Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 300111 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 911 PM EDT FRI APR 29 2016 .SYNOPSIS... LOW PRESSURE SHIFTS FROM THE SOUTHERN PLAINS INTO THE WESTERN OHIO VALLEY THROUGH SUNDAY. A WARM FRONT WILL MOVE NORTH AHEAD OF THIS SYSTEM AND ACROSS THE REGION BY SUNDAY...WITH THE COLD FRONT MOVING THROUGH MONDAY. && .NEAR TERM /THROUGH SATURDAY/... AS OF 845 PM EDT FRIDAY... SQUEEZE PLAY OF CLOUDS WILL OCCUR OVERNIGHT AS LOW LEVEL MOISTURE WITHIN THE PERSISTENT FAR EASTERN WEDGE OOZES BACK TOWARD THE BLUE RIDGE WHILE MID/HIGH CANOPY INCREASES FROM THE WEST AHEAD OF RETURN WARM ADVECTION TO THE SW. LATEST NAM ALSO QUITE MOIST WITH THE WEDGE ENHANCING OVERNIGHT IN THE WAKE OF PASSING SHORTWAVE ENERGY TO THE NORTH AND REINFORCING HIGH PRESSURE BUILDING SOUTH. FORECAST SOUNDINGS FROM OTHER SHORT TERM SOLUTIONS ALSO SHOW QUITE A BIT OF TRAPPED BOUNDARY LAYER MOISTURE ESPCLY NE. THEREFORE BEEFED UP CLOUDS AND INCLUDED SOME PATCHY DRIZZLE BACK WEST TO NEAR ROANOKE AFTER MIDNIGHT ALONG WITH PATCHY FOG. MAIN ASPECT WEST OF THE BLUE RIDGE WILL BE WITH DEEPENING CLOUD CANOPY ALTHOUGH APPEARS ENOUGH DRY AIR TO KEEP THINGS DRY OVERNIGHT ESPCLY GIVEN THE UPSTREAM MCS DIVING WELL TO OUR SOUTH. LATEST HRRR ABOUT THE ONLY GUIDANCE SHOWING ANY RAINFALL OVER THE FAR WEST LATE BUT APPEARS OVERDONE GIVEN ONLY WEAK FORECAST SOUTH/SE FLOW AND LITTLE SUPPORT ALOFT UNTIL SATURDAY. THUS WILL KEEP TREND OF BECOMING MOSTLY CLOUDY OVERNIGHT...BUT MAINLY DRY OUTSIDE OF DRIZZLE...WITH LOWS IN THE 50S...EXCEPT PERHAPS A FEW COOLER 40S WESTERN VALLEYS IF CLOUDS STAY THIN LONGER. PREVIOUS DISCUSSION AS OF 250 PM EDT FRIDAY... WEDGE STILL HOLDING ON OVER THE PIEDMONT MAINLY EAST OF LYNCHBURG AS FAR AS CLOUDS GO. TEMPERATURES RANGING WIDELY FROM AROUND 80 IN THE FOOTHILLS OF NORTH CAROLINA...AS WELL AS PORTIONS OF THE ROANOKE AND NEW RIVER VALLEY...TO AROUND 60 OUT TOWARD BUCKINGHAM TO KEYSVILLE. AS WE HEAD THROUGH THIS EVENING...SKIES WILL STAY CLEAR TO PARTLY CLOUDY EXCEPT MOSTLY CLOUDY NORTHEAST OF LYH. MODELS ARE FAVORING SOME TURNING TO THE SOUTHEAST OF THE WINDS OVERNIGHT WITH LOW CLOUDS MOVING WESTWARD AGAIN WELL AFTER MIDNIGHT. SOME PATCHY DRIZZLE POSSIBLE NEAR THE BLUE RIDGE...BUT UPSLOPE COMPONENT AND FORECAST SOUNDINGS DO NOT SUPPORT MUCH. WILL HAVE TO SEE WHERE THE MCS OVER WRN TN THIS AFTERNOON MOVES. MODELS TAKE IT EAST TO NORTHEAST TOWARD ERN KY BY 12Z SATURDAY...WEAKENING IT. SHOULD START TO SEE SHOWERS MOVE INTO THE MOUNTAINS OF WV/FAR SW VA AROUND 8-10AM...WITH LIGHT RAIN POSSIBLE IN THE WEDGE. THINK THE HIGH OVER GREAT LAKES BEHIND SHORTWAVE TONIGHT WILL BRING A STRONGER WEDGE TOWARD OUR AREA SATURDAY...AS EVIDENCED BY THE SFC LI FIELD IN THE MODELS. AS SUCH SHOULD SEE A COOLER DAY OVER MOST OF THE FORECAST AREA WITH HIGHS IN THE 60S. OUTSIDE THE WEDGE LOOKING FOR HIGHS IN THE LOWER 70S. MODELS FAVOR THE AFTERNOON WITH BETTER LOW LVL CONVERGENCE/UPPER DIVERGENCE MOVE ACROSS WV/FAR WRN VA ALONG THE FRONT. THEREFORE KEPT LIKELY TO LOW CATEGORICAL POPS GENERALLY ALONG/WEST OF THE BLUE RIDGE TO HIGH CHANCE EAST. THUNDER THREAT WILL BE CONFINED TO A FAR SW VA TO NW NC MTN LINE IN THE AFTERNOON...AND ISOLATED. NO SEVERE THREAT EXPECT TOMORROW DUE TO WEDGE. