Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 172344 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 644 PM EST MON NOV 17 2014 .SYNOPSIS...
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ARCTIC AIR WILL FOLLOW A STRONG COLD FRONT TONIGHT WITH HIGH PRESSURE MOVING INTO THE MID MISSISSIPPI VALLEY. EXPECT A PERIOD OF SNOW SHOWERS...WINDS AND COLD WIND CHILLS LATE TONIGHT INTO TUESDAY MORNING AS A RESULT. HIGH PRESSURE BUILDS ACROSS THE SOUTHEAST INTO WEDNESDAY.
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&& .NEAR TERM /THROUGH TUESDAY/...
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AS OF 640 PM EST MONDAY... THE SURFACE FRONT HAS REACHED LYNCHBURG AND DANVILLE. THE COLDER AIR IS LAGGING BEHIND BY A COUPLE OF HOURS. SNOW SHOWERS AND FLURRIES WILL SPREAD ACROSS THE MOUNTAINS THIS EVENING LINGERING INTO TUESDAY MORNING. SNOW ACCUMULATIONS ALONG WESTERN SLOPES OF GREENBRIER COUNTY WILL RANGE 2-3 INCHES. ALONG WESTERN SLOPES OF SUMMERS TO TAZEWELL...AROUND AN INCH OR SO AND UP TO AN INCH ACROSS NORTHWEST NORTH CAROLINA HIGHLANDS. OUTSIDE OF WESTERN SLOPES JUST FLURRIES...POSSIBLY LEADING TO A DUSTING IF SNOW BANDS DEVELOP. THE BIGGER HEADLINE WILL BE THE BLUSTERY CONDITIONS WITH TEMPERATURES DROPPING INTO THE 10-20F RANGE IN THE WEST TO L/M 20S IN THE EAST. COMBINING THE COLD TEMPERATURES WITH THE WIND...WIND CHILL TEMPERATURES WILL BE IN THE SINGLE DIGITS ACROSS MOST MOUNTAIN VALLEYS TO BELOW ZERO ALONG HIGHER RIDGES. THE WINDS WILL NOT BE AS STRONG IN THE EAST...HOWEVER WIND CHILL READINGS TUESDAY MORNING WILL RANGE 10F-20F. WINTER WEATHER ADVISORIES HAVE BEEN POSTED FOR WESTERN SLOPES ABOVE 2500 FT (SE WV-SW VA) AND 3000 FT (NW NC). THERE ARE SEVERAL CONCERNS TONIGHT...SNOW...WIND CHILLS...AND BLACK ICE. SNOW AND WINDS CONCERNS ARE NOTED ABOVE. RUNNING OFF FROM TODAYS RAIN MAY BE FLOWING OVER ROADS INTO THIS EVENING. SINCE COLD AIR WILL BE RUSHING IN...THIS RUNOFF WATER MAY FREEZE...ESPECIALLY ON LESS TRAVELED ROADS. ALL ADVISORIES WILL GO THROUGH NOON TUESDAY.
