Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 161401 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1001 AM EDT WED APR 16 2014 .SYNOPSIS...
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HIGH PRESSURE WILL BUILD SOUTHWARD ALONG THE EASTERN FACE OF THE APPALACHIANS TONIGHT. THIS HIGH PRESSURE WILL REMAIN IN CONTROL OF THE WEATHER PATTERN THROUGH FRIDAY. A WEAK DISTURBANCE MOVING TOWARD THE REGION FROM THE NORTHWEST MAY BRING THE NEXT CHANCE OF SHOWERS TO THE REGION FOR EARLY IN THE WEEKEND.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 950 AM EDT WEDNESDAY... HIGH PRESSURE WILL SHIFT NORTHEAST TODAY FROM ERN OHIO TO NY BUT WEDGE SOUTHWARD INTO OUR AREA. THE FEW SC OVER THE MTNS OF WV WILL CLEAR OUT SOON WITH EVERYONE EXPERIENCING SUNNY SKIES. NOT MUCH CHANGE TO FORECAST HIGH TEMPS WHICH WILL RUN ABOUT 10 DEGREES BELOW NORMAL FOR THIS TIME OF YEAR. PREVIOUS VALID DISCUSSION... EXPECT AFTERNOON TEMPERATURES TO CLIMB INTO THE UPPER 40S AND LOW 50S AREAWIDE. WINDS WILL BECOME LIGHT BY SUNSET AND...WHEN COMBINED WITH CONTINUED CLEAR SKIES...WILL RESULT IN ANOTHER NIGHT OF STRONG RADIATIONAL COOLING...ALLOWING TEMPERATURES AREAWIDE TO AGAIN FALL BELOW FREEZING. IN ADDITION...THE LACK OF ATMOSPHERIC MIXING WILL ALSO PROMOTE AREAS OF FROST. WILL THEREFORE ISSUE ANOTHER FREEZE WARNING FOR AREAS EAST OF THE BLUE RIDGE FOR WEDNESDAY NIGHT. OVERNIGHT LOWS WILL BOTTOM OUT RANGING FROM THE MID 20S TO THE LOW 30S MOST LOCATIONS...WITH A FEW VALLEY BOTTOMS FALLING INTO THE UPPER TEENS.
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&& .SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/... AS OF 400 AM EDT WEDNESDAY... MODELS IN GOOD AGREEMENT AT THE BEGINNING OF THIS PERIOD AS A LARGE CANADIAN HIGH DRIFTS TO THE NORTHEAST OF THE REGION. THIS WILL SET UP A WEDGE PATTERN...INITIALLY DRY. 850MB TEMPS REBOUND TOWARD 0C THU FROM THE VERY COLD -12C CURRENTLY IN PLACE...BUT THEN HOVER IN THE -2C TO 4C RANGE NORTH-SOUTH THROUGH FRIDAY AS NE FLOW FROM THE PARENT SFC HIGH SETS UP ACROSS THE REGION THUS RETARDING ANY APPRECIABLE WARMING. SKIES SHOULD REMAIN MOSTLY SUNNY THU...HELPING TO WARM TEMPS FROM WIDESPREAD BELOW FREEZING TEMPS AGAIN DURING THE EARLY MORNING. GIVEN THE PATTERN...HAVE FAVORED THE COLDER ECMWF MOS GUIDANCE. FRIDAY...THE MODELS BEGIN TO DIVERGE...WHICH BECOMES A MORE APPRECIABLE DIVERGENCE BY SATURDAY...ON THE TRACK/INTENSITY OF A NORTHERN STREAM SHORT WAVE AND THE TRACK/INTENSITY/DEVELOPMENT OF A SOUTHERN STREAM CLOSED LOW ALONG THE SOUTHEAST U.S. COAST. HPC MODEL PREFERENCE IS WITH THE ECMWF SOLUTION...WHICH FAVORS DEVELOPMENT OF A FAIRLY DEEP CLOSED LOW ALONG THE NE FL/GA/SC COAST. THE GFS FAVORS THE NORTHERN STREAM SHORT WAVE...AND AS A RESULT SHOWS ANOTHER FAIRLY SIGNIFICANT SURGE OF COLD AIR INTO THE REGION SATURDAY WITH UPSLOPE -SHRA POSSIBLE ACROSS THE ALLEGHANYS. WHILE THE ECMWF DOES NOT DISCOUNT THIS TROUGH...IT SHOWS LITTLE PCPN AND LITTLE APPRECIABLE COLD ADVECTION...FOCUSING MORE ENERGY INTO THE SE U.S. SYSTEM...HENCE INDICATING