Area Forecast Discussion
Issued by NWS Blacksburg, VA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KRNK 120459 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1159 PM EST THU FEB 11 2016 .SYNOPSIS... HIGH PRESSURE WILL BUILD EAST ACROSS THE REGION TONIGHT AHEAD OF A WEAK AREA OF LOW PRESSURE THAT WILL APPROACH FROM THE WEST BY EARLY FRIDAY. THIS CLIPPER SYSTEM WILL CROSS OUR AREA ON FRIDAY WITH SOME LIGHT SNOW ACCUMULATIONS POSSIBLE...ESPECIALLY IN THE MOUNTAINS. ARCTIC HIGH PRESSURE WILL BUILD IN FOR THE WEEKEND RESULTING IN VERY COLD BUT OVERALL DRY CONDITIONS INTO SUNDAY. && .NEAR TERM /THROUGH FRIDAY/...
-- Changed Discussion --
AS OF 1145 PM EST THURSDAY... 00Z LARGER SCALE MODELS AND HIGH-RES MODELS BOTH COMING IN SLOWER WITH SNOW IN THE MORNING. BASED ON UPSTREAM OBS THIS LOOKS REASONABLE. WILL DELAY ONSET OF SNOW TIL AFTER 12Z...WITH BEST LIFT ARRIVING TOWARD 15Z IN THE SW MTNS. THE NAM IS SHOWING ABOUT 2/10 INCH LIQUID WHICH FOR THIS AIRMASS AROUND 15-20:1 RATIO WILL SPIT OUT CLOSE TO 3 INCHES ACROSS THE HIGHEST TERRAIN LIKE MOUNT ROGERS...BEECH MTN AND THREE TOP MTN IN NW NC/SW VA. SHOULD QPF INCREASE MAY HAVE TO GO WITH WINTER WX ADVISORY FOR THE NC MTNS/GRAYSON...BUT GIVEN THAT IT IS CONFINED TO ABOVE 4000 FT...THE MAJORITY OF FOLKS WILL RECEIVE 2" OR LESS...SO NO ADVISORY PLANNED WITH THIS UPDATE. LOWERED TEMPS A FEW MORE DEGREES PER LATEST OBS. WITH MID/HIGH CLOUDS STREAMING IN OVERNIGHT EXPECT TEMPS TO START TO SLOWLY DECLINE OR STEADY OUT LATE. PREVIOUS MID EVENING DISCUSSION... ONLY A FEW MINOR EDITS WITH THE EVENING UPDATES. ADJUSTED SKY COVER BASED ON CURRENT IR SIGNATURES. MID DECK LOOKS DELAYED BY AN HOUR OR SO...AND MUCH DENSER TO THE SOUTH. THUS...ADJUSTED MINIMUM TEMPERATURE VALUES DOWN IN THE NORTHERN PORTION OF THE FORECAST AREA DUE TO A LONGER PERIOD OF RADIATIONAL COOLING. PREVIOUS VALID DISCUSSION... BRIEF LULL IN THE ACTION WILL OCCUR EARLY TONIGHT AS SURFACE HIGH PRESSURE BUILDS IN ALLOWING WINDS TO DIMINISH UNDER MAINLY CLEAR SKIES THIS EVENING. HOWEVER LACK OF MOISTURE WILL BE SHORT LIVED AS A WARM ADVECTION PATTERN QUICKLY DEVELOPS ALOFT LATE TONIGHT IN ADVANCE OF THE NEXT DIGGING UPSTREAM SHORTWAVE AHEAD OF THE NEXT ARCTIC SHOT. GUIDANCE SHOWS THIS LEADING TO AN INCREASE IN MID CLOUDS FROM THE NW BY MIDNIGHT WITH THIS CANOPY OVERSPREADING THE REGION BY DAYBREAK. BOUNDARY LAYER APPEARS TOO DRY FOR ANY PRECIP OTHER THAN MAYBE A FLURRY FAR WEST LATE SO KEEPING POPS OUT UNTIL JUST BEFORE DAWN SW. TEMPS REMAIN VERY COLD AND WITH LOW DEWPOINTS EXPECTING A QUICK DROP OFF AFTER SUNSET ESPCLY VALLEYS AS WIND DIMINISH BEFORE THINGS STEADY OUT WITH CLOUDS