Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 282355 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 755 PM EDT TUE OCT 28 2014 .SYNOPSIS... A COLD FRONT WILL MOVE EAST TONIGHT...PASSING THROUGH THE MID ATLANTIC REGION WEDNESDAY. TEMPERATURES RETURN TO MORE SEASONABLE LEVELS AFTER THE PASSAGE OF THE COLD FRONT ON WEDNESDAY. A LINE OF SHOWERS PERHAPS A THUNDERSTORM WILL ACCOMPANY THE FRONTAL PASSAGE...RAIN AMOUNTS OF A QUARTER INCH OR LESS. && .NEAR TERM /THROUGH WEDNESDAY/... AS OF 645 PM EDT TUESDAY... EARLY EVENING UPDATE WILL REFLECT MAINLY A SMALL TWEAK IN THE TIMING OF THE ARRIVAL OF SHOWERS IN THE WEST. LATEST PROJECTIONS BASED UP TRENDS ON REGIONAL RADARS IS FOR THE LEADING EDGE TO BE NEAR A BLUEFIELD TO LEWISBURG WEST VIRGINIA LINE AROUND 800 OR 900 PM. HAVE ALSO ADJUSTED HOURLY TEMPERATURES...DEW POINTS AND WIND SPEED AND DIRECTION BASED UPON THE LATEST OBSERVATIONS AND EXPECTED TRENDS THROUGH THE EVENING HOURS. NO OTHER MAJOR ADJUSTMENTS AT THIS TIME. AS OF 300 PM EDT TUESDAY... RIDGING ALOFT ALONG THE EAST COAST WILL MOVE EAST TONIGHT INTO WEDNESDAY. SFC COLD FRONT LOCATED TO OUR WEST FROM THE GREAT LAKE REGION SOUTHWARD TO TEXAS THIS AFTERNOON WILL MOVE EAST TONIGHT INTO THE WESTERN MOUNTAINS. INITIALLY SHAPED POPS THIS AFTERNOON TOWARDS A BLEND OF THE RNK WRFARW...HRRR AND NAM...THEN TOWARDS THE GFS WEDNESDAY. LEANED TONIGHT LOW TEMPERATURES TOWARDS THE ADJMAV WITH READINGS FROM THE UPPER 40S IN THE MOUNTAINS TO THE MID 50S IN THE PIEDMONT. COLD FRONT IS EXPECTED TO SWEEP RAPIDLY EAST THROUGH THE AREA ON WEDNESDAY...PRECEDED AND ACCOMPANIED BY A BAND OF PRE- AND POST FRONTAL CONVECTION. EXPECT THE HIGHEST THREAT FOR MEASURABLE PRECIPITATION TO OCCUR ACROSS THE WESTERN FLANKS OF THE APPALACHIANS THROUGH EARLY AFTERNOON...WITH AREAS LIKELY TO BECOME INCREASINGLY MORE SCATTERED IN NATURE EAST OF THE BLUE RIDGE AS BAND TRANSITIONS INTO A DOWNSLOPING ENVIRONMENT DURING THE AFTERNOON. UNDER PLENTY OF CLOUDS...HIGH TEMPERATURES WEDNESDAY WILL RANGE FROM THE MID 50S IN THE MOUNTAINS TO THE MID 70S IN THE PIEDMONT. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... AS OF 300 PM EDT TUESDAY... A WEAK COLD FRONT WILL MOVE EAST OF THE AREA WEDNESDAY NIGHT...FOLLOWED BY A CHILLY AREA OF HIGH PRESSURE THURSDAY. COLD AIR BEHIND THIS FRONT WILL KNOCK THURSDAY AFTERNOON HIGHS BACK DOWN BELOW NORMAL BY 5F-10F. THURSDAY AFTERNOON HIGHS WILL RANGE FROM THE MID 50S WEST TO LOWER 60S EAST. A BROAD UPPER LEVEL TROUGH MOVES EAST OF THE MISSISSIPPI VALLEY AND WILL RESIDE OVER THE EAST COAST THURSDAY NIGHT. THIS TROUGH WILL KEEP COOL AIR OVER THE AREA INTO FRIDAY. CLOUDS STREAMING INTO THE REGION WITH THIS TROUGH MAY KEEP TEMPERATURES EAST OF THE BLUE RIDGE FROM DROPPING DOWN INTO THE 30S. SINCE RADIATIONAL COOLING IS NOT IDEAL...FROST POTENTIAL OUTSIDE OF DEEPER MOUNTAIN VALLEYS IS NOT LIKELY. && .LONG TERM /FRIDAY THROUGH TUESDAY/... AS OF 100 PM EDT TUESDAY... LATEST 12Z GFS IS STARTING TO COME INTO AGREEMENT WITH THE PREVIOUS RUN OF THE ECMWF. A DEEP UPPER LEVEL TROUGH DIGS ACROSS THE EASTERN UNITED STATES ON FRIDAY AND SATURDAY. THERE ARE SIGNIFICANT DIFFERENCES IN 850MB TEMPS WITH THE 12Z GFS RUNNING MUCH WARMER THAN PREVIOUS RUNS. FOR NOW KEEPING THINGS MORE ALIGNED WITH WPC AND PREVIOUS MODEL RUNS. RAIN SHOWERS WILL ARRIVE FRIDAY EVENING ACROSS THE WEST AND SPILL OVER TO THE REST OF THE CWA ON SATURDAY. EXPECT A TRANSITION TO SNOW SHOWERS IN THE HIGHER ELEVATIONS OF THE MOUNTAINS EARLY SATURDAY...WITH SCATTERED SNOW SHOWERS CONTINUING IN THE FAVORED UPSLOPE REGIONS OF SOUTHEAST WV INTO EARLY SUNDAY BEFORE TAPERING OFF. DEPENDING ON WHEN THE TRANSITION TO SNOW TAKES