Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 041445 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 945 AM EST THU FEB 4 2016 .SYNOPSIS... COOL HIGH PRESSURE WILL GRADUALLY BUILD INTO THE CENTRAL APPALACHIANS FROM THE WEST TODAY...PASSING OVERHEAD FRIDAY INTO SATURDAY. SUNDAY...LOW PRESSURE MOVES ACROSS THE SOUTHEAST AND OFF THE COAST. AT THIS TIME THIS SYSTEM WILL KEEP THE MAIN PRECIPITATION SOUTHEAST OF OUR FORECAST AREA. && .NEAR TERM /THROUGH TONIGHT/...
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AS OF 930 AM EST THURSDAY... SURFACE COLD FRONT HAS FINALLY SLIPPED JUST EAST OF THE CWA THIS MORNING WHILE THE ACTUAL 85H FRONT IS NOW CROSSING THE BLUE RIDGE. THIS SHOULD ALLOW FOR INCREASING NORTH/NW FLOW FLOW THIS AFTERNOON WITH DRIER AIR GRADUALLY WORKING INTO THE MOUNTAINS EXCLUDING THE UPSLOPE AREAS WHERE LOW CLOUDS LIKELY TO LINGER. HOWEVER OVERALL DRY SINCE MOISTURE IS QUITE SHALLOW WITH DEEPER MOISTURE NOW TO THE EAST. ACROSS THE EAST MAIN CONCERN IS WITH A WEAK WAVE ALONG THE FRONT THAT WILL LIKELY HOLD A STRIPE OF DEEPER MOISTURE IN PLACE AHEAD OF ANOTHER WEAK IMPULSE THAT WILL SLIDE UP THE BOUNDARY LATER IN THE DAY. THIS MAY RESULT IN SOME LIGHT RAIN BEING PULLED BACK INLAND ACROSS THE SE LATE BUT MORE SO OVERNIGHT AS A STRONGER UPSTREAM TROUGH SWINGS THROUGH TOWARD MORNING. THIS SUPPORTS KEEPING SOME LOW POPS IN THE EAST LATER TODAY WITH SOME SUNNY BREAKS CENTRAL AND SW SECTIONS. GIVEN THE GRADUAL BLEEDING IN NATURE OF THE COLD AIR AND SLOWNESS TO REACH THE EAST...LOWERED HIGHS FAR WEST WHILE STAYING IN THE LOW/MID 50S EAST PER TEMPS ALREADY NEAR 50. AS OF 701 AM EST THURSDAY... RAIN THIS MORNING IS FURTHER EAST OVER CENTRAL AND EASTERN NC. MODELS ARE FAVORING SHIFTING SOME OF THIS WWD LATER THIS MORNING...BUT UNTIL THEN KEEPING IT DRY OVER OUR AREA. MAY SEE SOME SUNSHINE IN THE BLUE RIDGE AND ADJACENT AREAS...HUGGING THE FINE LINE BETWEEN THE DEEPER MOISTURE IN THE PIEDMONT AND THE LOW LVL UPSLOPE OVER THE HIGHER TERRAIN IN THE WEST. THEREFORE...LOWERED SKY COVER SOME IN THE NEW RIVER VALLEY/ROANOKE AND EAST TO THE FOOTHILLS FOR THE MORNING. PREVIOUS EARLY MORNING DISCUSSION... THE COLD FRONT IS SLOWLY MOVING ACROSS THE REGION THIS MORNING AND IS CURRENTLY ALONG THE BLUE RIDGE. THIS FRONT WILL MOVE AND STALL OVER THE COASTAL PIEDMONT BY THIS AFTERNOON. MEANWHILE...AN UPPER LEVEL TROUGH WILL TRACK ACROSS THE MISSISSIPPI VALLEY...GENERATING A SURFACE REFLECTION ALONG THE SOUTHEAST COAST. THIS REFLECTION WILL