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... AS OF 300 PM EDT FRIDAY... UNSETTLED WEATHER WITH PERIOD OF SHOWERS AND THUNDERSTORMS EXPECTED FOR WEEKEND INTO EARLY NEXT WEEK. ALOFT...AN UPPER TROUGH DEVELOPS IN THE EAST. LOW PRESSURE WITH AN ASSOCIATED WARM FRONT EXTENDING EASTWARD AND COLD FRONT FRONT TRAILING SOUTH WILL MOVES OUT OF THE MISSISSIPPI VALLEY AND SLIDES INTO THE MID ATLANTIC REGION. A WARM FRONT WILL LIFT NORTH ACROSS THE REGION SATURDAY EVENING INTO SATURDAY NIGHT. WIDESPREAD SHOWERS AND THUNDERSTORMS WILL DAMPEN OUR SATURDAY EVENING INTO SUNDAY MORNING. LOW TEMPERATURES SATURDAY NIGHT WILL RANGE FROM THE LOWER 50S IN THE NORTH TO AROUND 60 DEGREES IN THE SOUTH. LOW PRESSURE WILL MOVE TO OUR NORTH SUNDAY INTO SUNDAY NIGHT. THERE ARE INDICATIONS THAT BY SUNDAY AFTERNOON...THE WEDGE WILL BE LOSING ITS GRIP ON THE AREA AND WE WILL ENTER THE UNSTABLE WARM SECTOR AHEAD OF THE COLD FRONT TRAILING THE LOW. DYNAMIC SUPPORT...WITH HEALTHY CAPES AND SOME SHEAR MAY BE ADEQUATE TO CREATE SOME ORGANIZED CONVECTION SUNDAY. THE DAY THREE CONVECTIVE OUTLOOK PLACED OUR AREA UNDER MARGINAL THREAT FOR SEVERE WEATHER. THERE IS ALSO THE POTENTIAL FOR HYDRO ISSUES AS PWATS WILL BE RUNNING WELL OVER ONE INCH AND LOCALLY HEAVY RAIN WILL BE ADDED TO OUR RECENT WET SPELL. TRAINING OF CELLS AND RAIN RATES WILL BE IMPORTANT WITH THESE STORMS WITH ANY FLOODING POTENTIAL. HIGH TEMPERATURES WILL TRICKY WITH CLOUD COVER AND PRECIPITATION. HIGHS ON SUNDAY WILL VARY FROM THE MID 60S IN THE NORTHWEST MOUNTAINS TO THE MID 70S IN THE SOUTH. A COLD FRONT WILL PUSH EAST THROUGH THE AREA SUNDAY NIGHT INTO MONDAY. LOW TEMPERATURES SUNDAY NIGHT WILL GENERALLY BE IN THE LOWER 50S IN THE WEST TO NEAR 60 DEGREES IN THE EAST. BY MONDAY AFTERNOON...THE FRONT WILL BE THROUGH THE REGION WITH GENERALLY IMPROVING CONDITIONS EAST OF THE BLUE RIDGE...BUT SOME LINGERING MOISTURE IN NORTHWEST UPSLOPE FLOW SUPPORTS ISOLATED SHOWERS TO THE WEST. HIGHS ON MONDAY WILL WARM INTO THE UPPER 50S IN THE NORTHWEST TO THE MID 70S IN THE PIEDMONT. HIGH PRESSURE WILL BUILD EAST OUT OF THE OHIO VALLEY INTO OUR AREA MONDAY NIGHT. LOW TEMPERATURES MONDAY NIGHT WILL DROP INTO THE LOWER 40S IN THE WEST TO THE LOWER 50S IN THE EAST. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 300 PM EDT FRIDAY... A WAVY FRONTAL BOUNDARY REMAINS STALLED TO OUR SOUTH TUESDAY INTO WEDNESDAY. AS SEVERAL LOW PRESSURE CENTER RIDE NORTHWARD ALONG THE BOUNDARY EXPECT ROUNDS OF SHOWERS AND A FEW THUNDERSTORMS. THE TIMING OF THE SIGNIFICANT SHORTWAVES AND ASSOCIATED MOISTURE LIFTING NORTHEAST ALONG THE UPPER FLOW REMAINS A CHALLENGE. LOOKS LIKE DEEPER MOISTURE PUSHES FAR ENOUGH NORTH WITH A LOW ON TUESDAY TO PROVIDE US WITH UNSETTLED WEATHER. THIS