Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 301920 RRA AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 315 PM EDT WED JUL 30 2014 .SYNOPSIS...WEAK HIGH PRESSURE WILL REMAIN OVER THE AREA TODAY WITH MOSTLY DRY CONDITIONS BEFORE MOISTURE ASSOCIATED WITH AN UPPER LEVEL TROUGH AND RETROGRADING COASTAL FRONT CAUSES PRECIPITATION TO BECOME MORE LIKELY FOR THE END OF THE WEEK INTO THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 245 PM WEDNESDAY... SHOWERS STARTING TO BREAK OUT MAINLY ALONG THE HIGHWAY 1 CORRIDOR HIGHLIGHTED ON THE VISIBLE SATELLITE IMAGERY BY A MORE ENHANCED CUMULUS FIELD. THIS WAS CAPTURED WELL ON HIGH RESOLUTION MODELS...PARTICULARLY THE LATEST RUN OF THE HI-RES WRF NMM. THIS SOLUTIONS CONTINUES SHOWERS THROUGH THE EVENING BUT DOES NOT ENHANCE ACTIVITY MUCH. THEREFORE WILL KEEP SLIGHT CHANCE OF SHOWERS AND INTRODUCE ISOLATED THUNDER IN THE FORECAST...AS ALTHOUGH MOISTURE APPEARS VERY SHALLOW AT THIS TIME...SPC SURFACE ANALYSIS SUGGESTS 500 J/KG OF MIXED LAYER CAPE OVER CENTRAL NC AND A SMALL AREA OF 25- 30 KT EFFECTIVE SHEAR IN THE KFAY AREA. CLOUD COVER HAS LIMITED HIGH TEMPERATURES...ESPECIALLY IN THE NORTH AND WEST AND WILL LIKELY TOP OUT IN THE UPPER 70S NW TO LOW TO MID 80S IN THE EXTREME SOUTH. EXPECT TO HAVE CLOUD COVER AND POSSIBLY A LINGERING SHOWER RUN INTO THE OVERNIGHT HOURS WHICH SHOULD HELP LIMIT FOG/LOW STRATUS BUT A BRIEF PERIOD OF BOTH WILL BE POSSIBLE AT KRDU...KFAY...AND KRWI JUST BEFORE SUNRISE. THE INCREASE IN CLOUD COVER SHOULD HELP KEEP LOW TEMPERATURES UP A COUPLE DEGREES FROM LAST NIGHTS LOWS...MAINLY LOW TO MID 60S ACROSS THE AREA FROM NW TO SE. && .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/...
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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
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&& && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... AS OF 140 PM WEDNESDAY... 24 HOUR TAF PERIOD: MOSTLY VFR CONDITIONS EXPECTED THROUGH THE END OF THE TAF PERIOD. SCATTERED TO BROKEN CLOUD COVER AT THE 3-7 KFT RANGE MAY LEAD TO SOME SHALLOW SHOWER ACTIVITY THIS AFTERNOON. OTHERWISE VARIABLE WINDS AT LESS THAN 5KTS ARE EXPECTED FOR THE REST OF THE DAY. OVERNIGHT TONIGHT THERE REMAINS A SMALL CHANCE OF SOME SUB VFR CEILINGS AND VISIBILITIES...PRIMARILY AT CENTRAL AND EASTERN SITES BETWEEN 10Z AND 12Z. THERE WILL BE AN INCREASING CHANCE FOR SHOWERS AND THUNDERSTORMS TOMORROW AFTERNOON...BUT LARGELY AFTER THE END OF THE TAF PERIOD. OTHERWISE BROKEN CEILINGS AT 5 KFT SHOULD PREVAIL THROUGH 18Z WITH WINDS LESS THAN 5 KTS GENERALLY OUT OF THE SOUTH. LONG TERM: CHANCES FOR SHOWERS AND THUNDERSTORMS WILL INCREASE THURSDAY EVENING THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK AS A COASTAL TROUGH RETROGRADES WESTWARD INTO THE COASTAL PLAIN. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...ELLIS NEAR TERM...ELLIS SHORT TERM...ELLIS LONG TERM...BLAES AVIATION...ELLIS

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