-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 310217
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1015 PM EDT WED JUL 30 2014

.SYNOPSIS...
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HIGH PRESSURE WILL WEAKEN THROUGH FRIDAY AS ATLANTIC
MOISTURE GRADUALLY RETURNS TO THE REGION. A MORE UNSETTLED PATTERN
WILL DEVELOP OVER THE WEEKEND AS AN UPPER LEVEL TROUGH APPROACHES
FROM THE WEST AND AN ASSOCIATED COASTAL FRONT MOVES INLAND ACROSS
THE CENTRAL CAROLINAS.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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AS OF 1015 PM WEDNESDAY...

LOW LEVEL DEW POINTS HAVE COME UP INTO THE MID 60S (UP 10 DEGREES
FROM 24 HOURS AGO)... AND CLOUDINESS HAS ALSO INCREASED AS WELL. THE
MID AND HIGH CLOUDS ARE COURTESY OF THE UPPER JET. THE LOW LEVEL
CLOUDINESS IS COURTESY OF THE INCREASE IN LOW LEVEL MOISTURE AND
CONVERGENCE. THE CONVERGENCE IN RECENT HOURS HAS BECOME LIMITED TO
THE LOCATIONS NEAR THE STATIONARY BOUNDARY OVER THE COASTAL PLAIN.
EARLIER SHOWERS AND ISO THUNDERSTORMS HAVE DIED OFF. FOR THE REST OF
THE NIGHT... EXPECT MOSTLY CLOUDY SKIES. LOWS GENERALLY IN THE LOWER
TO MID 60S EXPECTED.
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&&

.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
AS OF 245 PM WEDNESDAY...

THE UPPER LEVEL TROUGH WILL REMAIN DRAPED ACROSS THE EASTERN CONUS
ON THURSDAY. AT THE LOW LEVELS SOUTHERLY FLOW WILL BEGIN TO RETURN
TO THE AREA...INCREASING MOISTURE IN THE SOUTHWESTERN CWA VIA RETURN
FLOW. THIS PROCESS WILL TAKE A WHILE TO GET GOING HOWEVER AND MOST
OF THE MORNING/EARLY AFTERNOON SHOULD REMAIN DRY WITH INCREASING
CLOUD COVER FROM THE SOUTHWEST DURING THE DAY. AFTER 18Z...THE
CHANCES FOR SHOWERS AND POTENTIALLY A THUNDERSTORM WILL INCREASE
WITH MOST MODEL SIMULATIONS PRODUCING QPF BY 00Z FRIDAY AS
PRECIPITABLE WATER VALUES BEGIN TO CLIMB TOWARDS TWO INCHES.
INSTABILITY WILL BE VERY LIMITED THURSDAY AFTERNOON AND EVENING
ALTHOUGH ABOUT 40 KTS OF BULK SHEAR WILL BE AVAILABLE. ANY
SHOWERS/STORMS THAT DO COMMENCE THURSDAY AFTERNOON WILL HAVE A
CHANCE OF CONTINUING THROUGH THE OVERNIGHT HOURS AS SOME ELEVATED
INSTABILITY MAY BE PRESENT IN THE FORM OF A VORT MAX MOVING THROUGH
ON THE EASTERN SIDE OF THE UPPER TROUGH FROM SOUTHWEST TO NORTHEAST.
WITH INCREASE CLOUDS FROM THE SOUTHWEST...MAX TEMPS MAY BE HIGHEST
IN THE NORTHEAST ON THURSDAY WITH TEMPS IN THE MID TO UPPER 80S AND
ONLY LOWER 80S IN THE WEST AND SOUTHWEST. OVERNIGHT LOWS THURSDAY
NIGHT WILL MODERATE INTO THE UPPER 60S.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
AS OF 315 PM WEDNESDAY...

THE OVERALL PATTERN DURING THE LONG TERM PERIOD FEATURES AN EASTERN
CONUS TROUGH AND A WESTERN U.S. RIDGE WHICH WILL SUPPORT NEAR OR
COOLER THAN AVERAGE TEMPERATURES AND NEAR OR GREATER THAN NORMAL
THREAT OF PRECIPITATION.

