Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 310336 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1136 PM EDT THU OCT 30 2014 .SYNOPSIS...
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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.
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&& .NEAR TERM /THROUGH FRIDAY/...
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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.
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&& .SHORT TERM /FRIDAY NIGHT 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 /04Z FRIDAY THROUGH TUESDAY/... AS OF 725 PM EDT THURSDAY... EXPECT VFR AT ALL SITES OVERNIGHT...THOUGH SOME MODELS HINTING AT A FEW HOURS AFTER MIDNIGHT FOR BLF/LWB TO DROP INTO MVFR CIGS...AND THINK THIS APPEARS REASONABLE GIVEN CIGS UPSTREAM...THOUGH THIS CLOUD FIELD HAS BEEN SHRINKING. CONFIDENCE LOW ATTM IN THE CIGS OVERNIGHT OUT WEST. HAVE NO FOG IN THE FORECAST AS WELL BUT CANNOT RULE IT OUT COMPLETELY IF SKIES STAY CLEAR AS WINDS ARE NEAR CALM. LOOK FOR INCREASING CLOUDS FRIDAY AHEAD OF THE FRONT MOVING SOUTHEAST FROM THE OHIO VALLEY. MODELS FAVOR RAIN MOVING INTO BLF/LWB BY 20Z...THEN BCB BEFORE END OF THIS TAF PERIOD. CIGS WILL BE DROPPING DURING THE AFTERNOON AND EXPECT HIGH END MVFR/LOW END VFR IN THE MTNS...WITH MVFR VSBYS IN RAIN. BEYOND THIS TAF PERIOD...AVIATION CONDITIONS START TO DROP TO POOR AS THE STORM SYSTEM STRENGTHENS OVER THE CAROLINAS AND OFF THE COAST INTO SATURDAY. COLDER AIR WORKING INTO THE MOUNTAINS WILL SHIFT PTYPE FROM RAIN TO SNOW AT LWB/BLF...AND INTO BCB BY SAT MORNING. LOOKING FOR SUB VFR...AS LOW AS LIFR AT TIMES IN THE MTNS THROUGH SATURDAY EVENING...BEFORE THE SYSTEM SHIFTS TO OFF THE NEW ENGLAND COAST SUNDAY MORNING. WINDS WILL BE SHIFTING FROM SOUTHERLY TO NW AS THIS SYSTEM MOVES THROUGH AND GUSTS OVER 45 MPH AT THE TERMINALS AT BCB/ROA AND PERHAPS BLF COULD BE POSSIBLE SAT AFTERNOON/EVENING. CIGS WILL IMPROVE IN THE PIEDMONT BY SUNDAY AFTERNOON AND BY SUNDAY NIGHT INTO THE BLF/LWB AREA. EXPECT MAINLY VFR INTO TUESDAY AS HIGH PRESSURE MOVES BACK IN. && .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... VA...WINTER STORM WARNING FROM 8 PM FRIDAY TO 8 PM EDT SATURDAY FOR VAZ007-009-015. NC...WINTER STORM WARNING FROM 8 PM FRIDAY TO 8 PM EDT SATURDAY FOR NCZ001-018. WV...NONE. && $$ SYNOPSIS...RCS NEAR TERM...RCS/WP SHORT TERM...AMS LONG TERM...AMS AVIATION...WP EQUIPMENT...PM

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