Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 301650 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1250 PM EDT SAT APR 30 2016 .SYNOPSIS...
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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.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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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 MOVINGTO THE 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.
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&& .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 745 AM EDT SATURDAY... WEDGE FRONT VERY WELL DEPICTED IN THE LAPS ANALYSIS AND GOES-R PROVING GROUND MVFR/IFR GRAPHIC...NOW NEAR A LWB-PSK-UKF LINE. LOW CLOUDS SPREAD INTO THE REGION VERY QUICKLY BEHIND THE FRONT WITH A SHARP LINE NOTED FROM JUST OVC250 CIGS AT BCB/BLF/LWB TO CIGS AOB 010 ROA/DAN/LYH...EVEN WIDESPREAD CIGS AOB005 BEHIND THE WEDGE FRONT. MODELS CONTINUE TO MOVE WEDGE FRONT WEST THROUGH THE REST OF THE CWA BY THE 12Z-15Z TIME FRAME. AS THE WEDGE DEEPENS AND MID-LEVEL MOISTURE BEGINS TO SPREAD OVER TOP OF THE SHALLOW WEDGE...-DZ WILL CONTINUE TO EVOLVE...ESPECIALLY IN UPSLOPE AREAS ALONG THE BLUE RIDGE AND ALLEGHANY FRONT. -DZ HAS ALREADY BEEN NOTED AT BCB AND SOME COOPS EAST OF THE BLUE RIDGE REPORTING -DZ THIS MORNING. BONAFIDE -RA OR -SHRA SHOULD BEGIN TO SPREAD INTO THE REGION LATER IN THE AFTERNOON AS THE FIRST OF SEVERAL SHORT WAVES EMANATING FROM A PERSISTENT UPPER LOW IN THE SOUTHWEST U.S. EJECT ENE-NE ACROSS THE REGION. THE WEDGE COULD POTENTIALLY BREAK LATE IN THE DAY TOWARD THE KBLF/KMKJ/KTNB AREA...BUT MOST LIKELY THIS WILL NOT OCCUR UNTIL AFT 06Z. MORE SIGNIFICANT RAINFALL IS EXPECTED TO SPREAD INTO THE REGION AFTER 06Z AS A STRONG SHORT WAVE MOVES NORTHEAST FROM THE SOUTHERN PLAINS. ELEVATED CONVECTION APPEARS POSSIBLE WITH THIS FEATURE AND LOCALLY HEAVY RAINFALL...BUT GIVEN LACK OF INSTABILITY WITHIN THE WEDGE...HAVE REFRAINED FROM MENTIONING TSRA IN THE TAFS AT THIS TIME. BETTER THREAT FOR THUNDER WILL COME SUN AFTERNOON. CIGS STILL VFR AT KBLF/KLWB...BUT HAVE DROPPED AOB 010 ELSEWHERE. LITTLE IMPROVEMENT EXPECTED THROUGH THE DAY AND KBLF AND KLWB SHOULD TREND IFR-LIFR AS THE DAY PROGRESSES AS WELL. SOME VSBYS NOW IN THE IFR RANGE ALONG AND EAST OF THE BLUE RIDGE...BUT MOSTLY EXPECTING MVFR VSBYS AFT 15Z. MOSTLY IFR CIGS AND MVFR VSBYS EXPECTED OVERNIGHT AS HEAVIER RAIN SHOWERS MOVE INTO THE AREA. WINDS LIGHT/VARIABLE WEST OF THE WEDGE. OTHERWISE...NORTHEAST 6-9KTS EAST OF THE BLUE RIDGE...EAST-SOUTHEAST TO SOUTHEAST 7-10KTS WEST OF THE BLUE RIDGE...WITH LOW END GUSTS DEVELOPING DURING THE MORNING KBLF VICINITY...AND POSSIBLY OTHER LOCATIONS...ESPECIALLY EAST OF THE BLUE RIDGE. MEDIUM TO HIGH CONFIDENCE IN CIGS THROUGH THE TAF VALID PERIOD. MEDIUM CONFIDENCE IN VSBYS THROUGH THE TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN WIND DIR/SPD THROUGH THE TAF VALID PERIOD. EXTENDED AVIATION DISCUSSION... WIDESPREAD SHOWERS WITH MVFR INCLUDING LOCALLY IFR CONDITIONS PERSIST OVERNIGHT INTO SUNDAY MORNING...LIKELY IMPROVING TO MVFR/VFR BY AFTERNOON AS THE WEDGE ERODES...SHIFTS NORTHEAST AND THE REGION MOVES INTO THE WARM SECTOR. 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

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