Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 200258 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 958 PM EST WED NOV 19 2014 .SYNOPSIS... A FAST MOVING COLD FRONT WILL CROSS THE AREA EARLY THURSDAY WITH RENEWED COLD HIGH PRESSURE BEHIND IT BRINGING DRY WEATHER INTO SATURDAY. A COMPLEX LOW PRESSURE SYSTEM PASSING TO THE WEST SUNDAY WILL SWING A FRONTAL SYSTEM THROUGH THE REGION SUNDAY NIGHT BRINGING A CHANCE FOR WIDESPREAD RAINFALL. && .NEAR TERM /THROUGH THURSDAY/... AS OF 945 PM EST WEDNESDAY... MID-LEVEL CLOUDS ASSOCIATED WITH INCOMING SHORT-WAVE AND SURFACE FRONT ACROSS THE OHIO VALLEY HAVE REACHED FAR NORTHERN SECTIONS OF THE CWA AND SHOULD CONTINUE TO BUILD IN OVER THE NEXT SEVERAL HOURS WHICH WILL ARREST THE SLIDE IN OVERNIGHT TEMPS. STILL LOOKING FOR MID 20S TO LOW 30S AND POSSIBLY COOLEST IN THE FAR EAST WHERE CLEAR SKIES PERSIST THE LONGEST. FRONT SHOULD ARRIVE AROUND 12Z AND INTRODUCE A REINFORCING PUSH OF COOL AIR AS H85 TEMPS FALL TO -8C IN THE NW TO -3C SE AFTER THE VERY MODEST REBOUND WE EXPERIENCED TODAY. ANY POPS CONFINED TO THE FAR NW SECTIONS OF GREENBRIER COUNTY. PREVIOUS VALID DISCUSSION... AS OF 210 PM EST WEDNESDAY... NEXT SURFACE RIDGE AXIS STARTS TO BUILD IN FROM THE WEST BEHIND THE FRONT THURSDAY ALLOWING FOR MORE SUBSIDENCE AND DRYING EXCEPT ALONG THE WESTERN SLOPES WHERE MORNING LOW CLOUDS/FLURRIES MAY HANG IN UNTIL MIDDAY. OTRW GRADIENT REMAINS RATHER TIGHT WITH DAYTIME MIXING/HEATING AIDING TRANSPORT OF STRONGER GUSTS TO THE SURFACE SO CONTINUED BREEZY/WINDY ESPCLY EARLY. HOWEVER RATHER NEUTRAL ADVECTION DESPITE SITTING UNDER THE 85H BAROCLINIC ZONE SUGGESTS BETTER DOWNSLOPE WARMING EAST WHERE HIGHS COULD TOP 50 SE. ELSW LINGERING CLOUDS UNDER COOLER AIR ALOFT LIKELY TO KEEP THE MOUNTAINS IN THE UPPER 30S TO MID 40S FOR THE MOST PART. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... AS OF 300 PM EST WEDNESDAY... FINAL WEAK SHORT WAVE EXPECTED TO SCOOT RAPIDLY EAST THROUGH NEW ENGLAND ON THURSDAY NIGHT...MAINTAINING COLD ADVECTION PATTERN ALONG WITH UPSLOPING CLOUDS AND THE THREAT OF ADDITIONAL FLURRIES OVER THE WEST FACING SLOPES OF THE APPALACHIANS...MOST NOTABLY ACROSS WESTERN GREENBRIER COUNTY. DOWNSLOPING WINDS EAST OF THE BLUE RIDGE SHOULD SUPPORT MAINLY CLEAR SKIES ACROSS THE PIEDMONT. SURFACE HIGH PRESSURE WILL THEN BUILD OVER THE AREA FROM THE WEST FRIDAY INTO FRIDAY NIGHT...THEN DRIFT EAST OFF THE MID ATLANTIC COAST LATER SATURDAY INTO SATURDAY NIGHT. THIS SYSTEM WILL MAINTAIN DRY AND CONTINUED COLD WEATHER OVER THE ENTIRE FORECAST AREA FRIDAY INTO SATURDAY MORNING BEFORE SOUTHERLY WINDS