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&& .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... AS OF 210 PM EST MONDAY... ARCTIC HIGH PRESSURE WILL SLOWLY NOSE INTO THE AREA FROM THE SW ON TUESDAY WITH THE CORE OF THE 85H COLD POOL PASSING ACROSS DURING THE AFTERNOON. THIS ALONG WITH AN INFLUX OF THE VERY DRY ARCTIC SHOULD GRADUALLY TAPER OFF THE ONGOING UPSLOPE SNOW SHOWERS ESPCLY IN THE AFTERNOON UNDER A MORE WESTERLY TRAJECTORY. HOWEVER ENOUGH LINGERING LOW LEVEL MOISTURE UNDER A PASSING FINAL SHORTWAVE TO WARRANT A RIBBON OF HIGH POPS WESTERN SLOPES DURING THE MORNING...BEFORE DWINDLING TO JUST CLOUDS NW DURING THE AFTERNOON. OTRW DRY AND VERY COLD WITH HIGHS LIKELY TO STRUGGLE TO GET OUT OF THE TEENS FAR WEST AND TO REACH 30 ALONG THE EASTERN SLOPES OF THE BLUE RIDGE. EVEN LOCATIONS IN THE PIEDMONT MAY STRUGGLE TO GET MUCH ABOVE FREEZING DESPITE SUNSHINE AND DOWNSLOPE GIVEN SUCH COLD TEMPS ALOFT. THIS ALONG WITH STRONG WESTERLY WINDS IN THE MORNING LIKELY TO PUSH WIND CHILLS TO NEAR ZERO MOUNTAINS AND LIKELY CLOSE TO ADVISORY AT ELEVATION OVER THE WESTERN SLOPES TO START THE DAY. APPEARS THE INVERSION WILL STAY HIGH ENOUGH OFF FORECAST SOUNDINGS TO PRECLUDE ADVISORY LEVEL WIND SPEEDS OUTSIDE OF THE FAR SW BUT SOMETHING TO WATCH BEFORE THINGS MIX OUT AND SPEEDS LEVEL OFF AFTER MIDDAY. SURFACE HIGH BUILDS INTO THE SOUTH AND WEST WEDNESDAY MORNING BEFORE GETTING NUDGED TO THE SE BY THE APPROACH OF THE NEXT UPSTREAM 5H TROUGH AND ASSOCIATED WEAK COLD FRONT. APPEARS RADIATIONAL COOLING WONT BE IDEAL TUESDAY NIGHT WITH COMBO OF WARM ADVECTION ALOFT AND SOME MIXING ON THE NORTH SIDE OF THE RIDGE...BUT AIRMASS IS COLD ENOUGH TO SEE LOWS IN THE TEENS MOST SPOTS UNDER MAINLY CLEAR SKIES. WARM ADVECTION PATTERN CONTINUES WEDNESDAY UNDER INCREASING SW FLOW BETWEEN THE EXITING SURFACE HIGH AND THE UPSTREAM COLD FRONT THAT LOOKS TO CROSS THE MOUNTAINS EARLY THURSDAY BEFORE DISSIPATING. MOISTURE ALSO LACKING WITH THIS BOUNDARY SO ONLY RUNNING WITH A 20ISH POPS ACROSS THE NW. OTRW MAINLY CLEAR WEDNESDAY INTO THURSDAY NIGHT EXCEPT FOR A PERIOD OF UPSLOPE CLOUDS THAT LOOK TO MAINLY AFFECT THE FAR NW DURING THURSDAY. TEMPS SLOWLY REBOUNDING WITH HIGHS 30S/LOW 40S WEDNESDAY...THEN 40S TO LOW 50S THURSDAY UNDER A GUSTY WESTERLY BREEZE THAT MAY TEND TO HOLD LOWS UP SOME ESPCLY THURSDAY NIGHT. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 330 PM EST MONDAY... THE FINAL ARCTIC HIGH OF THE SERIES WILL BE CENTERED ACROSS THE REGION EARLY FRIDAY. WHILE NOTHING COMPARED TO THE ONE SLATED TO CROSS THE REGION TUE-WED...IT WILL SIMPLY SET BACK ANY ATTEMPT AT A WARM UP UNTIL THE WEEKEND. 