Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 300551
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
150 AM EDT SUN AUG 30 2015

.SYNOPSIS...WEAK SURFACE HIGH PRESSURE WILL REMAIN OVER THE AREA
THROUGH EARLY NEXT WEEK. IN THE MEANTIME...AN UPPER LEVEL
DISTURBANCE WILL TRACK NORTH FROM THE NORTHERN GULF OF MEXICO AND
WILL CROSS THE WESTERN CAROLINAS LATE TONIGHT AND MONDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 945 PM SATURDAY...

THE ATMOSPHERE HAS SLOWLY BEEN MOISTENING UP IN THE PAST 24 HOURS.
HOWEVER... THERE WAS STILL A LOT OF DRY AIR AT SEVERAL LEVELS NOTED
ON THE AREA RAOBS THIS EVENING. THE SURFACE CONTINUED TO BE DRY WITH
DEW POINTS STILL IN THE MID 50S TO A FEW MID 60S SE (WELL BELOW
CLIMATOLOGY FOR LATE AUGUST). THE SURFACE HIGH PRESSURE WAS OVERHEAD
AND THIS HAS BEEN PREVENTING A RAPID RETURN OF LOW LEVEL MOISTURE.
SATELLITE DATA INDICATED MOSTLY CLOUDY SKIES MOST OF THE CLOUDINESS
OF THE CIRRUS VARIETY. THE TEMPERATURES WERE GENERALLY ABOUT WHERE
THERE WERE 24 HOURS AGO AT THIS TIME (MID 60S TO LOWER 70S). RADAR
INDICATED ONLY A FEW VERY PATCHY REFLECTIVITY RETURNS FROM THE MID
LEVELS. THE CLOSEST MEASURABLE SHOWERS HAVE BEEN CONFINED TO AREAS
SOUTH OF AUGUSTA GEORGIA.

ESSENTIALLY NO CHANGES WERE NEEDED THROUGH THE OVERNIGHT AS THE
MID/UPPER LOW NEAR THE FLORIDA PANHANDLE SLOWLY DRIFTS NORTHWARD.
OUR REGION SHOULD CONTINUE TO SEE PLENTY OF MOSTLY HIGH CLOUDINESS
UNTIL ADDITIONAL MOISTENING IN THE MID LEVELS INCREASES SUNDAY.
EXPECT PARTLY TO MOSTLY CLOUDY SKIES WITH LOWS MOSTLY 60-65 WITH
SOME 50S IN THE RURAL AREAS.

&&

.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
AS OF 300 PM SATURDAY...

THE GFS AND NAM ARE FAIRLY SIMILAR ON THE OVERALL EVOLUTION OF
SYNOPTIC FEATURES...WITH A WEAKENING UPPER-LEVEL LOW MOVING NORTH
FROM THE GULF INTO AND THROUGH THE WESTERN CAROLINAS...WHILE HIGH
PRESSURE REMAINS IN PLACE AT THE SURFACE. OVERALL MOISTENING OF THE
AIR MASS CONTINUES...AND BY 00Z MONDAY PRECIPITABLE WATER VALUES
SHOULD RANGE FROM 1.5 INCHES IN THE FAR WESTERN PIEDMONT TO JUST
OVER 1.75 INCHES TOWARD INTERSTATE 95. THE 850MB THETA-E TROUGH OVER
CENTRAL NORTH CAROLINA OVERNIGHT SLOWLY RETREATS NORTH AND
NORTHEAST...WITH K INDICES FINALLY ABOVE 30 THROUGHOUT CENTRAL NORTH
CAROLINA BY SUNDAY NIGHT WHEN A 55 TO 60KT 300MB JET MAXIMUM MOVES
OVER THE AREA COUPLED WITH THE LEFT EXIT REGION OF A 35KT 500MB
JETLET.

