Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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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

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