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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 230640
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
240 AM EDT WED JUL 23 2014

.SYNOPSIS...ATLANTIC HIGH PRESSURE WILL EXTEND WESTWARD OVER THE
CAROLINAS TODAY. A COLD FRONT WILL APPROACH FROM THE NORTHWEST
TONIGHT... THEN PUSH SOUTHEAST THROUGH NORTH CAROLINA THURSDAY AND
THURSDAY NIGHT. WEAK HIGH PRESSURE WILL PUSH IN FROM THE NORTH ON
FRIDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 824 PM TUESDAY...

ISOLATED SHOWERS HAVE GENERALLY DIED OFF IN THE PAST HOUR WITH THE
EXCEPTION OF THE SANDHILLS AND SOUTHERN COASTAL PLAIN REGION WHERE
SCATTERED SHOWERS AND THUNDERSTORMS CONTINUED AT MID EVENING. THE
THUNDERSTORMS HAVE VERY SMALL CORES WITH SOME LOCALLY INTENSE
RAINFALL. EVEN WITH THE SLOW MOVEMENT OF THESE STORMS... ONLY VERY
LOCALIZED DOWNPOURS WERE OCCURRING WITH NO REPORTED RUNOFF PROBLEMS
YET. THE AREAS AFFECTED EXTEND FROM NEAR SOUTHERN PINES TO
FAYETTEVILLE AND FORT BRAGG EAST TO NEAR CLINTON. IT APPEARS THAT
THESE STORMS ARE AGAIN LARGELY DIURNALLY DRIVEN. EXPECT THAT WITH
INCREASING CINH IN THE NEXT FEW HOURS... THEY WILL DIE OFF QUICKLY
AS WELL. OTHERWISE... THE ISOLATED SHOWERS WILL DIMINISH AS WELL.
THIS SHOULD LEAVE MOSTLY CLEAR TO PARTLY CLOUDY SKIES OVERNIGHT.
LOWS GENERALLY 68-73 N TO SE.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 245 PM TUESDAY...

ON WEDNESDAY...LOOKS LIKE MORE OF A CONVENTIONAL SUMMERTIME
CONVECTIVE PATTERN WITH SOUTHWEST TO WESTERLY FLOW ALOFT ENHANCING
LEE TROFFING OVER THE AREA. MIXING WILL BE DEEPER TO PROVIDE BREAKS
IN THE CLOUDS TOMORROW AS WELL...ALLOWING HIGHS TO REACH THEIR
POTENTIAL IN THE LOW 90S. WE WILL REMAIN IN THE SOUPY AIRMASS...OF
COURSE...SO INSTABILITY WILL BE FAIRLY IMPRESSIVE...AROUND 1.5K
JOULES...SO POPS IN THE 40 PERCENT RANGE ARE IN ORDER...GRADUATED
SLIGHTLY HIGHER IN THE WEST WHERE DIFFERENTIAL HEATING SHOULD
PROVIDE EARLIER INITIATION...AND EAST OF THE SURFACE TROF AXIS.
SHEAR WILL BE MINIMAL...UNIDIRECTIONAL AROUND 15 KNOTS...SO ONLY A
MARGINAL SEVERE THREAT. CONVECTION WILL WANE WITH LOSS OF INSOLATION
AND WILL MAINTAIN A SLIGHT CHANCE OF A SHOWER OVERNIGHT. MINS
WEDNESDAY NIGHT WILL BE MILD IN LIGHT SOUTHWEST FLOW...72-75.

