Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 251721 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1221 PM EST SUN JAN 25 2015 .SYNOPSIS... AN ALBERTA CLIPPER WILL APPROACH THE REGION FROM THE WEST BY EARLY THIS EVENING...BEFORE MOVING ACROSS THE CENTRAL APPALACHIANS OVERNIGHT INTO MONDAY. THIS SYSTEM WILL BRING PERIODS OF SNOW AND RAIN TO MUCH OF THE REGION LATER TONIGHT INTO MONDAY. STRONG NORTHWEST FLOW SHOULD FOLLOW THIS FEATURE MONDAY NIGHT INTO TUESDAY BEFORE HIGH PRESSURE BUILDS IN FOR THE MIDDLE OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 940 AM EST SUNDAY... INCREASING WARM ADVECTION PATTERN TO DEVELOP THROUGH THIS AFTERNOON WITH WINDS TURNING MORE SOUTH/SW AHEAD OF THE DIGGING UPSTREAM CLIPPER THAT WILL BE APPROACHING FROM THE WEST LATE THIS EVENING. LATEST TEMP GUIDANCE CONTINUES TO SHOW ADDED WARMING THIS AFTERNOON BUT HIGHLY DEPENDENT UPON THE DEGREE OF CLOUDS SINCE OVERALL MIXING LOOKS TO STAY RATHER LIGHT. HOWEVER EVEN WITH PASSING MID/HIGH CLOUDS AND SOME INCREASE IN LOW LEVEL MOISTURE LATE IN THE FAR NW...THICKNESS VALUES SUPPORTING MID/UPPER 40S MOST OF THE MOUNTAINS...AND 50-55 FROM THE BLUE RIDGE EAST. THUS BUMPED UP HIGHS A DEGREE OR TWO MORE ESPECIALLY EAST. OTHERWISE SLOWING UP ANY PRECIP CHANCES UP UNTIL THIS EVENING...WHILE GOING WITH A PERIOD OF MORE SUN FROM LATE MORNING INTO MID AFTERNOON FOR MOST SECTIONS AS DRY AIR ALOFT GRADUALLY MIXES OUT RESIDUAL CLOUDS. AS CLOUDS THICKEN BY TONIGHT...SHOULD KEEP TEMPERATURES FROM DROPPING TOO QUICKLY AND QUESTION IS WILL BOUNDARY LAYER TEMPS GET COLD ENOUGH FOR ANY PRECIP TO FALL AS SNOW THAT COMES IN AHEAD OF SFC LOW...GENERALLY TIMED FOR MIDNIGHT OR LATER IN THE WEST. WHILE THIS CLASSIFIES AS A CLIPPER SYSTEM...IT HAS BEEN TRENDING TO DIG A LITTLE DEEPER AND SLOW DOWN A BIT WITH NEW MODEL CYCLES...SO MEASURABLE PRECIP MIGHT NOT REACH EAST OF THE BLUE RIDGE UNTIL CLOSER TO DAWN MONDAY MORNING. THERMAL PROFILES OF NAM AND OTHER HIGH RESOLUTION MODELS SUGGEST MOST AREAS WILL NOT SEE SNOW TONIGHT EXCEPT FOR HIGHEST ELEVATIONS...3000 FT OR EVEN HIGHER. I MAY EVEN HAVE TEMPS TOO COLD AT THESE HIGHEST ELEVATIONS AND CHANGING TO SOME ACCUMULATING LIGHT SNOW TOO EARLY. AN INCH OR SO IS CERTAINLY POSSIBLE BY MONDAY MORNING AT PLACES LIKE BEECH MTN NC...MT ROGERS VA...TO WESTERN GREENBRIER COUNTY WV AND HIGHER RIDGES IN THE ALLEGHANY HIGHLANDS OF VIRGINIA...BUT MUCH OF THIS DEPENDS ON IF PRECIP RATES