Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 312340 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 740 PM EDT MON AUG 31 2015 .SYNOPSIS... AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL STRENGTHEN OVER THE APPALACHIANS AND CENTRAL MID ATLANTIC REGION...KEEPING US IN A RATHER STAGNANT PATTERN WITH A CHANCE FOR AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS THROUGH THE MIDDLE OF THE WORKWEEK. && .NEAR TERM /THROUGH TUESDAY/... AS OF 730 PM EDT MONDAY... LOSS OF HEATING WILL RESULT IN SHOWERS DISSIPATING AS NOT SEEING ANY UPPER FORCING AND LOW LVL CONVERGENCE TO KEEP NOTHING MORE THAN A SCT/BKN DECK OF 5-10KFT CLOUDS AROUND. JUST A FEW TWEAKS TO THE FORECAST TO LOWER POPS AND ADJUST SKY/TEMPS A LITTLE BASED ON OBS AND TRENDS. FOG POTENTIAL OVERNIGHT IS MODERATE SINCE SKIES SHOULD CLEAR ENOUGH BUT THINK RIVER VALLEYS WILL BE MORE PRONE THAN ANYONE ELSE. PREVIOUS AFTERNOON DISCUSSION... THE SHORT WAVE WHICH BROUGHT PRECIPITATION TO THE REGION LAST NIGHT HAS PULLED OFF TO OUR EAST...ALLOWING THE UPPER LEVEL RIDGE TO REBUILD AND KEEP US IN A WARM AND MOIST ENVIRONMENT WITH LITTLE IN THE WAY OF DYNAMIC ENERGY TO FOCUS CONVECTIVE DEVELOPMENT. THUS... WIDELY SCATTERED SHOWERS THAT HAVE DEVELOPED THIS AFTERNOON WILL BE FADING BY EARLY TONIGHT WITH THE LOSS OF DAYTIME HEATING. SATELLITE IMAGES SHOW THAT MID AND HIGH CLOUDS WHICH HAVE BEEN OVER THE REGION FOR THE PAST SEVERAL DAYS HAVE DIMINISHED WHICH SHOULD ALLOW FOR GOOD COOLING OVERNIGHT. COMBINED WITH A MOIST AIRMASS IN PLACE WE CAN EXPECT AREAS OF FOG TO DEVELOP TOWARD DAYBREAK...ESPECIALLY IN THE VALLEYS WEST OF THE BLUE RIDGE. LOW TEMPERATURES WILL RANGE FROM THE MIDDLE 60S ACROSS THE PIEDMONT TO AROUND 60 WEST OF THE RIDGE. ANY FOG AND LOW CLOUDS WILL DISSIPATE AFTER DAYBREAK ON TUESDAY AND MORE DIURNAL SHOWERS/POSSIBLY A RUMBLE OF THUNDER WILL DEVELOP DURING THE AFTERNOON...MAINLY FROM THE BLUE RIDGE WEST WHERE OROGRAPHIC EFFECTS CAN INITIATE CONVECTION. EVEN WITH PRECIPITABLE WATER VALUES WELL OVER ONE INCH IT WILL BE HARD TO GENERATE ANY HEAVY DOWNPOURS DUE TO THE LACK OF INSTABILITY AND DYNAMIC SUPPORT. HIGH TEMPERATURES TOMORROW WILL BE NEAR 90 DEGREES EAST OF THE RIDGE AND GENERALLY IN THE LOW/MID 80S WEST. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... AS OF 330 PM EDT MONDAY... MODELS WERE CONSISTENT SHOWING A SHORT WAVE OVER THE OHIO VALLEY TRACKING THROUGH THE MID ATLANTIC STATES ON WEDNESDAY. THIS FEATURES WILL HELP RE-ENFORCE A SURFACE COASTAL TROUGH THAT WILL EXTEND FROM NEW JERSEY TO EASTERN NORTH CAROLINA ON WEDNESDAY NIGHT. BEHIND THIS SHORT WAVE ON WEDNESDAY NIGHT AND THURSDAY 850 WINDS INCREASE TO AROUND 15 KNOTS FROM THE NORTH-NORTHWEST. WITH THE LACK OF ANY FORCING ON THURSDAY...BEST PROBABILITY