Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 222037 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 337 PM EST SAT NOV 22 2014 .SYNOPSIS... HIGH PRESSURE WILL SLIDE EAST INTO THE ATLANTIC TONIGHT INTO SUNDAY. THEN...A STORM SYSTEM MOVING NORTHWARD THROUGH THE MISSISSIPPI VALLEY WILL PUSH A WARM FRONT INTO THE APPALACHIANS AND CENTRAL MID ATLANTIC REGION...BRINGING WET AND WINDY CONDITIONS TO THE AREA BY SUNDAY AFTERNOON. UNSEASONABLY WARM CONDITIONS ARE EXPECTED MONDAY IN THE WAKE OF THIS SYSTEM...BEFORE A COLD FRONT MOVES THROUGH TUESDAY...RETURNING TEMPERATURES TO BELOW NORMAL FOR THE REST OF NEXT WEEK. && .NEAR TERM /THROUGH SUNDAY/... AS OF 330 PM EST SATURDAY... HIGH PRESSURE CENTERED IN EASTERN NORTH CAROLINA THIS AFTERNOON WILL SLIDE EAST TONIGHT INTO MONDAY. MOISTURE WILL SLOWLY INCREASE TONIGHT AS DEEP SOUTHWEST FLOW SETS UP IN THE BOUNDARY LAYER AHEAD OF APPROACHING WARM FRONT. WINDS WILL REMAIN GENERALLY LIGHT THROUGH TONIGHT...BUT WILL INCREASE IN THE WEST SUNDAY MORNING. LOW TEMPERATURES TONIGHT WILL RANGE FROM THE MID 20S IN THE COLDER NORTHWEST MOUNTAINS TO THE MID 30S IN THE SOUTHEAST. A STRONG SOUTHERN STREAM SHORTWAVE WILL MOVE ACROSS THE REGION FROM SOUTHWEST TO NORTHEAST SUNDAY AFTERNOON INTO SUNDAY NIGHT. IN ADVANCE OF A BROAD TROF WILL CURVES OUT IN THE CENTRAL U.S. SUNDAY INTO MONDAY...LEADING SHORTWAVE WILL TAKE ON A STRONG NEGATIVE TILT AND ROTATE OUT OF THE ARKLATEX REGION TOWARD THE OHIO VALLEY SUNDAY EVENING INTO SUNDAY NIGHT. A WARM FRONT WILL APPROACH THE REGION FROM THE SOUTH SUNDAY AFTERNOON WITH WIDESPREAD OVERRUNNING RAIN. SHAPED TIMING AND POPS FOR RAIN TOWARDS A BLEND OF GFS...NAM AND HIRESW-ARW WITH MOISTURE SPREADING QUICKLY UP THE SOUTHERN BLUE RIDGE WITH THE ISENTROPIC LIFT. WINDS ARE ANOTHER CONCERN WITH A 70-80KT LLJ TRAVERSES THE AREA IN ASSOCIATION WITH THE WARM FRONT/UPPER TROUGH SUNDAY AFTERNOON INTO SUNDAY EVENING. HIGH WINDS NEAR ADVISORY LEVELS ARE POSSIBLE ACROSS THE HIGHER TERRAIN IN THE NORTHWEST NORTH CAROLINA AND SMYTH/TAZEWELL/MERCER REGION WITH THE STRONG LLJ. SOME MODERATE RAIN MAY ALSO BE POSSIBLE SUNDAY AFTERNOON INTO SUNDAY NIGHT ESPECIALLY ALONG THE EASTERN SLOPES OF BLUE RIDGE MOUNTAINS WITH UPSLOPE COMPONENT. HIGH TEMPERATURES SUNDAY WILL RANGE FROM THE UPPER 40S IN THE MOUNTAINS TO THE MID 50S IN THE PIEDMONT. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... AS OF 335 PM EST SATURDAY... BROAD SOUTHWEST 500 MB FLOW ON SUNDAY NIGHT WITH WELL DEFINED VORTICITY MAXIMUM TRACK FROM THE TENNESSEE VALLEY INTO THE EASTERN GREAT LAKES BY MONDAY MORNING. STRONG WARM AIR ADVECTION AND IMPRESSIVE UPSLOPE WINDS SUNDAY EVENING WILL FOCUS THE HIGHEST PRECIPITATION AMOUNTS ON THE EAST SLOPES AND FOOTHILLS OF THE BLUE RIDGE. PLUS THE SOUTHEAST WIND WILL BE ADVECTING PRECIPITABLE WATER VALUES CLOSE TO 1.5 INCHES UP THE RIDGES. AXIS OF CONVERGENCE CROSSES THE FORECAST AREA BY 