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000
FXUS62 KRAH 200025
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
825 PM EDT WED JUN 19 2013

.SYNOPSIS...
DRIER AND COOLER HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE
NORTHEAST THROUGH THE END OF THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 725 PM WEDNESDAY...

ISOLATED SHOWERS HAVE BEEN CONFINED TO THE FOOTHILLS WHERE THE LOW
LEVEL FLOW WAS CONVERGENT AND UPSLOPE. OTHER SHOWERS AND
THUNDERSTORMS WERE ASSOCIATED WITH THE PRIMARY COLD FRONT TO OUR
SOUTH. THE INCREASING LOW LEVEL STABILITY ASSOCIATED WITH THE NE
FLOW AND THE HIGH PRESSURE BUILDING INTO OUR REGION FROM THE NORTH
ESSENTIALLY PUT A LID ON SHOWER DEVELOPMENT OVER CENTRAL AND EASTERN
NC. WITH INCREASING STABILITY THIS EVENING... WE WILL FORECAST DRY
CONDITIONS. HOWEVER... THE SKIES HAVE BEEN MOSTLY CLOUDY WITH A
LAYER OF STRATOCUMULUS AND ALTOCUMULUS OVER THE EAST WITH MOSTLY
CIRRUS OVER THE WEST. THE LATEST SATELLITE DATA SUGGESTS MOSTLY
CLOUDY SKIES WILL CONTINUE THROUGH THE EVENING AND WELL INTO THE
OVERNIGHT HOURS. LOWS TONIGHT SHOULD FALL INTO THE LOWER TO MID 60S
(3-5 DEGREES BELOW THE 30 YEAR AVERAGES FOR JUNE 20).

&&

.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
AS OF 300 PM WEDNESDAY...

SURFACE HIGH PRESSURE WILL EXTEND INTO THE AREA FROM THE
NORTHEAST... AND NORTHEASTERLY FLOW WILL CONTINUE. 500 MB HEIGHTS
WILL RISE THROUGH THE DAY... WITH DRYING AND SUBSIDENCE AS MID LEVEL
RIDGING BEGINS TO BUILD IN... LEADING TO DRY CONDITIONS. HIGHS WILL
REMAIN SEVERAL DEGREES BELOW NORMAL... IN THE LOW TO MID 80S. LOWS
WITHIN A FEW DEGREES OF 60.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
AS OF 300 PM WEDNESDAY...

FRIDAY THROUGH SATURDAY...THE GUIDANCE HAS TRENDED MORE MOIST
ESPECIALLY AS WE GET INTO THE DAY ON SATURDAY...AS A MID-LEVEL SHEAR
AXIS IS FORECAST BY THE NAM AND GFS TO MOVE SLOWLY NORTH...INTO
CENTRAL NORTH CAROLINA OR AT LEAST NEAR THE SOUTH CAROLINA BORDER BY
THE END OF THE DAY SATURDAY. THE NAM IS FASTER THAN THE GFS...AND
FOR THIS FORECAST WILL FOLLOW THE GFS WHICH TRENDS MORE MOIST BUT
WITHOUT SUCH A RAPID CHANGE IN FORECASTS FROM ONE PRIMARY FORECAST
ISSUANCE TO ANOTHER. ON FRIDAY...BOTH THE NAM AND GFS SHOW PART OF
THE SANDHILLS AND THE FAR SOUTHERN COASTAL PLAIN IN THE FRONTAL ZONE
OR NEAR THE INVERTED TROUGH...SUCH THAT THERE MAY BE ENOUGH LIFT AND
INSTABILITY FOR AN ISOLATED SHOWER TO DEVELOP OR MOVE INTO AREAS
MAINLY ALONG AND SOUTH OF A LINE FROM ABOUT KMEB TO KGSB DURING THE
LATE AFTERNOON AND EVENING. OVERNIGHT FRIDAY AND ESPECIALLY INTO
SATURDAY MORNING...GFS AND NAM BUFR SOUNDINGS BECOME VERY MOIST
TOWARD KFAY...AND WHILE CURRENTLY THINK WITH DIMINISHING LIFT AND
INSTABILITY WITH LOSS OF DAYTIME HEATING SHOWERS SHOULD TEND TO
WANE...IT IS POSSIBLE AS THE MID-LEVEL SHEAR AXIS LIFTS NORTH NEAR
THE STATIONARY...ALBEIT WEAK...850MB BOUNDARY A FEW SHOWERS COULD
PERSIST OVERNIGHT IN THE FAR SOUTH. A SOMEWHAT LOW-CONFIDENCE
FORECAST FOR FRIDAY NIGHT CURRENTLY SOUTH OF U.S. 64...LEANING DRY
FOR NOW WITH LOWS IN THE 60S AFTER DAYTIME HIGHS FRIDAY IN THE MID
80S.

