Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 280008 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 808 PM EDT FRI MAR 27 2015 .SYNOPSIS... A STRONG COLD FRONT WILL CONTINUE TO MOVE SOUTHEAST THIS EVENING AND TONIGHT. HIGH PRESSURE WILL COVER THE EASTERN UNITED STATES SATURDAY AND SUNDAY. MOISTURE APPROACHES SUNDAY NIGHT AHEAD OF THE NEXT COLD FRONT...WHICH MOVES THROUGH OUR REGION MONDAY. && .NEAR TERM /THROUGH SATURDAY/... AS OF 735 PM EDT FRIDAY... MADE A FEW MINOR ADJUSTMENTS TO FORECAST GRIDS TO REFLECT LATEST HOURLY TRENDS IN TEMPERATURE...DEW POINTS...AND CLOUDS...AND ELIMINATED THREAT OF ANY ADDITIONAL SHOWERS AFTER 5 AM ACROSS THE EASTERN PORTION OF THE COUNTY WARNING AREA BASED ON LATEST WRF AND HRRR MODEL OUTPUT. OVERNIGHT LOW TEMPERATURES STILL LOOK TO BE ON TARGET...SO NO NEED TO MAKE ANY ADDITIONAL THERMAL ADJUSTMENTS. LATEST SATELLITE PICTURES SHOW WEAK SHORT WAVE TROF MOVING EAST THROUGH EASTERN TN...WITH SOME LIGHT SPRINKLES/SHOWERS MOVING NORTHEAST IN ADVANCE OF THIS FEATURE EAST OF A LINE EXTENDING FROM NEAR MOUNT AIRY NC TO NEAR LYNCHBURG VA. BACK EDGE OF PRECIPITATION WILL CONTINUE TO GRADUALLY SHIFT EAST AS THE NIGHT PROGRESSES WITH THE PASSAGE OF THE SHORT WAVE...WITH ALL AREAS IN PIEDMONT EXPECTED TO BE PRECIPITATION FREE NO LATER THAN 5 AM SATURDAY MORNING. ARRIVAL OF COLD AIR WILL LIKELY COME TOO LATE TO SEE ANY CHANGE-OVER TO SNOW EAST OF THE BLUE RIDGE. FURTHER WEST...ARRIVAL OF COLDER AIR ON BACKSIDE OF THE SHORT WAVE SHOULD RESULT IN INCREASING UPSLOPING LIGHT SNOWS ACROSS THE WESTERN FLANKS OF THE APPALACHIANS. AN INCH OR TWO OF ACCUMULATION IS STILL QUITE POSSIBLE TONIGHT INTO SATURDAY AFTERNOON IN PREFERRED UPSLOPE AREAS...SUCH AS WESTERN GREENBRIER COUNTY WV...AND THIS THREAT ALREADY WELL ADVERTISED IN EXISTING FORECAST. AS OF 300 PM EDT FRIDAY... UPPER LEVEL TROUGH WILL DIG SOUTHWARD INTO THE APPALACHIANS TONIGHT AND SLIDE EAST ON SATURDAY. ANA-FRONT PRECIPITATION WILL CONTINUE TO MOVE EAST THIS EVENING INTO TONIGHT. DRIER AIR WILL PUSH INTO THE REGION SLOWLY ENDING THE PRECIPITATION IN THE EAST. A SHORTWAVE WILL DROP SOUTHEAST AROUND THE UPPER TROUGH TONIGHT. THIS SHORTWAVE WILL COMBINE WITH LOW LEVEL MOISTURE AND NORTHWEST FLOW TO PRODUCE UPSLOPE CLOUDS AND SCATTERED SNOW SHOWERS IN WESTERN MOUNTAINS. A LIGHT COATING UP TO 2 INCHES OF SNOW MAY BE POSSIBLE TONIGHT INTO SATURDAY IN THE NORTHWEST UPSLOPE FAVORED LOCATIONS. IN CONTRAST... THE DOWNSLOPING WINDS ON THE EAST SIDE OF THE BLUE RIDGE WILL GENERATE CLEARING ESPECIALLY LATE TONIGHT. SHAPED CLOUD COVER TONIGHT TOWARDS THE CANADIAN TONIGHT. INITIALLY LEANED POPS TOWARDS A BLEND OF HRRR...HIRESW-ARW AND NAM THEN MORE TOWARDS GFS WHICH SEEMS TO CAPTURES UPSLOPE PRECIPITATION IN THE WEST BETTER TONIGHT. LOW TEMPERATURES TONIGHT WILL RANGE FROM THE LOWER TEENS IN THE NORTHWEST MOUNTAINS TO THE LOWER 30S IN THE PIEDMONT. COLD HIGH PRESSURE WILL BUILD IN FROM THE UPPER MIDWEST ON SATURDAY AND BRING AN END TO ANY LINGERING UPSLOPE SNOW SHOWERS OVER THE FAR WESTERN SLOPES. GUSTY NORTHWEST WINDS WILL CONTINUE INTO SATURDAY AFTERNOON. HIGH TEMPERATURES SATURDAY WILL BE CHILLY WITH READINGS FROM THE MID 20S IN THE NORTHWEST TO THE UPPER 40S IN THE PIEDMONT. