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[Printable]
141
FXUS62 KRAH 302352 RRA
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
752 PM EDT SAT AUG 30 2014

.SYNOPSIS...DEEP HIGH PRESSURE WILL EXTEND OVER THE REGION THROUGH
THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 740 PM SATURDAY...

THE LATEST SURFACE ANALYSIS SHOWED A SLACK GRADIENT OVER CENTRAL
NORTH CAROLINA. RADAR IMAGERY SHOWED THE SEA BREEZE HAD MOVED WELL
INLAND...MOVING NORTH THROUGH THE TRIANGLE AND HEADED TOWARD
INTERSTATE 40/85. THE SPC MESOANALYSIS SHOWED MLCAPE AROUND
1500J/KG...THOUGH DESPITE THE INSTABILITY SHEAR WAS VERY WEAK AND
THERE WAS JUST ENOUGH LIFT TO PRODUCE ISOLATED SHOWERS. TOTAL LIFT
AND CONVECTIVE DEVELOPMENT COULD ALSO BE FURTHER INHIBITED BY AN
AXIS OF VERY DRY MID-LEVEL AIR NOTED ON WATER VAPOR OVER CENTRAL
NORTH CAROLINA. DIURNALLY...THE SHOWERS SHOULD DIMINISH THIS EVENING
ESPECIALLY AS AN AXIS OF LOWER PRECIPITABLE WATER VALUES...NEAR
NORMAL AT ABOUT 1.3 INCHES...IS FORECAST BY THE RAP TO MOVE EAST
FROM THE FOOTHILLS AND FAR WESTERN PIEDMONT OVERNIGHT...WITH K
INDICES FALLING INTO THE TEENS AS BUFR SOUNDINGS FROM THE GFS AND
NAM ALONG WITH RAP SOUNDINGS SHOW AN OVERALL STABLE AIR MASS THEN.

OVERNIGHT LOW TEMPERATURES HAVE WARMED ON THE MAV MOS GUIDANCE FROM
12Z TO 18Z...CLOSER TO THE MET MOS GUIDANCE WHICH HAS APPARENTLY
PERFORMED A LITTLE BETTER OVER THE LAST DAY OR TWO. STILL...THE
BASIC FORECAST FOR MINIMUM TEMPERATURES REMAINS THE SAME...MOSTLY
WITHIN A DEGREE OR TWO OF 70. SOME LOW CLOUDS ARE POSSIBLE LATE
TONIGHT PARTICULARLY AS NOTED ON NAM BUFR SOUNDINGS AND THE SREF
PROBABILISTIC GUIDANCE...AND ALLUDED TO MORE ON THE GFS 18Z MOS
GUIDANCE OUTPUT FROM ITS EARLIER...MORE OPTIMISTIC 12Z GUIDANCE.
925MB WINDS SEEM A LITTLE HIGH FOR FOG IN MOST PLACES...TO 20KT
TOWARD THE TRIAD LATE TONIGHT...BUT THE LOWER VALUES OF 10 TO 15KT
TOWARD INTERSTATE 95 ALONG WITH EXPECTED DEW POINTS IN THE LOWER 70S
COULD ALLOW A LITTLE MORE NOTICEABLE FOG IN PATCHES TOWARD THERE
LATE.

&&

.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
AS OF 230 PM SATURDAY...

