Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 171151 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 751 AM EDT FRI OCT 17 2014 .SYNOPSIS... A COLD FRONT PUSH THROUGH THE REGION THIS EVENING AND WILL BRING A CHANCE OF SHOWERS ON THE MOUNTAINS ON SATURDAY AND SATURDAY NIGHT. HIGH PRESSURE WITH COOLER TEMPERATURES WILL FOLLOW FOR SUNDAY AND MONDAY. THE NEXT LOW PRESSURE SYSTEM ARRIVES BY TUESDAY...RESULTING IN ANOTHER CHANCE OF SHOWERS INTO WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 400 AM EDT FRIDAY... RISING HEIGHTS AT 500MB TODAY AND RISING 850MB TEMPERATURES. SOUTHWEST WINDS AND WARM AIR ADVECTION AHEAD OF THE NEXT COLD FRONT BRING 850 MB TEMPERATURES UP TO ABOUT +12 BY 2PM. MOISTURE THIS MORNING IS CONFINED TO BELOW 700 MB AND CONTINUED TO ERODE THIS MORNING. EXPECT PLENTY OF SUNSHINE...EVEN IN THE MOUNTAINS BY MID MORNING. TRENDED TOWARD WARMER GUIDANCE FOR MAXIMUM TEMPERATURES TODAY. SURFACE COLD FRONT WILL CROSS THROUGH THE AREA THIS EVENING WHICH WILL BRING UPSLOPE CLOUDS BACK INTO THE MOUNTAINS. LOW LEVEL JET PEAKS AROUND 40 KNOTS AND MODELS SHOWED ENOUGH OF A PRESSURE RISE AND COLD AIR ADVECTION TO SUPPORT GUSTY WINDS BEHIND THE FRONT UNTIL LATE TONIGHT...PRIMARILY IN THE HIGHER ELEVATIONS. CLOUDS IN THE WEST AND MIXING ACROSS ALL OF THE COUNTY WARNING AREA WILL CAP THE DROP IN TEMPERATURE OVERNIGHT. BLEND OF BIAS CORRECTED MET AND MAV GUIDANCE LOOKED REASONABLE FOR MINIMUM TEMPERATURES. && .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... AS OF 400 AM EDT FRIDAY... FOCUS THROUGH MUCH OF THIS PERIOD WILL BE ON A STRONG SHORT WAVE/ALBERTA CLIPPER SLATED TO DIVE THROUGH THE REGION SAT NIGHT/SUN. AN ALMOST WINTERLIKE FEATURE...WHICH PROMISES TO BRING A QUICK SHOT OF COLD AIR...THE COLDEST IN NEARLY TWO WEEKS...ALONG WITH A BRIEF CHANCE FOR A FEW -SHSN IN NORTHWEST GREENBRIER COUNTY. IN ADVANCE OF THIS FEATURE...WESTERLY WINDS WILL INCREASE ALONG WITH LOW-LEVEL WAA. EVEN THOUGH MOISTURE IS LIMITED...STRONG DYNAMICS SHOULD ALLOW FOR A DECENT THREAT FOR -SHRA WEST OF THE ALLEGHANY FRONT SAT AFTERNOON/EVENING...WITH A FEW SPRINKLES OR LIGHT RAIN SHOWERS SPILLING EASTWARD TOWARD THE BLUE RIDGE LATE AFTERNOON/EVENING SATURDAY. LITTLE IF ANY PRECIPITATION WILL REACH AREAS EAST OF THE BLUE RIDGE WHERE DOWNSLOPE WEST WINDS WILL LEAD TO WARMING/DRYING. A FAIRLY WIDE SPREAD IN MAX TEMPS ARE EXPECTED SAT WITH HIGHS ONLY IN THE 50S MOUNTAINS TO THE 70S ACROSS THE PIEDMONT. SATURDAY NIGHT...850MB TEMPS LOWER INTO THE -2C TO -3C RANGE AND 1000-850MB THICKNESS LEVELS DROP TO AROUND 1305 ACROSS THE ALLEGHANYS OF WESTERN GREENBRIER. THIS COMBINED WITH ABOUT A 6HR WINDOW OF FAIRLY DECENT NW ORTHOGONAL FLOW/UPSLOPE SHOULD SUPPORT A FEW -SHSN...ESPECIALLY AS SFC TEMPS DROP INTO THE LOWER 30S AT ELEVATIONS ABOVE 3000 FEET. AS THE UPPER TROUGH RAPIDLY SWINGS OUT OF THE REGION TOWARD 12Z SUN...THE UPSLOPE COMPONENT RELAXES AND ANY -SHSN SHOULD END FAIRLY QUICKLY AT THAT TIME. AT THIS POINT...THE ONLY AREAS EXPECTED TO SEE BELOW FREEZING TEMPERATURES SUN MORNING WOULD BE THE AFOREMENTIONED NORTHWEST COUNTIES...MAINLY ELEVATIONS ABOVE 3000 FEET WHERE 850MB TEMPS ARE BELOW 0C. HIGH PRESSURE WILL QUICKLY BUILD ACROSS THE REGION FOR THE REMAINDER OF SUN PROVIDING CLEAR OR CLEARING SKIES...DIMINISHING WINDS...AND SEASONABLY COOL TEMPERATURES. MON MORNING SHOULD BRING THE BEST RADIATIONAL