THE BROAD EASTERN U.S. TROUGH SHARPENS ACROSS THE LOWER MISSISSIPPI
VALLEY ON FRIDAY AND A STRENGTHENING INVERTED TROUGH/COASTAL FRONT
DEVELOPS. AN INCREASINGLY MOIST ENVIRONMENT COMBINED WITH ISENTROPIC
LIFT WILL PROMOTE A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS FRIDAY
AFTERNOON AND EVENING THAT WILL LINGER BUT BECOME MORE SCATTERED
FRIDAY NIGHT.

THE UPPER TROUGH SHARPENS FURTHER OVER THE WEEKEND AS THE INVERTED
TROUGH MOVES INLAND AND DEEP MOISTURE OVERSPREADS THE REGION.
PRECIPITABLE WATER VALUES CLIMB TO AROUND OR JUST OVER 2 INCHES
WHICH IS 2 STANDARD DEVIATIONS ABOVE CLIMATOLOGY DURING THE WEEKEND.
THE AXIS OF GREATEST MOISTURE EXTENDING SOUTH-NORTHEAST ACROSS
CENTRAL NC. NWP GUIDANCE ADVERTISE MULTIPLE DISTURBANCES IN THE
SHARPENING UPPER TROUGH THAT WILL LIKELY ENHANCE PRECIPITATION
COVERAGE AND INTENSITY ALTHOUGH IT IS DIFFICULT TO PIN POINT THE
TIMING AND LOCATION AT THIS POINT. FOR NOW WILL INCLUDE LIKELY POPS
FOR SATURDAY AND VERY HIGH CHANCE POPS FOR SUNDAY WITH THE GREATEST
COVERAGE DURING THE AFTERNOON AND  EVENING HOURS.

BOTH THE GFS AND THE ECMWF SUGGEST A PORTION OF THE TROUGH WILL
BREAK OFF AND MOVE ACROSS THE NORTHEAST ON MONDAY AND OFFSHORE
TUESDAY WHILE A PORTION OF THE TOUGH LINGERS ACROSS THE LOWER
MISSISSIPPI VALLEY. THIS SHOULD RESULT IN A DECREASE IN CONVECTIVE
COVERAGE AND MORE TYPICAL CHANCES OF MAINLY AFTERNOON AND EVENING
THUNDERSTORMS. ANOTHER DISTURBANCE DROPS INTO HE TROUGH ON WEDNESDAY
BRING A COLD FRONT WITH IT THAT COULD ONCE AGAIN ENHANCE
PRECIPITATION CHANCES FOR THE MID WEEK.

HIGH TEMPS WILL GENERALLY RANGE IN THE UPPER 70S TO LOWER 80S ON
FRIDAY THROUGH SUNDAY AN THEN MODERATE SLIGHTLY INTO THE LOWER TO
MID 80S BY MID WEEK. MORNING LOWS WILL RANGE IN THE MID 60S TO NEAR
70 FOR MOST OF THE PERIOD. -BLAES

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AS OF 815 PM WEDNESDAY...

24-HR TAF PERIOD: VFR CONDITIONS WILL PREVAIL THROUGH THE MAJORITY
OF THE TAF PERIOD. THE ONLY EXCEPTION WILL BE A SMALL POTENTIAL FOR
SUB-VFR FOG NEAR SUNRISE THU MORNING (09-12Z THU) AT THE FAY/RWI
TERMINALS...AND ISOLD/SCT CONVECTION THAT COULD AFFECT ANY TERMINAL
DURING THE AFTERNOON AND EVENING HOURS. WINDS WILL REMAIN LIGHT AND
VARIABLE AT 4-7 KNOTS IN MOST LOCATIONS.

LOOKING AHEAD: EXPECT AN INCREASING POTENTIAL FOR ADVERSE AVIATION
CONDITIONS ASSOCIATED WITH LOW CEILINGS AND SCATTERED TO WIDESPREAD
CONVECTION FRIDAY NIGHT THROUGH THE WEEKEND AS A COASTAL FRONT
RETROGRADES INLAND INTO CENTRAL PORTIONS OF THE STATE IN ADVANCE OF
AN UPPER LEVEL TROUGH APPROACHING FROM THE WEST. -VINCENT

&&

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

&&

$$

SYNOPSIS...32
NEAR TERM...32
SHORT TERM...ELLIS
LONG TERM...BLAES
AVIATION...VINCENT