TRACK NORTH ALONG THE STALLED FRONT AS THE UPPER LEVEL TROUGH APPROACHES THE OHIO AND TENNESSEE VALLEYS. MOISTURE IS EXPECTED TO BUCKLE BACK ACROSS THE PIEDMONT THIS AFTERNOON AND EVENING WITH A CHANCE OF LIGHT RAIN EAST OF HWY 29. THIS REFLECTION WILL INCREASE CLOUDS OVER THE AREA...WHICH WILL KEEP WINDS SPEEDS LOWER. WITH LESS WESTERLY WINDS...UPSLOPE RAIN AND SNOW SHOWERS WILL BE LIMITED. THEREFORE WE HAVE REDUCED POPS AND ACCUMULATIONS ALONG WESTERN SLOPES TODAY AND TONIGHT. ALSO WITH THE FRONT STALLING FARTHER INLAND THAN PREVIOUSLY FORECASTED...TEMPERATURES WILL RUN SLIGHTLY WARM THAN NORMAL WITH 40S WEST TO LOWER AND MID 50S EAST. AS THIS REFLECTION MOVES OFF THE EAST COAST TONIGHT...TEMPERATURES WILL DROP INTO THE 20S ACROSS THE MOUNTAINS AND LOWERS 30S ACROSS THE PIEDMONT.
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&& .SHORT TERM /FRIDAY THROUGH SUNDAY/... AS OF 328 AM EST THURSDAY... MODELS SEEM IN GENERAL AGREEMENT THAT WE WILL STAY SEASONABLY COLD AND DRY THIS PERIOD WITH HIGH PRESSURE IN CONTROL. WILL HAVE TO WATCH THE SRN STREAM SYSTEM MOVING FROM THE GULF CAST STATES SAT NIGHT OFF THE SOUTHEAST COAST SUNDAY EVENING. MODELS HAVE CONTINUED TO TREND IN THIS DIRECTION BUT WILL BEAR WATCHING FOR SUNDAY AS MAY SEE SOME LIGHT SNOW SNEAK NWD TOWARD SOUTHSIDE VA INTO NW NC PIEDMONT...BUT EXPECT BULK OF DEEPER MOISTURE TO STAY ON THE COAST. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... AS OF 330 AM EST THURSDAY... ONLY CHANGE THIS PERIOD WAS TO GO WITH PTYPE CHANGE TO MORE SNOW INSTEAD OF RAIN MONDAY-TUESDAY...AS MODELS SHOW 8H TEMPS WELL BELOW ZERO AND THICKNESSES SUPPORTING MOSTLY SNOW. WILL KEEP SOME RAIN SHOWERS FOR TEMPS ABOVE 42F...BUT THE MODELS HAVE BEEN TRENDING VERY COLD FOR EARLY-MID WEEK WITH -10 TO -16C AIR PUSHING INTO THE MTNS BY MIDWEEK. PREVIOUS DISCUSSION FROM WEDNESDAY AFTERNOON... PROGRESSIVE FLOW WILL ALLOW A VIGOROUS UPPER TROF TO MOVE OVER THE EASTERN US AND DEVELOP A STRONG COASTAL LOW OFF THE SOUTHEAST COAST. ALL GUIDANCE CURRENTLY KEEPS THE PRECIPITATION SHIELD ASSOCIATED WITH THIS LOW TO THE EAST OF THE REGION WITH JUST SOME SPRINKLES POSSIBLE FOR THE FAR SOUTHEASTERN PORTIONS OF SOUTHSIDE LATE ON SUNDAY. BY MONDAY A MUCH DEEPER TROF WILL MOVE INTO THE EASTERN US AND SET UP A SIGNIFICANTLY COLDER PATTERN...WHILE A COMPLEX SURFACE PATTERN DEVELOPS AS LOW PRESSURE APPROACHES FROM THE GREAT PLAINS...FOLLOWED BY A TRANSFER OF ENERGY TO A DEVELOPING LOW OFF THE MIDDLE ATLANTIC COAST. THE COMBINATION