Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 222352 RRA
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
752 PM EDT FRI AUG 22 2014

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

&&

.NEAR TERM /OVERNIGHT/...
AS OF 745 PM FRIDAY...

EARLIER SMALL CLUSTERS OF THUNDERSTORMS HAVE MOVED SE OF OUR REGION
THIS EVENING. THE ACTIVITY UPWIND APPEARS TO BE DISSIPATING AS IT
COMES OVER THE HIGHER TERRAIN IN SW VA/WVA. CONVECTIVE PARAMETERS
OVER CENTRAL NC ARE NOT FAVORABLE FOR ADDITIONAL DEVELOPMENT OTHER
THAN ON AN ISOLATED BASIS. CONVECTION UPWIND SHOULD ALSO DISSIPATE
AS IT MOVES EAST OF THE MOUNTAINS THIS EVENING AND OVERNIGHT.
THEREFORE... WE WILL LOWER POP TO A SLIGHT (15-20) PERCENT CHANCE
FOR ANY ONE GIVEN SPOT FOR 0.01 OVERNIGHT. OTHERWISE... 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 /00Z SATURDAY THROUGH WEDNESDAY/...
AS OF 735 PM FRIDAY...

24-HR TAF PERIOD: SCATTERED CONVECTION WILL PASS WITHIN 5-15 MILES
OF THE FAY TERMINAL THROUGH 00Z. CONVECTION UPSTREAM OVER SOUTHERN
WV AND SOUTHWEST VA AT 23Z WILL TRACK SOUTHEAST TOWARD THE INT/GSO
TERMINALS THROUGH THE REMAINDER OF THE EVENING...THOUGH THIS
ACTIVITY MAY WEAKEN OR ALTOGETHER DISSIPATE PRIOR TO REACHING THE
TRIAD. ISOLD SHOWER ACTIVITY WILL REMAIN POSSIBLE AT ANY TERMINAL
OVERNIGHT...THOUGH CONFIDENCE IS TOO LOW TO WARRANT ANY MENTION.
PATCHY FOG AND/OR LOW CEILINGS WILL BE POSSIBLE AT ANY TERMINAL IF
CLOUD COVER THINS OUT FOR SEVERAL HOURS PRIOR TO SUNRISE. WILL
MENTION FOG DEVELOPING AT THE MORE CLIMATOLOGICALLY LIKELY FAY/RWI
TERMINALS IN THE 07-12Z TIME FRAME.

LOOKING AHEAD: GREATER CONVECTIVE COVERAGE IS EXPECTED ON SATURDAY
AS A SERIES OF UPPER LEVEL DISTURBANCES TRACK S/SSE ACROSS THE
CAROLINAS AND A BACK DOOR COLD FRONT PROGRESSES INTO CENTRAL NC FROM
THE N/NE. IFR CEILINGS WILL BE POSSIBLE IN THE WAKE OF THE BACKDOOR
COLD FRONT SAT NIGHT THROUGH MID-DAY SUNDAY...THOUGH COVERAGE AND
DURATION REMAIN 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). -VINCENT

&&

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

&&

$$

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


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