ON SATURDAY 850MB THETA-E RIDGING REMAINS OVER THE SOUTHERN PART OF
CENTRAL NORTH CAROLINA WITH SUBSIDENCE PERSISTING NORTH. WEAK UPPER
DIFFLUENCE AND LOW-LEVEL CONVERGENCE ARE FORECAST OVER THE SOUTHERN
TWO TIERS OF COUNTIES...AS PRECIPITABLE WATER VALUES THERE INCREASE
LATE IN THE DAY TO NEAR TWO INCHES...AND K INDICES RISE INTO THE
30S. K INDICES ARE CURRENTLY FORECAST BY THE GFS TO REMAIN VERY LOW
NORTH OF U.S. 64. HAVE INTRODUCED A SLIGHT CHANCE OF THUNDERSTORMS
IN THE AFTERNOON ALONG AND MAINLY SOUTH OF A LINE FROM ABOUT KVUJ TO
KGSB...DRY TO THE NORTH. WINDS ALOFT ARE LIGHT...AND MLCAPE IN THE
LOWEST KM IS ONLY ABOUT 500-1000J/KG AT BEST...WITH WEAK 0-3KM SHEAR
AND POOR DOWNDRAFT CAPE IN THE HIGHER MOISTURE AREAS TO THE SOUTH.
HIGH TEMPERATURES SATURDAY WILL BE FORECAST IN THE MID 80S.

SUNDAY THROUGH WEDNESDAY...MOISTURE CONTINUES TO GRADUALLY INCREASE
OVER CENTRAL NORTH CAROLINA. THE CONSENSUS OF THE LONG-TERM GUIDANCE
IS FOR AN EARLIER ONSET TO THE MOISTURE INCREASE...POSSIBLY DEEP
ENOUGH THROUGHOUT CENTRAL NORTH CAROLINA THAT BY SUNDAY AFTERNOON
THERE COULD BE AN ISOLATED SHOWER OR THUNDERSTORM. GUIDANCE CHANCES
FOR RAIN HAVE INCREASED TO THE VICINITY OF CLIMATOLOGY FOR
SUNDAY...OR EVEN ABOVE. SOME OF THE LONG-TERM GUIDANCE ALSO SUGGESTS
THAT THE MID-LEVEL SHEAR AXIS REMAINS OVER CENTRAL NORTH CAROLINA
DURING THE DAY. FOR THIS FORECAST WILL ADD A SLIGHT CHANCE OF A
SHOWER OR THUNDERSTORM THROUGHOUT CENTRAL NORTH CAROLINA SUNDAY
AFTERNOON BASED ON THE LATEST MODEL TRENDS.

THERE SHOULD DEVELOP A WEAKNESS IN THE MID-LEVEL RIDGE BY TUESDAY...
LIKELY DUE TO MID-LEVEL LOW PRESSURE MOVING ACROSS THE GREAT LAKES
AND SOUTHEAST CANADA FLATTENING THAT RIDGE. AIDED BY THE PIEDMONT
TROUGH AND SLIGHT STEEPENING OF LAPSE RATES ON COARSE MODEL
SOUNDINGS...ALONG WITH DECENT MOISTURE IN PLACE AS PRECIPITABLE
WATER VALUES ARE FORECAST BETWEEN 1.75 INCHES AND 2 INCHES...
ANTICIPATE AT LEAST ISOLATED TO SCATTERED MAINLY AFTERNOON AND
EVENING SHOWERS AND THUNDERSTORMS FROM MONDAY THROUGH WEDNESDAY. MOS
AND WPC GUIDANCE TEMPERATURES ARE VERY CLOSE TO EXPECTED HIGHS BASED
ON 1000-850MB THICKNESSES...MID TO UPPER 80S SUNDAY AND WITHIN A
DEGREE OR THREE OF 90 MONDAY THROUGH WEDNESDAY. OVERNIGHT LOWS IN
THE MID TO UPPER 60S SATURDAY NIGHT...AND OTHERWISE MOSTLY AROUND
70.


&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AS OF 825 PM WEDNESDAY...

24 HOUR TAF PERIOD: HIGH CONFIDENCE OF VFR CONDITIONS THROUGH
MIDNIGHT...WITH THE POTENTIAL FOR SOME MVFR/IFR VISBYS AND CIGS IN
THE PRE-DAWN HOURS...MAINLY FROM 08Z-12Z. THE RESULT OF NE FLOW
ADVECTING MOIST AIR INTO THE BOUNDARY LAYER WILL LIKELY BE LOW
STRATUS AS WINDS SHOULD STAY UP ENOUGH OVERNIGHT TO KEEP FOG
DEVELOPMENT AT BAY. CONFIDENCE IN THE REDUCED CIGS IS STILL MARGINAL
AT THIS TIME...BUT WITH THE GUIDANCE SPLIT WILL KEEP IT IN FOR NOW.
AFTER SUNRISE ANY LOW STRATUS THAT HAS DEVELOPED SHOULD LIFT...WITH
HIGH CONFIDENCE FOR VFR CONDITIONS THROUGH THE REMAINDER OF THE TAF
PERIOD. -KC

LOOKING AHEAD: GENERALLY VFR CONDITIONS WILL REMAIN IN PLACE AS A
RIDGE BUILDS OVER THE AREA. THERE IS THE POTENTIAL FOR FOG OR LOW
STRATUS IN THE MORNING FRI AND SAT... AS WINDS REMAIN NE TO E. -SEC

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SYNOPSIS...SEC/PWB
NEAR TERM...SEC/PWB
SHORT TERM...SEC
LONG TERM...DJF
AVIATION...KC/SEC