Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 230559
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
159 AM EDT SAT AUG 23 2014

.SYNOPSIS...A COLD FRONT WILL MOVE SOUTH THROUGH THE STATE SATURDAY
NIGHT INTO SUNDAY. HIGH PRESSURE WILL THEN BUILD SOUTH INTO THE
REGION FOR EARLY NEXT WEEK.

&&

.NEAR TERM /OVERNIGHT/...
AS OF 1020 PM FRIDAY...

THE LATEST DATA ANALYSIS INDICATED AN UPTICK IN THE SURFACE MOISTURE
FLUX CONVERGENCE OVER WEST CENTRAL NC IN THE VICINITY OF STATESVILLE
AND SALISBURY. THE SURFACE ANALYSIS ALSO INDICATED A WEAK LOW
PRESSURE HAD FORMED JUST SE OF HICKORY. ENERGY IN THE NW FLOW ALOFT
CONTINUED TO LIFT OVER THE CENTRAL AND SOUTHERN APPALACHIANS... WITH
MOST OF THE CONVECTION AFFECTING THE WINDWARD SIDE OF THE MOUNTAINS
IN THE NW FLOW. HOWEVER... WITH CONVERGENCE AND LIFT NOW DEVELOPING
OUT OVER THE WESTERN PIEDMONT AND THE INCREASING LOW LEVEL MOISTURE
(DEW POINTS IN THE MID 70S TO NEAR CLT)... WE WILL PLACE CHANCE POP
OVERNIGHT ALONG AND SOUTHWARD DOWN THE YADKIN RIVER... EXTENDING
EASTWARD INTO THE SOUTHERN PIEDMONT AND SANDHILLS. OTHERWISE... NO
CHANGES TO THE FORECAST UPDATE FROM EARLIER... PARTLY TO MOSTLY
CLOUDY WITH PLENTY OF MID AND HIGH RESIDUAL CONVECTIVE DEBRIS
CLOUDINESS FROM UPWIND CONVECTION. LOWS 68-73.

&&

.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
AS OF 220 PM FRIDAY...

A WEAK BOUNDARY...POTENTIALLY OUTFLOW INDUCED...FORECAST TO MOVE
INTO THE AREA TONIGHT WILL SETTLE ACROSS THE SOUTHERN PORTIONS OF THE
AREA...WHILE THE TRUE COLD FRONT REMAINS TO OUR NORTHEAST.  AHEAD OF
THE FRONT...H85 TEMPS REMAIN ABOVE 18C...THOUGH MIXING SHOULD STOP
SHORT OF THAT LEVEL WITH PW NEAR 2 INCHES. PERIODS OF HIGH CLOUDS IN
NORTHWEST FLOW ALOFT SHOULD ALSO TEMPER HIGHS A BIT...ESPECIALLY
ACROSS THE NORTHEAST AS THE FRONT BEGINS TO PUSH INTO THE AREA LATE
IN THE DAY.  COOLER GUIDANCE GIVES A WIDE RANGE OF TEMPS FROM LOWER
90S SOUTHWEST TO MID 80S NORTHEAST.  DUE TO THIS...INSTABILITY WILL
BE GREATEST ACROSS THE SOUTHEAST...WITH MARGINALLY STRONGER SHEAR
BACK TO THE NORTHEASTER CLOSER TO THE FRONTAL ZONE.  THERE IS STILL
THE POTENTIAL FOR ANOTHER DISTURBANCE TO APPROACH FROM THE
NORTHEAST...WHICH COMBINED WITH INCREASINGLY CONVERGENT LOW LEVEL
FLOW AND HIGH PW...SHOULD LEAD TO A BETTER CHANCE OF SHOWERS
AREAWIDE.

THE BACKDOOR COLD FRONT WILL MAKE ITS WAY INTO THE AREA LATE
SATURDAY AND OVERNIGHT...WITH DRYING ALOFT BEHIND THE FRONT ZONE.
MOIST NORTHEASTERLY FLOW WILL LIKELY LEAD TO FAIRLY WIDESPREAD
STRATUS...AND POSSIBLY A FEW LIGHT SHOWERS AS A SHORTWAVE ROTATES
SOUTH ACROSS THE AREA.  LOWS WILL BE IN THE UPPER 60S NORTHEAST TO
LOWER 70S SOUTHWEST.