OF THE COLDER AIR AND DEVELOPING SURFACE FEATURES LOOKS LIKE IT MAY BRING SOME LIGHT SNOW/SNOW SHOWERS TO THE AREA MAINLY WEST OF THE BLUE RIDGE. THE PATTERN DOES NOT FAVOR DEVELOPMENT OF A STRONG STORM SYSTEM TO AFFECT THE REGION SO WIDESPREAD WINTER WEATHER ISSUES ARE NOT LIKELY. BY THE MIDDLE OF NEXT WEEK WHEN THE COLDER AIR ARRIVES...HIGH TEMPERATURES WEST OF THE BLUE RIDGE WILL GENERALLY BE IN THE MIDDLE 20S WITH READINGS IN THE MIDDLE 30S EAST OF THE RIDGE. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... AS OF 700 AM EST THURSDAY... FRONTAL BOUNDARY LINGERING IN THE EAST THIS MORNING BUT SHOULD BE EAST OF DAN/LYH SHORTLY. WILL SEE MAINLY VFR EAST OF THE UPSLOPE AREAS...THOUGH SOME TEMPO MVFR IS POSSIBLE AT DAN THIS MORNING AS UPSTREAM OBS OVER CENTRAL NC FAVOR CIGS AROUND 2500-3500 FT. SOME POTENTIAL FOR LIGHT RAIN TO PUSH AS FAR WEST AS DANVILLE THIS AFTERNOON AS ANOTHER WAVE OF LOW PRESSURE TRACKS ALONG THE FRONT. HOWEVER...THE CONSENSUS AMONG MODELS IS TO KEEP THIS EAST...SO NOT ADDING RAIN TO DAN AT THIS POINT. THE MOISTURE IN THE WEST LINGERS THROUGH MOST OF THIS TAF PERIOD WHILE DRIER AIR MOVES IN THROUGH TONIGHT EAST OF THE ALLEGHANY FRONT. CIGS IN THE WEST WILL BE MAINLY MVFR...THOUGH LWB DRIES OUT LATER TONIGHT AND CIGS SHOULD LIFT TO VFR THERE. ATTM NOT EXPECTING ANY FOG CONCERNS FRIDAY MORNING. EXTENDED DISCUSSION... ON FRIDAY...HIGH PRESSURE WILL BUILD OVERHEAD TO PROVIDE COLDER AND DRIER CONDITIONS...AND WILL KEEP VFR CONDITIONS AT ALL TAF SITES THROUGH SATURDAY. ANOTHER SYSTEM MOVING ACROSS THE SOUTHEAST APPEARS TO STAY JUST SOUTH OF US SUNDAY WITH POSSIBLE LIGHT PRECIP AND MVFR CIGS EDGING TOWARD THE VA/NC BORDER SUNDAY AFTERNOON. AN ARCTIC FRONT/CLIPPER PUSHES IN MONDAY AND WILL BRING SOME SNOW TO PORTIONS OF THE AREA...MAINLY THINKING BLF/LWB AND EAST TOWARD ROA/LYH. SHOULD SEE SOME MVFR TO AT TIMES IFR CIGS/VSBYS IN WV AND POTENTIALLY TO BCB/ROA/LYH MONDAY. && .HYDROLOGY... AS OF 330 AM EST THURSDAY ALL RIVERS IN THE MOUNTAINS AND ROANOKE AREA HAVE CRESTED AND FALLEN BACK BELOW FLOOD STAGE. WILL SEE RISES TO AT OR ABOVE FLOOD STAGE DOWNSTREAM OF BROOKNEAL ON THE ROANOKE RIVER...AND DOWNSTREAM OF WENTWORTH NC ON THE DAN RIVER. MAY APPROACH MODERATE FLOOD STAGE AT RANDOLPH AND SOUTH BOSTON BY FRIDAY MORNING. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...PM/WP NEAR TERM...JH/RCS/WP SHORT TERM...WP LONG TERM...MBS/WP AVIATION...RCS/WP HYDROLOGY...PC/WP

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