DESPITE THE AIR MASS MOISTENING AND THE APPROACH AND PASSAGE OF MID-
LEVEL VORTICITY ALONG AND AHEAD OF THE WEAKENING UPPER LOW...THE
PRESENCE OF SURFACE HIGH PRESSURE RESULTS IN LIMITED LIFT...AND THE
BROAD...RELATIVELY WEAK LIFT WILL HAVE TO OVERCOME THE INITIAL LOW-
LEVEL DRY AIR TO GENERATE ANY PRECIPITATION. THROUGH 18Z SUNDAY
BOTH THE NAM AND THE GFS HAVE ESSENTIALLY NO QPF IN CENTRAL NORTH
CAROLINA. THERE COULD BE PATCHY SPRINKLES BEFORE THEN...BUT BUFR
SOUNDINGS AND PLAN VIEW 700MB MOISTURE FIELDS SHOW THE 700MB LAYER
MOISTENING GRADUALLY SUNDAY MORNING AND SUNDAY AFTERNOON. BY 00Z
MONDAY THE NAM HAS MEASURABLE PRECIPITATION...WITH A SLIGHTLY FASTER
APPROACH OF THE UPPER LOW...ALONG AND SOUTH OF A LINE FROM ABOUT
KAFP TO KRWI...WHILE THE GFS IS DRY. IN GENERAL THINK THERE MAY BE
JUST ENOUGH LIFT SUNDAY AFTERNOON IN THE MID- AND UPPER-LEVELS AS
THOSE LEVELS MOISTEN WITH THE APPROACH OF THE WEAKENING UPPER LOW TO
PROVIDE FOR A SMALL CHANCE OF A SHOWER MAINLY OVER THE SANDHILLS AND
SOUTHERN COASTAL PLAIN WITH A CHANCE OF SPRINKLES FARTHER NORTH.

FOR SUNDAY NIGHT...WEAK DIFFLUENCE AND LIFT ARE FORECAST OVER
CENTRAL NORTH CAROLINA WITH MOST MOS GUIDANCE POPS IN THE CHANCE
CATEGORY. FOR THIS FORECAST...WILL BLEND THE GFS AND NAM OUTPUT IN
THE GRIDDED FORECAST WITH HIGHER CHANCE POPS ALONG AND SOUTH OF A
LINE FROM ABOUT KVUJ TO KRWI...LOW CHANCES NORTH OF THERE. PROS FOR
SOME MEASURABLE PRECIPITATION ARE THE MID- AND UPPER-LEVEL SUPPORT
AND THE AVAILABLE MOISTURE. CONS ARE THE SURFACE HIGH PRESSURE AND
CONCERNS OVER HOW FAST THE LOW-LEVELS ARE ABLE TO MOISTEN. SOME
CONVECTIVE ALLOWING MODELS SHOW HARDLY ANY PRECIPITATION AT ALL...
AND WHERE THERE IS QPF ON THE GFS AND NAM IT IS MOSTLY PRETTY LIGHT.
WHERE RAIN IS ABLE TO OCCUR...IF IT IS ABLE...AMOUNTS SHOULD BE
LIGHT. BUFR SOUNDINGS SEEM TO INDICATE AN AIR MASS CAPPED FOR
THUNDER SO WILL JUST NOTE SHOWERS FOR NOW...ALTHOUGH THE GFS DOES
FORECAST ABOUT 100-200J/KG OF MARGINAL CAPE OVERNIGHT SUNDAY. HIGHS
SUNDAY 84 TO 88. OVERNIGHT LOWS SUNDAY NIGHT IN THE MID TO UPPER
60S.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
AS OF 300 PM SATURDAY...

A SHORTWAVE TROUGH THAT WILL HAVE ORIGINATED FROM THE NORTHERN GULF
OF MEXICO IS PROGGED TO CONTINUE ITS TREK INTO THE MID ATLANTIC ON
MONDAY. SCATTERED SHOWERS AND STORMS WILL BE POSSIBLE (BEST CHANCES
SHIFTING EAST THROUGHOUT THE DAY) AS THIS FEATURE GRADUALLY GETS
PICKED UP AND MOVED OUT OF THE AREA AS A STRONGER MID LEVEL TROUGH
TRACKS OVER THE NORTHEAST US/SOUTHEAST CANADA.

