Area Forecast Discussion
Issued by NWS Blacksburg, VA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
552 FXUS61 KRNK 050511 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1211 AM EST FRI FEB 5 2016 .SYNOPSIS... A STRONG UPPER LEVEL DISTURBANCE WILL CROSS THE REGION FROM THE WEST LATE TONIGHT BRINGING INCREASING NORTHWEST WINDS AND PERHAPS A PERIOD OF LIGHT SNOW OR SNOW SHOWERS. COLD HIGH PRESSURE BUILDS IN BEHIND THIS SYSTEM FRIDAY INTO THE WEEKEND WITH DRIER WEATHER EXPECTED. ANOTHER LOW PRESSURE SYSTEM WILL SKIRT THE SOUTHEAST COAST SUNDAY FOLLOWED BY A CLIPPER AREA OF LOW PRESSURE FOR EARLY NEXT WEEK. && .NEAR TERM /THROUGH FRIDAY/... AS OF 700 PM EST THURSDAY... BUFKIT CONTINUES TO INDICATE A GRADUAL DESCENT OF THE INVERSION AS THE LOW LEVEL FLOW BECOMES ENHANCED BY THE DEVELOPING LOW ALONG THE COAST. THIS WILL LEAD TO INCREASING WINDS ALONG AND WEST OF THE BLUE RIDGE...AND WINDS FROM THE NORTHWEST MOUNTAINS OF NORTH CAROLINA UP THROUGH THE GRAYSON HIGHLANDS OF VA WILL LIKELY EXCEED 40 MPH LATE TONIGHT THROUGH EARLY FRIDAY MORNING SO A WIND ADVISORY HAS BEEN ISSUED THERE. WINDS WILL SUBSIDE AFTER DAYBREAK. SATELLITE IMAGERY IS ALSO SHOWING A NICE BAROCLINIC LEAF AS A SHARP SHORT WAVE APPROACHES THE LINGERING LOW LEVEL BAROCLINIC ZONE AND HELPS DEVELOP THE SURFACE LOW. EXPECT IT WILL BE A TIGHT PRECIPITATION GRADIENT FAR EAST AS DYNAMIC FORCING IN THE DEFORMATION ZONE GENERATES PRECIPITATION. WILL HANG MY HAT ON TRENDS IN THE LATEST MESO MODELS WHICH KEEP THE BULK OF THE PRECIPITATION JUST TO OUR EAST AND LOWER POPS IN THE PIEDMONT AND SOUTHSIDE. WILL CONTINUE TO REVISIT PRECIPITATION POTENTIAL ACROSS THE EAST AND ADJUST GRIDS AS NEEDED. AND AS TEMPERATURES FALL OVERNIGHT WHATEVER PRECIPITATION THAT DOES MANAGE TO AFFECT LOCATIONS EAST OF THE BLUE RIDGE WILL CHANGE TO LIGHT SNOW WITH SOME LOCATIONS RECEIVING A LIGHT DUSTING. MEANWHILE WEST OF THE BLUE RIDGE...UPSLOPE NORTHWEST WINDS WILL GENERATE SNOW SHOWERS AS A SURGE OF MOISTURE ACCOMPANIES THE SHORT WAVE AS IT MOVES INTO THE REGION TONIGHT. EXPECT A DUSTING OF SNOW FOR THE FAR WESTERN SLOPES OF THE APPALACHIANS WITH AROUND HALF IN INCH OR SO OF ACCUMULATION FOR WESTERN GREENBRIER COUNTY. THE SNOW SHOWERS WILL DISSIPATE TO LINGERING FLURRIES BY FRIDAY MORNING. PREVIOUS AFD... COLD FRONT AND ITS ASSOCIATED SURFACE LOW TO THE SOUTHEAST WILL CONTINUE TO DRIFT EAST OVERNIGHT AHEAD OF A VERY STRONG SHORTWAVE TROUGH THAT WILL QUICKLY SPILL EAST...CROSSING THE REGION EARLY FRIDAY. THIS MAY ALLOW SOME PARTIAL PHASING TO TAKE SHAPE AS THE LOW HEADS TO THE COAST LATE TONIGHT WITH THE CORE OF COLD POOL SLIDING OVERHEAD AFTER MIDNIGHT. QPF REMAINS BELOW A TENTH OF AN INCH WITH MORE TO THE EAST WHERE WOULD BE LIQUID ACROSS THE PIEDMONT EARLY ON BEFORE CHANGING TO WET SNOW. HOWEVER WITH COLD AIR ALOFT...APPEARS PRECIP MIGHT SWITCH TO TRACE AMOUNTS OF