Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 182324 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 724 PM EDT SAT OCT 18 2014 .SYNOPSIS... A COLD FRONT CROSSING THE AREA THIS AFTERNOON WILL PUSH EAST OF THE AREA TONIGHT...BRINGING RAIN SHOWERS TO THE MOUNTAINS THROUGH THE EARLY MORNING HOURS OF SUNDAY. HIGH PRESSURE WILL BUILD IN SUNDAY AFTERNOON AND EVENING...BRINGING CLEARING CONDITIONS. ON MONDAY AND TUESDAY LOW PRESSURE WILL TRACK FROM THE GREAT LAKES TO OFF THE VIRGINIA COAST. && .NEAR TERM /THROUGH SUNDAY/... AS OF 345 PM EDT SATURDAY... A REINFORCING COLD FRONT IS MAKING ITS WAY ACROSS THE MOUNTAINS THIS AFTERNOON...AND WILL CONTINUE SOUTHEAST THROUGH THE EVENING. WHILE WINDS ACROSS THE FORECAST REGION ARE ALREADY FROM THE NORTHWEST...THE COLD FRONT IS BRINGING WITH IT SHOWER ACTIVITY WHICH WILL AFFECT OUR WESTERN RIDGES THROUGH THE AFTERNOON AND EVENING. CURRENTLY KEEPING AN EYE ON A SLUG OF MOISTURE THAT THE NORTHWEST FLOW HAS PICKED UP FROM LAKE MICHIGAN...WHICH RAPID UPDATE MODELS ARE IN GOOD AGREEMENT WILL MAKE IT TO OUR WESTERN RIDGES LATE THIS EVENING. AS A RESULT...HAVE INCREASE THE RAIN CHANCES ACROSS THE MOUNTAINS TO ADD LIKELY WORDING TO THE FORECAST FOR THE 10 PM TO 3 AM TIMEFRAME...WITH THE HIGHEST CHANCES LOCATED IN WESTERN GREENBRIER COUNTY. ASIDE FROM PRECIPITATION...HIGH PRESSURE BUILDING IN FROM THE WEST HAS TIGHTENED THE PRESSURE GRADIENT ENOUGH TO SUPPORT 20 TO 25 MPH GUSTS FOR MUCH OF THE AREA. WINDS WILL GRADUALLY DIMINISH IN SPEED THROUGH THE EVENING AS THE PRESSURE GRADIENT RELAXES. CLOUD COVER IS WIDESPREAD ACROSS THE MOUNTAINS THIS AFTERNOON...TAPERING DOWN TO MOSTLY/PARTLY CLOUDY SKIES ACROSS THE SOUTHSIDE AS CLOUDS BREAK UP IN THE DOWNSLOPE FLOW. EXPECT LITTLE CHANGE IN CLOUD COVER THROUGH EARLY SUNDAY. THE INCREASED CLOUDS WILL KEEP RADIATIONAL COOLING TO A MINIMUM...AND THEREFORE EXPECT WINDS TO REMAIN A LITTLE GUSTY THROUGH THE NIGHT...MAINLY FOR THE MOUNTAINS. NORTHWESTERLY FLOW WILL ALSO CARRY COLDER AIR INTO THE REGION OVERNIGHT...WITH TEMPERATURES APPROACHING FREEZING IN WESTERN GREENBRIER COUNTY. MAY SEE A FEW SNOWFLAKES MIXED IN WITH WHATEVER RAIN SHOWERS ARE LEFT THERE TOWARD DAWN...HOWEVER NO ACCUMULATIONS ARE EXPECTED. SHOWER ACTIVITY WILL DIMINISH THROUGH THE NIGHT...WITH CLOUDS DECREASING FROM EAST TO WEST AS HIGH PRESSURE BEGINS TO SETTLE ACROSS THE AREA. AS SUCH...LOOKING FOR MOSTLY CLEAR SKIES ACROSS THE PIEDMONT FOR SUNDAY AFTERNOON...WITH A MIXTURE OF CLOUDS AND SUNSHINE ACROSS THE MOUNTAINS. EXPECT HIGHS TO RANGE FROM THE LOW/MID 50S ACROSS THE MOUNTAINS...TO THE MID 60S ACROSS THE SOUTHSIDE. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... AS OF 230 PM EDT SATURDAY... SUNDAY NIGHT INTO MONDAY...THE CENTER OF THE SURFACE HIGH SHIFTS TO OUR EAST ALL WHILE SOUTHWEST FLOW INCREASES AT 850 MB AND HIGHER. WHILE WE ARE EXPECTING ONE OF THE COLDEST NIGHTS SO FAR OF THE SEASON FOR MOST AREA...THE THE ABOVE SCENARIO IS GOING TO MITIGATE THE EXTENT OF THE COOL DOWN. IT MAY BE ONE OF THOSE SITUATIONS WHERE THE RIDGE TOPS STAY MILDER THAN THE VALLEYS THANKS TO CONTINUED MIXING OF WINDS AT THE HIGHER ELEVATIONS...AND THE ELEVATIONS THEMSELVES COULD BE HIGHER THAN THE TOP OF THE NOCTURNAL INVERSION. ACROSS THE PIEDMONT...THIS AREA WILL BE STILL CLOSEST TO THE CENTER OF THE DEPARTING SURFACE HIGH...AND WINDS ALOFT WILL BE WEAKER...PLUS HAVE LESS OF A CHANCE TO MIX TO THE SURFACE GIVEN A MORE LAMINAR FLOW LOFT SANS STEEPER TOPOGRAPHY. FORECAST LOWS ACROSS THE MOUNTAINS WILL RANGE FROM THE UPPER 20S IN THE DEEPER VALLEYS TO NEARLY 40 DEGREES AT THE RIDGE TOPS. IN BETWEEN THESE EXTREMES IS THE POTENTIAL FOR AREAS WHERE TEMPERATURES ARE COLD ENOUGH AND WINDS ARE LIGHT ENOUGH FOR FROST FORMATION. LIKEWISE...SOME LOCATIONS WILL EXPERIENCE FREEZING TEMPERATURES IN THE LOWER 30S TO NEAR 30 DEGREES. A PATCHWORK OF FROST POSSIBILITIES STILL DOTS MY FORECAST MAP. OUR HAZARDOUS WEATHER OUTLOOK WILL STILL MENTION THIS POTENTIAL LATE SUNDAY NIGHT INTO EARLY MONDAY MORNING. WE ARE STILL TO FAR AWAY IN THE FORECAST PACKAGE FOR THE POSTING OF ANY FROST ADVISORIES AT THIS TIME. HOWEVER...ENOUGH OF GREENBRIER COUNTY...BOTH WESTERN AND EASTERN SECTIONS...ARE FORECAST TO REACH LOWS AT OR BELOW FREEZING SUNDAY NIGHT THAT A FREEZE WATCH WILL BE ISSUED THIS AFTERNOON TO ACCOUNT FOR THAT POTENTIAL. EAST OF THE BLUE RIDGE...THE FORECAST WILL REFLECT NO LOCATIONS FORECAST AT OR BELOW FREEZING FOR LOW TEMPERATURES. HOWEVER...PATCHY FROST STILL IS POSSIBLE WITHIN A CORRIDOR BETWEEN ROUGHLY AMHERST...BEDFORD AND MARTINSVILLE VA. THERE IS LESS CONFIDENCE THAT A FROST ADVISORY MAY EVENTUALLY BE POSTED IN THIS AREA GIVEN THE MORE PATCHY NATURE OF THE FROST. HOWEVER...CONFIDENCE IN THE PATCHY FROST IS STILL HIGH ENOUGH TO CONTINUE TO MENTION IT IN THE HAZARDOUS WEATHER OUTLOOK. BY THE LATE MORNING MONDAY...SOUTHWEST WINDS WILL HAVE MIXED NICELY TO THE SURFACE TO HELP START THE PROCESS OF MODERATING TEMPERATURES. ANY FROST IS UNLIKELY TO SURVIVE PAST ROUGHLY 900 AM. TEMPERATURES WILL CONTINUE TO INCREASE TO THE LOW TO MID 60S IN THE MOUNTAIN AND MID TO UPPER 60S ACROSS THE PIEDMONT. CLOUDS WILL START TO INCREASE DURING THE AFTERNOON IN THE WEST IN ADVANCE OF THE NEXT APPROACHING UPPER LEVEL TROUGH. WE CANNOT RULE OUT SOME ISOLATED SHOWERS BY SUNSET ALONG AND EAST OF INTERSTATE 64 IN SOUTHEAST WEST VIRGINIA AND SOUTHWEST VIRGINIA. MONDAY NIGHT INTO TUESDAY NIGHT THE AXIS OF A DEEPENING UPPER TROUGH WILL MOVE INTO AND THROUGH OUR REGION. THE RESULT WILL BE AN INCREASE IN SHOWER ACTIVITY ACROSS THE ENTIRE AREA BY TUESDAY AFTERNOON...WITH THE GREATEST POTENTIAL ACROSS THE PREFERRED UPSLOPE REGIONS IN THE WESTERN PART OF THE FORECAST AREA. BY TUESDAY NIGHT...MOST OF THE PRECIPITATION THAT REMAINS WILL BE CONFINED TO THE UPSLOPE AREAS IN THE WEST...BUT BE DECREASING IN COVERAGE. EARLY TUESDAY EVENING...THERE STILL WILL BE A CHANCE OF SHOWERS ACROSS THE NORTHEAST PART OF THE REGION ON THE BACKSIDE OF THE CENTER OF THE DEPARTING UPPER LOW. TEMPERATURES DURING THIS PORTION OF THE FORECAST WILL TREND MILDER THROUGH TUESDAY...BUT START TO SLIDE A BIT TUESDAY NIGHT ON THE WEST SIDE OF THE DEPARTING UPPER LOW. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 245 PM EDT SATURDAY... WEDNESDAY THROUGH THURSDAY...THE SLOWLY DEPARTING UPPER LOW WILL CONTINUE TO DO JUST THAT...SLOWLY DEPART. THIS PATTERN WILL MAINTAIN A GUSTY NORTHWEST FLOW ALOFT ACROSS THE AREA THAT WILL MAINTAIN SOME CLOUD COVER AND ISOLATED SHOWERS OVER WESTERN PARTS OF SOUTHEAST WEST VIRGINIA. THE REMAINDER OF THE AREA SHOULD EXPERIENCE LIMITED CLOUD COVER...NEAR NORMAL TEMPERATURES...AND WINDS A BIT ON THE GUSTY SIDE. FRIDAY INTO SATURDAY...THE LOW DEPARTS FAR ENOUGH EAST THAT OUR PREVAILING FLOW BECOMES NORTHERLY...THUS SHUTTING OFF THE UPSLOPE MACHINE. A BROAD UPPER RIDGE BECOMES POSITIONED ACROSS THE MID- MISSISSIPPI VALLEY AND BUILDS SLIGHTLY EASTWARD. DRY CONDITIONS...LIMITED CLOUD COVER...MODERATING TEMPERATURES...AND STILL A BIT OF A NORTH BREEZE WILL BE THE FORECAST FOR THE REGION. && .AVIATION /23Z SATURDAY THROUGH THURSDAY/... AS OF 720 PM EDT SATURDAY... WATER VAPOR SATELLITE PICS SHOW A FAST MOVING...VIGOROUS...UPPER LEVEL DISTURBANCE ACROSS THE LOWER OHIO VALLEY. THIS SYSTEM WILL QUICKLY PUSH THROUGH OUR AREA TONIGHT...EXITING BY 09Z. WORST CONDITIONS FOR FLYING WILL BE BETWEEN NOW AND 07Z...WITH MVFR TO IFR CIGS. CLOUDS WILL DECREASE SUNDAY MORNING WITH GOOD SUBSIDENCE BEHIND THIS SYSTEM. LOCAL MESOSCALE MODEL INDICATES WINDS PEAKING BETWEEN 04-08Z...THEN DIMINISHING SHORTLY AFTER DAYBREAK SUNDAY. GUSTS TO 20-25KT POSSIBLE AT THE MOUNTAIN TAF SITES AND KROA...WITH HIGHER GUSTS IN THE HIGHER ELEVATIONS. UPSLOPE GENERATED RAIN WILL BE FOUND OFF AND ON AT THE MOUNTAIN TAF SITES THROUGH 07Z...AND TEMPERATURES WILL BECOME COLD ENOUGH TOWARD DAWN THAT A FEW SNOW FLAKES WILL BE POSSIBLE AT THE TAIL END OF THE SHOWER ACTIVITY NEAR KLWB CONDITIONS SHOULD RAPIDLY IMPROVE SUNDAY AS THE SFC HIGH PRESSURE BUILDS FROM THE WEST...BRINGING CLEARING SKIES AND DIMINISHING WINDS. KLWB AND KBLF WILL BE THE LAST TAF SITES TO EXPERIENCE CLEARING...AROUND 16Z. MEDIUM TO HIGH CONFIDENCE IN CIG THROUGH THE TAF VALID PERIOD. HIGH CONFIDENCE IN VSBYS THROUGH THE TAF VALID PERIOD. HIGH CONFIDENCE IN WIND DIR/SPD THROUGH THE TAF VALID PERIOD. EXTENDED AVIATION DISCUSSION... VFR CONDITIONS ARE EXPECTED SUNDAY EVENING INTO MONDAY. ANOTHER UPPER LOW WILL SETTLE INTO THE REGION FROM THE NORTH LATE MONDAY AND LINGER THROUGH MID-WEEK WITH SCT -SHRA AND MOSTLY MVFR CEILINGS AND BRIEF PERIODS OF MVFR VISIBILITIES IN -SHRA. IMPROVING CONDITIONS ARE EXPECTED TOWARD THE VERY END OF THE WEEK. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...FREEZE WATCH FROM LATE SUNDAY NIGHT THROUGH MONDAY MORNING FOR WVZ507-508. && $$ SYNOPSIS...NF NEAR TERM...NF SHORT TERM...DS LONG TERM... AVIATION...PH

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