Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 310630 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 230 AM EDT FRI OCT 31 2014 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH THE FIRST HALF OF THE DAY FRIDAY. WEATHER CONDITIONS WILL RAPIDLY DETERIORATE FRIDAY EVENING AS A FAST MOVING DISTURBANCE FROM CANADA MOVES SOUTHEAST ACROSS THE OHIO VALLEY...THEN ACROSS THE SOUTHERN APPALACHIANS FRIDAY NIGHT AND SATURDAY. WINTER STORM CONDITIONS ARE LIKELY IN THE HIGH COUNTRY OF NORTH CAROLINA...AND INTO THE HIGHER ELEVATIONS OF FAR WESTERN VIRGINIA VICINITY OF MOUNT ROGERS FRIDAY NIGHT AND SATURDAY. ELEVATIONS ABOVE 3000 FEET WILL SEE THE GREATEST WINTRY IMPACT. && .NEAR TERM /THROUGH TODAY/... AS OF 1120 PM EDT THURSDAY... EXPECT MAINLY CLEAR SKIES INTO EARLY OVERNIGHT BEFORE CLOUDS INCREASE FROM THE WEST. JUST A LITTLE SC ACROSS THE NEW RIVER VALLEY. TEMPS HAVE SUNK INTO THE UPPER 20S TO LOWER 30S OVER PORTIONS OF THE MOUNTAINS SO EXPECT FROST IN THE MOUNTAINS...THOUGH THE GROWING SEASON IS OVER. PATCHY FROST TO FORM IN THE FOOTHILLS AND SOUTHERN SHENANDOAH VLY. NOT ENOUGH COVERAGE TO WARRANT AN ADVISORY AS CLOUDS WILL BE HEADING INTO THE REGION BY DAWN. NO OTHER MAJOR CHANGES TO THE FORECAST. PREVIOUS VALID DISCUSSION... DETERIORATING CONDITIONS EXPECTED THROUGH THE DAY FRIDAY AS A STRONG DISTURBANCE DIVES SOUTHEAST FROM THE GREAT LAKES INTO THE OHIO VALLEY. ONE SHORT WAVE COMING AROUND THIS DISTURBANCE WILL BRING LIGHT RAIN SHOWERS TO WESTERN SLOPES OF SOUTHEASTERN WEST VIRGINIA AROUND NOON FRIDAY. THE ATMOSPHERE WILL CONTINUE TO SATURATE THROUGH THE AFTERNOON AS THIS SHORT WAVE TRACKS EAST OVER THE FORECAST AREA. RAIN SHOWERS ADVANCE TO THE BLUE RIDGE BY EARLY AFTERNOON THEN INTO THE FOOTHILLS LATE. THE PIEDMONT MAY NOT SEE ANY RAIN UNTIL FRIDAY EVENING. LOW LEVEL THICKNESSES AND 85H TEMPERATURES STAY WARM THROUGH THE DAY TO KEEP P-TYPE AS A COLD RAIN. && .SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... AS OF 400 PM EDT THURSDAY... DEEP CLOSED 500MB LOW OVER INDIANA WILL TRACK SOUTH-SOUTHEAST INTO WESTERN NORTH CAROLINA BY SATURDAY MORNING THEN EAST TO THE OUTER BANKS BY SATURDAY EVENING. 110 KNOT UPPER JET ROUNDS THE BASE OF THE TROF SATURDAY THEN TROF AXIS MOVES EAST OF THE FORECAST AREA SATURDAY NIGHT. SURFACE LOW FEATURE WILL BE SUBTLE AS IT CROSSES THE CAROLINAS FRIDAY NIGHT BUT THEN LOW SHARPLY DEEPENS JUST OFF THE COAST ON SATURDAY. EXPECTING GOOD UPSLOPE ON THE WESTERN SIDE OF THE APPALACHIANS SATURDAY AND SATURDAY NIGHT. 850 MB WINDS WILL BE 45 TO 50 KNOTS FROM THE NORTH-NORTHWEST SO DIRECTION IS NOT IDEAL BUT SPEEDS ARE CERTAINLY PLENTY STRONG. BEST PRESSURE RISES WILL BE ON SATURDAY NIGHT AS LOW DEEPENS WHICH WILL ENHANCE WIND SPEEDS. BUFKIT SOUNDINGS AND PARTIAL THICKNESS FORECASTS SUGGEST A GRADUAL CHANGE OVER FROM RAIN TO SNOW AROUND MIDNIGHT FRIDAY NIGHT IN MOST LOCATIONS. A BETTER EASTWARD PUSH OF THE UNSEASONABLY COLD AIR COMES IN SATURDAY NIGHT BEHIND THE PRECIPITATION IN THE EAST. MODELS PULL THE DEEP MOISTURE EAST OF THE COUNTY WARNING AREA SATURDAY NIGHT FASTER THAN THE NAM. BUT EVEN NAM BUFKIT SOUNDING SHOWS MOISTURE BECOMING SHALLOW BY LATE SATURDAY NIGHT. LITTLE ADDITIONAL ACCUMULATION WITH SUCH SHALLOW MOISTURE ON SATURDAY NIGHT. SURFACE HIGH PRESSURE BUILDS IN SUNDAY AND SUNDAY NIGHT. WINDS AND UPSLOPE WILL DIMINISH ALTHOUGH SOME CLOUDS MAY LINGER IN SOUTHEAST WEST VIRGINIA SUNDAY EVENING. HAVE UPGRADE TO A WINTER STORM WARNING. OTHER ADVISORIES WILL LIKELY BE ISSUED LATER. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 400 PM EDT THURSDAY... UPPER RISING AT 500 MB MONDAY AND TUESDAY THEN EVOLVES INTO A SPLIT FLOW PATTERN ACROSS THE UNITED STATES BY WEDNESDAY WHICH MAY BRING A SHORT WAVE THROUGH THE NORTHERN STREAM. SURFACE HIGH PRESSURE REMAINS OVER THE SOUTHEAST MONDAY AND TUESDAY. INFLOW OFF THE GULF OF MEXICO INCREASES AS THE HIGH MOVES OFFSHORE WEDNESDAY AND THURSDAY. MODELS SHOWING A BOUNDARY APPROACHING THE FORECAST AREA FROM THE WEST ON WEDNESDAY. WILL BE INCREASING THE PROBABILITY OF PRECIPITATION ON WEDNESDAY AND WEDNESDAY NIGHT. TEMPERATURES THROUGH THE PERIOD WILL BE NEAR OR JUST ABOVE NORMAL. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/...