06Z/1AM SUNDAY NIGHT WITH A SHARP DRY SLOT IMMEDIATELY FOLLOWING. IN-SITU WEDGE ERODES ONCE THE PRECIPITATION ENDS WITH STRONG WARM AIR ADVECTION LATE SUNDAY NIGHT AND MONDAY. BEHIND THE RAIN ON MONDAY 850 MB TEMPERATURES CONTINUE TO RISE INTO THE +10 TO +12 RANGE. BUT BY THE END OF THE DAY THE SURFACE COLD FRONT HAS CROSSED EAST THROUGH THE AREA. MODELS BRING THE 850 MB FRONT THROUGH DURING THE EVENING. EXPECTING A NON DIURNAL RISE IN TEMPERATURES SUNDAY NIGHT THEN ABOVE NORMAL MAXIMUM TEMPERATURES ON MONDAY...ESPECIALLY EAST OF THE BLUE RIDGE. THE BIG PUSH OF COLDER AIR COMES IN TUESDAY NIGHT. SURFACE HIGH PRESSURE WILL BE OVER THE COUNTY WARNING AREA TUESDAY AND TUESDAY NIGHT. WINDS DIMINISH LATE TUESDAY. LOW PRESSURE DEVELOPING OFF THE SOUTHEAST COAST WILL RESULT IN EAST WINDS OVER THE FORECAST AREA. THIS WILL BRING DEEPER MOISTURE BACK INTO THE AREA AS WELL AS A CHANCE OF PRECIPITATION. HOW FAR WEST THE PRECIPITATION WILL REACH WAS STILL QUESTIONABLE. IF PRECIPITATION EXTENDS ALL THE WAY TO THE BLUE RIDGE...TEMPERATURES MAY BE COLD ENOUGH ON THE WESTERN EDGE TO HAVE SNOW OR A RAIN SNOW MIX. TOO SOON TO TELL IF THERE WILL BE ANY PRECIPITATION ACTUALLY FALLING...MUCH LESS ANY AMOUNTS. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 130 PM EST SATURDAY... TWO DISTINCT SYSTEMS HAVE THE POTENTIAL FOR BRING SOME PRECIPITATION TO PARTS OF THE AREA DURING THIS SEGMENT OF THE FORECAST. THE FIRST ITEM OF INTEREST IS A LOW PRESSURE WAVE MOVING NORTHWARD ALONG A BAROCLINIC ZONE THAT WILL BE POSITIONED ALONG THE COAST DURING THE WEDNESDAY AND WEDNESDAY NIGHT TIME PERIOD. THE VARIOUS MODELS ARE STILL INCONSISTENT WITH EACH OTHER...AND WITH THEIR OWN PREVIOUS MODEL RUNS REGARDING THE TIMING...TRACK AND ASSOCIATED PRECIPITATION WITH THIS FEATURE. YESTERDAY...THE ECWMF WAS THE ONLY OPERATIONAL MODEL RUN THAT HINTED AT PRECIPITATION SKIRTING THE EASTERN EXTENT OF THE FORECAST AREA. TODAY...ITS SOLUTIONS IS MORE ROBUST ON THIS SCENARIO WITH PRECIPITATION NOW THE WHOLE WAY WEST TO EASTERN KENTUCKY. TODAY...THE GFS SOLUTION IS ONLY SLIGHTLY MORE ROBUST AS COMPARED TO THE ECWMF FROM YESTERDAY...BUT STILL...HAS ALL BUT OUR SOUTHEAST WEST VIRGINIA COUNTIES WITH AT LEAST 0.01 PRECIP. THE CANADIAN SOLUTION KEEPS THE SYSTEM FARTHER OFF THE COAST WITH NOT A DROP OF PRECIPITATION REACHING THE FORECAST AREA. OUR FORECAST FROM YESTERDAY REFLECTED A MODEL BLEND CONSENSUS THAT WAS MORE IN LINE WITH THE WETTER ECWMF SOLUTION. GIVEN BOTH THE GFS AND ECWMF ARE WETTER FOR THE REGION...AND THE MODEL BLEND CONSENSUS IS ALSO WETTER ACROSS THE REGION...HAVE FOLLOWED SUIT IN THE FORECAST. PRECIPITATION CHANCES FOR WEDNESDAY HAVE BEEN INCREASED TO REFLECT 50 PERCENT IN THE EAST...WITH 20 TO 25 PERCENT IN THE WEST. SURFACE AND LOW LEVEL THERMAL PROFILES SUGGEST MAINLY A SNOW OR RAIN/SNOW FORECAST ACROSS THE MOUNTAINS ON TUESDAY...WITH PRIMARILY RAIN ACROSS THE PIEDMONT. WEDNESDAY