850MB TEMPS EARLY FRI WILL RANGE FROM AROUND 0C IN THE FAR SOUTHERN COUNTIES TO -8C IN THE FAR NORTHERN COUNTIES. FROM HERE...IT ONLY GETS WARMER THROUGH THE REMAINDER OF THE EXTENDED PERIODS. THERE HAD BEEN SOME CONCERN WHEN LOOKING AT THIS YESTERDAY THAT THERE WOULD BE UPSLOPE -SHSN BEHIND THIS SYSTEM THU NIGHT INTO FRI MORNING. UPPER FLOW IS QUICKLY BECOMING CONFLUENT AS THE NE UPPER TROUGH LIFTS OUT OF THE REGION AND A STRONG SOUTHERN STREAM SHORT WAVE TRACKS TOWARD THE REGION FROM THE MID-SOUTH. THUS...LITTLE IF ANY SUPPORT FOR -SHSN GIVEN THIS PATTERN AND POPS HAVE BEEN REDUCED TO LESS THAN MENTIONABLE THROUGH FRI MORNING WITH THIS UPDATE. A MUCH WARMER...YET VERY UNSETTLED PATTERN EVOLVES THROUGH THE REMAINDER OF THE EXTENDED PERIOD. A NEAR COMPLETE OPPOSITE FROM THE WEATHER AT THE BEGINNING OF THE WORK WEEK. THE FOCUS THROUGH THE EXTENDED WILL BE ON A STRONG SOUTHERN STREAM SHORT WAVE PROGGED TO ACQUIRE CONSIDERABLE DYNAMICS AND SHEAR AND TAKE ON A NEGATIVE TILT AS IT MOVES FROM THE ARKLATEX REGION INTO THE SE AND MID-ATLANTIC LATE SUN-MON. A WEAK WEDGE APPEARS IN PLACE ACROSS OUR REGION AS INITIAL HIGH-LEVEL MOISTURE SPREADS INTO THE REGION SUN. MUCH OF THIS PRECIPITATION MAY REMAIN WEST OF THE CWA BORDER...BUT WILL HELP TO REINFORCE THE WEDGE SUN. AS WE MOVE INTO SUN NIGHT...THE STRONG NEGATIVELY TILTED UPPER SHORT WAVE MERGES WITH NORTHERN STREAM ENERGY ACROSS THE MID-ATLANTIC. THE WEDGE WILL BEGIN TO ERODE AS A VERY STRONG 60-80KT SSW LLJ INVADES THE REGION. EXPECT WIDESPREAD MODERATE RAINFALL...POTENTIALLY ON THE ORDER OF 1-2 INCHES ACROSS MUCH OF THE CWA BY THE TIME THE MAIN PRECIPITATION SHIELD SHIFTS EAST OF THE REGION. HAVE NOT INCLUDED ANY THUNDER FOR SUN AT THIS POINT...BUT DEPENDING ON THE STRENGTH OF THE WEDGE...THIS MAY NEED TO BE ADDED WITH LATER FORECAST PACKAGES. TEMPERATURES WILL TRANSITION FROM 10-15 DEGREES BELOW NORMAL FRIDAY MORNING TO 15 DEGREES ABOVE NORMAL BY THE END OF THE EXTENDED PERIOD. BIGGER QUESTIONS ARISE WITH REGARD TO THE FORECAST FOR MONDAY. WHILE THE MAIN UPPER SHORT WAVE AND DYNAMICS LIFT NORTHEAST OF THE REGION SUN NIGHT/EARLY MON...THE MAIN UPPER TROUGH REMAINS IN PLACE WELL BACK TO THE WEST ACROSS THE CENTRAL U.S. HENCE...SW FLOW ALOFT REMAINS IN PLACE ALONG WITH STRONG SW LOW-LEVEL FLOW. A PERSISTENT BAROCLINIC ZONE APPEARS TO REMAIN IN PLACE ACROSS THE PIEDMONT WITH THE POTENTIAL FOR MORE SHOWERS AND PERHAPS EVEN THUNDERSTORMS VIEWING VARIOUS INSTABILITY/SHEAR PARAMETERS IN PLACE. THERE CERTAINLY IS NO CLEAR END TO THE PCPN FOR THE SE HALF OF THE CWA. ALTHOUGH THE ECMWF DOES SHIFT THE BAROCLINIC ZONE FURTHER SOUTHEAST THAN THE GFS/CANADIAN...NONE OF THE MODELS DEPICT A DEFINITE DRYING PATTERN. HAVE TEMPERED TEMPERATURES SLIGHTLY FROM THE VERY WARM MEXMOS FOR SUN/MON...WHICH ADVERTISED READINGS WELL INTO THE MID 70S ACROSS THE PIEDMONT AND NEAR 60 IN THE MOUNTAINS. INSTEAD...HAVE GONE MORE WITH UPPER 40S WEST TO MID 60S PIEDMONT. SURGE OF ARCTIC AIR TO INVADE THE REGION INTO THURSDAY. THIS WAS NOT ADVERTISED A FEW RUNS BACK...BUT