Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 301748 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 148 PM EDT SAT APR 30 2016 .SYNOPSIS... LOW PRESSURE APPROACHES FROM THE WEST THIS AFTERNOON AND TONIGHT. WARM FRONT WILL MOVE NORTH OF THE AREA SUNDAY AFTERNOON. A STRONGER COLD FRONT WILL THEN MOVE THROUGH THE REGION BY MIDWEEK. EXPECT SEVERAL DAYS OF UNSETTLED WEATHER WITH WIDESPREAD RAIN...WITH SOME THUNDERSTORMS SUNDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 1237 PM EDT SATURDAY... SLOWED DOWN TIMING OF HIGHER POPS WITH RADAR TRENDS SHOWING MOISTURE OVER KY/TN MOVING NE. HIGH-RES MODELS HAVE SLOWED DOWN RAIN ONSET AS WELL. WILL STILL SEE A GOOD CHANCE OF RAIN MOVING TOTHE MOUNTAINS BY 5PM...BUT NOT MUCH EAST OF THE BLUE RIDGE UNTIL THIS EVENING. TOOK OUT THUNDER AS MAJORITY OF CLOUD COVER WITH WEDGE WILL KEEP INSTABILITY DOWN. MAY SEE SOME ELEVATED CONVECTION INTO SW VA/NW NC BY 9PM. PREVIOUS VALID DISCUSSION... A NORTHERN STREAM SHORT WAVE WILL DROP SOUTHEAST FROM THE GREAT LAKES TONIGHT AND COMBINE WITH A SHORT WAVE EMANATING FROM THE SOUTHWEST U.S. UPPER LOW TO BRING WIDESPREAD OVERRUNNING RAINFALL TO THE AREA AFT 00Z. RAINFALL AMOUNTS SHOULD AVERAGE FROM ABOUT 1 INCH WESTERN AREAS TO ABOUT 1/2 INCH EASTERN AREAS THROUGH THIS TIME FRAME. SPC HAS INDICATED A MARGINAL RISK FOR SEVERE IN THE FAR SOUTHWESTERN AREAS FOR DAY 1. AT THIS TIME...HAVE NOT MENTIONED ANY SEVERE IN THE GRIDS THROUGH 12Z SUN AS INSTABILITY PARAMETERS ARE MARGINAL AT BEST WITHIN THE WEDGE AREA. SOME CONCERN NEAR THE WEDGE BOUNDARY...BUT FEEL THAT WILL BE A MORE SIGNIFICANT PROBLEM LATER IN THE DAY SUNDAY. TEMPERATURES WILL FALL LITTLE AFT 00Z...LIKELY ENDING UP ONLY A FEW DEGREES LOWER THAN MAX TEMPS TODAY. THE SYNOPTIC PATTERN DOES SUGGEST SOME POTENTIAL FOR GUSTY SOUTHEAST WINDS LATE TONIGHT/EARLY SUNDAY IN THE MERCER/TAZEWELL/SMYTH COUNTY REGION...BUT SHOULD BE FAR BELOW WIND ADVISORY CRITERIA. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... AS OF 330 AM EDT SATURDAY... A QUASI ZONAL UPPER PATTERN WILL BE TRANSITIONING TO A BROAD EASTERN TROF THROUGH EARLY NEXT WEEK AND KEEP SYSTEMS FAIRLY PROGRESSIVE. ON SUNDAY AS AN UPPER SHORT WAVE WILL DRIVE A SURFACE LOW FROM THE MISSISSIPPI VALLEY INTO NEW ENGLAND THERE MAY BE ENOUGH PUSH TO NUDGE THE WEDGE ALONG THE COAST A BIT FURTHER EAST...ALLOWING UNSTABLE AIR AHEAD OF A COLD FRONT ASSOCIATED WITH THE LOW TO GENERATE SOME THUNDERSTORMS ACROSS THE REGION. SEVERE PARAMETERS SUPPORT THE CURRENT SPC MARGINAL OUTLOOK SO LONG AS THE WEDGE EXITS ON SCHEDULE. THE RETREATING WEDGE FRONT WILL BE AN AREA TO WATCH FOR ENHANCED SEVERE POTENTIAL. LOCALLY HEAVY RAIN WILL ALSO BE A CONCERN WITH PWATS STILL RUNNING WELL OVER ONE INCH AND TRAINING OF STORMS MAY CREATE SOME HYDRO ISSUES. AS THE FRONT SINKS