ARRIVING. THIS SUPPORTS GOING A LITTLE BELOW MOS WITH LOWS MOSTLY TEENS WITH A FEW SINGLE DIGITS NW VALLEYS WHERE SNOW COVER PREVAILS. FAST MOVING MID LEVEL WAVE AND ASSOCIATED SURFACE CLIPPER WILL PASS TO THE SOUTH FRIDAY WITH THE SURFACE LOW QUICKLY DEEPENING UPON REACHING THE CAROLINA COAST. LATEST MODELS BRING A SWATH OF LIFT WITH WEAK FRONTOGENETIC FORCING INTO THE WESTERN SLOPES FRIDAY MORNING BEFORE UPWARD MOTION JUMPS TO THE COASTAL SYSTEM. JUST HOW FAR SNOW ASSOCIATED WITH THIS WESTERN SLUG OF MOISTURE MAKES IT REMAINS IFFY BUT APPEARS MAY RUN OUT TO THE BLUE RIDGE BEFORE FADING/REDEVELOPING PIEDMONT PRIOR TO ENDING. LATEST QPF OF AROUND A TENTH OF AN INCH OR LESS WESTERN MOUNTAINS SUPPORTS AN INCH OR TWO OF SNOW PER HIGH RATIOS...WITH LESS THAN AN INCH I-81 CORRIDOR/BLUE RIDGE...AND ONLY TRACE AMOUNTS TO THE EAST. THEREFORE UPPED POPS A BIT FAR WEST AND EXTENDED HIGHER CHANCES EAST GIVEN FAST MOVEMENT AND POTENTIAL FOR A BAND TO SNEAK OUT ESPCLY IF THE SHORTWAVE IS A BIT FASTER UNDER STRONG LOW LEVEL BACKED FLOW PER THE GFS. AMOUNTS STILL BELOW ADVISORY CRITERIA AND GIVEN TIMING OF MOSTLY BETWEEN THE MORNING/EVENING RUSH HOURS WILL HOLD OFF ON ANY HEADLINES FOR NOW. OTRW A BRIEF REPRIEVE IN THE ONGOING FRIGID TEMPS WITH WEAK WARM ADVECTION LIKELY TO PUSH HIGHS INTO THE 30S EAST...AND POSSIBLY INTO THE UPPER 20S/LOWER 30S ELSEWHERE BEFORE THE FRONT CROSSES LATE.
-- End Changed Discussion --
&& .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... AS OF 330 PM EST THURSDAY... UPSLOPE SNOW SHOWERS WILL BE ONGOING FRIDAY NIGHT. WINDS TURN TO THE NORTHWEST WITH A LOW LEVEL JET PEAKING AROUND 50 KNOTS OVERNIGHT. MUCH DRIER AIR COMES IN BEHIND THE CLIPPER. MODELS SUGGEST ONLY ENOUGH LOW LEVEL MOISTURE FOR SNOW SHOWERS IN WESTERN GREENBRIER COUNTY BY SATURDAY EVENING. BUFKIT SOUNDINGS...PRESSURE RISES AND INVERSION HEIGHT ALONG THE SOUTHERN BLUE RIDGE AND INTO THE NORTHWEST NORTH CAROLINA MOUNTAINS SUPPORT THE POSSIBILITY OF ADVISORY LEVEL WIND GUSTS FRIDAY NIGHT. HAVE MENTIONED THIS POTENTIAL THREAT IN THE HAZARDOUS WEATHER OUTLOOK. COLDEST AIR WITH THIS ARCTIC AIRMASS WILL BE OVER THE REGION ON SATURDAY AND SATURDAY NIGHT. BY SUNDAY AFTERNOON THE CENTER OF THE SURFACE HIGH IS CROSSING THE MID ATLANTIC STATES. MINIMUM TEMPERATURES SATURDAY NIGHT WILL BE 15 TO 25 DEGREES BELOW NORMAL. ON SATURDAY NIGHT THE WINDS WILL NOT BE AS STRONG...BUT WITH COLDER TEMPERATURES...THE COMBINATION WILL STILL RESULT IN DANGEROUS WIND CHILLS ACROSS PARTS OF THE MOUNTAINS. MID AND HIGH CLOUDS SPREAD BACK OVER THE AREA ON SUNDAY FROM THE WEST. LOW CONFIDENCE IN HOW LONG IT WILL TAKE TO SATURATE LOWER LAYERS ENOUGH FOR PRECIPITATION FOR SUNDAY NIGHT. NO CHANGES IN THE ARRIVAL TIME OF THE PRECIPITATION FOR NOW. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 100 PM EST THURSDAY... A PIECE OF THE SURFACE HIGH REMAINS WEDGED DOWN THE EAST SIDE OF THE APPALACHIANS WITH COASTAL TROFING ALSO DEVELOPING ON MONDAY. THE GFS AND CANADIAN BRING A SURFACE LOW FROM THE LOWER MISSISSIPPI VALLEY SUNDAY THEN DEEPEN THE LOW AND TRACK IT NORTHEAST TO THE CAROLINAS BY TUESDAY. THE ECMWF IS INITIALLY WEAKER WITH THE LOW THEN FASTER TRACKING IT NORTHEAST ALONG THE COAST TUESDAY. OF COURSE THE TRACK OF THE LOW WILL HAVE TREMENDOUS INFLUENCE ON THE RESULTING WEATHER FOR THE COUNTY WARNING AREA. WPC FAVORING ENSEMBLES FORECASTS IN THIS TIME FRAME. BULK OF THE PRECIPITATION WITH THIS STORMS SYSTEM AT THIS TIME LOOKS TO BE ON LATE MONDAY THROUGH TUESDAY MORNING. ENTIRE FORECAST AREA STAYS COLD ENOUGH AT ALL LEVEL FOR SNOW THROUGH MONDAY MORNING. THEN VERY STRONG SOUTHERLY JET BRINGS IN WARMER AIR ABOVE THE SURFACE. THIS WILL LIKELY CAUSE MIXED WINTER PRECIPITATION. WITH THE WEDGE IN PLACE...MODELS MAY BE TOO AGGRESSIVE WARMING UP THE SURFACE THROUGH 850 MB LAYER MONDAY NIGHT. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
AS OF 1150 PM EST THURSDAY... VFR THROUGH 12Z WITH INCREASING MID/HIGH CLOUDS. MODELS SLOWING TIMING OF SNOW AND LOWER CIGS DOWN UNTIL 12Z OR AFTER. STILL LOOKS LIKE MVFR CIGS ARE LIKELY AT BLF/LWB/BCB BETWEEN 17-18Z...WITH LIGHT SNOW/FLURRIES MOVING IN A COUPLE HOURS BEFORE THIS. CONFIDENCE HIGH IN MVFR CIGS BUT NOT HIGH ENOUGH TO WARRANT IFR CIGS/VSBYS BUT POSSIBLE DURING THE EARLY AFTERNOON FRIDAY. FLURRIES ALSO EXPECTED AT DAN/ROA...WITH LOW END VFR CIGS. WINDS LIGHT THROUGH THE DAY TOMORROW. ONCE LOW MOVES OFF THE COAST WINDS INCREASE FROM THE WEST-NORTHWEST FRIDAY EVENING AND ESPECIALLY OVERNIGHT. THIS WILL LEAD TO INCREASE IN SNOW SHOWERS THROUGH SAT MORNING IN THE WEST...WITH WINDS GUSTING UP TO 30 TO 40 KTS...ESPECIALLY ROA/BCB. EXTENDED DISCUSSION... EXPECT VFR SAT AFTERNOON THROUGH SUNDAY WITH SUBSIDING WINDS...THOUGH SOME MVFR INTO SAT NIGHT POSSIBLE AT BLF. THE NEXT LOW PRESSURE SYSTEM WILL ARRIVE ON SUNDAY NIGHT. CONFIDENCE IS HIGH THAT POOR FLYING WEATHER WILL TAKE PLACE DURING MONDAY AND TUESDAY. THIS SYSTEM COULD BRING SOME WINTRY PRECIPITATION...BUT FURTHER UPDATES FROM THE LONGER RANGE MODELS MAY IMPACT THE DETAILS ON PRECIPITATION TYPE AND STORM TRACK.
-- End Changed Discussion --
&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH NEAR TERM...JH/JM/WP SHORT TERM...AMS LONG TERM...AMS AVIATION...PW/WP

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.