GIVEN GENERAL CONSENSUS AMONG THE MODELS AND A PREVAILING MEAN DEEP MERIDIONAL TROUGH ACROSS THE EASTERN HALF OF THE U.S...THIS APPEARS TO BE A REASONABLE SOLUTION AND THUS WILL LEAN IN THIS DIRECTION. HOWEVER...IN TERMS OF INTENSITY...THIS FINAL ARCTIC SURGE WILL NOT EVEN COME CLOSE TO THE ONE EARLIER IN THE WEEK. MOISTURE IS LIMITED...BUT SLIGHT CHC TO LOW CHC POPS FOR UPSLOPE -SHSN ACROSS THE USUAL WESTERN UPSLOPE AREAS OF THE ALLEGHANYS SEEMS REASONABLE AND HAVE BEEN INCLUDED...WITH NO MENTION OF POPS EAST OF THE ALLEGHANY FRONT. THE PARENT ARCTIC HIGH WILL SETTLE OVER THE REGION EARLY SATURDAY...SO BELOW NORMAL TEMPERATURES SHOULD REMAIN IN PLACE THROUGH SAT MORNING. MODEL TEMPS IN REASONABLE AGREEMENT THROUGH FRI...BUT FEEL THE GFS MOS IS TOO QUICK TO SPREAD WARMER RETURN FLOW INTO THE REGION SAT...SO LEANED TOWARD THE COLDER ECMWF MOS. BIGGER QUESTIONS REMAIN FOR THE REMAINDER OF THE EXTENDED PERIODS. AS THE ARCTIC HIGH RETREATS TOWARD THE COAST SAT...THE LONG AWAITED RETURN TO A LESS AMPLIFIED FLOW PATTERN BEGINS TO EVOLVE. THE EASTERN U.S. TROUGH IS REPLACED BY A SHORT WAVE RIDGE AS BROAD MEAN TROUGHING RELOCATES TO THE WESTERN/CENTRAL U.S. THE MAIN CONCERN FOR THE WEEKEND IS THE TIMING AND ASSOCIATED WARMING/MOISTENING WITH A STRONG NEGATIVELY TITLED HIGHLY PROGRESSIVE SHORT WAVE PROGGED TO EJECT OUT OF THE BASE OF THE MEAN TROUGH INTO THE SOUTHEAST STATES SAT NIGHT-SUN. 12Z ECMWF IN EXCELLENT AGREEMENT WITH 12Z GFS IN BRINGING THIS SYSTEM THROUGH OUR REGION SUN AFTERNOON. SUPERBLEND POPS WERE LIKELY TO CATEGORICAL SUN NIGHT-MON. GIVEN THE ASSOCIATED PVA...AND AMOUNT OF MOIST/WARM ADVECTION INTO THE REGION...THIS SEEMED REASONABLE. HOWEVER...NEIGHBORING OFFICES WERE NOT ON BOARD WITH THESE HIGH VALUES THIS FAR OUT...SO STOPPED AT A MORE REASONABLE 50 PERCENT VALUE FOR NOW. GIVEN RECENT MODEL RUN-TO-RUN VARIATION...THAT SEEMED REASONABLE FOR SURE. A SIGNIFICANT WARM UP WILL ENSUE SAT- SUN...BUT AS NOTED ABOVE...PERHAPS NOT TO THE DEGREE ADVERTISED BY THE MEX MOS. THUS...HAVE USED A MODEL BLEND FOR SAT- SUN. AN EVEN MORE SIGNIFICANT NEGATIVELY TILTED UPPER TROUGH APPEARS ON TRACK FOR THE REGION INTO MON. ECMWF/GFS SHOWING SOME INCREDIBLY WARM/MOIST AIR FOR THIS TIME OF YEAR SPREADING INTO THE REGION FROM THE SOUTH BY MON MORNING ON THE HEELS A STRONG LOW- LEVEL SOUTHERLY JET WITH DEWPOINTS APPROACHING 60 DEGREES BY MON AFTERNOON ACROSS THE PIEDMONT AND SOUTHSIDE. PROGGED LIFTED INDICES AND CAPES ALONG WITH EVIDENT SHEAR SUGGEST SOME -TSRA MAY NEED TO BE CONSIDERED BY MON AFTERNOON ACROSS THE PIEDMONT. TO SAY THE LEAST...EARLY NEXT WEEK WILL BE IN SHARP CONTRAST TO THE WEATHER EXPECTED THIS WEEK WITH TEMPERATURES ACTUALLY ABOVE SEASONAL NORMALS...ESPECIALLY IF LOWS ARE ONLY IN THE 50S MON MORNING WITH HIGHS IN THE 60S. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/...