THEN FOR EARLY/MID NEXT WEEK...THE SUBTROPICAL RIDGE IS PROGGED TO
EXPAND WESTWARD TOWARDS THE SOUTHEAST COAST. IN ADDITION ANOTHER
UPPER LEVEL RIDGE WILL SHIFT OVER THE UPPER MIDWEST/GREAT LAKES
REGION. THE COMBINATION OF THESE TWO FEATURES WILL PROVIDE LITTLE IN
THE WAY OF FORCING FOR PRECIP. IN ADDITION...ERIKA HAS WEAKENED INTO
A TROUGH OF LOW PRESSURE AND ONLY HAS A SMALL CHANCE OF REDEVELOPING
INTO A TROPICAL CYCLONE AS IT REEMERGES AND MOVES OVER THE EASTERN
GULF SUNDAY INTO MONDAY. THEREFORE...IT NOW APPEARS THAT ERIKA IS
LOOKING TO BEST LESS AND LESS A FACTOR IN OUR WEATHER...ALTHOUGH
RICH TROPICAL MOISTURE MAY STILL BE DRAWN UP TOWARDS OUR REGION
(ESPECIALLY IN THE SOUTHERN AND EASTERN PORTIONS OF THE FORECAST
AREA)...PROVIDING A CHANCE FOR SCATTERED TO WIDELY SCATTERED (MOSTLY
DIURNAL) SHOWERS AND STORMS EACH DAY. THE PATTERN WILL BEGIN TO
SHIFT SOME TOWARDS THE END OF THE WEEK AS THE RIDGE GETS SUPPRESSED
WHILE A SHORTWAVE TROUGH TRACKS ACROSS THE NORTHEAST...PUTTING
CENTRAL NC UNDER NORTHWESTERLY FLOW ALOFT. REGARDLESS...PRECIP
CHANCES ARE EXPECTED TO BE NEAR TO SLIGHTLY ABOVE CLIMATOLOGY
THROUGH THE REMAINDER OF THE EXTENDED AS IT IS HARD TO FAVOR ONE DAY
OVER ANOTHER. TEMPS WILL ALSO BE NEAR CLIMO.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AS OF 150 AM SUNDAY...

VFR CONDITIONS WILL PREVAIL THROUGH SUNDAY EVENING/EARLY MONDAY AS
SFC HIGH PRESSURE PERSISTS OVER THE REGION. A WEAKENING UPPER-LEVEL
LOW...CURRENTLY OVER THE NORTHERN GULF OF MEXICO...WILL TRACK NORTH
AND OVER THE WESTERN CAROLINAS LATE TONIGHT/EARLY MONDAY. TOP-DOWN
MOISTENING IS EXPECTED IN ADVANCE OF THIS FEATURE WITH RAIN/SHOWER
CHANCES INCREASING FROM THE SOUTH BETWEEN 06 TO 12Z MONDAY. COULD
SEE SOME MVFR CONDITIONS WITHIN THE HEAVIER SHOWERS...OTHERWISE....
EXPECT MOSTLY LOW END VFR CEILINGS.

SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE MONDAY AFTERNOON AND EVENING AS THE AFOREMENTIONED UPPER
LEVEL DISTURBANCE MOVES THROUGH THE AREA. THEN THROUGH THE REMAINDER
OF THE WEEK...SCATTERED SHOWERS AND THUNDERSTORMS WITH THEIR
ASSOCIATED SUB-VFR CONDITIONS WILL BE POSSIBLE EACH DAY...ALONG WITH
THE POTENTIAL OF LATE NIGHT AND EARLY MORNING AREAS OF LOW CLOUDS
AND FOG.

&&

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

&&

$$

SYNOPSIS...DJF
NEAR TERM...DJF/BADGETT
SHORT TERM...DJF
LONG TERM...KRD
AVIATION...CBL



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