MORE SUBSIDENCE ACROSS OUR CWA. THE NAM AND CANADIAN OFFER SLIGHTLY DIFFERENT SOLUTIONS AS WELL...BOTH SHOWING GREATER POTENTIAL FOR -SHRA FURTHER NORTH WITH THE SOUTHERN SYSTEM AND THE NAM HAVING MORE FROM BOTH. AT ANY RATE...AT LEAST THROUGH SAT AND UNTIL THE MODELS CAN COME TO BETTER CONSENSUS...HAVE KEPT THE SOUTHERN COUNTIES DRY...BUT DID INCREASE POPS ACROSS THE NC PIEDMONT TO 14 PERCENT LEANING TOWARD THE ECMWF. FOR THE MOUNTAINS...HAVE SHOWN SLIGHT CHC POPS INTO GREENBRIER/SUMMERS IN ASSOCIATION WITH NW FLOW SHORT WAVE...DEPICTED TO SOME EXTENT BY ALL MODELS. USED A ECMWF/GFS BLEND FOR TEMPS FRI-SAT...BUT HAVE LEANED TOWARD THE COLDER ECMWF MOS AS NOTED ABOVE WITH PREVAILING NE FLOW ACROSS THE PIEDMONT AND/OR COLDER NW FLOW SAT BEHIND SHORT WAVE. && .LONG TERM /SUNDAY THROUGH TUESDAY/... AS OF 415 AM EDT WEDNESDAY... MUCH OF WHAT OCCURS...AT LEAST AT THE BEGINNING OF THIS PERIOD...WILL DEPEND ON THE TRACK OF THE SE U.S. UPPER LOW. BY MON...THIS SYSTEM SHOULD BE FAR ENOUGH EAST TO NO LONGER INFLUENCE THE AREA. OVERALL...MOSTLY DRY CONDITIONS EXPECTED...BUT WILL NEED TO WATCH SE-E PARTS OF THE CWA FOR CLOUD COVER AND COOL...MARITIME EASTERLY FLOW AS LOW PRESSURE REMAINS JUST SOUTHEAST OF THE CWA. A WEAK UPPER RIDGE WILL BUILD OVER THE TOP OF THE SE UPPER LOW PROMISING TO CONTINUE A GRADUAL WARMING TREND THROUGH THE PERIOD...BUT AGAIN LIKELY TEMPERED BY THE EASTERLY FLOW IN PLACE BETWEEN THE LOW TO THE SOUTHEAST AND SFC HIGH PRESSURE TO THE NORTHEAST. MODEL DIFFERENCES CONTINUE TO BE QUITE SIGNIFICANT WITH RESPECT TO THE NEXT SYSTEM POTENTIALLY IMPACTING THE AREA EARLY NEXT WEEK...WITH THE ECMWF BRINGING ANOTHER AREA OF CLOSED LOW PRESSURE...ALBEIT WEAKER...INTO THE SE U.S. CLOSED LOW...WHILE THE GFS BRINGS MORE OF AN OPEN TROUGH TOWARD THE REGION. AT ANY RATE...EXPECT INCREASING CHANCES FOR RAIN BY MON-TUE OF NEXT WEEK. INSTABILITY APPEARS MARGINAL AT THIS POINT...ESPECIALLY PER ECMWF SOLUTION. THUS...HAVE MADE NO CHANGES TO CURRENT LONG TERM GRIDS WITH LOW CHC POPS AND NO MENTION OF TSRA. SURFACE HIGH FILLING IN BEHIND FRIDAY`S WEAK BOUNDARY EVENTUALLY COVERS NEW ENGLAND AND THE ENTIRE MIDDLE ATLANTIC TO CLOSE THE WEEKEND. AGAIN...THIS HIGH MAY EVENTUALLY PARK OVER NEW ENGLAND SETTING UP ANOTHER DRY WEDGE PER THE ECMWF. THUS...SUNDAY MAY BE COLDER THAN SATURDAY. THE GFS HAS ANOTHER SURFACE HIGH JUST OFF THE CAROLINA COAST...WITH ELIMINATES THE EASTERLY COMPONENT/DRY WEDGE...GIVING MORE OF A SOUTHERLY BREEZE AND A WARMER SUNDAY. WILL GO BETWEEN THE MEX AND ECMWF MOS FOR HIGHS ON SUNDAY. THE PATTERN REMAINS DRY AND BENIGN...UNTIL NEXT TUESDAY NIGHT...WHEN BOTH THE ECMWF AND GFS AGREE ON A FRONT WITH RAIN SHOWERS. WENT WITH CHC POPS AT THE END OF THE LONG TERM WITH THE MODEL AGREEMENT AT THIS TIMERANGE. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... AS OF 730 AM EDT WEDNESDAY... LINGERING UPSLOPE LOW CLOUDS HAVE LIFTED NORTH AWAY FROM BLF/LWB INTO POCAHONTAS AND RANDOLPH COUNTIES OF WV...WHERE THEY SHOULD CONTINUE TO DISSIPATE THROUGH THE MORNING AS CONDITIONS FOR SUCH BECOME LESS FAVORABLE. OTHERWISE...VFR CIGS/VSBYS EXPECTED THROUGH THE TAF VALID PERIOD WITH SKC. IT APPEARS ANY UPSTREAM CIRRUS WILL HOLD OFF UNTIL THU AFTERNOON...SO HAVE GONE WITH SKC AT ALL TAF SITES AFT 15Z THIS MORNING. WINDS CONTINUE TO DIMINISH AND GUSTINESS HAS GENERALLY ENDED. CANNOT RULE OUT A FEW LOW END GUSTS THROUGH MID-MORNING AT THE USUAL WINDIER LOCATIONS...SUCH AS ROA. HOWEVER...AS SFC HIGH DRIFTS FAIRLY QUICKLY TO THE NE OF THE REGION...EXPECT WINDS TO COME AROUND TO THE NE AND ENE THROUGH LATE MORNING/AFTERNOON...WITH LOW END GUSTS THEN POSSIBLE ACROSS THE PIEDMONT...ESPECIALLY LYH TO DAN. NE WINDS AT 5-7KTS WILL CONTINUE THROUGH THE REMAINDER OF THE TAF VALID PERIOD...BUT MAY TAKE SLIGHTLY LONGER TO DEVELOP INTO EASTERN WV/FAR SW VA WEST OF THE ALLEGHANY FRONT. HIGH CONFIDENCE IN VFR CIGS/VSBYS THROUGH THE TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN WIND SPD/DIR THROUGH THE TAF VALID PERIOD. EXTENDED AVIATION DISCUSSION... HIGH PRESSURE WILL LINGER INTO FRIDAY...MAINTAINING VFR CONDITIONS THROUGH THE END OF THE WORKWEEK UNDER LIGHT EAST TO NORTHEAST FLOW. THE NEXT COLD FRONT APPROACHES FROM THE WEST FRIDAY BUT APPEARS SLOW AND WEAK ENOUGH TO MAINTAIN VFR DURING THE DAY FOR NOW. THIS SYSTEM MAY BRING MVFR CIGS TO THE MOUNTAINS SATURDAY...ALONG WITH A FEW SHOWERS. OTRW VFR FOR THE WEEKEND WITH HIGH PRESSURE FOLLOWING THIS SYSTEM FOR SUNDAY. && .HYDROLOGY... AS OF 200 AM EDT TUESDAY... RAINFALL OF 1 TO 2 INCHES ON TUESDAY WILL CAUSE RISES ALONG MAINSTEM RIVERS INTO MIDWEEK. MUCH OF THE HEAVIEST RAIN OCCURRED ALONG THE DAN RIVER BASIN WITH LEVELS FORECASTED TO REACH MINOR FLOOD STAGE AT SOUTH BOSTON WEDNESDAY MORNING. OTHER LOCATIONS ALONG THE DAN AROUND DANVILLE AND PACES AS WELL AS RANDOLPH ALONG THE LOWER ROANOKE RIVER WILL SEE BANKFULL CONDITIONS. A RIVER FLOOD WARNING REMAINS IN EFFECT AT SOUTH BOSTON INTO LATE THURSDAY. && .CLIMATE...
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AS OF 1000 AM EDT WEDNESDAY... RECORD LOWS AT BLACKSBURG...BLUEFIELD AND LEWISBURG THIS MORNING BLACKSBURG TIED THEIRS AT 24...BLUEFIELD TIED THEIRS AT 23 AND LEWISBURG BROKE THEIRS AT 23. APRIL 17TH RECORD LOWS ROANOKE 27F 1980......FORECASTED LOW 31F. LYNCHBURG 27F 1904....FORECASTED LOW 30F. DANVILLE 28F 1962.....FORECASTED LOW 30F. BLUEFIELD 25F 2001....FORECASTED LOW 32F. BLACKSBURG 20F 1974...FORECASTED LOW 26F. LEWISBURG 25F 2001....FORECASTED LOW 20F.
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&& .RNK WATCHES/WARNINGS/ADVISORIES...
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VA...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT THURSDAY FOR VAZ022>024-032>035-043>047-058-059. NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT THURSDAY FOR NCZ003>006-019-020. WV...NONE.
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&& $$ SYNOPSIS...NF NEAR TERM...NF/WP SHORT TERM...RAB LONG TERM...KM AVIATION...JH/NF/RAB HYDROLOGY...JH CLIMATE...JC/KM/WP

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