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AS OF 630 PM EST MONDAY... A COLD FRONT EXTENDED FROM CENTRAL PENNSYLVANIA TO WESTERN SOUTH CAROLINA THIS EVENING AND WAS JUST CROSSING THROUGH KLYH AND KDAN AT 00Z/7PM. PRESSURE RISES BEHIND THE FRONT WILL BRING WINDY/GUSTY CONDITIONS TO THE AREA. STRONGER WINDS WILL BE OVER THE MOUNTAINS THROUGH TONIGHT...THEN AS INVERSION LOWERS ALL SITES WILL HAVE GUSTY CONDITIONS THROUGH THE DAY TUESDAY. WIND GUSTS OF 20 TO 30 KNOTS ARE LIKELY THROUGH 12Z/7AM. THE ARCTIC BLAST OF AIR MAY LEAD TO WATER RAPIDLY FREEZING ON RUNWAYS/AIRPLANES THIS EVENING...THOUGH WINDS MAY LEAD TO QUICKER EVAPORATION OF THE WET SURFACES. CLOUDS WILL CLEAR EAST OF THE BLUE RIDGE THIS EVENING WITH VFR CONDITIONS CONTINUING THROUGH TUESDAY. IN THE MOUNTAINS...EXPECT MVFR CEILINGS WITH SCATTERED TO NUMEROUS SNOW SHOWERS WITH MVFR VISIBILITIES...ESPECIALLY AT KBLF AND KLWB. MEDIUM CONFIDENCE THAT THE MVFR STRATOCUMULUS WILL EXPAND AS FAR EAST AS KROA. MOST LIKELY SCENARIO WILL BE THAT KROA WILL BE ON THE EDGE OF THE CLOUDS AND WILL VARY BETWEEN SCT AND BKN CLOUD AMOUNTS OVERNIGHT. EXTENDED DISCUSSION... EXPECT MAINLY VFR WEATHER TUESDAY NIGHT-THURSDAY. NEXT SYSTEM APPEARS TO ARRIVE FRIDAY WITH MVFR CIGS IN THE MTNS. THURSDAY NIGHT THROUGH SATURDAY WILL AGAIN BE VFR.
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&& .CLIMATE... AS OF 315 PM EST SUNDAY... RECORD COOLEST HIGHS...TUESDAY NOV 18TH BLACKSBURG VA...30 IN 2008 BLUEFIELD WV....27 IN 2008 DANVILLE VA.....38 IN 1959 ROANOKE VA......33 IN 1951 LEWISBURG WV....30 IN 2008 LYNCHBURG VA....32 IN 1924 && .EQUIPMENT...
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AS OF 640 PM EST MONDAY... THE VISIBILITY SENSOR AT KLYH...LYNCHBURG AIRPORT...WILL BE OUT OF SERVICE UNTIL PARTS ARRIVE TO REPLACE THE SENSOR. UNTIL THEN THE VISIBILITY WILL ONLY BE REPORTED WHEN THE CONTROL TOWER IS STAFFED. KFCX RADAR IS OUT OF SERVICE AT THIS TIME. MAJOR REPAIRS TO THE TRANSMITTER ARE PLANNED FOR TUESDAY MORNING.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...WINTER WEATHER ADVISORY UNTIL NOON EST TUESDAY FOR VAZ015. WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST TUESDAY FOR VAZ007-009-010. NC...WINTER WEATHER ADVISORY UNTIL NOON EST TUESDAY FOR NCZ001-018. WV...WINTER WEATHER ADVISORY UNTIL NOON EST TUESDAY FOR WVZ508. WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST TUESDAY FOR WVZ042-043. && $$ SYNOPSIS...RCS NEAR TERM...RCS SHORT TERM...JH LONG TERM...RAB AVIATION...AMS/RCS CLIMATE...RCS EQUIPMENT...AMS/WERT/WP

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