SATURDAY AND SATURDAY NIGHT: HIGH PRESSURE OVER NEW ENGLAND WILL
BEGIN TO RIDGE SOUTH DOWN THE MID-ATLANTIC SEABOARD WHICH SHOULD
PUSH THE BACK-DOOR FRONT SLOWLY SOUTH INTO THE AREA ON SATURDAY. AS
USUAL...TIMING OF THESE BACK-DOOR FRONTS THIS TIME OF YEAR IS
SUSPECT(USUALLY SLOWER IS BETTER)...WITH DIURNAL HEATING AND
RESULTANT DESTABILIZATION AIDING IN SCATTERED COVERAGE. THE LATE
ARRIVAL OF A SHORTWAVE TROUGH ROTATING SOUTHWARD DOWN THE BACK-SIDE
OF THE UPPER TROUGH SATURDAY NIGHT MAY EVEN SUPPORT A FEW ANAFRONTAL
SHOWERS OVERNIGHT.

COOLER ON SATURDAY WITH CLOUDS AND NELY FLOW NORTH OF THE FRONT.
HIGHS RANGING FROM LOWER/MID 80S NORTH TO LOWER 90S SOUTH. LOWS
SATURDAY NIGHT IN THE UPPER 60S TO LOWER 70S.

SUNDAY AND SUNDAY NIGHT: AS THE UPPER AIR PATTERN AMPLIFIES (RIDGE
BUILDING OVER THE MISSISSIPPI RIVER VALLEY...TROUGH DEEPENING ACROSS
THE WESTERN ATLANTIC) ON SUNDAY...CENTRAL NC WILL BE UNDER
NORTHWEST/NORTHERLY FLOW ALOFT. AT THE SURFACE...A COLD FRONT WILL
BE SHUNTED SOUTH OF THE REGION AS HIGH PRESSURE BEGINS TO RIDGE DOWN
FROM THE NORTHEAST. AS THIS OCCURS...DRIER AIR WILL FILTER INTO THE
REGION THROUGHOUT THE DAY...BUT SOME DEEP MOISTURE WILL REMAIN IN
PLACE...MOSTLY ACROSS THE SOUTH AND WEST WHERE PWAT VALUES ARE
PROGGED TO HOVER BETWEEN 1.5-1.75 INCHES THROUGH SUNDAY NIGHT. GIVEN
THIS AND THE LINGERING FRONT...AND THE POSSIBILITY OF ANY WEAK
DISTURBANCES MOVING OVER THE AREA WITHIN THE NORTHWESTERLY FLOW
ALOFT...WILL MAINTAIN SLIGHT CHANCE TO CHANCE POPS...HIGHEST ACROSS
THE SOUTH AND WEST. IN FACT...NORTHEASTERN PORTIONS OF THE FORECAST
AREA MAY STAY DRY. TEMPS WILL RANGE FROM NEAR 80 DEGREES TO THE MID
80S...WITH OVERNIGHT LOWS GENERALLY IN THE MID 60S.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
AS OF 1250 PM FRIDAY...

AN AMPLIFIED UPPER PATTERN WILL PERSIST THROUGH EARLY NEXT WEEK...
WITH AN UPPER RIDGE GRADUALLY BUILDING EAST TOWARDS THE REGION. A
COLD FRONT WILL BE SUPPRESSED SOUTH OF THE AREA BY LATE SUNDAY AS
DRY AND COOLER SURFACE HIGH PRESSURE BECOMES FIRMLY ENTRENCHED
DOWN THE ATLANTIC COAST. THERE WILL BE A LINGERING CHANCE OF SHOWERS
SUNDAY AS THE FRONT SURGES SOUTH...FOLLOWED BY DRY CONDITIONS
THROUGH THURSDAY. THE UPPER RIDGE WILL DEAMPLIFY/FLATTEN OUT AS THE
NEXT UPPER TROUGH AND ASSOCIATED SURFACE FRONT APPROACHES THE AREA
LATE THURSDAY INTO FRIDAY...BRINGING INCREASING PRECIPITATION
CHANCES BY THE END OF THE WEEK.