NIGHT...COLDER AIR ARRIVING ON THE BACKSIDE OF THE DEPARTING SYSTEM WILL ALLOW FOR MORE LIGHT SNOW...BUT WITH THE SYSTEM EXITING...MUCH LESS COVERAGE. OUT NEXT POTENTIAL WEATHER MAKER WILL BE ASSOCIATED WITH A SHORTWAVE TROUGH THAT ZIPS THROUGH THE OHIO VALLEY AND MID-ATLANTIC REGION DURING THE THURSDAY AND THURSDAY NIGHT TIME PERIOD. BOTH THE GFS AND ECWMF SOLUTIONS HAVE CHANGED COMPARED TO THEIR -24 HOUR COUNTERPARTS. PRIOR...MODEL SOLUTIONS WERE HINTING AT A MORE PROLONGED CLOSED LOW STRENGTHENING OVER THE CENTRAL APPALACHIANS WITH A MORE PROFOUND SHOT OF COLDER AIR IN ITS WAKE. THE LATEST SOLUTIONS OFFER A MORE GLANCING BLOW OF ENERGY ACROSS THE AREA...WITH THE COLDER AIR NOT HAVING AS MUCH CHANCE TO MAKE THE TURN SOUTH PRIOR TO ZONAL FLOW DEVELOPING IN THE WAKE OF THE PASSAGE OF THE SHORTWAVE TROUGH. WHILE THE FORECAST WILL STILL OFFER SOME ISOLATED TO SCATTERED RAIN/SNOW SHOWERS ACROSS PARTS OF SOUTHEAST WEST VIRGINIA AND NEIGHBORING COUNTIES OF SOUTHWEST VIRGINIA THROUGH THURSDAY NIGHT...THE TEMPERATURE FORECAST FROM THURSDAY THROUGH SATURDAY WILL BE A BIT MILDER THAN WHAT AS OFFERED IN THE PREVIOUS PACKAGE. && .AVIATION /21Z SATURDAY THROUGH THURSDAY/... AS OF 1250 PM EST SATURDAY... HIGH PRESSURE CONTINUE TO MOVE EAST THIS AFTERNOON INTO TONIGHT. VFR CONDITIONS WILL PREVAIL THIS AFTERNOON INTO SUNDAY. LOW CLOUDS UPSTREAM ARE FORECAST TO ROTATE AROUND THE BACK SIDE OF THE HIGH TO OUR WEST AND NORTH. SOME AFTERNOON CU MAY BE POSSIBLE ACROSS THE WESTERN MOUNTAINS. MODEL UPPER LEVEL RH FIELDS CORRELATE WELL WITH CIRRUS SEEN STREAMING IN OUR DIRECTION ON SATELLITE LOOP. INCREASING HIGH CLOUDINESS EXPECTED TONIGHT INTO SUNDAY. LIGHT WINDS THIS AFTERNOON WILL BECOME SOUTHWEST TO SOUTH AND MORE GUSTY ON SUNDAY. WINDS AT BLF MAY STAY UP A BIT TONIGHT AS THE INFLUENCE OF APPROACHING LOW PRESSURE AND WARM FRONT START TO BE FELT. TOWARDS THE END OF THE TAF PERIOD MOISTURE WILL START TO ENCROACH FROM THE SOUTH. SCT TO BKN MVFR CLOUDS WILL INCREASE SUNDAY MORNING INTO SUNDAY AFTERNOON. MEDIUM TO HIGH CONFIDENCE IN CEILINGS...VISIBILITIES AND WINDS DURING THE TAF PERIOD. EXTENDED DISCUSSION... THE NEXT SIGNIFICANT WEATHER WILL ARRIVE ON SUNDAY AFTERNOON WITH WINDY CONDITIONS DEVELOPING...AND RAIN WITH MVFR TO IFR CONDITIONS SUNDAY AFTERNOON AND SUNDAY NIGHT. ALSO...STRENGTHENING LOW LEVEL WINDS LATER ON SUNDAY MAY LEAD TO LLWS...ESPECIALLY THE BLF AREA. 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. MONDAY INTO TUESDAY LOOK TO FEATURE QUITE A BIT OF WIND. FOR THE REMAINDER OF NEXT WEEK...EXPECT PERIODS OF MVFR CIGS ACROSS EASTERN WV/FAR SW VA...BUT MOSTLY VFR ELSEWHERE WITH A COLDER NW FLOW. && .EQUIPMENT... AS OF 215 PM EST FRIDAY... 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...KK/MBS NEAR TERM...KK SHORT TERM...AMS LONG TERM...DS AVIATION...KK/MBS EQUIPMENT...RAB

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