A SHORT WAVE TROUGH OVER THE MS RIVER VALLEY TO START THE DAY WILL
LIFT TO THE NORTHEAST INTO THE OH VALLEY THROUGH SUNDAY NIGHT.
HOWEVER...ITS ASSOCIATED ENERGY AND DEEP MOISTURE PLUME (EMANATING
FROM THE GULF) WILL LARGELY REMAIN WEST AND NORTH OF CENTRAL NC. IN
ADDITION...THE SUBTROPICAL RIDGE CENTERED OVER THE SOUTHEAST COAST
SHOULD ALSO HELP KEEP THE BETTER RAIN CHANCES WEST OF THE AREA.
THEREFORE...WILL CONTINUE THE FORECAST THINKING OF ONLY ISOLATED TO
WIDELY SCATTERED SHOWERS/STORMS...WITH THE BEST CHANCES ACROSS THE
WEST DUE TO THE PROXIMITY OF THE ABOVE FEATURES. TEMPS WILL CONTINUE
TO BE ABOVE NORMAL...WITH HIGHS GENERALLY IN THE LOWER 90S AND
OVERNIGHT LOWS AROUND 70 DEGREES.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
AS OF 200 PM SATURDAY...

WITH ROUGHLY 3 WEEKS OF SUMMER REMAINING (AUTUMN EQUINOX IS SEPT
23)...THE WESTWARD EXPANSION OF THE SUBTROPICAL RIDGE ACROSS MUCH OF
THE SOUTHERN CONUS...WITH THE MAIN BELT OF WESTERLIES RETREATING
NORTHWARD ALONG THE US-CANADA BORDER WILL RESULT IN THE FIRST
PROLONGED PERIOD OF SUMMERTIME HEAT AND CONVECTIVE RAIN CHANCES THAT
CENTRAL NC HAS SEEN THIS SEASON. AFTERNOON THICKNESSES ARE PROGGED
TO RUN 25 TO 30 METERS ABOVE CLIMATOLOGY...WHICH SHOULD SUPPORT
DAYTIME HIGHS RANGING FROM 90 TO 95F WITH LOWS IN THE UPPER 68 TO
74F.

A LOW AMPLITUDE TROUGH MOVING EASTWARD ACROSS THE NORTHEAST AND MID-
ATLANTIC STATES WILL TEMPORARILY FLATTEN THE UPPER ANTICYCLONE LONG
ENOUGH TO ALLOW A WEAK SURFACE FRONT TO APPROACH NC FROM THE
NORTH...BUT RECENT MODEL TRENDS OVER THE LAST COUPLE OF DAYS REALLY
WASHES OUT THE FRONT TO OUR NORTH DURING THE LATE WEDNESDAY/THURSDAY
PERIOD. AS SUCH...GRIDDED DATABASE WILL CONTINUE TO EXHIBIT
DIURNALLY DRIVEN CONVECTION ISOLATED TO WIDELY SCATTERED STORMS EACH
AFTERNOON...FIRING WITHIN A MODERATELY UNSTABLE AIRMASS ALONG A LEE
SIDE SURFACE TROUGH.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
AS OF 751 PM SATURDAY...

VFR CONDITIONS WILL CONTINUE THROUGH THE EVENING. LOW LEVEL MOISTURE
REMAINS HIGH ACROSS THE AREA WITH LIGHT SURFACE WINDS... AND IFR
CONDITIONS WITH STRATUS... AND POSSIBLY SOME PATCHY FOG.... ARE
EXPECTED TO DEVELOP IN THE EARLY MORNING HOURS SUNDAY AT
KRDU...KRWI...AND KFAY... WHERE DEWPOINTS ARE HIGHEST. MVFR
CONDITIONS ARE POSSIBLE AT KGSO AND KINT. CONDITIONS WILL RETURN TO
VFR AFTER 12Z SUNDAY... WITH A FEW SHOWERS/THUNDERSTORMS POSSIBLE IN
THE AFTERNOON.

OUTLOOK...A SUMMERTIME PATTERN WILL PERSIST THROUGH EARLY/MID NEXT
WEEK...WITH ISOLATED TO SCATTERED AFTERNOON/EVENING CONVECTION AND A
POTENTIAL FOR EARLY MORNING FOG/STRATUS.

&&

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

&&

$$

SYNOPSIS...GIH
NEAR TERM...DJF
SHORT TERM...KRD
LONG TERM...CBL
AVIATION...SEC/KRD




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