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... AS OF 215 PM EDT FRIDAY... VERY COLD SURFACE HIGH PRESSURE WILL SETTLE ABOUT OVERHEAD THE MOUNTAINS LATE SATURDAY NIGHT INTO EARLY SUNDAY WITH OPTIMAL RADIATIONAL COOLING EXPECTED UNDER CLEAR SKIES AND VERY DRY AIR. GIVEN 85H TEMPS OF BETWEEN -10 AND -15C SHOULD SEE TEMPS PLUMMET INTO THE TEENS IN MOUNTAIN VALLEYS...WITH UPPER TEENS TO LOW 20S EAST PENDING JUST HOW FAST WINDS DECOUPLE. THUS TRENDED ON THE COLD SIDE OF MOS WHICH WILL PUSH LOWS TO AT OR BELOW RECORD LEVELS BY EARLY SUNDAY IN SPOTS PER THE CLIMATE SECTION BELOW. FAST FLOW ALOFT WILL BRING QUICK CHANGES SUNDAY INTO MONDAY WITH PASSING SHORTWAVE RIDGING BEING REPLACED BY ANOTHER UPSTREAM 5H TROUGH AND SUBSEQUENT COLD FRONTAL PASSAGE MONDAY. FAST REBOUND WITH WARM ADVECTION DEVELOPING ON THE BACKSIDE OF THE EXITING HIGH ON SUNDAY SHOULD ALLOW TEMPS TO RECOVER TO THE UPPER 40S-MID 50S GIVEN HEATING OF DRY AIR DESPITE SOME INCREASE IN MID/HIGH CLOUDS LATE. PRE-FRONTAL MOISTURE AHEAD OF THE NEXT FRONT WILL ALSO ARRIVE PRETTY QUICK SUNDAY NIGHT WITH MODELS SHOWING AN AXIS OF SHOWERS PUSHING ACROSS THE MOUNTAINS BY MIDNIGHT AND THEN EXITING TO THE SOUTH BY MONDAY AFTERNOON. THIS SUPPORTS GOING FROM BASICALLY DRY EARLY SUNDAY EVENING TO HIGH CHANCE OR LOW LIKELYS MOUNTAINS SUNDAY NIGHT AND CHANCES SOUTH- WEST MONDAY MORNING. EXPECT LOW TEMPS TO REMAIN JUST WARM ENOUGH...MOSTLY 30S TO SEE MOSTLY LIQUID PTYPE WITH ONLY THE HIGHER ELEVATIONS ACROSS THE NW SEEING THINGS COLD ENOUGH FOR SNOW SHOWERS. WINDS LATER SUNDAY NIGHT INTO MONDAY AN ISSUE GIVEN SQUEEZING OF THE GRADIENT WITH THE FRONT BUT FOR NOW APPEARS SHOULD STAY MOSTLY BELOW ADVISORY LEVELS GIVEN A MARGINAL 85H JET AND UNIMPRESSIVE PRESSURE RISES. OTRW HIGHS MONDAY MOSTLY 50S WEST TO MID/UPPER 60S EAST PER STRONG DOWNSLOPE AND MORE SUN. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AS OF 1215 PM EDT FRIDAY... NW FLOW ALOFT PER CONTINUED UPPER TROFFINESS ACROSS THE NE STATES WILL KEEP PERIODIC PIECES OF CLIPPER ENERGY FLOWING SE INTO MIDWEEK WITH PERHAPS A FEW SHOWERS OVER THE NW WITH A STRONGER FRONT INTO TUESDAY NIGHT. HOWEVER MOISTURE LOOKS LIMITED SO THINKING MAY STAY DRY WITH THE CORE OF THESE FEATURES WELL NORTH SUPPORTING ONLY ISOLATED POPS AT THIS POINT TUESDAY INTO TUESDAY EVENING. BOUNDARY SHOULD DRIVE THROUGH THE REGION BY LATE TUESDAY NIGHT ALLOWING WEAK HIGH PRESSURE TO BRING EVEN DRIER WEATHER FOR WEDNESDAY ALONG WITH TEMPERATURE MODERATION UNDER GRADUAL 85H WARMING. MODELS CONTINUE TO FOCUS ON BOTH LEAD SOUTHERN STREAM ENERGY HEADING EAST ACROSS THE MID MISSISSIPPI VALLEY LATER IN THE WEEK IN ADVANCE OF MORE PRONOUNCED DIGGING NORTHERN STREAM 5H TROFFINESS BY THURSDAY. ALTHOUGH PHASING LOOKS RATHER UNLIKELY...APPEARS DEEPENING MOISTURE TRANSPORT FROM THE GULF WILL BE IN PLACE ALLOWING AN INITIAL SHOT OF SHOWERS TO GET LIFTED NORTH OUT OF THE DAMPENING SOUTHERN WAVE. THIS ALONG A SURFACE WARM FRONT AHEAD OF THE NORTHERN TROUGH/COLD FRONT THAT SHOULD ENHANCE LIFT ESPCLY WESTERN HALF LATER WEDNESDAY