PLACE AND HOW MUCH AVAILABLE MOISTURE REMAINS WILL DICTATE IF THERE ARE ANY SNOWFALL ACCUMULATIONS ACROSS THE HIGHER ELEVATIONS. SURFACE TEMPS WILL BE WELL BELOW NORMAL THIS WEEKEND. LOW TEMPS WILL BE IN THE UPPER 20S TO LOWER 30S ACROSS THE MOUNTAINS WITH MID 30S EAST OF THE BLUE RIDGE. HIGH TEMPS ON SATURDAY WILL HOLD IN THE 40S IN MOST LOCATIONS...AND ADDING JUST A FEW DEGREES TO THAT ON SUNDAY. AS HIGH PRESSURE BUILDS IN AND SLOWLY MOVES EAST OF THE AREA EARLY NEXT WEEK...THE FLOW WILL BECOME MORE SOUTHERLY AND TEMPERATURES WILL MODERATE CLOSER TO NORMAL. ALSO THIS WEEKEND...PRESSURE RISES...STRONG COLD AIR ADVECTION AND A 45-55KT CROSS BARRIER LOW LEVEL JET WILL BRING WINDY AND GUSTY CONDITIONS TO THE MOUNTAINS STARTING LATE FRIDAY NIGHT THROUGH SATURDAY BEFORE TAPERING OFF ON SUNDAY AS HIGH PRESSURE TAKES HOLD. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
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AS OF 745 PM EDT TUESDAY... MAIN CONCERN THROUGH THE TAF VALID PERIOD WILL BE INITIAL FRONTAL SYSTEM AND ASSOCIATED -SHRA ACTIVITY. MODELS IN GENERAL CONSENSUS THAT MUCH OF THIS WILL DISSIPATE AS IT MOVES TOWARD AND THROUGH THE CWA OVERNIGHT...BUT SOME -SHRA APPEAR ALMOST CERTAIN IN THE 08Z TIME FRAME EXTREME WEST TO NEARLY 20Z TIME FRAME EXTREME EAST. THERE ARE SOME DISCREPANCIES BETWEEN OBSERVED TIMING AND MODEL TIMING...WITH THE MODELS APPEARING TO BE A FEW HOURS TOO SLOW BASED ON CURRENT TRENDS. AT ANY RATE...CANNOT SEE MUCH IN THE WAY OF PCPN...ESPECIALLY EAST OF THE BLUE RIDGE AT ANY POINT AND LITTLE IN THE WAY OF CIG/VSBY ISSUES ASSOCIATED WITH THE -SHRA. MORE THAN LIKELY...PRECIPITATION EAST OF THE BLUE RIDGE WILL BE SIMPLY SPRINKLES. WEST OF THE BLUE RIDGE...AND ESPECIALLY ACROSS EASTERN WV...THE BIGGER PROBLEM WILL BE THE USUAL DEVELOPMENT OF UPSLOPE MVFR CIGS BEHIND THE FRONT LATE TONIGHT...CONTINUING INTO WED. CLOUDS MAY TEND TO BREAK SOME LATE IN THE DAY AS DRIER AIR WORKS IN FROM THE WEST AS THIS IS NOT THE MOST IDEAL UPSLOPE SITUATION OR EXTENDED PERIOD OF UPSLOPE AS NEXT SYSTEM QUICKLY ON THE HEELS OF THIS ONE. EAST OF THE BLUE RIDGE...CIGS SHOULD BECOME VFR FAIRLY QUICKLY BY EARLY TO MID-AFTERNOON. WINDS SW 5-7KTS OVERNIGHT...BECOMING WNW BEHIND THE FRONT FROM MORNING THROUGH EARLY AFTERNOON AT SPEEDS OF 8-15KTS WITH GUSTS 18-25KTS DEPENDING ON LOCATION. ROA/BCB/BLF WILL HAVE THE STRONGEST WINDS OVERALL. MEDIUM CONFIDENCE IN CIGS THROUGH THE TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN VSBYS THROUGH THE TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN WIND SPD/DIR THROUGH THE TAF VALID PERIOD. EXTENDED AVIATION DISCUSSION... VFR CONDITIONS TO RETURN TO ALL SITES THURSDAY. A DEEP LOW PRESSURE AREA IS THEN SLATED TO DIVE SOUTHWARD INTO THE REGION OVER THE WEEKEND PROVIDING A LONGER PERIOD OF POTENTIALLY IFR-LIFR CIGS AND PRECIPITATION...POTENTIALLY EVEN -SHSN OR -SN BLF/LWB AREA...WITH -RA ELSEWHERE. CONSIDERABLE UNCERTAINTY REGARDING THIS NEXT EVENT AT THIS POINT BECAUSE OF MODEL FLIP-FLOPS FROM RUN-TO- RUN. WINDS WILL ALSO BE QUITE STRONG AS CANADIAN AIR FILTERS INTO THE SYSTEM AND ANY POTENTIAL COASTAL LOW DEVELOPMENT ALSO EVOLVES WITH TIME. OVERALL...VERY POOR AVIATION CONDITIONS EXPECTED FRI- SUN.
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&& .EQUIPMENT... KFCX WSR-88D RADAR HAS BEEN PUT IN STANDBY DUE TO EXTREME SHELTER TEMPERATURES AND BAD AC UNITS. RADAR OPERATION WILL BE INTERMITTENT UNTIL SUCH TIME THE AC UNITS ARE FIXED. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...KK NEAR TERM...DS/KK SHORT TERM...RCS LONG TERM...CF AVIATION...KK/RAB EQUIPMENT...DS

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