TO OUR SOUTH SUNDAY NIGHT CONVECTIVE PRECIPITATION WILL COME TO AN END WITH SOME LINGERING SHOWERS IN UPSLOPE FLOW WEST OF THE BLUE RIDGE. MONDAY LOOKS TO BE QUIET WITH HIGH PRESSURE BRINGING A RESPITE FROM THE RAINFALL...BUT THIS LOOKS TO BE A BRIEF BREAK AS MORE SHORT WAVE ENERGY MOVING THROUGH THE DEVELOPING UPPER TROF STARTS TO DEVELOP A WAVES ALONG THE FRONTAL BOUNDARY TO OUR SOUTH AND BRING A CHANCE OF SHOWERS BACK TO THE FORECAST. GUIDANCE IS NOT OFFERING A FOCUSED SET OF SOLUTIONS REGARDING HOW FAR NORTH THE WAVES WILL DRAG THE FRONTAL BOUNDARY AND PRECIPITATION SO CONFIDENCE ON BEST TIMING/LOCATION OF PRECIPITATION MONDAY NIGHT THROUGH TUESDAY IS RATHER LOW. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 300 PM EDT FRIDAY... 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 /18Z SATURDAY THROUGH THURSDAY/... AS OF 140 PM EDT SATURDAY... SFC WEDGE SHOULD HANG AROUND FOR MOST OF THE TAF PERIOD...ERODING FROM BLF-LWB BY 120-14Z SUNDAY AND MAYBE EAST OF THE BLUE RIDGE BY 18Z SUNDAY. GIVEN THIS...CONFIDENCE IS HIGH THAT LOW CIGS WILL STICK AROUND DURING THIS TAF VALID PERIOD. QUESTION WILL BE VSBYS AS RAIN/DRIZZLE THIS AFTERNOON WILL BRING MVFR TO IFR VSBYS AT TIMES....WHILE CIGS STAY IFR OR WORSE...EXCEPT EARLY ON AT BLF/LWB. RAIN LOOKS TO BECOME MORE STEADY OVERNIGHT AND COULD BE MODERATE TO HEAVY AT TIMES IN THE BLF/LWB AREA. NOT SEEING ANY THUNDER RIGHT THRU 18Z SUNDAY. WILL BRING CIGS ABOVE 1KFT AT 10-12Z WEST TO 16Z EAST. BACKED OFF ON WINDS IN THE EAST AS DO NOT SEE MUCH GRADIENT FOR GUSTS THIS EVENING. MEDIUM TO HIGH CONFIDENCE IN CIGS THROUGH THE TAF VALID PERIOD. MEDIUM CONFIDENCE IN VSBYS THROUGH THE TAF VALID PERIOD. EXTENDED AVIATION DISCUSSION... CIGS/VSBYS IMPROVING TO MVFR/VFR BY SUNDAY AFTERNOON AS THE WEDGE ERODES. SUNDAY AFTERNOON BRINGS THE POTENTIAL FOR SCATTERED CONVECTION...SOME POSSIBLY STRONG TO SEVERE AS SHORT WAVE ENERGY TRACKS NORTHEAST ACROSS THE REGION IN THE WARM/UNSTABLE AIR MASS. SITUATION APPEARS SOMEWHAT SIMILAR TO WHAT WAS OBSERVED THURSDAY ACROSS THE REGION...BUT PERHAPS MORE ACTIVITY NORTH-WEST OF THE BLUE RIDGE THIS TIME AROUND THAN WHAT WAS OBSERVED SUNDAY. SFC LOW PRESSURE TRACKS NORTHEAST ACROSS GA/SC/NC SUN NIGHT-TUE...LIKELY PROLONGING SUB-VFR CIGS AND POTENTIALLY LEAVING SOME LIGHT PRECIPITATION ACROSS THE REGION...ESPECIALLY EAST OF THE BLUE RIDGE. FOR THE MID AND LATER PART OF NEXT WEEK...A DEEP UPPER LOW IS EXPECTED TO DROP DOWN ACROSS THE GREAT LAKES INTO THE APPALACHIANS AND MID-ATLANTIC REGION...WHICH WILL LEAVE THE REGION WITH VARIABLE CLOUDINESS...SHOWERS...AND PERIODS OF SUB-VFR CONDITIONS. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...RAB/WP NEAR TERM...RAB/WP SHORT TERM...MBS LONG TERM...KK/MBS AVIATION...RAB/WP

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