Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 302001 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 401 PM EDT THU OCT 30 2014 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OVER THE REGION PROMOTING MOSTLY CLEAR SKIES AND LIGHT WINDS...FAIR WEATHER PERSISTING 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 FRIDAY/... AS OF 400 PM EDT THURSDAY... A WEAK AREA OF HIGH PRESSURE WILL PROMOTE GOOD RADIATIONAL COOLING CONDITIONS THIS EVENING...BEFORE CLOUDS MOVE OVER IN THE MORNING. TEMPERATURES WILL DROP OFF QUICKLY THIS EVENING WITH MOST AREAS BEING IN THE 30S BY SUNRISE FRIDAY. PATCHY FROST EXPECTED IN MOUNTAIN VALLEYS TO ISOLATED IN RURAL LOCATIONS ACROSS THE FOOTHILLS OF SOUTHWEST VIRGINIA AND NORTHWEST NORTH CAROLINA EARLY FRIDAY MORNING. 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 /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 /20Z THURSDAY THROUGH TUESDAY/... AS OF 115 PM EDT THURSDAY... HIGH PRESSURE WILL BUILD OVERHEAD THIS AFTERNOON AND TONIGHT PROMOTING LIGHT AND VARIABLE WINDS. SOME WEAK ISENTROPIC LIFT PUSHED HIGH-END MVFR CLOUDS ACROSS THE MOUNTAINS THIS MORNING. INTO THIS EVENING...A WEST WIND ALOFT WILL ERODING CLOUDS ESPECIALLY EAST OF THE BLUE RIDGE. ANY CLOUDS MAKING IT TO BCB/ROA SHOULD ONLY DROP TO LOW-END VFR. EXTENDED AVIATION DISCUSSION... EXPECTATION IS FOR VFR CONDITIONS TO PERSIST THROUGH THE FIRST HALF OF THE DAY FRIDAY...THEN DETERIORATING AS A STRONG STORM SYSTEM MOVES IN FROM THE NORTHWEST. THIS SYSTEM WILL BRING A PROLONGED PERIOD OF POTENTIALLY IFR-LIFR CIGS AND PRECIPITATION...WITH SNOW IN THE MOUNTAINS OF NC/WV/AND FAR WESTERN VA...AND RAIN IN THE VALLEYS. ATTM IT LOOKS LIKE SIGNIFICANT IMPACT TO AVIATION WILL DEVELOP WITHIN THE VICINITY OF THE NC MTNS AND UP INTO THE HIGHER ELEVATIONS OF FAR WRN VA AND WV. MODELS SUGGEST THIS STORM SYSTEM WILL BE VERY DYNAMIC WITH LOW FREEZING LEVELS AND HEAVY WET SNOW UNDERNEATH THE CORE OF THE STORM WHICH IS PROGGED TO PASS DIRECTLY OVER THE NC MTNS. IN ADDITION...STRONG WINDS ARE EXPECTED TO DEVELOP SATURDAY IN THE WAKE OF THIS DEPARTING STORM SYSTEM. STRONG CROSS BARRIER FLOW...50 KTS...IS EXPECTED OVER THE MOUNTAINS...RESULTING IN SURFACE WIND GUSTS OF 30 KTS LEE OF THE BLUE RIDGE SATURDAY AFTERNOON AND EVENING. THIS STORM WILL QUICKLY MOVE AWAY FROM THE AREA SUNDAY WITH VFR CONDITIONS RETURNING FOR MONDAY AND TUESDAY. && .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 SHORT TERM...AMS LONG TERM...AMS AVIATION...RCS EQUIPMENT...PM

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