Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 021358 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 958 AM EDT SUN AUG 2 2015 .SYNOPSIS... HIGH PRESSURE WILL REMAIN IN PLACE THROUGH TONIGHT. A COLD FRONT SINKS SOUTHEAST TOWARD THE CENTRAL APPALACHIANS BY MONDAY AFTERNOON...REACHING THE NORTH CAROLINA/VIRGINIA BORDER BY TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 955 AM EDT SUNDAY... CURRENT FORECAST OF A VERY NICE SUNDAY IS ON TRACK WITH HIGH PRESSURE OVER THE REGION. SATELLITE IMAGES AND SURFACE OBS SHOW THAT MORNING FOG IN THE RIVER VALLEYS HAS JUST ABOUT COMPLETELY DISSIPATED WHILE UPPER LEVEL SHORT WAVE ENERGY IS PUSHING CIRRUS INTO THE AREA...WHICH GUIDANCE KEEPS AROUND MOST OF THE DAY. TEMPS ARE STARTING OFF QUITE COOL AND COMBINED WITH THE LOSS OF GOOD DOWNSLOPING FLOW EAST OF THE BLUE RIDGE THIS WILL LIKELY MAKE FOR MAX TEMPS JUST A HAIR LOWER THAN READINGS YESTERDAY. GENERALLY LOOKING FOR UPPER 80S/AROUND 90 EAST OF THE RIDGE AND UPPER 70S/LOWER 80S WEST. PREVIOUS AFD... TONIGHT...STILL LOOKING AT A QUIET WX NIGHT WITH CALM/LIGHT WINDS. THE FRONT THAT MOVED THROUGH A COUPLE DAYS OR SO AGO MAY SHIFT NWD WITH A SFC WAVE MOVING ACROSS THE CAROLINAS. NOT SEEING ANY MOISTURE THOUGH CANNOT RULE OUT SOME SCATTERING OF LOWER CLOUDS TOWARD SOUTHSIDE VA AND NC PIEDMONT LATE TONIGHT BUT MAJORITY OF MODEL SOLUTIONS KEEP THE CLOUDS EAST AND SOUTHEAST OF OUR AREA...SO WILL MAINTAIN MOSTLY CLEAR SKIES. LOWS AGAIN GOING TO VARY FROM THE LOWER 50S DEEPER MOUNTAIN VALLEYS TO MID TO UPPER 50S REST OF THE MOUNTAINS...EXCEPT LOWER 60S ACROSS THE HIGHER PEAKS OF SE WV AS ENOUGH FLOW TO KEEP IT MIXED. THE PIEDMONT/FOOTHILLS AND ROANOKE VALLEY WILL BE IN THE LOWER TO MID 60S. PATCHY RIVER VALLEY FOG EXPECTED AGAIN LATE IN THE WEST. && .SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/... AS OF 300 AM EDT SUNDAY... UPPER LEVEL TROUGHING IS EXPECTED TO HOLD ACROSS THE NORTHEAST PORTION OF THE COUNTY THROUGH THE PERIOD...ALTHOUGH THE TROUGH WILL BECOME LESS PRONOUNCED DURING THE SECOND HALF OF THIS WEEK AS THE CENTER PUSHES OVER THE NORTH ATLANTIC. REGARDLESS...THE PATTERN WILL ALLOW US TO MAINTAIN A GENERAL WEST TO EAST UPPER LEVEL WINDFLOW FOR THE CENTRAL APPALACHIANS. MONDAY WILL START DRY...BUT EXPECT A FEW SHOWERS/STORMS TO PUSH AGAINST THE WESTERN RIDGES DURING THE EVENING AND OVERNIGHT AS A COLD FRONT SINKS SOUTH FROM THE GREAT LAKES. MODELS ARE NOT OPTIMISTIC THAT MUCH...IF ANY...OF THE RAINFALL WILL SURVIVE EAST OF THE CONTINENTAL DIVIDE AS THEY ENCOUNTER DRY AIR IN PLACE AND DOWNSLOPE WINDFLOW. DOWNSLOPING AND COMPRESSIONAL HEATING AHEAD OF THE FRONT WILL ALSO PUSH AFTERNOON HIGHS INTO THE MID 80S MOST SPOTS ACROSS THE MOUNTAINS...AND AS HIGH AS THE MID 90S ACROSS THE