Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 020600 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 200 AM EDT THU APR 2 2015 .SYNOPSIS... HIGH PRESSURE WILL PASS OVERHEAD TONIGHT PROVIDING CLEAR SKIES AND LIGHT WINDS. A WARM FRONT WILL PUSH NORTH THROUGH THE OHIO VALLEY THURSDAY...SUPPORTING SPOTTY SHOWER MAINLY WEST OF THE MOUNTAINS. A STRONG COLD FRONT WILL PASS ACROSS THE AREA FRIDAY NIGHT...PRODUCING SHOWERS AND THUNDERSTORMS...FOLLOWED BY BREEZY BUT DRY CONDITIONS FOR THE WEEKEND. && .NEAR TERM /THROUGH TODAY/... AS OF 330 PM EDT WEDNESDAY... 1022 MB SURFACE HIGH PRESSURE WAS CENTERED OVERHEAD. THIS FEATURE WILL PROMOTE CLEAR SKIES TONIGHT WITH NEAR CALM WINDS. A LIGHT SOUTHEAST BREEZE MAY DEVELOP ALONG THE RIDGETOPS TOWARD DAYBREAK THURSDAY...BUT VALLEYS SHOULD REMAIN DECOUPLED WITH POTENTIAL FOR PATCHY FROST...LOWS IN THE 30S. THE HIGH SHOULD BE CENTERED NEAR THE ATLANTIC COAST TO START THE DAY THURSDAY. CLOCKWISE FLOW AROUND THE HIGH RESULTING IN INCREASING SOUTHERLY WINDS AND DEWPOINTS. MOISTURE WILL BEGIN TO RETURN TO THE AREA AS A WARM FRONT LIFTS NORTH THROUGH THE TN/OH VALLEYS ON THURSDAY...PROMOTING INCREASING CLOUDINESS AND THE THREAT FOR A FEW SPRINKLES WEST OF THE BLUE RIDGE. PENDING CLOUD COVER...TEMPERATURES SHOULD WARM WELL INTO THE 60S... POTENTIALLY TESTING 70 DEGREES ACROSS THE PIEDMONT. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... AS OF 345 PM EDT WEDNESDAY... OUR AREA WILL BE IN A WARM SECTOR SQUEEZE PLAY FOR THE LATTER PORTION OF THE WEEK WITH HIGH PRESSURE MOVING OFF TO OUR EAST AND A SLOW MOVING COLD FRONT APPROACHING FROM THE WEST. THIS WARM OUR TEMPERATURES IN THE 60S AND 70S ON FRIDAY AND KEEP US IN A CHANCE OF SHOWERS UNTIL LATE FRIDAY NIGHT WHEN SHOWERS ARE LIKELY AS THE FRONT MOVES THROUGH. WHILE THE BEST DYNAMICS WITH THE FRONT WILL SLIDE BY TO OUR NORTHWEST THE AMOUNT OF SHEAR ACROSS THE AREA FRIDAY AFTERNOON INTO FRIDAY NIGHT IS NOT TRIVIAL AND THE LOW LEVEL WIND FIELD HAS A GOOD AMOUNT OF BRISK EARLY SPRING ENERGY. THE BIG LIMITING FACTOR FOR CONVECTION IS THE LACK OF SIGNIFICANT INSTABILITY WITH CAPES AT OR BELOW 500J/KG LATE FRIDAY AFTERNOON. WILL CONTINUE THE FORECAST FOR SHOWERS/CHANCE OF THUNDER AND AGREE WITH SPC DAY THREE SEVERE OUTLOOK WHICH PLACES THE FAR WESTERN PORTION OF THE AREA IN A MARGINAL RISK FOR A WIND THREAT. SIGNIFICANTLY COLDER AIR MOVES IN BEHIND THE FRONT LATE FRIDAY NIGHT AND SATURDAY ON BLUSTERY NORTHWEST WINDS. THE FAR WESTERN SLOPES WILL SEE SOME UPSLOPE SNOW SHOWERS DEVELOP BEFORE DAYBREAK SATURDAY AND A MINIMAL SLUSHY COATING OF SNOW IS POSSIBLE...ESPECIALLY FOR WESTERN GREENBRIER COUNTY...BEFORE THE PRECIPITATION DISSIPATES AS WE GO THROUGH SATURDAY MORNING. CURRENTLY EXPECT WINDS BEHIND THE FRONT TO REMAIN BELOW ADVISORY CRITERIA BUT CONDITIONS WILL CERTAINLY BE QUITE GUSTY. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 345 PM EDT WEDNESDAY... EVOLVING UPPER PATTERN WILL REMAIN PROGRESSIVE AND FEATURE SOME FLAT RIDGING THROUGH THE EXTENDED PERIOD AND LOOKS TO KEEP OUR AREA IN THE MILD AIR AT LEAST THROUGH MIDWEEK. HIGH PRESSURE WILL BUILD IN WITH QUIET WEATHER AND THE START OF A WARMING TREND ON SUNDAY TO CLOSE OUT THE WEEKEND. THE FIRST PART OF NEXT WEEK WILL SEE A SERIES OF WEAK UPPER LEVEL SHORT WAVES MOVE THROUGH AS THE AIRMASS OVER THE EASTERN US BECOMES WARMER AND MORE MOIST THANKS TO PERSISTENT SOUTHWESTERLY WINDS. THIS SHOULD SET US UP FOR BOUTS OF DIURNAL CONVECTION WITH A CHANCE OF SHOWERS AND THUNDERSTORMS JUST ABOUT EACH AFTERNOON...BECOMING MORE LIKELY ACROSS WESTERN PORTIONS OF THE AREA. AS WE GO OUT IN TIME MODEL GUIDANCE STARTS TO DIFFER ON TIMING OF WEATHER SYSTEMS BUT IT APPEARS THE NEXT COLD FRONT APPROACHING FROM THE WEST WILL NOT AFFECT OUR REGION UNTIL LATE WEDNESDAY AT THE EARLIEST. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... AS OF 145 AM EDT THURSDAY... A VERY DRY AIR MASS RESIDES OVER THE AREA EARLY THIS MORNING IN THE WAKE OF A LARGE AREA OF HIGH PRESSURE MOVING OFF THE VA COAST AT THIS HOUR. UPSTREAM ARE A SERIES OF SHORT WAVES EMBEDDED WITHIN AN INCREASINGLY ZONAL AND ACTIVE UPPER FLOW. THE FIRST OF THESE SHORT WAVES WILL SPREAD RAPIDLY TOWARD THE REGION THROUGH THE DAY. MODELS...ESPECIALLY THE GFS...ARE WAY TO AGGRESSIVE GIVEN THE VERY DRY AIR MASS IN PLACE...DEWPOINTS STILL IN THE SINGLE DIGITS AND TEENS ACROSS MUCH OF THE AREA...IN GENERATING MEASURABLE QPF WITH THIS FIRST FEATURE. FEEL LARGELY THAT THIS FIRST FEATURE WILL SIMPLY SERVE TO MOISTEN THE ATMOSPHERE FOR MORE APPRECIABLE MOISTURE WITH THE SECOND SHORT WAVE TO ARRIVE THU NIGHT/FRI MORNING. MODEL TIME-HEIGHT CROSS-SECTIONS AND BUFKIT MODEL SOUNDINGS SHOW THAT THE BULK OF THE MOISTURE THROUGH THE TAF VALID PERIOD REMAINS AOA100. THUS...FOR NOW...HAVE IGNORED THE WIDESPREAD 0.10-0.20 INCH 6-HR QPF GENERATED BY THE GFS AND THE MODEL GENERATED TAFS OF CIGS AOB 025 BY 00Z. HAVE NOT INTRODUCED ANY SUB-VFR CIGS AT THIS POINT. WILL INCLUDE A PROB30 FOR -RA/SPRINKLES BLF- LWB WHERE THE MOISTURE SHOULD BECOME A LITTLE DEEPER MORE QUICKLY AND ANY UPSTREAM -SHRA MAY SPREAD INTO EASTERN WV/FAR SW VA AS SPRINKLES BEFORE DISSIPATING. VISIBILITIES WILL NOT BE AN ISSUE THROUGH THE TAF VALID PERIOD. WINDS...LIGHT SE MOST LOCATIONS