CAN BRIEFLY GET HIGH ENOUGH TO START STICKING...WITH THE GROUND GETTING FAIRLY WARM SUNDAY. BY 12Z MONDAY THE SFC LOW IS STILL IN THE FAR SW PART OF THE FCST AREA AND COLDER AIR NOT EXPECTED TO FILTER IN BEHIND WITH BETTER UPSLOPE FLOW UNTIL LATER IN THE DAY MONDAY. FOR MONDAY MORNING LOWS...GOING WITH MILDER MET GUIDANCE GIVEN WARM ADVECTION CONTINUING AND SOLID CLOUD COVER. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 340 AM EST SUNDAY... AS THE CLIPPER APPROACHES THE SOUTHERN APPALACHIANS MONDAY MORNING...A SECONDARY LOW WILL DEVELOP OFF THE CAROLINA COAST. DURING THE DAY MONDAY...THE CLIPPER WILL BECOME A COASTAL LOW. AS THE COASTAL LOW BECOMES DOMINATE BY LATE MORNING...LOW LEVEL FLOW WILL TURN EASTERLY...THEN NORTHERLY IN THE AFTERNOON...DROPPING TEMPERATURES ACROSS THE NORTHERN HALF OF RNK CWA. THE COLD FRONT SHOULD STALL ACROSS THE SOUTHERN OHIO VALLEY MONDAY MORNING...THEN RACE ACROSS THE REGION EARLY AFTERNOON. MOUNTAIN TEMPERATURES WILL PEAK BY MID MORNING THEN FALL IN THE AFTERNOON. MODELS CONTINUE TO RUN WARM MONDAY BUT LOWERED THEM WITH INCREASING EASTERLY FLOW IN THE MORNING AND THE COLD FRONT ZIPPING ACROSS THE AREA IN THE AFTERNOON. THE RESULTING P-TYPE WOULD BE MOSTLY RAIN IN THE MORNING TURNING TO SNOW ACROSS THE HIGHER ELEVATIONS AROUND NOON THEN ACROSS THE REST OF THE MOUNTAINS BY RUSH HOUR MONDAY EVENING. ADDITIONAL ACCUMULATIONS MONDAY AROUND AN INCH. MONDAY NIGHT...THE ONCE CLIPPER TURNED COASTAL LOW TRACKS NORTH AND BECOMES A BONAFIDE NOR-EASTER. WITH THE TRACK CLOSE TO THE COAST...WRAP-AROUND MOISTURE MAY KEEP RAIN ACROSS THE PIEDMONT THROUGH MIDNIGHT...WHILE THE MOUNTAINS HAVE SCATTERED SNOW SHOWERS. LATE MONDAY NIGHT...A SIGNIFICANT SHORT WILL DROP SOUTH OUT OF THE GREAT LAKES...BRING MORE ACCUMULATING SNOW TO THE MOUNTAINS TUESDAY MORNING. THIS WAVE WILL BE STRONG ENOUGH TO OVER COME DOWNSLOPING AND PUSH SNOW EAST OF THE BLUE RIDGE TUESDAY MORNING. ACCUMULATIONS ACROSS THE MOUNTAINS COULD RANGE 1-3 INCHES AND UNDER AN INCH EAST OF THE BLUE RIDGE INTO THE FOOTHILLS. BY TUESDAY AFTERNOON...THE SNOW STOPS WITH THE EXCEPTION OF WESTERN SLOPES WHERE SNOW SHOWERS WILL CONTINUE INTO TUESDAY NIGHT. NOT LOOKING AT MUCH UPSLOPE WITH NORTHERLY WINDS AND HIGH PRESSURE BUILDING IN BY WEDNESDAY MORNING. ONCE THE NOR-EASTER BOMBS OFF THE MID ATLANTIC COAST MONDAY NIGHT...A PRESSURE GRADIENT WILL REMAIN OVER THE REGION UNTIL HIGH PRESSURE BUILDS IN WEDNESDAY MORNING. THIS GRADIENT WILL KEEP BREEZY CONDITIONS OVER THE REGION. PRESSURE RISES BEHIND THE FRONT ON MONDAY AND AGAIN TUESDAY AFTERNOON AND EVENING WILL INCREASE WINDS AND GUSTS BUT SHOULD NOT EXCEED ADVISORY CRITERIA. WIND CHILLS DROP INTO THE TEENS MONDAY MORNING AND TO NEAR 10F ABOVE WEDNESDAY MORNING. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 230 PM EST SATURDAY... A HIGH AMPLITUDE UPPER TROF ALONG THE EAST COAST WILL LIFT OUT BY WEDNESDAY EVENING INTO WEDNESDAY NIGHT. MEANWHILE...A 1026 MB SFC HIGH PRESSURE WILL SLIDE EAST ACROSS THE REGION WEDNESDAY INTO WEDNESDAY NIGHT. AS HIGH PRESSURE MOVES EAST ACROSS THE AREA...THE LOW LEVEL WINDS BACK AROUND WEDNESDAY...BRINGING AN END TO ANY LINGERING UPSLOPE SNOW SHOWERS OR SNOW FLURRIES WITH TEMPERATURES MODERATING. HIGH TEMPERATURES WEDNESDAY WILL RANGE FROM THE UPPER 20S IN THE MOUNTAINS TO THE LOWER 40S IN THE PIEDMONT. ON WEDNESDAY NIGHT...THE HIGH CENTER WILL BE LOCATED ACROSS EASTERN NORTH CAROLINA...AND A LOW PRESSURE CENTER IN THE CHICAGO AREA WITH AN APPROACHING TRAILING COLD FRONT IN THE OHIO VALLEY. LOW TEMPERATURES WEDNESDAY NIGHT WILL GENERALLY BE FROM THE UPPER TEENS TO THE UPPER 20S. A COLD FRONT WILL MOVE EAST ACROSS OUR AREA THURSDAY AFTERNOON INTO FRIDAY. HIGH TEMPERATURES THURSDAY WILL WARM INTO THE UPPER 30S IN THE NORTHWEST MOUNTAINS TO THE UPPER 40S IN THE PIEDMONTS. WILL KEEP PTYPE AS RAIN/SNOW MIXTURE WITH HIGHEST PROBABILITIES IN THE NORTHWEST...AS INDICATED BY THICKNESS AND TEMPERATURE PROFILES. ENOUGH COLD AIR ARRIVES BY THURSDAY NIGHT FOR MAINLY SNOW SHOWERS OR SNOW FLURRIES. LOW TEMPERATURES THURSDAY NIGHT WILL VARY FROM THE MID 20S IN THE MOUNTAINS TO THE LOWER 30S IN THE PIEDMONT. THE COLD FRONT PUSHES INTO THE ATLANTIC OCEAN ON FRIDAY AS THE UPPER TROUGH SETUPS ALONG THE EAST COAST. A WEAK SHORTWAVE WILL ROTATE EAST ACROSS OUR AREA WITH SOME SCATTERED SHOWERS FOR THE EAST. HIGHS FRIDAY WILL RANGE FROM NEAR THE FREEZING MARK IN THE NORTHWEST MOUNTAINS TO THE UPPER 40S IN THE PIEDMONT. WITH THE NORTHWEST FLOW ALOFT MAY BE SOME SNOW FLURRIES IN THE NORTHWEST UPSLOPE LOCATIONS FRIDAY NIGHT...BUT MODELS LOOKED RELATIVELY DRY. LOW TEMPERATURES FRIDAY NIGHT WILL GENERALLY BE IN THE MID TEENS TO THE MID 20S. THE UPPER FLOW BECOMES WESTERLY SATURDAY...WITH HIGHS IN THE MID 20S IN THE NORTHWEST MOUNTAINS TO THE MID 40S IN THE SOUTHEAST. MOISTURE SLOWLY APPROACHES FROM THE WEST SATURDAY EVENING INTO SUNDAY