IS SUPPORTED BY GFS AND ECMWF...DESPITE THE DIFFERENCES IN LOW PRESSURE AND ITS TIMING ALONG WITH THE STRENGTH OF SHORTWAVE DIGGING SOUTH TO OUR WEST IN OHIO VALLEY. HIGH TEMPERATURES TUESDAY WILL VARY FROM THE UPPER 50S IN THE MOUNTAINS TO THE LOWER 70S IN THE PIEDMONT. DECIDED TO KEEP SCATTERED POPS FOR TUESDAY NIGHT. LOW TEMPERATURES TUESDAY NIGHT INTO WEDNESDAY MORNING WILL RANGE FROM THE MID 40S IN THE WEST TO THE LOWER 50S IN THE EAST. A COLD FRONT APPROACHES FROM THE WEST ON WEDNESDAY AND MOVES ACROSS REGION ON WEDNESDAY INTO THURSDAY. WITH UNCERTAINTY...HELD ON TO THE ISOLATED TO SCATTERED SHOWERS WITH THIS BOUNDARY. HIGHS ON WEDNESDAY AND THURSDAY WILL BE IN THE LOWER TO MID 60S IN THE WEST TO THE UPPER 60S TO LOWER 70S IN THE EAST. OVERNIGHT LOW TEMPERATURES WILL DROP TO AROUND 40 IN THE MOUNTAINS TO NEAR 50 IN THE PIEDMONT. DRIER AIR ARRIVE THURSDAY NIGHT INTO FRIDAY ON A WEST TO NORTHWEST FLOW. && .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/... AS OF 735 PM EDT FRIDAY... VRF CONDITIONS PREVAIL ACROSS MOST OF THE REGION CURRENTLY. THE EXCEPTION IS THE REGION OF VIRGINIA NORTH...AROUND...AND EAST OF KLYH. MVFR CIGS ARE CONTINUING IN THIS AREA FROM THE DAYTIME HOURS. ALL VISIBILITIES ARE VFR ACROSS THE REGION. AS THE NIGHT PROGRESSES...LOOK FOR MVFR/IFR CEILINGS AND MVFR VSBYS TO DEVELOP ACROSS MOST LOCATIONS ALONG AND EAST OF THE CREST OF THE BLUE RIDGE...WITH SOME INROADS WESTWARD INTO THE NEW RIVER VALLEY. THIS AREA WILL BE UNDER THE INFLUENCE OF A SURFACE HIGH PRESSURE RIDGE. THE REDUCTION IN VISIBILITY WILL BE DUE TO THE DEVELOPMENT OF PATCHY FOG AND/OR LIGHT DRIZZLE. KBLF AND KLWB ARE EXPECTED TO REMAIN WITH AN AREA OF VFR CIGS OVERNIGHT...ALTHOUGH VSBYS WILL DROP INTO MVFR RANGE. THIS ALL WILL BE TAKING PLACE AS MOISTURE LEVELS PROGRESSIVELY INCREASE ACROSS THE AREA WITH THE WEDGE HOLDING FAST INTO THE DAY SATURDAY. LIGHT RAIN IS EXPECTED DEVELOP WITHIN THIS REGION SATURDAY...WITH SHOWER ACTIVITY MORE LIKELY BY MID-DAY BETWEEN KBLF-KLWB...OUTSIDE THE INFLUENCE OF THE WEDGE. LIMITED IF ANY IMPROVEMENT IN FLIGHT CATEGORIES ARE EXPECTED WITHIN THE WEDGE UNTIL SATURDAY AFTERNOON...AND THESE WILL BE ONLY SLIGHT IMPROVEMENTS. WHILE NOT INCLUDED IN THE KBLF TAF AT THIS POINT...INSTABILITY MAY BE GREAT ENOUGH IN THIS REGION FOR SOME ISOLATED THUNDERSTORMS BY LATE SATURDAY AFTERNOON. EXTENDED AVIATION DISCUSSION... WIDESPREAD SHOWERS WITH MVFR INCLUDING LOCALLY IFR CONDITIONS PERSIST INTO SUNDAY NIGHT AS LOW PRESSURE TRACKS UP THE RESIDUAL STALLED FRONT RESULTING IN WIDESPREAD RAINFALL...AND SUB VFR CONDITIONS. THE FRONT WILL STALL ALONG THE COAST OF NC TO GA THROUGH MIDWEEK AND COULD KEEP SHOWERS AND LOWER CIGS AROUND...ESPECIALLY FROM BCB-ROA-LYH SOUTH. MODELS STILL VARY ON THIS BUT CONSENSUS IS FOR SOME AVIATION IMPACT IN TERMS OF SUB VFR CIGS. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/WP NEAR TERM...JH/WP SHORT TERM...KK LONG TERM...KK AVIATION...DS/WP

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