LIGHT SNOW FASTER PROVIDED CURRENT DRY AIR IS NOT TOO MUCH. KEPT LOWS SIMILAR TO BEFORE WITH LOW/MID 20S WEST...NEAR 30 BLUE RIDGE AND 30-35 EAST OVERNIGHT. WINDS BEHIND THE PASSING WAVE ALSO OF CONCERN GIVEN STRONG SUBSIDENCE LATE ONCE THE LOW OFFSHORE STARTS TO DEEPEN AND A QUICK SHOT OF 85H COLD ADVECTION SWINGS EAST. ALTHOUGH THE JET IS RATHER MARGINAL...LATE NIGHT TIMING ALONG WITH A LOWERING INVERSION WILL PUSH SPEEDS TO ADVISORY CRITERIA NW NC RIDGES TOWARD DAYBREAK AS SEEN VIA LOCAL SCHEME OUTPUT. MOISTURE EXITS EARLY FRIDAY ALLOWING SURFACE HIGH PRESSURE TO BUILD IN UNDER SHORTWAVE RIDGING FRIDAY AFTERNOON. WIND/PRESSURE GRADIENT WILL REMAIN IN PLACE WITH GUSTS TO 30-40 MPH OVER THE MOUNTAINS INTO THE AFTERNOON WHERE HIGHS WILL STAY IN THE 30S DESPITE SUNSHINE. SHOULD GET A BIT OF A BOOST VIA DOWNSLOPE WARMING OUT EAST AND UNDER STRONG INSOLATION APPEARS HIGHS MOSTLY MID-UPPER 40S FOR NOW. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... AS OF 240 PM EST THURSDAY... SURFACE HIGH PRESSURE WILL BE OVER THE FORECAST AREA FRIDAY NIGHT AND SATURDAY WITH SOME MID AND HIGH LEVEL CLOUDS COMING IN FROM THE WEST SATURDAY AFTERNOON. WATER VAPOR LOOP SHOWED WELL DEFINED SHORT WAVES OVER THE WESTERN UNITED STATES THIS MORNING THAT WILL MOVE EAST AND AMPLIFY INTO A DEEP TROF OVER THE MISSISSIPPI VALLEY BY SATURDAY MORNING. AN UPPER LOW CLOSES OFF SOMEWHERE OVER THE SOUTHEAST BY SUNDAY MORNING. SURFACE LOW PRESSURE DEVELOPS OFF THE SOUTHEAST COAST SATURDAY NIGHT AND TRACKS NORTH-NORTHEAST THROUGH MONDAY. MODELS KEEP PRECIPITATION WITH THIS COASTAL LOW WELL SOUTH AND EAST OF THE FORECAST AREA. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 245 PM EST THURSDAY... THE LONG WAVE TROF OVER THE EAST CONTINUES TO DEEPEN MONDAY...WITH A CLOSED UPPER LOW WITHIN THIS TROF OVER THE OHIO VALLEY ON TUESDAY. BY TUESDAY NIGHT...500 MB HEIGHTS WILL BE DOWN AROUND 522 DECAMETERS AND 850 MB TEMPERATURES AROUND -12C. BY MONDAY MORNING THE COASTAL LOW IS WELL NORTHEAST OF THE DELMARVA PENINSULA WITH ANOTHER LOW OVER THE GREAT LAKES AND MID ATLANTIC REGION. A COLD FRONT WILL CROSS THROUGH THE FORECAST AREA ON MONDAY...WITH A RE-ENFORCEMENT OF COLDER AIR ON TUESDAY. UPSLOPE FLOW AND PERSISTENT LOW LEVEL MOISTURE WILL RESULT IN A PROLONGED PERIOD OF SNOW SHOWERS IN THE FAVORED MOUNTAIN AREAS MONDAY NIGHT THROUGH WEDNESDAY NIGHT. WENT ON THE COOLER SIDE OF GUIDANCE ON MONDAY WITH CLOUDS AND PRECIPITATION EXPECTED. ECMWF AND GFS ARE DIFFERENT WITH HOW FAST THE TROF LIFTS OUT AND THE COLDER AIR MASS MODERATES ON WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT THURSDAY WILL BE DRY WITH UNDER SURFACE HIGH PRESSURE. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
