Area Forecast Discussion
Issued by NWS Blacksburg, VA

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KRNK 241117 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 717 AM EDT TUE MAR 24 2015 .SYNOPSIS... HIGH PRESSURE WILL REMAIN WEDGED ALONG THE EASTERN SLOPES OF THE APPALACHIANS TODAY INTO TONIGHT. A WARM FRONT WILL LIFT SLOWLY NORTH INTO THE AREA BY WEDNESDAY AHEAD OF A STRONG COLD FRONT APPROACHING FROM THE WEST. THE FRONT CROSS THE REGION LATER THURSDAY BRINGING MORE WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS. && .NEAR TERM /THROUGH TONIGHT/... AS OF 245 AM EDT TUESDAY... FORECAST REMAINS RATHER UNCERTAIN OVER THE NEXT 24 HOURS WITH ENHANCED WEDGING TAKING SHAPE BEHIND A PASSING SHORTWAVE TO THE NORTH THIS MORNING AND A WAVY RESIDUAL FRONT TO THE SW LIFTING BACK NORTH TONIGHT. MODELS CONTINUE TO SHOW LITTLE PRECIP WITH THE INITIAL IMPULSE TO THE NORTH THIS MORNING AND BASED ON LATEST RADAR TRENDS BASICALLY REMOVED POPS TO INIT. HOWEVER BEHIND THIS FEATURE WILL SEE A BETTER EASTERLY TRAJECTORY DEVELOP THIS MORNING...MAINLY EAST OF THE BLUE RIDGE...WITH GUIDANCE AGAIN TRYING TO FILL IN WITH LOW CLOUDS WHICH HAVE BEEN QUITE OVERDONE OF LATE. THUS APPEARS MORE PC FLAVOR THIS MORNING WITH AREAS OF STRATO-CU BUT OVERALL DRY. WEAK CONVERGENCE ZONE LOOKS TO BECOME BETTER DEFINED OVER THE WEST THIS AFTERNOON WHERE THE EASTERN WEDGE INTERSECTS RETURN SOUTHERLY FLOW ALONG THE INTERSTATE 77 CORRIDOR. GUIDANCE DIFFERS ON THE DEGREE OF PRECIP THAT DEVELOPS IN THIS AREA JUST NORTH OF THE RESIDUAL BOUNDARY BUT DO HAVE SOME LIFT AND EVEN WEAK INSTABILITY FAR SW WHERE MORE HEATING MAY EXIST. FOR NOW WILL GO WITH A GRADUAL INCREASE IN CHANCE POPS WESTERN THIRD THIS AFTERNOON WITH SOME OF THIS PRECIP PERHAPS SPREADING OUT EAST AROUND SUNSET. OTRW SHOULD BE MORE IN THE WAY OF CLOUDS THIS AFTERNOON WITH ANOTHER TRICKY RANGE IN TEMPS FROM MUCH COOLER HIGHS NE SECTIONS TO PERHAPS QUITE WARM SW. WITH MOS WAY TOO COOL OF LATE...TRENDED WARMER ESPCLY SW WHERE MAY REACH INTO THE 60S AGAIN WHILE KEEPING AREAS EAST OF THE BLUE RIDGE MOSTLY LOW/MID 50S WITH NEAR 60 ACROSS THE SOUTH. BOUNDARY STARTS TO LIFT BACK NORTH TONIGHT AS A WARM FRONT WITH DEEPENING SOUTHERLY FLOW AROUND AND OVER THE LINGERING LOW LEVEL COLD POOL. THIS ALONG WITH FAINT IMPULSES RIDING IN ALOFT JUST NORTH OF THE FRONT MAY ALLOW FOR BETTER COVERAGE OF -RA WITHIN THE WEDGE WITH MORE SHOWERY NATURE SW AS WELL AS THE WESTERN SLOPES. MAY EVEN BE SOME DRIZZLE AROUND BLUE RIDGE EAST LATE PENDING DEGREE OF SATURATION WITHIN THE CAD. THUS KEEPING OVERALL DECENT CHANCE POPS WITH ONLY A FEW POCKETS OF RAIN/SNOW MIX AT THE HIGHEST ELEVATIONS ACROSS THE EXTREME NORTH. SHOULD SEE TEMPS STEADY OUT AFTER MIDNIGHT AND POSSIBLY RISE OVER THE SW GIVEN INCREASING WARM ADVECTION. EXPECT COLDEST READINGS IN THE NORTH/EAST UNDER THE DEEPER COLD POOL WITH LOWS IN THE 30S...WHILE SPOTS FROM ALONG THE BLUE RIDGE WEST ONLY FALL INTO THE 40S FOR THE MOST PART. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 345 AM EDT MONDAY... WEDNESDAY WILL START WITH A CONTINUING WEDGE SITUATION AS HIGH PRESSURE OVER THE NORTHEAST EXTENDS DOWN THE EASTERN SEABOARD. THIS WILL KEEP A SHALLOW LAYER OF COOL AIR AT THE SURFACE EAST OF THE BLUE RIDGE AS A SERIES OF LOW PRESSURE SYSTEMS MOVE THROUGH THE OHIO VALLEY TO OUR WEST. THIS WILL ALLOW FOR WARM AND MOIST AIR TO RUN UP OVER THE WEDGE WITH THE ISENTROPIC LIFT AND SOUTHEASTERLY UPSLOPE WINDS EAST OF THE BLUE RIDGE GENERATING SOME LIGHT PRECIPITATION INTO WEDNESDAY NIGHT. THE WEDGE WILL WEAKEN AND GIVE WAY EARLY WEDNESDAY NIGHT WITH TEMPERATURES SLOWLY RISING AFTER MIDNIGHT. WITH THE WEDGE NO LONGER KEEPING