NIGHT INTO THURSDAY EVENING. THUS RUNNING WITH MAINLY LOW POPS MOUNTAINS WED NIGHT AND HIGH CHANCE TO LIKELYS THURSDAY GIVEN THE OVERRUNNING NATURE TO THE WARM ADVECTION PRECIP. WEAK COLD FRONT ARRIVES BY FRIDAY BUT UNCERTAINTY IN HOW FAR THROUGH THE REGION THE BOUNDARY MAKES IT IF AT ALL GIVEN DIFFERING GUIDANCE SOLUTIONS OF MORE ENERGY SPILLING INTO THE UPPER TROUGH TO THE WEST. FOR NOW WILL RUN WITH CHANCE POPS ON FRIDAY WHICH SUPPORTS THE PREVIOUS SLOWER EC SOLUTION. TEMPS TO REBOUND TO ABOVE NORMAL LEVELS BY MID OR LATE WEEK GIVEN FLATTER FLOW ALOFT AND LOW LEVEL WARM ADVECTION BY WEDNESDAY INTO FRIDAY WHEN SHOULD SEE WIDESPREAD 60S/70S FOR HIGHS. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
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AS OF 740 PM EDT FRIDAY... DEEP UPPER TROUGH WILL SWEEP EASTWARD THROUGH THE REGION TONIGHT SHIFTING THE WINDS TO GUSTY NORTHWEST AND BRINGING SHARPLY COLDER TEMPERATURES INTO THE REGION FOR THE WEEKEND. A STRONG SHORT WAVE ROTATING THROUGH THE BASE OF THE TROUGH WILL SUPPORT LIGHT PRECIPITATION IN SOME AREAS FOR THE NEXT FEW HOURS. IN ADDITION...NE-E FLOW EAST OF THE BLUE RIDGE IN ADVANCE OF THE COLD FRONT IS SUPPORTING A CONTINUATION OF IFR-LIFR ONCE THIS PASSES...DOWNSLOPE CONDITIONS WILL DEVELOP QUICKLY EAST OF THE BLUE RIDGE AND CLOUDS WILL DISSIPATE. MEANWHILE...UPSLOPE CONDITIONS WILL DEVELOP ACROSS THE WESTERN MOUNTAINS AND PREVAIL INTO MID-DAY SATURDAY. HRRR/GFS SUPPORT THE UPPER TROUGH AXIS/DISTURBANCE MOVING EAST OF THE REGION IN THE 06Z-08Z TIME FRAME WEST TO EAST. -RA WILL BE POSSIBLE EAST OF THE BLUE RIDGE UNTIL THE FRONT PASSES...WHILE UPSLOPE -SHSN WILL BE POSSIBLE ACROSS THE WESTERN MOUNTAINS FOR THE NEXT FEW HOURS UNTIL THE TROUGH PASSES. THE NEXT DISTURBANCE TO ROTATE THROUGH THE BASE OF THE TROUGH SHOULD PASS WELL SOUTH OF THE REGION SAT...THUS SUPPORTING CLEARING ACROSS EVEN THE MOUNTAINS BY SAT AFTERNOON WITH A VERY DRY AIR MASS IN PLACE. WINDS WILL BECOME NW BEHIND THE FRONT AT SPEEDS OF 10-12KTS WITH GUSTS 20-23KTS...CONTINUING AT OR NEAR SIMILAR SPEEDS THROUGH THE DAY SATURDAY. MEDIUM CONFIDENCE IN CIGS THROUGH 14Z...THEN MEDIUM TO HIGH CONFIDENCE IN CIGS. MEDIUM TO HIGH CONFIDENCE IN MOSTLY VFR VISIBILITIES THROUGH THE TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN WIND SPEED/DIRECTION THROUGH THE TAF VALID PERIOD. EXTENDED AVIATION FORECAST... VFR CONDITIONS ARE EXPECTED SATURDAY NIGHT THROUGH SUNDAY UNDER HIGH PRESSURE. THERE IS A POTENTIAL FOR STRONG GUSTY WINDS BEHIND A COLD FRONT MONDAY NIGHT AND TUESDAY. SOME MVFR CIGS WILL BE POSSIBLE ACROSS THE MOUNTAINS WITH AN ALBERTA CLIPPER MON AS WELL.
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&& .CLIMATE... AS OF 455 AM EDT FRIDAY... RECORD LOWS FOR MARCH 29: ROANOKE......19 IN 1982 BLACKSBURG...17 IN 2001 LYNCHBURG....23 IN 1923 AND 1982 DANVILLE.....23 IN 1966 BLUEFIELD....19 IN 1966 AND 1982 LEWISBURG....18 IN 1983 && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...KK NEAR TERM...KK/WERT SHORT TERM...JH LONG TERM...JH AVIATION...KK/RAB CLIMATE...AMS/SK

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