MORNING. && .AVIATION /17Z SUNDAY THROUGH THURSDAY/... AS OF 1205 PM EST SUNDAY... OVERALL CONTINUED VFR THIS AFTERNOON WITH MAINLY PASSING MID AND HIGH CLOUD CANOPY UNTIL LATE WHEN SOME LOWER VFR CIGS MAY ARRIVE ACROSS THE FAR WESTERN SITES. STEADY SOUTHWEST WINDS SHOULD REMAIN IN THE 7-15 KNOT RANGE BEFORE DIMINISHING THIS EVENING. CIGS SHOULD THEN QUICKLY LOWER TO MVFR IN LIGHT RAIN AHEAD OF THE CLIPPER SYSTEM...STARTING AT WESTERN SITES BY 03Z/10PM...AND AFTER 06Z/1AM EASTERN SITES. THE LOWER LEVEL SOUTHERLY FLOW SHOULD HELP LOWER CEILINGS MAY RESULT IN WIDESPREAD IFR TO LIFR CONDITIONS BEFORE DAYBREAK...BUT PRECIPITATION SHOULD REMAIN RATHER LIGHT. AT KBLF AND KLWB THERE MAY BE SNOW MIXED IN AT TIMES...AND EVEN MAY START BRIEFING AS SNOW...AND THEN CLOSER TO DAWN MONDAY MAY SWITCH OVER TO ALL SNOW ESPCLY AT KLWB AS MODEL CONTINUE TO TREND COLDER MAKER FOR A BIT HIGHER CONFIDENCE OF MORE SNOW AT KWLB WHERE SOME ACCUMULATION POSSIBLE BY EARLY MONDAY. MONDAY...EXPECT MVFR TO IFR CEILINGS AND VISIBILITIES TO PERSIST WITH THE CLIPPER AND THE ASSOCIATED LIGHT RAIN/SNOW. FLOW TURNS MORE WESTERLY BY MIDDAY AND COLDER AIR FILTER IN BEHIND SURFACE FRONT...AND RAIN OR RAIN SHOWERS WILL CHANGE OVER TO SNOW AT KBLF WHILE REMAINING MOSTLY SNOW AT KLWB...AND INTERMITTENT SNOW SHOWERS AT KBCB...PERHAPS KROA AS WELL. LATE MONDAY AND MONDAY NIGHT SOME ADDED VERY LIGHT ACCUMULATIONS OF SNOW ARE MORE LIKELY AT KBLF/KLWB WITH NW WINDS INCREASING ACROSS THE REGION AS WELL. MVFR TO VFR CONDITIONS SHOULD RETURN AT KROA...KLYH AND KDAN DURING THE DAY MONDAY. TUESDAY...A REINFORCING SHOT OF ENERGY COMES IN THROUGH THE NORTHWEST UPPER FLOW. HIGH CONFIDENCE FOR MVFR CONDITIONS IN THE MOUNTAINS BOTH MONDAY AND TUESDAY WITH OCNL IFR DUE TO SCATTERED SNOW SHOWERS. LOWER CONFIDENCE THE MVFR CIGS WILL SPILL OVER THE MOUNTAINS INTO THE ROANOKE VALLEY AND SOUTHSIDE VIRGINIA. BY MONDAY NIGHT...ANY PTYPE WILL BE SNOW DUE TO COLDER TEMPERATURES. WINDS WILL ALSO BE GUSTY MONDAY NIGHT AND TUESDAY BEHIND THE REINFORCING SURGE OF COLD AIR. BY WEDNESDAY...HIGH PRESSURE WILL PROVIDE A DAY OF TRANQUIL WEATHER AND REGION-WIDE VFR CONDITIONS BEFORE ANOTHER CLIPPER ARRIVES THURSDAY AFTERNOON WITH POSSIBLE ADDED SUB-VFR IN LIGHT PRECIPITATION. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...SK NEAR TERM...JH/SK SHORT TERM...RCS LONG TERM...KK AVIATION...AMS/JH/PM/SK

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