THE BOUNDARY LAYER COOL TEMPERATURES ON THURSDAY WILL RISE INTO THE 60S AND 70S AHEAD OF AN APPROACHING COLD FRONT. THE WARM AND MOIST CONDITIONS WILL CREATE ENOUGH INSTABILITY FOR A CHANCE OF THUNDERSTORMS AHEAD OF THE FRONT THURSDAY AFTERNOON INTO THURSDAY NIGHT. THE MODELS DIFFER A BIT ON TIMING THE FRONTAL PASSAGE AND THE TREND SEEMS TO BE FOR SLOWER MOVEMENT...BUT THE FRONT LOOKS TO BE PUSHING OFF TO OUR EAST BY FRIDAY MORNING. MUCH COLDER AIR WILL MOVE IN BEHIND THE FRONT AND BRING AN EARLY SPRING COLD SNAP WITH TEMPERATURES WELL BELOW NORMAL INTO THE WEEKEND. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... AS OF 245 PM EDT MONDAY... RETURN TO WINTER DURING THIS PERIOD. SIGNIFICANTLY COLDER TEMPERATURES WILL ADVECT INTO THE REGION FROM THE NORTHWEST. 850MB TEMPS WILL PLUNGE TO WELL BELOW ZERO...BOTTOMING OUT AROUND -16C ACROSS THE MOUNTAINS BY 12Z SAT. THE COLD ADVECTION SIGNAL/AND POCKET OF COLD AIR ASSOCIATED WITH THIS SYSTEM...-22C NEAR PIT...APPEARS SIMILAR TO SEVERAL EVENTS WE SAW IN FEBRUARY...SO NEEDLESS TO SAY IT IS GOING TO BE A RUDE AWAKENING COMPARED TO RECENT DAYS. THE WEEKEND SHOULD BE DRY WITH MUCH BELOW NORMAL TEMPERATURES AS THE CANADIAN HIGH SETTLES OVER THE REGION BY EARLY SUN...THEN A SLIGHT REINFORCING SURGE IS NOTED FOR LATE IN THE WEEKEND INTO MONDAY. && .AVIATION /11Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
AS OF 711 AM EDT TUESDAY... OVERALL VFR CONDITIONS UNDER MID DECK CANOPY EXPECTED TO LINGER INTO THIS MORNING EXCEPT ALONG THE SOUTHERN BLUE RIDGE WHERE LOW CLOUDS MAY PRODUCE PERIODS OF MVFR. MODELS SEEM TOO AGGRESSIVE TO PRODUCE SUB- VFR CONDITIONS AND PREFER TO HOLD OFF ON WIDESPREAD LOW CIGS UNTIL LOW LEVEL MOISTURE BECOMES DEEPER THIS AFTERNOON OR EVENING AT THIS POINT. AS AN IMPULSE PASSES BY TO THE NORTH BY MIDDAY...SHOULD SEE THE LOW LEVEL WEDGE DEEPEN IN ITS WAKE THIS AFTERNOON WITH MOISTURE INCREASING BETWEEN ONSHORE FLOW AND A WARM FRONT ALOFT TO THE SW. THIS COMBINATION LOOKS TO BRING CIGS DOWN FROM WEST TO EAST ESPCLY IF MORE RAIN/SHOWERS DEVELOP ALONG THE RESIDUAL FRONT TO THE SOUTH/WEST AND SPREAD BACK INTO THE REGION. GIVEN MODEL UNCERTAINTY AND RECENT WET BIAS...KEPT VFR GOING A BIT LONGER INTO EARLY THIS AFTERNOON BEFORE LOWERING TO MVFR MOUNTAINS LATER TODAY AND MOST LOCATIONS EXCLUDING KDAN THIS EVENING. SOME LIGHT RAIN OR SHOWERS ALSO POSSIBLE ESPCLY KBCB/ROA AND POINTS WESTWARD LATER THIS AFTERNOON BUT WITH LIMITED VSBY REDUCTION FOR NOW. A SECOND DISTURBANCE IS PROGGED TO CROSS THE AREA TONIGHT. MOISTURE PROFILES ARE FORECAST TO BE DEEPER SUPPORTING LOWER CLOUD BASES AND POTENTIAL FOR LIGHT RAIN BUT WITH RESTRICTED VISIBILITIES. THINK ALL TERMINALS ALONG AND NORTH OF HIGHWAY 460 WILL TREND INTO THE MVFR CATEGORY WITH POTENTIAL FOR IFR CONDITIONS IN THE MOUNTAINS INCLUDING KLYH OVERNIGHT. SOUTHWEST WINDS ARE EXPECTED TO INCREASE AHEAD OF AN APPROACHING COLD FRONT LATER WEDNESDAY...ALLOWING FOR IMPROVEMENT TO VFR WEDNESDAY NIGHT INTO THURSDAY. THIS COLD FRONT IS EXPECTED TO MOVE INTO OUR AREA THURSDAY EVENING...WITH SHOWERS AND THE POTENTIAL FOR A FEW THUNDERSTORMS. DO SEE SOME POTENTIAL FOR FRONTAL SLOWDOWN AHEAD OF ANOTHER DISTURBANCE APPROACHING FROM THE WEST FRIDAY... RESULTING IN LINGERING RAIN/MOUNTAIN SNOW SHOWERS AND SUB VFR CEILINGS OVER THE WEST. VFR RETURNS TO AREAS EAST OF THE BLUE RIDGE SATURDAY WHILE UPSLOPE DRIVEN MVFR LOW CLOUDS LIKELY PERSIST MOUNTAINS UNDER CONTINUED GUSTY NW WINDS.
-- End Changed Discussion --
&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/NF NEAR TERM...JH SHORT TERM...MBS LONG TERM...AMS/MBS/RAB AVIATION...JH/PM

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