IS EXPECTED
WITH AN EASTERLY WIND AS CHILLY HIGH PRESSURE NOSES INTO CENTRAL NC
FROM THE NORTH. OTHERWISE... VFR CONDITIONS SHOULD HOLD THROUGH
SUNDAY... BUT ANOTHER STORM SYSTEM APPROACHING FROM THE WEST AND
SOUTHWEST MAY BRING MORE IFR CONDITIONS AND PRECIP SUN NIGHT/MON.
-GIH

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL NOON EST TODAY FOR NCZ007>011-
021>028-038>043-073>078.
WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR NCZ083>086-
088-089.

&&

$$

SYNOPSIS...BADGETT
NEAR TERM...WSS
SHORT TERM...BSD
LONG TERM...DJF
AVIATION...HARTFIELD