AS OF 1150 PM EST THURSDAY... INITIAL CONCERN WILL BE FOCUSED AROUND A COASTAL LOW PRESSURE AREA DEVELOPING ALONG THE SC/NC COAST OVERNIGHT IN RESPONSE TO A VIGOROUS NEGATIVELY TILTED UPPER TROUGH LIFTING OUT OF THE SOUTHEAST STATES. WHILE THE BULK OF THE ASSOCIATED PRECIPITATION WILL REMAIN EAST OF THE CWA...OVER THE NEXT 4-8 HOURS...POTENTIAL FOR LOW-LEVEL MOISTURE AND LIGHT PRECIPITATION TO BE PULLED BACK INTO THE PIEDMONT. MORE IMPORTANTLY...A DEFORMATION ZONE IS NOW DEVELOPING NEAR KROA THAT WILL ALSO BRING LIGHT -RA AND/OR -RASN TO AREAS BACK TOWARD THE BLUE RIDGE...INCLUDING KROA. KROA IS OBSERVING -RASN MIX AT THIS HOUR. TO THE WEST...UPSLOPE CLOUDS HAVE ALREADY COMMENCED AND UPSLOPE -SHSN CAN BE EXPECTED AFT 06Z AS LOW PRESSURE INTENSIFIES ALONG THE COAST AND THE NORTHWEST FLOW INTENSIFIES. ANY REDUCTIONS TO VISIBILITY WILL BE BRIEF...IF AT ALL...AND HIGH END MVFR AT WORST. BY 12Z...ANY COASTAL LOW ASSOCIATED PRECIPITATION WILL BE MOVING RAPIDLY AWAY FROM THE CWA AND UPSLOPE WILL BE WINDING DOWN FAIRLY QUICKLY. UPSLOPE CLOUDS WILL PERSIST ALONG THE ALLEGHANY FRONT UNTIL EARLY AFTERNOON...THEN SCATTER OUT. FURTHER EAST...EXPECT CLEARING EAST OF THE BLUE RIDGE BY LATE MORNING/EARLY AFTERNOON. AFT LATE AFTERNOON...JUST SCT250. WINDS WILL BE AN INCREASING CONCERN THROUGH THE TAF VALID PERIOD AS THE COASTAL LOW INTENSIFIES. EXPECT N-NNW 7-10KTS INCREASING TO 12-15KTS WITH GUSTS 25-30KTS AFT 08Z THROUGH LATE AFTERNOON FRIDAY. WINDS WILL BECOME MORE NORTHWEST AS THE LOW MOVES FURTHER UP THE COAST. WIND GUSTS HIGHER THAN 40KTS WILL BE POSSIBLE ACROSS THE HIGHER ELEVATIONS OF THE WESTERN MOUNTAINS. WINDS WILL DIMINISH QUICKLY TOWARD SUNSET FRIDAY EVENING...BECOMING NW 3-7KTS BY 00Z. MEDIUM CONFIDENCE IN CIGS AND VSBYS THROUGH THE TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN WIND SPD/DIR THROUGH THE TAF VALID PERIOD. EXTENDED DISCUSSION... 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 KBLF/KLWB AND EAST TOWARD KROA/KLYH. SHOULD SEE SOME MVFR TO AT TIMES IFR CIGS/VSBYS IN WV AND POTENTIALLY TO KBCB/KROA/KLYH MONDAY. LINGERING NW FLOW WILL SUPPORT A CONTINUATION OF MVFR CIGS OVER THE MOUNTAINS MONDAY NIGHT INTO TUESDAY WITH PERIODIC SUB-VFR IN SNOW SHOWERS. EXPECT CIGS EAST OF THE MOUNTAINS TO RETURN TO MAINLY VFR BY MONDAY NIGHT INTO TUESDAY.
-- End Changed Discussion --
&& .HYDROLOGY... AS OF 1130 AM EST THURSDAY... MINOR FLOODING CONTINUES ALONG THE LOWER ROANOKE RIVER AROUND RANDOLPH AND ACROSS THE DAN RIVER BASIN MAINLY FROM DANVILLE DOWNSTREAM TO SOUTH BOSTON. THIS FLOODING IS EXPECTED TO PERSIST INTO FRIDAY. SEE THE LATEST WBCFLSRNK PRODUCT FOR ADDED DETAILS. && .RNK WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
VA...WIND ADVISORY UNTIL 10 AM EST FRIDAY FOR VAZ015. NC...WIND ADVISORY UNTIL 10 AM EST FRIDAY FOR NCZ001-002-018. WV...NONE.
-- End Changed Discussion --
&& $$ SYNOPSIS...JH NEAR TERM...JH SHORT TERM...AMS LONG TERM...AMS AVIATION...JH/RAB/RCS/WP HYDROLOGY...JH

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.