SOUTHSIDE. THE COLD FRONT WILL PROGRESS SLOWLY SOUTHWARD MONDAY NIGHT...AND SOME DISAGREEMENT REMAINS AS TO HOW FAR ACROSS OUR AREA THE FRONT WILL SINK ON TUESDAY. THE CONSENSUS IS THAT THE FRONT WILL ADVANCE TO NEAR THE VA/NC BORDER BY EVENING. AS SUCH...WILL MAINTAIN HIGHER RAIN CHANCES FOR LOCATIONS SOUTH OF HIGHWAY 460 DURING THE AFTERNOON AND EVENING. THAT STATED...DO NOT EXPECT ANY STRONG RETURN OF MOISTURE AHEAD OF THE FRONT...AND THEREFORE EXPECT CONVECTION TO REMAIN WIDELY SCATTERED AT BEST. ATTENTION TURNS TO OUR WEST ON WEDNESDAY...ESPECIALLY WEDNESDAY NIGHT...AS A SERIES OF UPPER LEVEL DISTURBANCES APPROACH FROM THE CENTRAL PLAINS/MIDWEST. LATEST MODELS ARE FOCUSING ON ONE SUCH DISTURBANCE...POTENTIALLY THE DECAYING REMNANTS OF A THUNDERSTORM COMPLEX RIDING UP THE OHIO RIVER VALLEY LATE WEDNESDAY NIGHT. WILL CONTINUE TO MONITOR THE DEVELOPMENT OF THIS FEATURE IN THE MODELS OVER THE NEXT COUPLE DAYS FOR TRACK...TIMING AND INTENSITY. && .LONG TERM /THURSDAY THROUGH SATURDAY/... AS OF 325 AM EDT SUNDAY... EAST-WEST BAROCLINIC ZONE REMAINS ESTABLISHED OVER OR NEAR THE FORECAST AREA THROUGH MUCH OF THE LONG-TERM PERIOD AS ADDITIONAL UPSTREAM SHORT WAVES AND/OR MESOSCALE VORTICITY CENTERS FROM DECAYING OLD MIDWEST CONVECTIVE COMPLEXES PROVIDE SUFFICIENT ENERGY/SUPPORT TO MAINTAIN THREAT FOR DAILY SCATTERED CONVECTION. STRENGTH AND MOVEMENT/POSITIONING OF EACH WAVE IN MAINLY ZONAL UPPER FLOW WILL INFLUENCE DAILY POSITION OF DECAYING FRONTAL BOUNDARY... EXTENT OF CLOUD COVER...AND EXTENT OF WARM OR COOL ADVECTION DEPENDING ON POSITION RELATIVE TO FRONT. HIGHEST THREAT FOR PRECIPITATION FOR THIS PERIOD APPEARS TO COME ON FRIDAY...WHEN TWO OF THE MORE NOTABLE UPSTREAM WAVES ARRIVE...AND THIS IS REFLECTED ACCORDINGLY IN GRIDS FOR THIS TIMEFRAME. OTHERWISE...A LOWER AND MORE GENERALIZED THREAT FOR DAILY PRECIPITATION WILL BE MAINTAINED INTO SATURDAY UNTIL REGIONAL/ MESOSCALE FEATURES BECOME BETTER RESOLVED. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... AS OF 720 AM EDT SUNDAY... EXPECT VFR TODAY INTO THIS EVENING WITH PASSING HIGH CLOUDS. MAY SEE A LITTLE FOG AT LWB LATER SUNDAY NIGHT TAKING VSBYS TO IFR LEVELS. EXTENDED AVIATION FORECAST... AS OF 1230 PM EDT SATURDAY... MOSTLY VFR OUTSIDE OF ANY CONVECTION THROUGH THE PERIOD. A FRONT WILL SET UP IN THE MID ATLANTIC WHICH COULD BRING A FEW SHRA/TSRA BY TUESDAY...WITH PERHAPS A BIT MORE COVERAGE LATER WEDNESDAY AT THIS POINT. THUS THE THREAT OF SUB-VFR REMAINS LOW UNTIL AROUND MIDWEEK...EXCEPT FOR THE TYPICAL FOG POTENTIAL AT KLWB/KBCB EACH MORNING BETWEEN 09-13Z. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/WP NEAR TERM...MBS/WP SHORT TERM...NF LONG TERM...NF/WERT AVIATION...DS/JH/WP

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