ON BACKSIDE OF THE DEPARTING SYSTEM ALLOW TEMPERATURES TO BEGIN A MODERATION BACK CLOSER TO SEASONAL AVERAGES BY MID AFTERNOON. NEXT SIGNIFICANT SHORT WAVE TROF EXPECTED TO BEGIN LIFTING NORTHEAST OUT OF THE SOUTHERN PLAINS AND WESTERN GULF COAST STATES ON SATURDAY NIGHT...PRECEDED BY INCREASING MID AND HIGH LEVEL CLOUDS. LOWER AND MID TROPOSPHERE OVER THE MID ATLANTIC AND MID APPALACHIAN REGION IN PROXIMITY TO COASTAL SURFACE RIDGE EXPECTED TO REMAIN SUFFICIENTLY DRY THROUGHOUT THE NIGHT SUCH THAT ANY LATE-NIGHT PRECIPITATION LIKELY TO REMAIN ALOFT (VIRGA) IN BLACKSBURG AREA OF CONCERN. IF ANY GROUND-BASED PRECIPITATION DOES OCCUR...IT SHOULD BE CONFINED TO THE HIGHER ELEVATIONS OF THE NW NC MOUNTAINS TOWARD DAYBREAK SUNDAY...WHICH WILL BE CLOSEST TO THE APPROACHING SYSTEM. ATMOSPHERIC PROFILE EXPECTED TO BE RAPIDLY WARMING DURING THIS PERIOD SUCH THAT P-TYPE THREAT WILL BE MINIMIZED...ALTHOUGH A BRIEF PERIOD OF SOME SLEET CAN NOT BE ENTIRELY RULED OUT DUE TO WET- BULBING INFLUENCES OF AN INITIALLY VERY DRY ATMOPSHERE. AT THE PRESENT TIME...FORECAST SOUNDINGS DO NOT SUPPORT ANY SLEET OR FREEZING RAIN ALONG THE LEADING EDGE OF THE ADVANCING PRECIPITATION SHIELD...SO ONLY RAIN IS CURRENTLY BEING REFLECTED IN GRIDS...IF ANY FALLS AT ALL BEFORE DAYBREAK SUNDAY. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 330 PM EST WEDNESDAY... EXPECT TO START SUNDAY OFF WITH ATLANTIC MOISTURE RIDING NORTH ACROSS OUR AREA AHEAD OF A DEEP LOW PRESSURE SYSTEM APPROACHING FROM THE CENTRAL PLAINS. LIKELY TO SEE POCKETS OF DRIZZLE OR LIGHT RAIN ACROSS THE AREA AT SUNRISE...POSSIBLY WITH ISOLATED SPOTS OF VERY LIGHT FREEZING RAIN ACROSS PORTIONS OF THE GREENBRIER AND SHENANDOAH VALLEYS IF THE PRECIPITATION ARRIVES EARLIER THAN EXPECTED. HEAVIER...MORE WIDESPREAD RAIN WILL WORK NORTHWARD ACROSS THE AREA BY LATE MORNING...BECOMING WIDESPREAD RAIN ACROSS THE ENTIRE AREA DURING AFTERNOON. HAVE ENOUGH CONFIDENCE GIVEN THE CONSISTENCY BOTH AMONG THE VARIOUS WEATHER MODELS...AS WELL AS FROM MODEL RUN TO RUN...TO GO CLOSE TO 100% CHANCE OF RAIN FOR SUNDAY AFTERNOON. THIS WILL BE A DEEP LOW PRESSURE SYSTEM...SUPPORTED ALOFT BY A INTENSE NEGATIVELY TILTED TROUGH THAT WILL PRODUCE 50KT TO 60KT OF WIND SHEAR IN THE LOWEST KILOMETER OF THE ATMOSPHERE. THE GREATEST ENERGY ASSOCIATED WITH TROUGH WILL PASS ACROSS OUR REGION DURING THE AFTERNOON AND EVENING...HOWEVER IT IS DIFFICULT TO GET MORE SPECIFIC IN THE TIMING AND MOST AFFECTED LOCATIONS THIS FAR INTO THE FUTURE. WILL SAY AT THIS POINT THAT THERE IS A POTENTIAL FOR SOME SEVERE ACTIVITY ON SUNDAY AS A FEW CELLS MAY CARRY STRONGER