BOTH THE GFS AND THE NAM SHOW A WEAKENING MID-LEVEL WAVE MOVING
THROUGH CENTRAL NORTH CAROLINA THURSDAY AND THURSDAY NIGHT AS A
TROUGH AXIS ALOFT PUSHES SLOWLY EAST. MEAN MOISTURE INCREASES
THURSDAY WITH GOOD LIFT FORECAST BY THE GFS AND THE NAM.
PRECIPITABLE WATER VALUES INCREASE TO AT OR JUST OVER TWO INCHES
OVER MUCH OF CENTRAL NORTH CAROLINA THURSDAY...WITH THE HIGHEST
VALUES ALONG AND EAST OF U.S. 1. DYNAMICALLY...THE GFS FORECASTS THE
RIGHT ENTRANCE REGION OF A 60KT 300MB JET OVER CENTRAL NORTH
CAROLINA BY 18Z THURSDAY...AND THIS JET GRADUALLY MOVES EAST INTO
THURSDAY NIGHT. BUFR SOUNDINGS BECOME MOIST AND MORE UNSTABLE DURING
THE DAY NORTHWEST TO SOUTHEAST...AND IT APPEARS AT LEAST GOOD CHANCE
POPS FOR CENTRAL NORTH CAROLINA ARE WARRANTED...WHICH MAY BECOME
LIKELY CHANCES OVER TIME OVER MUCH OF THE AREA. 1000-500MB LAPSE
RATES ARE NOT REALLY HIGH BUT DECENT...TO 6.8C/KM...AND AS LOW-LEVEL
WINDS AT BOTH 850MB AND 925MB ARE FORECAST TO ACTUALLY DIMINISH SOME
DURING THE DAY FROM THE NORTHWEST...0-3KM SHEAR IS MODEST...MOSTLY
IN THE TEENS KNOTS TO AROUND 20KT TOWARD THE VIRGINIA BORDER. THE
BEST CAPE AROUND 18Z IS FORECAST BY THE GFS JUST WEST OF U.S. 1...
AROUND 900J/KG...SHIFTING EAST DURING THE AFTERNOON WITH THE BETTER
DOWNDRAFT CAPE CERTAINLY BETTER EAST OF U.S. 1. GIVEN A COMBINATION
OF THESE MODEST PARAMETER VALUES...SCATTERED-TO-NUMEROUS SHOWERS AND
THUNDERSTORMS WITH AN ISOLATED SEVERE WEATHER THREAT DUE TO WIND IS
A REASONABLE FORECAST. IN A RELATIVE SENSE...THE BETTER CHANCE OF
ISOLATED SEVERE WEATHER MAY BE ALONG AND EAST OF U.S. 1 DUE TO THE
COMBINATION OF GREATER INSTABILITY AND LOW-LEVEL WIND. THERE APPEARS
TO BE ENOUGH WIND AND SHEAR THAT STORMS SHOULD MOVE...POSING A LOCAL
FLOOD THREAT TO THE TYPICAL URBAN AND POOR DRAINAGE LOCATIONS WHERE
LOCAL TRAINING COULD OCCUR. 0-3KM HELICITY VALUES ARE LOW AND
ACTUALLY GET LOWER...INTO THE LOWER DOUBLE DIGITS...DURING THE DAY.

THE NAM IS A LITTLE FASTER WITH CLEARING AND INCREASING STABILITY
OVERNIGHT THURSDAY COMPARED TO THE GFS...BUT NOT GREATLY SO...SUCH
THAT CHANCES FOR PRECIPITATION BASED ON THE BUFR SOUNDINGS SHOULD
WANE IN THE TRIAD BY 03Z...BY 06Z TOWARD KRDU...AND BY 09Z TOWARD
INTERSTATE 95. DEPENDING ON THE DEGREE OF CLEARING...WITH THE
WEAKENING FRONT MAKING SLOW PROGRESS SOUTH THERE COULD BE SOME AREAS
OF FOG OVERNIGHT THURSDAY...BUT THE CONFIDENCE IN THIS DEPENDENT ON
THE OVERALL DIMINISHING CLOUD COVER IS NOT HIGH ENOUGH TO PLACE IN
THE FORECAST CURRENTLY. ON FRIDAY...ALTHOUGH THE WEAK SURFACE FRONT
SHOULD START TO GET HUNG UP NEAR THE SOUTH CAROLINA BORDER AND
TOWARD THE COAST...BUFR SOUNDINGS ESPECIALLY ON THE GFS BECOME
FAIRLY STABLE TO DEEP CONVECTION. PRECIPITABLE WATER VALUES CONTINUE
TO GRADUALLY DIMINISH...WITH VALUES APPROACHING AN INCH IN THE TRIAD
BY 00Z SATURDAY. BOTH THE NAM AND THE GFS FORECAST MINIMAL QPF
MAINLY ALONG AND EAST OF U.S. 1 FRIDAY AFTERNOON...AND GIVEN THE
PROXIMITY OF THE SURFACE FRONT AND SLOWLY DIMINISHING MOISTURE...
THERE MAY BE JUST ENOUGH INSTABILITY AND LIFT TO PROVIDE FOR
ISOLATED SHOWERS OR THUNDERSTORMS FRIDAY AFTERNOON MAINLY OUTSIDE
THE TRIAD...WHERE IT JUST SEEMS TOO STABLE FOR DEEP CONVECTION
FRIDAY AFTERNOON. NAM BUFR SOUNDINGS HAVE QUITE HIGH MOISTURE AROUND
850MB WHILE THE GFS IS SOMEWHAT LESS...AND BLENDING THEM SHOULD
RESULT IN SOME AREAS OF GOOD CU IN MUCH OF CENTRAL NORTH CAROLINA
FOR A TIME FRIDAY ESPECIALLY AWAY FROM THE TRIAD. HIGHS THURSDAY
MOSTLY A BLEND OF MOS...LEANING COOLER TOWARD THE TRIAD AND HIGHER
TOWARD I-95 FOR VALUES FROM THE UPPER 80S TO MID 90S. LOWS THURSDAY
NIGHT 67 TO 73...THEN HIGHS FRIDAY MOSTLY 85 TO 90...JUST A TOUCH
COOLER THAN 1000-850MB THICKNESSES WOULD IMPLY DUE MOSTLY TO THE
POTENTIAL FOR CU FOR A PERIOD THEN.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 240 AM WEDNESDAY...

