Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 310349 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1149 PM EDT WED JUL 30 2014 .SYNOPSIS... AN UPPER TROUGH OF LOW PRESSURE WILL RETROGRADE WEST TO THE MISSISSIPPI RIVER VALLEY...AND THE CENTER OF SURFACE HIGH PRESSURE WILL SHIFT TO OUR EAST. THE RESULT THROUGH THE WEEKEND AND INTO THE EARLY PART OF NEXT WEEK WILL BE AN INCREASED CHANCE OF SHOWERS AND STORMS ACROSS OUR REGION STARTING ON THURSDAY. CURRENTLY...FRIDAY INTO SATURDAY LOOKS TO BE THE TIME WINDOW WITH THE GREATEST POTENTIAL FOR THE ENTIRE AREA. && .NEAR TERM /THROUGH THURSDAY/...
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AS OF 1130 PM EDT WEDNESDAY... SHOULD BE A DRY NIGHT OVERALL...WITH A FEW SHOWERS STILL POSSIBLE ACROSS SE WV EARLY. CANT RULE OUT ISOLATED SPRINKLE/SHOWERS OUT EAST AS THETA-E RIDGE AND SOME INCREASE IN DEWPOINTS OCCURS. SKIES FOR MOST OF US WILL BE MAINLY CLEAR THOUGH SOME HIGH CLOUDS ARE A LITTLE THICKER TOWARD THE NC MOUNTAINS. FORECAST LOWS STILL OVERALL LOOKING ONLINE TO REACH THE UPPER 40S DEEPER VALLEYS TO AROUND 60 SOUTHEAST. PATCHY FOG IN THE RIVER VALLEYS SHOULD ALSO FORM GIVEN LIGHT/CALM WINDS. PREVIOUS VALID DISCUSSION... ON THURSDAY...THE TREND TOWARDS E-SE LOW LEVEL FLOW AND GREATER MOISTURE WILL CONTINUE. INCREASING CLOUDS WILL BE THE NORM THROUGHOUT THE DAY WITH UPSLOPE RAIN SHOWERS DEVELOPING AND GROWING IN COVERAGE. THE GREATEST CONCENTRATION WILL BE ACROSS THE NORTHERN MOUNTAINS OF NORTH CAROLINA...NORTHEAST ALONG THE CREST OF THE BLUE RIDGE TO NEAR FLOYD VA. HIGH TEMPERATURES WILL RANGE FROM THE MID 70S TO AROUND 80 IN THE MOUNTAINS TO THE LOW TO MID 80S ACROSS THE PIEDMONT.
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&& .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... AS OF 330 PM EDT THURSDAY... MODELS CONSISTENT BRINGING A SHORT WAVE THROUGH THE SOUTHWEST FLOW ALOFT THURSDAY NIGHT THROUGH FRIDAY NIGHT. THURSDAY NIGHT AND FRIDAY THERE IS ALSO SOME SUPPORT FROM THE DIFFLUENT AREA OF THE UPPER JET. MAY KEEP PROBABILITY OF THUNDERSTORMS LOW SINCE GUIDANCE IS SHOWING LITTLE CAPE AND INSTABILITY OVER MUCH OF THE FORECAST AREA. BY FRIDAY MORNING...PRECIPITABLE WATER VALUES WILL BE BACK IN THE 1.0 TO 1.5 INCH RANGE WITH SURFACE DEW POINTS IN THE 60S. WPC 24 HOUR QPF FROM 12Z FRIDAY TO 12Z SATURDAY OF 0.25 TO 0.50 INCHES LOOKS REASONABLE. HOWEVER...MODELS DO NOT HAVE A PARTICULARLY GOOD CONSENSUS OF WHERE THE HEAVIEST AMOUNTS WILL BE. EASTERLY COMPONENT OF LOW LEVEL WINDS FAVORS THE EASTERN SLOPES OF THE BLUE RIDGE. PUTTING THE HIGHEST PROBABILITY OF PRECIPITATION IN FROM LATE THURSDAY NIGHT THROUGH LATE MORNING ON FRIDAY. WIDE RANGE IN GUIDANCE FOR MAXIMUM TEMPERATURES ON FRIDAY. WITH ALL THE CLOUDS AND PRECIPITATION EXPECTED...HAVE TRENDED TOWARD THE COOLER BIAS CORRECTED MAV NUMBERS. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AS OF 330 PM EDT THURSDAY... FRONT AT THE SURFACE REMAINS ALONG THE COAST SATURDAY NIGHT THROUGH MONDAY. ON TUESDAY AND WEDNESDAY...A COLD FRONT WILL PUSH INTO THE REGION FROM THE NORTHWEST. UNTIL THIS FRONT GOES THROUGH...THERE WILL BE A DAILY THREAT OF SHOWERS AND THUNDERSTORMS EACH AFTERNOON AND EVENING. CHALLENGING TO NARROW DOWN WHICH DAY OF TIME FRAME WILL BE MORE FAVORABLE FOR PRECIPITATION...ALTHOUGH MODELS SUGGEST A SHORT WAVE COMING THROUGH THE OHIO VALLEY ON SUNDAY MAY BRING A MORE ORGANIZED AREA OF SHOWERS AND THUNDERSTORMS TO THE COUNTY WARNING AREA. POCKET OF WARMER 850 MB AIR WITH +20 TEMPERATURES COMES OUT OF THE MISSISSIPPI VALLEY...REACHING THE FORECAST AREA ON WEDNESDAY BASED