WINDS ALOFT TO THE SURFACE. BECAUSE OF THE STRONG LOW LEVEL SHEAR...MAY ALSO SEE A FEW ROTATING CELLS PASS ACROSS THE AREA. THE LOW PRESSURE SYSTEM WILL LIFT NORTH TOWARD THE GREAT LAKES SUNDAY NIGHT...SHIFTING WINDS SOUTHWESTERLY ACROSS OUR AREA. THE SOUTHWESTERLY FLOW WILL BRING STRONGER HEATING FOR MONDAY AFTERNOON AS HIGHS RANGE FROM THE LOW 60S WEST TO AROUND 70 EAST. EXPECT A COLD FRONT TO ARRIVE AS EARLY AS MONDAY EVENING TO RETURN OUR TEMPERATURES CLOSER TO NORMAL FOR TUESDAY. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... AS OF 630 PM EST WEDNESDAY... STILL LOOKNIG AT POTENTIAL LLWS THIS EVENING/OVERNIGHT AS A STRONG JET MOVES ATOP A WEAK SURFACE INVERSION. THIS WOULD LIKELY AFFECT ALL TAF LOCATIONS EXCLUDING KDAN AT THIS POINT AND WHERE BETTER MIXING SUCH AS AT KBLF LOOKS TO KEEP SURFACE WINDS RATHER GUSTY ALONG THE RIDGES. THUS INCLUDING A PERIOD OF LLWS AT THE OTHER FOUR TAF SITES STARTING THIS EVENING AND CONTINUING OVERNIGHT UNTIL THE JET PASSES AND MORE CLOUDS ARRIVE LATE. MEANWHILE A COLD FRONT CURRENTLY LOCATED ACROSS THE OHIO VALLEY WILL REACH WESTERN EDGE OF THE CWA BY AROUND 12Z THURSDAY. MOISTURE AHEAD OF THE FRONT WILL BRING BKN/OVC VFR CIGS AT KBLF/KLWB AFTER MIDNIGHT...WITH BASES POSSIBLY LOWERING INTO MVFR ALONG AND JUST BEHIND THE BOUNDARY EARLY THURSDAY. SOME SNOW SHOWERS ALSO POSSIBLE AT TIMES BETWEEN DAWN AND MID MORNING THURSDAY BUT NOT ENOUGH TO INCLUDE MUCH MENTION OUTSIDE OF PERHAPS KBLF IN THE TAFS FOR NOW. SOME OF THESE VFR/OCNL MVFR CIGS COULD ALSO SPILL OUT TO THE BLUE RIDGE...AFFECTING KBCB/KROA EARLY THURSDAY MORNING AS WELL WITH MAINLY CLEAR SKIES TO THE EAST. MVFR/VFR CIGS LIKELY TO LINGER THURSDAY MORNING IN THE WEST BEFORE DRYING ALLOWS ALL LOCATIONS TO RETURN TO VFR IN THE AFTERNOON. WILL AGAIN BE GUSTY BEHIND THE PASSING FRONT WITH WESTERLY WINDS LIKELY TO GUST TO 20-25 KTS FROM MID MORNING THURSDAY THROUGH MUCH OF THE AFTERNOON. EXTENDED DISCUSSION... THURSDAY NIGHT THROUGH SATURDAY WILL AGAIN BE VFR...WITH HIGH PRESSURE IN THE REGION. A MORE SIGNIFICANT SYSTEM WILL APPROACH THE AREA WITH RAIN AND SUB-VFR CONDITIONS SUNDAY INTO SUNDAY NIGHT. MAY SEE A BRIEF RETURN TO VFR DURING MONDAY OUTSIDE OF THE MOUNTAINS AS A DRY SLOT DEVELOPS BETWEEN THE EXITING FRONT FROM SUNDAY AND THE NEXT UPSTREAM COLD FRONT. && .EQUIPMENT... AS OF 355 AM EST WEDNESDAY... 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. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH NEAR TERM...JH/PC SHORT TERM...WERT LONG TERM...NF AVIATION...JH/NF/PC EQUIPMENT...

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