FRIDAY AND FRIDAY NIGHT: THE SURFACE FRONT AND THE UPPER LEVEL
TROUGH WILL MOVE EAST OF MUCH OF CENTRAL NC BY FRIDAY...WITH WINDS
VEERING TO THE NORTHWEST AND COOL HIGH PRESSURE BUILDING IN. IT
APPEARS THAT THE COOLEST AIR MAY ONLY MAKE IT INTO THE FAR NW ON
FRIDAY AS WEAK LOW PRESSURE IS EXPECTED TO SIT ALONG THE CAROLINA
COAST FRIDAY AND FRIDAY NIGHT. HIGHS ON FRIDAY IN THE MID TO UPPER
80 WITH LOWS IN THE MID 60S TO AROUND 70 DEGREES EXPECTED. GIVEN THE
LINGERING SFC LOW ALONG THE COAST AND THE FRONT STALLING IN THAT
GENERAL VICINITY...THERE WILL BE THE CHANCE FOR ADDITIONAL SHOWERS
AND STORMS ON FRIDAY...MAINLY ACROSS THE SOUTHEAST. PWATS WILL
DECREASE TO UNDER AN INCH FOR FRIDAY AS MID LEVEL DRY AIR IS
ADVECTED INTO THE REGION.

SATURDAY THROUGH TUESDAY: THERE MAY BE A LINGERING CHANCE FOR SOME
CONVECTION IN THE EAST SATURDAY WITH A SURFACE TROUGH AND WARM
SOUTHERLY FLOW SETTING UP ALONG THE CAROLINA COAST. OTHERWISE...
EXPECT MAINLY DRY WEATHER FOR MUCH OF THE AREA AS THE UPPER LEVEL
TROUGH SHIFTS OFFSHORE. HIGHS WILL BE GENERALLY IN THE UPPER 80S TO
LOW 90S AND LOWS IN THE UPPER 60S TO LOW 70S. THE PIEDMONT TROUGH
WILL REMAIN IN PLACE SUNDAY AND SUNDAY NIGHT AS ANOTHER FRONTAL
SYSTEM APPROACHES FROM THE WEST. EXPECT INCREASING CHANCES FOR
CONVECTION...DIURNAL IN NATURE...SUNDAY AND MONDAY AS THE FRONT
APPROACHES. ALTHOUGH THE TIMING OF THIS SYSTEM IS STILL A BIT
UNCERTAIN...AS IS THE MODEL FORECAST PRECIPITATION...EXPECT THE BEST
CHANCE OF CONVECTION ON MONDAY. AS OF THE LATEST (00Z) GFS MODEL
RUN...THE FRONT SHOULD MOVE THROUGH THE AREA MONDAY NIGHT...WITH
COOLER AND DRIER CONDITIONS FOR TUESDAY. SUNDAY SHOULD BE THE
WARMEST DAY...HIGHS IN THE LOW TO MID 80S AND LOWS IN THE LOW TO MID
70S. TEMPERATURES ON MONDAY WILL DEPEND ON THE TIMING OF THE FRONT
AND ITS ASSOCIATED CONVECTION...BUT FOR NOW WILL FORECAST HIGHS A
FEW DEGREES COOLER THAN SUNDAY...MID 80S TO AROUND 90 DEGREES.
NOTICEABLE TEMPERATURE CHANGE MONDAY NIGHT AND TUESDAY...WITH LOWS
IN THE MID 60S TO AROUND 70 DEGREES AND HIGHS IN THE LOW TO MID 80S.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AS OF 1250 AM WEDNESDAY...