AT THE ONSET...VEERING TO SSW THROUGH THE DAY AND INCREASING TO 10-12KTS WITH GUSTS 20-22KTS POSSIBLE AS THE PRESSURE GRADIENT INCREASES BETWEEN THE DEPARTING SFC HIGH AND LOW PRESSURE DRAPED FROM THE SOUTHERN PLAINS TO THE NORTHEAST. MEDIUM TO HIGH CONFIDENCE IN CIGS THROUGH THE TAF VALID PERIOD. HIGH CONFIDENCE IN VFR VSBYS THROUGH THE TAF VALID PERIOD. MEDIUM CONFIDENCE IN WIND DIR THROUGH THE TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN WIND SPD THROUGH THE TAF VALID PERIOD. EXTENDED AVIATION FORECAST... A SLOW MOVING...INCREASINGLY WEST-EAST ORIENTED COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST FRI...MOVING THROUGH THE REGION FRI NIGHT/SAT MORNING AS AN UPSTREAM NORTHERN STREAM SHORT WAVE FINALLY KICKS THE FRONT SOUTHEAST. MUCH OF THE DAY FRIDAY...EXPECT THE PRECIPITATION TO REMAIN MOSTLY NORTHWEST OF THE CWA...MOVING INTO EASTERN WV DURING THE AFTERNOON...SPREADING ACROSS THE REMAINDER OF THE CWA AS A NARROW LINE OF CONVECTION FRI EVENING/EARLY SATURDAY. A FEW THUNDERSTORMS ARE POSSIBLE...MAINLY WESTERN AREAS. SEVERE WEATHER IS NOT EXPECTED. COLDER TEMPERATURES AND UPSLOPE -SHRA...POSSIBLY -SHSN AT THE HIGHER ELEVATIONS...ARE POSSIBLE EARLY SATURDAY BEFORE CLEARING TAKES PLACE. GUSTY NORTHWEST WINDS ARE EXPECTED SATURDAY BEHIND THE FRONT. HIGH PRESSURE WILL BUILD INTO THE REGION SAT AFTERNOON-SUN WITH VFR CONDITIONS EXPECTED. AN EXTENDED PERIOD OF SUB-VFR CONDITIONS APPEARS LIKELY MUCH OF NEXT WEEK AS THE AREA REMAINS TRAPPED UNDER AN ACTIVE STORM TRACK FROM A BROAD AREA OF LOW PRESSURE IN THE SOUTHWEST U.S. MULTIPLE ROUNDS OF SHOWERS AND A FEW THUNDERSTORMS APPEAR LIKELY THROUGH THE PERIOD. && .FIRE WEATHER... HIGH PRESSURE WILL PASS OVERHEAD EARLY TONIGHT RESULTING IN CLEAR SKIES AND NEAR CALM WINDS. AS THE HIGH MOVES TO ALONG THE ATLANTIC COAST...A SOUTHEAST WIND WILL DEVELOP ALONG THE RIDGE TOPS...BUT REMAINING NEARLY CALM IN THE VALLEYS. SOUTHERLY WIND SPEEDS AND CLOUD COVER WILL INCREASE ON THURSDAY AS A COLD FRONT MOVES ACROSS THE MIDWEST STATES. LITTLE OR NO PRECIPITATION IS EXPECTED THURSDAY. BY FRIDAY...THE FRONT WILL BE CLOSE ENOUGH TO PRODUCE SCATTERED SHOWERS...AND BY FRIDAY NIGHT SHOWERS WILL BECOME LIKELY WITH THE OPPORTUNITY FOR THUNDERSTORMS. THIS IS EXPECTED TO BE A STRONG FRONTAL PASSAGE WITH GUSTY SOUTHWEST WINDS AHEAD OF THE FRONT...FOLLOWED BY GUSTY NORTHWEST WINDS BEHIND THE FRONT FROM SATURDAY INTO SUNDAY MORNING. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...PM NEAR TERM...PM SHORT TERM...MBS LONG TERM...MBS AVIATION...RAB/RCS FIRE WEATHER...PM

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