Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 301944 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 344 PM EDT SUN AUG 30 2015 .SYNOPSIS... A SERIES OF WEAK UPPER LEVEL DISTURBANCES WILL LIFT NORTH ALONG THE APPALACHIAN CHAIN THIS AFTERNOON INTO EARLY MONDAY...BRINGING A GREATER CHANCE FOR SHOWERS TO THE REGION. UPPER LEVEL HIGH PRESSURE WILL THEN STRENGTHEN AND KEEP US IN A RATHER STAGNANT PATTERN...MAINTAINING A CHANCE FOR AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS THROUGH THE MIDDLE OF THE WEEK. && .NEAR TERM /THROUGH MONDAY/... AS OF 330 PM EDT SUNDAY... SATELLITE IMAGES CONTINUE TO SHOW A SOLID MID/UPPER OVERCAST BUT SURFACE OBS ARE NOT INDICATING MUCH IN THE WAY OF LOWER CLOUDS UNDERNEATH. FOR MOST OF THE AFTERNOON THIS DRIER AIR IN THE LOW LEVELS HAS RESULTED IN RETURNS ON AREA RADARS YIELDING LITTLE MORE THAN SPOTTY SPRINKLES. HOWEVER BY LATE IN THE AFTERNOON SOME ISOLATED DIURNAL CONVECTION HAD BEGUN TO DEVELOP ALONG THE FAR WESTERN SLOPES OF THE APPALACHIANS. BELIEVE ISOLATED/SCATTERED DIURNAL CONVECTION WILL CONTINUE TO FORM ALONG THE FAR WESTERN SLOPES THROUGH EARLY THIS EVENING BEFORE WANING WITH THE LOSS OF HEATING. THEN AN APPROACHING SHORT WAVE WILL BEGIN TO BRING SOME LOW LEVEL MOISTURE INTO THE REGION FROM THE SOUTH AND HELP GENERATE ANOTHER CHANCE OF PRECIPITATION OVERNIGHT MAINLY FOR THE FOOTHILLS AND PIEDMONT OF NC AND INTO SOUTHSIDE VA. MONDAY WILL SEE MOST OF THIS SHORT WAVE ENERGY PULLING OFF TO THE EAST...LEAVING US IN A MOIST AND WEAKLY FORCED ENVIRONMENT THAT SHOULD HELP GENERATE SOME SCATTERED SHOWERS/THUNDERSTORMS DURING THE AFTERNOON. CLOUDS TONIGHT WILL KEEP TEMPERATURES IN THE MIDDLE 60S EAST OF THE BLUE RIDGE WITH UPPER 50S/LOWER 60S TO THE WEST. HIGHS TOMORROW LOOK TO BE IN THE MIDDLE 80S EAST TO UPPER 70S/AROUND 80 WEST. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... AS OF 330 PM EDT SUNDAY... EXPECTING 500 MB RIDGE TO BUILD OVER THE EASTERN UNITED STATES BY TUESDAY NIGHT. MODELS SUGGEST SOME POTENTIAL PIECES OF ENERGY BUT THESE WILL BE WEAK AND DO NOT APPEAR ORGANIZED ENOUGH TO PROVIDE ANY DECENT LIFT FOR THE REGION. BEST PROBABILITY OF PRECIPITATION WILL BE ON WEDNESDAY WHEN A SHORT WAVE CROSSES THE MID ATLANTIC STATES. WHILE THERE MAY BE WEAK SURFACE TROFS IN THE AREA THROUGH WEDNESDAY...OVERALL HIGH PRESSURE REMAINS IN PLACE AND NO CHANGE OF AIRMASS IS EXPECTED. COMBINATION OF MAV AND MOS GUIDANCE WAS REASONABLE FOR HIGHS AND LOWS THIS TIME FRAME. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... AS OF 330 PM EDT SUNDAY... MODELS SHOW A HIGH AMPLITUDE RIDGE OVER THE EASTERN UNITED STATES WITH 500 MB HEIGHTS AROUND 594 DM OVER THE OHIO VALLEY BY SUNDAY. CHALLENGING TO TRACK ANY SUBTLE SHORT WAVES ON THE EAST SIDE OF THE RIDGE THAT MAY IMPACT THE AREA. 850 MB TEMPERATURES GRADUALLY WARM INTO THE +16 TO +20 RANGE BY SUNDAY. BY SATURDAY AND SUNDAY MAXIMUM TEMPERATURES WILL BE 5 TO 10 DEGREES ABOVE NORMAL. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... AS OF 130 PM EDT SUNDAY... WILL GO WITH A LIGHT WIND VFR FORECAST THROUGH THE PERIOD AT ALL SITES...BUT WITH SOME CAVEATS. DIURNAL SHOWERS ARE DEVELOPING AHEAD OF INCREASING MOISTURE AND A SHORT WAVE APPROACHING FROM THE SOUTH. LOW LEVEL DRY AIR IS SLOW TO SATURATE DESPITE GOOD TRANSPORT OF TROPICAL MOISTURE ALOFT FROM THE GULF OF MEXICO. THE RESULT IS ABUNDANT MID/UPPER CLOUDS... SPOTTY SHOWERS/SPRINKLES... AND NO SUB VFR CIGS. BELIEVE THIS WILL CONTINUE TO BE THE CASE INTO EARLY THIS EVENING AS DIURNAL ACTIVITY STARTS TO WANE WITH THE LOSS OF HEATING SO WILL GO WITH VFR CONDITIONS AND VCSH THROUGH THE FIRST PART OF THE TAFS. HOWEVER...THE APPROACHING WAVE LOOKS TO BRING ANOTHER CHANCE OF SHOWERS IN FOR THE OVERNIGHT. MODELS ARE QUITE DIFFERENT IN HANDLING PRECIPITATION POTENTIAL AND ADVECTION OF LOW LEVEL MOISTURE SO DO NOT HAVE A LOT OF CONFIDENCE IN SPECIFIC LOCATION/TIMING OF ANY SHOWERS AND LOWER CIGS. THUS...WILL INDICATE A GRADUAL THICKENING/LOWERING OF VFR CLOUDS AND LEAVE OUT MENTION OF PRECIPITATION FOR NOW. WILL USE VCSH ONLY AT KDAN SINCE THEY WILL BE CLOSEST TO ADVANCING MOISTURE AND INTRODUCE SOME LOWER VFR CIGS FOR KBLF/KBCB/KDAN LATE TONIGHT. BELIEVE THICKENING/LOWERING CLOUDS WILL PREVENT FOG FORMATION SO WILL HEDGE AGAINST MOST GUIDANCE AND NOT INCLUDE ANY FOG AT KBCB OR KLWB. THERE WILL BE MORE DIURNAL SHOWERS AND POSSIBLY SUB VFR CIGS ON MONDAY BUT MOST LIKELY BEYOND THIS TAF PERIOD. 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. && .EQUIPMENT... AS OF 700 AM EDT SUNDAY... 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 SHORT TERM...AMS LONG TERM...AMS AVIATION...MBS/NF EQUIPMENT...PW

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