POST FRONTAL CONDITIONS WILL BE PLEASANT...WITH CONSIDERABLY COOLER
TEMPERATURES AND LOWER HUMIDITY. LOW LEVEL THICKNESS VALUES WILL
FALL THROUGH EARLY NEXT WEEK...TO THE TUNE OF 30 METERS EQUATING TO
AROUND A 10 DEGREE COOL OFF. HIGHS SUNDAY THROUGH TUESDAY WILL BE
WELL BELOW...5-7 DEGREES...NORMAL WITH UPPER 70S TO LOWER 80S OVER
ALL BUT THE FAR SOUTHERN TIER WHICH MAY SEE MID 80S. TEMPS WILL BEGIN
TO MODERATE WEDNESDAY THROUGH FRIDAY AS THE UPPER RIDGE SHIFTS EAST...
WITH MID/UPPER 80S EXPECTED BY THE END OF THE WEEK. OVERNIGHT LOWS
WILL FOLLOW THE SAME PATTERN...WITH MOSTLY LOW TO MID 60S EARLY
NEXT WEEK WARMING TO MID AND UPPER 60S BY LATE WEEK.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 155 AM SATURDAY...

24-HR TAF PERIOD: ISOLATED TO WIDELY SCATTERED SHOWERS CONTINUE TO
MOVE THROUGH CENTRAL NC THIS MORNING... WITH THE STRONGEST
CONVECTION LOCATED ACROSS WESTERN AND SOUTHERN PORTIONS OF THE AREA.
THUS... EXPECT KFAY/KGSO/KINT WILL HAVE THE BEST CHANCE AT SEEING
SOME CONVECTION OVER THE NEXT SEVERAL HOURS. HOWEVER... KRDU AND
KRWI COULD SEE SOME OF THIS ACTIVITY TOO... BUT MORE IN THE 08/09Z
TO 13Z TIME FRAME. IFR/MVFR CONDITIONS WILL BE POSSIBLE WITH ANY
SHOWERS AND/OR STORM THIS MORNING. GIVEN THE SUBTLE DISTURBANCES
ALOFT MOVING ACROSS THE REGION... SKIES HAVE GENERALLY REMAINED
MOSTLY CLOUDY TO OVERCAST (VFR THOUGH... LOTS OF MID AND HIGH
CLOUDS). THUS... WE HAVE SEEN LESS IN THE WAY OF SUB-VFR VISBYS/CIGS
DEVELOP THIS MORNING. STILL THINK THE BEST CHANCE OF SEEING SOME SUB-
VFR CONDITIONS WILL BE AT KRWI. THUS... WILL STILL SHOW SOME SUB-VFR
CONDITIONS POSSIBLE... MAINLY DURING THE PRE-DAWN HOURS THIS MORNING
AT KRWI.

GREATER CONVECTIVE COVERAGE IS EXPECTED LATER THIS MORNING INTO THE
AFTERNOON AS A SERIES OF UPPER LEVEL DISTURBANCES TRACK S/SSE ACROSS
THE CAROLINAS AND A BACK DOOR COLD FRONT/PRE-FRONTAL TROUGH
PROGRESSES TOWARDS CENTRAL NC FROM THE N/NE. THUS... WILL ADD A PROB-
30 GROUP TO THE TAFS FOR STORMS THIS AFTERNOON INTO THE EARLY
EVENING AT ALL TAF SITES.

OUTLOOK: IFR CEILINGS WILL BE POSSIBLE IN THE WAKE OF THE BACKDOOR
COLD FRONT TONIGHT THROUGH MID-DAY SUNDAY...THOUGH COVERAGE AND
DURATION REMAIN A BIT UNCERTAIN. AN UPPER LEVEL RIDGE CENTERED IN
VICINITY OF THE SOUTHERN APPALACHIANS SHOULD RESULT IN BETTER-THAN-
NORMAL CHANCES FOR VFR CONDITIONS MON-WED...THOUGH A PERSISTENT E/NE
LOW-LEVEL FLOW MAY ALLOW ADEQUATE MOISTURE FOR LOW-TOPPED SHOWER
ACTIVITY...ESP AT THE EASTERN TERMINALS (FAY/RWI).

&&

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

&&

$$

SYNOPSIS...BSD/PWB
NEAR TERM...PWB
SHORT TERM...BLS
LONG TERM...MLM
AVIATION...BSD/VINCENT


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