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AS OF 200 AM EDT FRIDAY... EXPECT VFR AT ALL PRIMARY TAF SITES THIS MORNING...THOUGH SOME MODELS HINTING AT A FEW HOURS OF MVFR IN THE MTNS OF WV VCNTY OF KLWB EARLY THIS MORNING. OVERALL TREND WILL BE FOR INCREASING CLOUDS TODAY. A STRONG UPPER LEVEL DISTURBANCE WILL DROP SOUTHEAST THROUGH THE OHIO VALLEY TODAY AND IS PROGGED BY ALL MODELS TO LEAD TO SURFACE CYCLOGENESIS LEE OF THE NORTH CAROLINA MOUNTAINS TONIGHT...THIS FEATURE DEEPENING RAPIDLY AS IT PASSES OFF THE NORTH CAROLINA COAST SATURDAY. LOOK FOR THICKENING AND LOWERING OF CLOUD BASES TODAY WITH ONSET OF RAIN IN THE MOUNTAINS AFTER 18Z/2PM...SPREADING EAST OF THE MOUNTAINS INTO THE PIEDMONT BY 00Z/8PM THIS EVENING. RAIN WILL BECOME MODERATE AT TIMES WITH CIGS LOWERING THROUGH MVFR CATEGORY BETWEEN 18Z/2PM TO 00Z/8PM TIME FRAME...THEN INTO THE IFR CATEGORY TONIGHT. THIS VIGOROUS STORM SYSTEM WILL RESULT IN LOWERING FREEZING LEVELS WITH TIME...PRECIPITATION CHANGING TO SNOW OVER THE HIGHER ELEVATIONS TONIGHT. DURING THE OVERNIGHT...PRIMARILY AFTER MIDNIGHT...HIGH CONFIDENCE THAT PTYPE CHANGE WILL OCCUR OVER THE MOUNTAINS NEAR THE APPALACHIAN DIVIDE...FROM BLUEFIELD WV (KBLF) TO BOONE NORTH CAROLINA (KTNB). THIS AREA WILL BE IMPACTED BY THE MAJORITY OF THE WINTRY PRECIPITATION WHICH WILL PLAY OUT LATE FRIDAY NIGHT INTO SATURDAY...WITH HEAVY SNOW ACCUMULATIONS EXPECTED FOR THE NC/TN MTNS ALL THE WAY DOWN TO THE SMOKIES. LIFR CONDITIONS ARE LIKELY OVER THE MOUNTAINOUS TERRAIN TONIGHT AND SATURDAY. AS CYCLOGENESIS TAKES PLACE AND THE STORM MOVES TO THE COAST SATURDAY...STRONG PRESSURE RISES IN THE WAKE OF THE SYSTEM WILL RESULT IN INCREASING WIND SPEEDS. GUSTS OF 25 TO 40 KTS ARE POSSIBLE VCNTY OF THE MTNS SATURDAY AFTERNOON AND EVENING...WITH STRONG GUSTS CONTINUING INTO THE DAY SUNDAY. VFR CONDITIONS WILL RETURN TO THE AREA SUNDAY...WINDS GRADUALLY DIMINISHING. FAIR WEATHER IS EXPECTED MONDAY AND TUESDAY AS AS HIGH PRESSURE PASSES OVER THE AREA...CONDITIONS REMAINING VFR.
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&& .EQUIPMENT... THE AC UNITS FOR THE RADAR SHELTER ARE BAD. RADAR OPERATION WILL BE INTERMITTENT UNTIL SUCH TIME THE AC UNITS ARE FIXED. IF SHELTER TEMPERATURES RISE ABOVE CRITICAL LEVELS WE WILL PLACE THE RADAR INTO STANDBY TO AVOID DAMAGE TO THE TRANSMITTER. && .RNK WATCHES/WARNINGS/ADVISORIES...
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VA...WINTER STORM WARNING FROM 8 PM THIS EVENING TO 8 PM EDT SATURDAY FOR VAZ007-009-015. NC...WINTER STORM WARNING FROM 8 PM THIS EVENING TO 8 PM EDT SATURDAY FOR NCZ001-018. WV...NONE.
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&& $$ SYNOPSIS...RCS NEAR TERM...RCS/WP SHORT TERM...AMS LONG TERM...AMS AVIATION...PM EQUIPMENT...PM

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