Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 220616 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 216 AM EDT WED APR 22 2015 .SYNOPSIS... HIGH PRESSURE WILL STAY SOUTH OF US TONIGHT WHILE A FRONT MOVES IN FROM THE NORTHWEST. THIS FRONT WILL CROSS THE REGION WEDNESDAY AND SHIFT OFFSHORE BY THURSDAY MORNING RESULTING IN BREEZY CONDITIONS WEDNESDAY INTO THURSDAY AHEAD AND BEHIND THE FRONT. BY FRIDAY...HIGH PRESSURE WILL BE SITUATED FROM THE WESTERN GREAT LAKES...SOUTH INTO THE SOUTHERN APPALACHIANS. && .NEAR TERM /THROUGH TODAY/... AS OF 200 AM EDT WEDNESDAY... SOME TEMPERATURE ADJUSTMENTS WERE NEEDED AS INCREASING CLOUD COVER ACROSS THE WESTERN MOUNTAINS RESULTING IN TEMPS HOLDING CLOSE TO 50...WHILE PIEDMONT AREAS WELL DOWN INTO THE 40S. CLOUDS WILL BE INCREASING FROM THE WEST...BUT REMAIN MOSTLY CLEAR EAST OF THE BLUE RIDGE THROUGH DAYBREAK. HAVE ADJUSTED WESTERN AREAS UP IN TEMPERATURE...BUT KEPT EASTERN AREAS NEAR OR EVEN A DEGREE OR TWO BELOW EARLIER ADVERTISED MIN TEMPS. MIN TEMPS COULD WELL BE REALIZED BY 10Z IN WESTERN AREAS...THEN INCREASING WITH WEST WINDS AND CLOUD COVER. OTHER FORECAST ELEMENTS APPEAR TO BE ON TRACK. AS OF 912 PM EDT TUESDAY... EVENING SOUNDINGS AND SURFACE OBS SHOW VERY DRY AIR LINGERING OVER THE REGION THIS EVENING AHEAD OF A WEAK TROUGH JUST WEST OF THE MOUNTAINS AND THE NEXT COLD FRONT IN THE UPPER MIDWEST. INITIAL BAND OF BROKEN CLOUDS NOW CROSSING THE OHIO RIVER MAY BRING A FEW SPRINKLES TO THE WESTERN SLOPES BEFORE FADING AFTER MIDNIGHT GIVEN DEEP WESTERLY FLOW AND A LINGERING WELL MIXED DRY LAYER JUST OFF THE SURFACE. APPEARS NEXT ROUND OF POTENTIAL SHOWERS WONT ARRIVE UNTIL WED MORNING AHEAD OF THE FRONT SO TRIMMING BACK WESTERN POPS A BIT MORE OVERNIGHT SIMILAR TO THE LATEST HRRR TRENDS. OTRW MOSTLY CLEAR TO INIT THEN BECOMING PARTLY TO MOSTLY CLOUDY AT TIMES FAR WEST AND PC ELSW LATE. TEMPS TO ZOOM DOWN IN THE WESTERN VALLEYS EARLY ON AS WINDS FADE WITH SOME SPOTS FALLING INTO THE 30S BEFORE BUMPING UP WITH CLOUDS LATER ON. LATEST LAV MOS SLOW TO DROP VALUES BUT LIKELY TOO WARM EXCEPT ON THE RIDGES GIVEN SUCH LOW DEWPOINTS THIS EVENING SO ONLY MAKING SLIGHT TWEAKS IN SPOTS. PREVIOUS DISCUSSION AS OF 300 PM EDT TUESDAY... VERY DRY AT THE MOMENT WITH FEW TO SCATTERED CU. UPSTREAM...SFC FRONT WORKING INTO THE MIDWEST WILL BE OUR NEXT WEATHER MAKER...AND WIND WILL BE THE MAIN CULPRIT. THIS EVENING INTO THE OVERNIGHT THE SKIES WILL BE STAY CLEAR TO PARTLY CLOUDY THEN SHOULD SEE MORE CLOUDS ARRIVE AFTER MIDNIGHT INTO THE MTNS. SLOWED DOWN ONSET OF POPS GIVEN DRY LOW LVLS...THOUGH WILL SEE A FEW SHOWERS MAKE IT TO GREENBRIER TO THE MTN EMPIRE AROUND DAWN. TEMPS WILL BE DROPPING QUICKER THIS EVENING ONCE THE WINDS SETTLE DOWN SOME. ALOFT HOWEVER...WINDS SHOULD STAY UP KEEPING HIGHER TERRAIN MIXED. KEEPING THE WRN SLOPES IN THE 40S FOR LOWS...WHILE VALLEYS IN THE MTNS AND FOOTHILLS FALL INTO THE UPPER 30S. NOT EXPECTING ANY FROST/FREEZE CONCERNS. FOR WEDNESDAY....THE LOW LEVEL JET SETS UP FROM KENTUCKY