ON THE ECMWF. && .AVIATION /04Z THURSDAY THROUGH MONDAY/... AS OF 745 PM EDT WEDNESDAY... GENERALLY VFR CONDITIONS EXPECTED THROUGH THE TAF VALID PERIOD...WITH THE EXCEPTION BEING POTENTIAL FOR BR HZ DURING THE LATE NIGHT/EARLY MORNING HOURS AT THE USUAL SPOTS...BUT ESPECIALLY WEST OF THE BLUE RIDGE. UPPER TROUGH WILL CONTINUE ACROSS THE REGION. A DISTURBANCE...NOW LOCATED IN THE SOUTHERN PLAINS WILL MOVE THROUGH THE BASE OF THE TROUGH THU...THEN BEGIN TO APPROACH THE REGION FROM THE SOUTHWEST THU NIGHT/FRI. LINE OF THUNDERSTORMS ACROSS WESTERN WV NORTHWARD INTO CENTRAL PA WILL DISSIPATE PER ALL MODEL SOLUTIONS AS IT MOVES TOWARD THE APPALACHIANS NOT AFFECTING ANY TAF SITES. HOWEVER...CI SHIELD MAY AFFECT LWB FOR A WHILE THIS EVENING. OTHERWISE...SCT AC/SC WILL DISSIPATE OVER THE NEXT COUPLE OF HOURS. MVFR BR CAN BE EXPECTED AGAIN TONIGHT AT LWB/BCB AND POTENTIALLY DAN/LYH...WITH LWB LIKELY SEEING A PERIOD OF IFR-LIFR ONCE AGAIN IN THE 08Z-13Z TIME FRAME. FOG IS NOT EXPECTED AT ROA OR BLF AT THIS TIME. FOR THU...LAYER OF MOISTURE WILL PERSIST IN THE 040-060 RANGE...RESULTING IN CONTINUATION OF SCT-BKN CU/SC/AC DURING THE MID DAY/AFTERNOON. LATE IN THE DAY...CI SHIELD WILL SPREAD NORTHEASTWARD TOWARD THE REGION FROM THE SOUTHEAST STATES. WILL HOLD OFF ON MENTIONING ANY SHRA/TSRA THIS TAF VALID PERIOD AS IT APPEARS TO REACH NO FURTHER THAN NW NC LATE IN THE DAY. WINDS...MOSTLY SW THROUGH THE TAF VALID PERIOD...BUT BCB/LYH/DAN/LWB WILL LIKELY SEE CALM WINDS MUCH OF THE NIGHT. SPEEDS THU REMAINING MOSTLY 5KTS OR LESS EVEN AFT 14Z. MEDIUM TO HIGH CONFIDENCE IN CIGS THROUGH THE TAF VALID PERIOD. MEDIUM CONFIDENCE IN VSBYS THROUGH 14Z...THEN HIGH CONFIDENCE IN VFR CONDITIONS. MEDIUM TO HIGH CONFIDENCE IN WIND SPD/DIR THROUGH THE TAF VALID PERIOD. EXTENDED AVIATION DISCUSSION... A BROAD TROUGH OF LOW PRESSURE WILL BE ACROSS THE EASTERN UNITED STATES THROUGH SUNDAY. IT WILL SLOWLY RETROGRADE FROM THE EASTERN/CENTRAL GREAT LAKES TO THE WESTERN GREAT LAKES BY THE WEEKEND. THIS WILL BEGIN TO TURN THE UPPER FLOW TO THE SOUTHWEST WITH TIME. THE AFOREMENTIONED DISTURBANCE COMING FROM THE SE STATES THU...WILL MOVE NORTHEASTWARD ACROSS THE REGION FRI. EXTENSIVE OVERRUNNING LIKELY WITH EMBEDDED ISOLD TSRA. SFC AIR MASS REMAINS QUITE STABLE...ESPECIALLY EAST OF THE ALLEGHANY FRONT...SO THUNDER APPEARS ISOLD AT THIS POINT. HOWEVER...WIDESPREAD MVFR CIGS/VSBYS WILL BE POSSIBLE FRI WITH THIS SCENARIO IN -RA -DZ BR. FOR SAT-SUN...AIR MASS WILL SLOWLY BECOME WARMER AND MORE UNSTABLE. SCT SHRA/TSRA AGAIN SAT WITH ONLY LIMITED INSTABILITY EVIDENT. FOR SUN...BETTER CHANCE OF TSRA WITH CAPES EXCEEDING 1000 J/KG ACROSS MUCH OF THE CWA...SW FLOW ALOFT...AND INCREASING MOISTURE LEVELS. THUS...BRIEF PERIODS OF MVFR-IFR CIGS/VSBYS EXPECTED IN SHRA/TSRA SAT AND MORE LIKELY SUN AFTERNOON. OTHERWISE...POTENTIAL FOR LATE NIGHT/EARLY MORNING IFR-LIFR BR/FG INCREASES THROUGH THE PERIOD...BUT MAINLY AT THE USUAL SITES...LWB/BCB/LYH. && .CLIMATE... JULY 31ST RECORD LOWS: ROANOKE......49...1914 BLUEFIELD....49...1997 DANVILLE.....55...1966 LEWISBURG....48...1997 LYNCHBURG....49...1997 BLACKSBURG...44...1997 && .EQUIPMENT... THE NOAA WEATHER RADIO AT WYTHEVILLE VA...WZ2500...BROADCASTING ON A FREQUENCY OF 162.450 MHZ...IS OFF THE AIR. TECHNICIANS ARE WAITING ON DELIVERY OF PARTS TO MAKE REPAIRS. THE EARLIEST THE RADIO WILL BE WORKING AGAIN IS FRIDAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...DS NEAR TERM...DS/WP SHORT TERM...AMS LONG TERM...AMS AVIATION...RAB CLIMATE...PH EQUIPMENT...DS

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