PATCHY SHOWERS NEAR FAY ARE EXPECTED TO SLOWLY MEANDER ABOUT BEFORE
WEAKENING AND DISSIPATING OVER THE NEXT FEW HOURS. THESE COULD
AFFECT FAY WITH A PERIOD OF MVFR VSBY... BUT THE REMAINDER OF THE
CENTRAL NC TAF AIRFIELDS SHOULD STAY DRY THIS MORNING. OTHERWISE...
CONFIDENCE IS LOWER THAN IN PAST MORNINGS BUT IT APPEARS THAT ALL
SITES ARE LIKELY TO SEE A PERIOD OF MVFR VSBYS PRIOR TO 12Z... AND
SUB-MVFR CONDITIONS ARE LESS LIKELY GIVEN THE SPARCITY OF RAINFALL
YESTERDAY. MVFR TO HIGH-END IFR CIGS ARE EXPECTED TO DOMINATE AT RWI
THROUGH 13Z... WITH ONLY BRIEF MVFR OR HIGH-END IFR CIGS AT
RDU/RWI... AND VFR CIGS LIKELY HOLDING AT INT/GSO. VFR CONDITIONS
ARE LIKELY FROM 14Z ON THROUGH THE DAY AS CIGS LIFT AND BREAK UP
WITH MIXING... WITH SURFACE WINDS FROM THE SW AT 8-12 KTS. ANY
SHOWERS/STORMS WILL BE ISOLATED OR IN SMALL CLUSTERS... AND THE
CHANCE OF THEM AFFECTING TAF SITES IS TOO SMALL TO INCLUDE IN THE
TAFS AT THIS TIME. VFR CONDITIONS SHOULD PREVAIL THROUGH 06Z EXCEPT
AT RWI... WHICH MAY SEE MVFR VSBYS IN FOG AFTER 03Z.

LOOKING BEYOND 06Z EARLY THU MORNING... EXCEPT FOR SOME LIGHT FOG AT
RWI... VFR CONDITIONS SHOULD HOLD ELSEWHERE OVERNIGHT WITH A LIGHT
BREEZE FROM THE SW. AN APPROACHING COLD FRONT WILL BRING NUMEROUS
SHOWERS AND STORMS WITH SUB-VFR CONDITIONS STARTING LATE MORNING
(15Z-18Z) AT INT/GSO BEFORE SPREADING EAST TO RDU DURING THE EARLY
AFTERNOON AND TO RWI/FAY DURING THE MID-LATE AFTERNOON. THE FRONT
MAY SLOW DOWN OVER COASTAL SECTIONS THU NIGHT/FRI... KEEPING A
CHANCE OF SUB-VFR SHOWERS/STORMS FRI AFTERNOON... BUT OTHERWISE VFR
CONDITIONS ARE EXPECTED FRI-SAT AS HIGH PRESSURE NOSES IN FROM THE
NORTH. AN UPPER LEVEL DISTURBANCE WILL MOVE IN FROM THE NORTHWEST ON
SUNDAY... POTENTIALLY BRINGING ANOTHER ROUND OF SHOWERS/STORMS. -GIH

&&

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

&&

$$

SYNOPSIS..HARTFIELD
NEAR TERM...32
SHORT TERM...DJF
LONG TERM...KC
AVIATION...HARTFIELD