OF PRECIPITATION WITH RETURN BACK TO THE TYPICAL AFTERNOON AND EVENING TERRAIN ENHANCED LOW CHANCE OF SHOWERS AND ISOLATED THUNDERSTORMS. LITTLE TO NO CHANGE IN THE AIR MASS IS EXPECTED THROUGH THE PERIOD. DEW POINTS WILL BE WELL INTO 60S FOR MOST LOCATIONS WHICH WILL KEEP LOWS MILD. HIGH TEMPERATURES WILL BE AT OR SLIGHTLY ABOVE NORMAL AND...AS ALWAYS...WILL BE HIGHLY DEPENDENT ON THE AMOUNT OF CLOUD COVER. GUIDANCE WAS REASONABLE FOR HIGHS AND LOWS THROUGH THE PERIOD. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... AS OF 330 PM EDT MONDAY... WARMER AIR ASSOCIATED WITH THE UPPER RIDGE EVENTUALLY PROGRESSES EAST INTO THE FORECAST AREA FOR FRIDAY AND SATURDAY. SURFACE HIGH PRESSURE WILL BE CENTERED OVER PENNSYLVANIA AND NEW YORK AND WILL WEDGE DOWN THE APPALACHIANS...PRODUCING EAST TO SOUTHEAST WINDS FROM THE SURFACE THROUGH AT LEAST 850 MB. SO DESPITE THE HIGHER HEIGHTS ALOFT...LOW LEVEL UPSLOPE CLOUD COVER WILL LIMIT HIGH TEMPERATURES OVER THE WEEKEND. ECMWF IS SUGGESTING SOME DRIER LOW LEVEL AIR MAY GET INTO THE EASTERN COUNTY WARNING AREA LATE SUNDAY. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... AS OF 730 PM EDT MONDAY... JUST SOME 4-10KFT CIGS AT THE MOMENT WITH SHOWERS SUBSIDING. THINK THE OVERNIGHT FORECAST TO BE TRICKY IN TERMS OF FOG FORMATION. THE SOUNDINGS SUGGEST FOG AT THE LWB AIRPORT...BUT TEMPO MORE ON THE REST OF THE CWA. NOT TOO CONFIDENT ON THE DENSE FOG WITH RESPECT TO BCB BUT I WILL LEAVE AT LEAST TEMPO GROUP HERE AS THE LOW LVL FLOW MAY SEND SOME GROUND FOG TOWARD THE NORTH END OF THE RUNWAY AROUND 09-11Z. MOST OTHER SITES WILL BE VFR THOUGH SOME FOG OF MVFR VARIETY IS POSSIBLE AT LYH WITH SOME IFR POTENTIAL AT DAN/BLF. FOG/STRATUS WILL LIFT AFTER SUNRISE TUESDAY SO EXPECT VFR CONDITIONS TOWARD THE END OF THE TAF PERIOD WITH THE NEXT ROUND OF DIURNAL CONVECTION HOLDING OFF UNTIL TUESDAY AFTERNOON. HAVE VCSH AT BLF/LWB WITH BKN VFR CIGS AT 4-6KFT. EXTENDED AVIATION DISCUSSION... THE FORECAST AREA WILL REMAIN IN A WEAKLY FORCED SYNOPTIC ENVIRONMENT THROUGH MIDWEEK...WITH CHANCES FOR DIURNAL CONVECTION MAINLY FROM THE BLUE RIDGE WEST...AND SOME MVFR/IFR FOG/STRATUS DEVELOPMENT AT NIGHT...ESPECIALLY AT KBCB AND KLWB. FOR FRIDAY INTO SATURDAY WILL SEE HIGH PRESSURE IN CONTROL THOUGH THE POSITION OF THE HIGH OVER THE MID ATLANTIC MAY SLIDE MORE MVFR CIGS OFF THE ATLANTIC INTO OUR EASTERN TAF LOCATIONS. && .EQUIPMENT... AS OF 400 AM EDT MONDAY... THE DEW POINT READING AT KJFZ...RICHLANDS VA AWOS...IS INCORRECT. AT THIS TIME WE DO NOT KNOW WHEN THIS SENSOR WILL BE REPAIRED. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...MBS NEAR TERM...MBS/WP SHORT TERM...AMS LONG TERM...AMS AVIATION...MBS/NF/WP EQUIPMENT...

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