TO MARYLAND DURING THE MORNING/EARLY AFTERNOON. SFC FRONT WILL MAKE IT INTO THE WV MTNS BY MIDDAY THEN SLOWLY DROP SE INTO THE PIEDMONT BY EVENING. STABILITY SEEMS MARGINAL BUT WIND ENERGY WITH SHOWERS ARE A CONCERN FOR GUSTY SHOWERS AND POSSIBLE THUNDERSTORMS. SPC HAS MARGINAL RISK EAST OF ROANOKE TOWARD LYH/RIC...FOR DAMAGING WINDS. ATTM...WILL HAVE GUSTY WIND WORDING IN THE THUNDERSTORMS FOR WED AFTERNOON. THE WAA PATTERN AND WINDS ALOFT FAVOR SOME OF THE HIGHER RIDGES FROM HSP TO BOONE TO GET CLOSE TO ADVISORY LEVELS OF 46 MPH FOR GUSTS. OVERALL..THE WINDS WILL STAY BELOW THIS AS WE USUALLY NEED A 50-55 KT 8H JET AND THE MODELS KEEP THE BEST WINDS SITUATED NORTH OF US. WEDNESDAY WILL NOT BE WASHOUT AND WSW FLOW AT TIMES SHOULD LIMIT STORM/SHOWER DEVELOPMENT EAST OF THE MTNS...BUT ENOUGH BACKING SHOULD ALLOW FOR OVERALL LOW LVL CONVERGENCE NOT TO KEEP IT COMPLETELY DRY. GOING TOWARD DUSK...THE SHOWERS WILL FADE IN COVERAGE. WEDNESDAY WILL BE MILD/SEASONAL WITH HIGHS FROM THE UPPER 50S SE WV TO LOWER TO MID 70 SOUTHEAST. && .SHORT TERM /TONIGHT THROUGH FRIDAY/... AS OF 230 PM EDT TUESDAY... A WEAK COLD FRONT WILL SLIDE EAST OF THE AREA WEDNESDAY EVENING. ANY LINGERING SHOWERS WILL DISSIPATE BY 10P WITH LOSE OF HEATING AND INCREASE DRIER AIR ADVECTION. THE 12Z GFS IS IN AGREEMENT WITH THIS SCENARIO...SO THE FORECAST IS MORE HEAVILY WEIGHTED TO THAT SOLUTION. HIGH PRESSURE CONTINUES TO BUILD EAST INTO THE AREA THURSDAY...HOWEVER A MODEST PRESSURE GRADIENT WILL KEEP BREEZY AND GUSTY NORTHWEST WINDS OVER THE AREA THROUGH THE DAY. THE CENTER OF THE HIGH DRIFTS OVER THE AREA THURSDAY NIGHT WITH CALMING WINDS AND COOLER THAN NORMAL TEMPERATURES INTO THE DAY FRIDAY. TEMPERATURES THURSDAY AND FRIDAY WILL RANGE FROM THE UPPER 50S TO LOWER 60S ACROSS THE MOUNTAINS TO MID TO UPPER 60S EAST. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... AS OF 240 PM EDT TUESDAY... A WARM FRONT WILL ENTER THE REGION FROM THE SOUTHWEST FRIDAY NIGHT BRINGING AN INCREASE IN CLOUDS AND THE CHANCE FOR RAIN SATURDAY MORNING. RAIN CHANCES INCREASE DURING SATURDAY AFTERNOON AS ISENTROPIC LIFT INCREASES WITH WARM MOIST AIR OVERRUNNING COOLER SURFACE AIR. A SURFACE WAVE IS EXPECTED TO TRACK OVER THE TENNESSEE VALLEY SATURDAY...THEN ACROSS THE CAROLINAS SUNDAY. THIS WAVE WILL CONTINUE THE CHANCE FOR RAIN IN THE AREA THROUGH SUNDAY MORNING...THEN A BACK DOOR COLD FRONT BRINGS COOLER DRIER AIR INTO THE REGION FOR SUNDAY AFTERNOON INTO MONDAY. A STRONGER SURFACE WAVE TRACKS ACROSS THE TENNESSEE VALLEY TO THE CAROLINA MONDAY NIGHT INTO TUESDAY. THIS WAVE WILL HAVE MORE MOISTURE AND DYNAMICS TO BRING SOME HEAVY RAIN AND STRONG STORMS TO THE REGION. TEMPERATURES THROUGH THE PERIOD WILL REMAIN COOLER THAN NORMAL WITH UPPER 50S TO LOWER 60S ACROSS THE MOUNTAINS TO MID TO UPPER 60S EAST. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... AS OF 200 AM EDT WEDNESDAY... BROAD UPPER TROUGH CENTERED OVER THE GREAT LAKES WILL CONTINUE TO DOMINATE THE WEATHER ACROSS THE EASTERN U.S. THROUGH THE PERIOD. MAIN FOCUS TODAY WILL BE ON A STRONG SHORT WAVE PROGGED TO TRACK THROUGH THE BASE OF THE TROUGH ACROSS OUR REGION DURING THE AFTERNOON. ALTHOUGH THE SFC AIR MASS IS VERY DRY IN THE WAKE OF THE SUN-MON SYSTEM...STRONG DYNAMICS ASSOCIATED WITH THIS SHORT WAVE WILL OVERCOME THE SFC DRYNESS AND RESULT IN ELEVATED CONVECTION FROM MID-MORNING INTO THE AFTERNOON. WITH A 50-60KT WESTERLY LLJ ASSOCIATED WITH THE SHORT WAVE...ANY CONVECTION COULD BRING THESE STRONG WINDS DOWN TO THE SFC. WINDS WILL BE AN ISSUE EVEN OUTSIDE CONVECTION...WITH A STRONG GRADIENT DEVELOPING QUICKLY THIS MORNING. MANY LOCATIONS WILL SEE SW-W WINDS 15-20KTS WITH GUSTS 25-35KTS IN THE 15Z-23Z TIME FRAME...VEERING MORE TO THE WNW BY 00Z BEHIND THE SHORT WAVE AND DECREASING INTO THE 10-15KTS WITH GUSTS 20-25KTS. CIGS SHOULD BOTTOM OUT MOSTLY IN THE 040-050 RANGE...EXCEPT IN UPSLOPE AREAS BLF-LWB WHERE CIGS MAY DROP INTO THE 030-035 RANGE DURING THE AFTERNOON IN ASSOCIATION WITH SHRA ACTIVITY. VSBYS COULD BRIEFLY BECOME MVFR IN HEAVIER SHOWERS MAINLY WESTERN MOUNTAINS. SPC HAS THE ENTIRE AREA EAST OF THE ALLEGHANY FRONT OUTLOOKED FOR MARGINAL SEVERE TODAY...WITH THE MAIN CONCERNS STRONG WINDS GUSTS GIVEN THE VERY STRONG WINDS ALOFT AND PENNY TO QUARTER- SIZED HAIL GIVEN THE VERY COLD TEMPERATURES ALOFT. FOR NOW...HAVE ONLY INTRODUCED TSRA FOR LYH...BUT CONDITIONS MAY WARRANT ADDING THIS FOR BCB/ROA/DAN WITH LATER TAF ISSUANCES. MEDIUM TO HIGH CONFIDENCE IN CIGS AND VSBYS THROUGH THE TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN WIND SPD/DIR THROUGH THE TAF VALID PERIOD. MEDIUM CONFIDENCE IN THUNDER POTENTIAL LATE MORNING THROUGH AFTERNOON. EXTENDED AVIATION DISCUSSION... FRONT WILL EXIT BY WEDNESDAY NIGHT WITH HIGH PRESSURE BUILDING INTO THE REGION FROM THE WEST THU-FRI. SOME GRADIENT REMAINS BETWEEN DEPARTING FRONT AND HIGH TO THE WEST THURSDAY AND POSSIBLY FRIDAY...SO GUSTY WINDS WILL REMAIN MAINLY DURING THE DAYTIME. OVERRUNNING CLOUDS WORK INTO THE AREA FRIDAY AHEAD OF A WARM FRONT. BY SATURDAY...ENOUGH MOISTURE TO ALLOW FOR SHOWERS AND MVFR WITH BEST FORCING ACROSS THE CAROLINAS. THIS WILL BE POSSIBLE INTO SUNDAY MORNING BEFORE THE SYSTEM EXITS AND SOME IMPROVEMENT IN CIGS STARTS TO OCCUR LATER SUNDAY. && .FIRE WEATHER... AS OF 330 PM EDT TUESDAY... WET FUELS WILL DRY OUT AS WE HEAD INTO WEDNESDAY. A FRONT WILL APPROACH WEDNESDAY WITH GOOD MIXING OUT AHEAD OF IT. GUSTY WINDS IN THE 25 TO 35 MPH RANGE WILL OCCUR AT TIMES OVER THE PIEDMONT WHERE MIN RH SINKS TO 30 PERCENT DURING THE AFTERNOON. AT THIS TIME A FEW SHOWERS AND STORMS COULD BE OCCURRING SO FIRE DANGER FOR NOW IS LOW TO MODERATE AS 1 AND 10 HOUR FUELS HAVE EITHER GREENED UP OR ARE GREENING UP. ISSUES WOULD BE WITH ANY LOOSE LEAF LITTER THAT CAN DRY OUT ENOUGH...THOUGH SOILS THEMSELVES STAY MOIST. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WP NEAR TERM...JH/RAB/WP SHORT TERM...RCS LONG TERM...RCS AVIATION...RAB FIRE WEATHER...WP

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