Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 190536 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 136 AM EDT SUN OCT 19 2014 .SYNOPSIS... A STRONG UPPER LEVEL DISTURBANCE WILL CROSS THE REGION OVERNIGHT BRINGING MOUNTAIN RAIN/SNOW SHOWERS ALONG WITH COOL TEMPERATURES. HIGH PRESSURE WILL BUILD IN ON SUNDAY RESULTING IN DRIER WEATHER UNDER DIMINISHING WINDS. ON MONDAY AND TUESDAY LOW PRESSURE WILL TRACK FROM THE GREAT LAKES TO OFF THE VIRGINIA COAST. && .NEAR TERM /THROUGH TODAY/... AS OF 127 PM EDT SUNDAY... MADE SOME MINOR ADJUSTMENTS IN TEMPERATURES AND CLOUD COVER FOR THIS MORNING. AS OF 835 PM EDT SATURDAY... BANDS OF SHOWERS CONTINUE ACROSS THE MOUNTAINS EARLY TONIGHT IN ADVANCE OF A STRONG UPSTREAM MID LEVEL SHORTWAVE THAT WILL CROSS THE MOUNTAINS AROUND MIDNIGHT AND THE PIEDMONT LATE. THIS FEATURE COMBINED WITH DEEP LOW LEVEL MOISTURE SEEN OFF THE EVENING RNK RAOB AND COLD ADVECTION SHOULD HELP SHOWERS EXPAND OVER THE FAR WEST AGAIN SHORTLY BEFORE COVERAGE AGAIN FADES A FEW HOURS AFTER MIDNIGHT. THUS KEEPING HIGH CHANCE TO LIKELY POPS WEST OF THE BLUE RIDGE WITH ONLY LINGERING SPILLOVER CLOUDS OUT EAST A BIT LONGER BEFORE THE WAVE PASSES AND DOWNSLOPE INCREASES. PROFILES ALSO SHOW THINGS COLD ENOUGH AT THE HIGHEST ELEVATIONS OVER THE NW TO SUPPORT SPOTTY SNOW SHOWERS SO BUMPED UP COVERAGE BUT EXPECTING OVERALL QPF TO BE VERY LIGHT. OTRW APPEARS EXPANSIVE CLOUDS AND MIXING WITH THE 85H JET REACHING AROUND 30 KTS SHOULD BE ENOUGH TO KEEP TEMPS UP SOME WEST. HOWEVER GIVEN THE DIGGING COLD POOL OVER THE MOUNTAINS AND LIGHTER WIND GRADIENT EAST...STAYED ON THE COOL SIDE OF MOS WITH SOME 30S WEST AND 40-45 EAST. SHOWER ACTIVITY WILL DIMINISH BY EARLY SUNDAY...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 /TONIGHT 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 ALOFT AND 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 /06Z SUNDAY THROUGH THURSDAY/... AS OF 135 AM EDT SUNDAY... AN UPPER LEVEL DISTURBANCE WILL QUICKLY PUSH THROUGH OUR AREA THIS MORNING. SCT TO BKN MVFR TO IFR CLOUDS EXPECTED IN LOW CLOUDS AND SHOWERS WHICH EXIT BY 12Z THIS MORNING. CLOUDS WILL DECREASE SUNDAY MORNING WITH GOOD SUBSIDENCE BEHIND THIS SYSTEM. LOCAL MESOSCALE MODEL INDICATES WINDS PEAKING BETWEEN NOW AND 09Z ..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 SHOWERS ARE POSSIBLE IN THE WESTERN MOUNTAINS THROUGH 09Z...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. VFR CONDITIONS ARE EXPECTED SUNDAY EVENING INTO MONDAY. MEDIUM TO HIGH CONFIDENCE IN CIGS 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... 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 TONIGHT THROUGH MONDAY MORNING FOR WVZ507-508. && $$ SYNOPSIS...JH/NF NEAR TERM...JH/KK/NF SHORT TERM...DS LONG TERM... AVIATION...PH/KK

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