Area Forecast Discussion
Issued by NWS Blacksburg, VA

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087 FXUS61 KRNK 120250 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 950 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/... AS OF 945 PM EST THURSDAY... .NEAR TERM /THROUGH FRIDAY/... AS OF 945 PM EST THURSDAY... 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. && .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 /03Z FRIDAY THROUGH TUESDAY/... AS OF 700 PM EST THURSDAY... VFR CONDITIONS WITH LIGHT WINDS SHOULD PERSIST OVERNIGHT AT ALL SITES. HOWEVER...AN APPROACHING LOW PRESSURE SYSTEM OVER THE CENTRAL PLAINS SHOULD BRING INCREASING MID LEVEL CLOUDS AFTER MIDNIGHT. CEILINGS WILL STEADILY DROP BY DAWN ON SATURDAY. CONFIDENCE FOR MVFR/IFR CEILINGS AND VISIBILITIES INCREASES AFTER 12Z SATURDAY FOR BLF/LWB/BCB...AS THE LOW PRESSURE SYSTEM MOVES OVERHEAD TO BRING LIGHT SNOW. ROA MAY SEE PASSING FLURRIES...BUT IT SHOULD HOLD AT VFR. LYH AND DAN SHOULD STAY VFR AND REMAIN DRY. WINDS WILL TURN TOWARD THE NORTHWEST BEHIND THE LOW PRESSURE SYSTEM ON SATURDAY EVENING...AND GUST UP TO 20 KT AT BLF AND BCB. EXTENDED DISCUSSION... ANOTHER ROUND OF UPSLOPE SNOW SHOWERS WILL ENSUE BEHIND THE DEPARTING LOW PRESSURE SYSTEM DURING SATURDAY NIGHT INTO SUNDAY MORNING. NORTHWEST WINDS WILL BECOME GUSTY AS ANOTHER SURGE OF ARCTIC AIR ARRIVES. ROA/LYH/DAN SHOULD STAY VFR THROUGH SUNDAY...BUT CONDITIONS COULD REMAIN MVFR/IFR FOR BLF/LWB/BCB UNTIL SUNDAY AFTERNOON WHEN HIGH PRESSURE MOVES OVERHEAD. 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. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH NEAR TERM...JM/JH SHORT TERM...AMS LONG TERM...AMS AVIATION...PW

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