COOLING TO THE AREA BEFORE THE PROGRESSIVE PATTERN CONTINUES AND THE NEXT UPSTREAM SYSTEM RAPIDLY APPROACHES THE AREA FROM THE WEST LATE IN THE DAY. THUS...MON MORNING ANY FREEZING TEMPERATURES SHOULD BE CONFINED TO DEEPER VALLEYS WEST OF THE BLUE RIDGE...WITH MOUNTAIN TOPS STAYING WARMER AS WAA ALREADY IN PLACE ABOVE THE SFC LAYER. STILL...THOUGH...NO SIGN OF ANY WIDESPREAD FREEZE EITHER SUN OR MON AT THIS POINT. BY AFTERNOON...THE NEXT UPSTREAM TROUGH IS RAPIDLY DIGGING INTO THE REGION. LATEST MODEL GUIDANCE IN GENERAL AGREEMENT...ALTHOUGH WPC PREFERENCE IS THE SLOWER ECMWF. AT ANY RATE...THIS SYSTEM APPEARS DESTINED FOR ANOTHER DEEP CUTOFF LOW OVER THE REGION BY MIDWEEK. HAVE INTRODUCED SLIGHT CHC -SHRA BY MON AFTERNOON WESTERN COUNTIES WITH TEMPERATURES WARMING INTO THE 50S WEST TO ALMOST 70 PIEDMONT. && .LONG TERM /TUESDAY THROUGH THURSDAY/... AS OF 430 AM EDT FRIDAY... AS NOTED ABOVE...ANOTHER DEEP CUTOFF UPPER LOW APPEARS DESTINED TO SETTLE ACROSS THE REGION BY TUE-WED OF NEXT WEEK. MODELS HAVE A 555- 560DM UPPER LOW PARKED OVER THE REGION SOMEWHERE BETWEEN BCB AND DCA BY WED MORNING. TAKING A COMPROMISE POSITION STILL PUTS THE UPPER LOW SOMEWHERE IN CENTRAL VA. THIS SYSTEM WILL BE SLOW TO LIFT OUT OF THE REGION. ALTHOUGH AVAILABLE MOISTURE IS A FAR CRY FROM OUR MOST RECENT SYSTEM AND THE SYSTEM IS INITIATING WITHIN DRIER NW FLOW ALOFT...A COLD POOL ALOFT AND THE LONGEVITY OF THE SYSTEM REQUIRE ME TO INCREASE POPS TO HIGH CHANCE...EVEN LOW LIKELY POPS ACROSS THE WESTERN/NORTHERN MOUNTAINS TUE-WED. HAVE ALSO INCREASED POPS INTO THU...ESPECIALLY NORTHERN/EASTERN AREAS AS LOW SLOWLY MEANDERS TOWARD THE COAST. THE CLOUD COVER AND SHOWERS WILL ALSO MAX TEMPS DOWN...BUT MIN TEMPS UP THROUGH THE PERIOD. ADJUSTMENTS TO PREVIOUSLY ADVERTISED TEMPS WERE MADE. DRIER CONDITIONS SHOULD RETURN BY NEXT WEEKEND. CERTAINLY NO SIGN OF ANY FREEZING TEMPERATURES THROUGH THIS PERIOD. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/...
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AS OF 745 AM EDT FRIDAY... SATELLITE PICTURES SHOWED LARGE HOLES IN THE LOW CLOUDS OVER THE MOUNTAIN. MOUNTAIN WAVE CIRRUS HAD ALSO DEVELOP ALONG THE SOUTHERN BLUE RIDGE. CONTINUED IMPROVEMENT IN EXPECTED THIS MORNING. HIGH CONFIDENCE THAT CONDITIONS WEST OF THE BLUE RIDGE WILL BE VFR BY 15Z/11AM. THE REST OF THE DAY WILL BE VFR. VFR CONDITIONS ARE EXPECTED ON TODAY AND TONIGHT ACROSS THE PIEDMONT. A COLD FRONT WILL CROSS THROUGH THE AREA THIS EVENING. WINDS WILL BE GUSTY FROM THE SOUTHWEST AHEAD OF THE FRONT...BUT GUSTS WILL REMAIN BELOW 25 KNOTS. ONCE THE FRONT PASSES WINDS WILL TURN TO THE WEST WITH GUST AS HIGH AS 30 KNOTS...ESPECIALLY AT HIGHER ELEVATION. LOWER CLOUDS RETURN TO THE MOUNTAINS LATE TONIGHT. HAVE ADDED MVFR CLOUDS IN AT KBLF AND KLWB AFTER MIDNIGHT. EXTENDED AVIATION DISCUSSION... ANOTHER SHORT WAVE WILL BRING A CHANCE FOR SCATTERED SHOWERS SATURDAY NIGHT INTO SUNDAY. HIGH PRESSURE AND LIGHT WINDS BUILD IN BEHIND THIS FEATURE ON SUNDAY NIGHT AND MONDAY. ANOTHER LOW CROSSES THROUGH THE MID ATLANTIC REGION WITH MORE SHOWERS ON MONDAY NIGHT INTO WEDNESDAY. IT MAY BE COLD ENOUGH FOR THE FIRST FEW SNOW SHOWERS OF THE SEASON ON SATURDAY NIGHT.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS SHORT TERM...RAB LONG TERM...PM/RAB AVIATION...AMS/JH

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