Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 280431 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1131 PM EST Sun Nov 27 2016 .SYNOPSIS... High pressure across the region tonight shifts east and offshore by Monday. A weakening cold front will push a band of showers east into the area later Monday night and Tuesday. Another wave of low pressure will develop along the front across the southeast states by midweek bringing another surge of rainfall to the area Wednesday into Wednesday night. && .NEAR TERM /THROUGH MONDAY/... As of 815 PM EST Sunday... Very dry air remains across the region tonight with dewpoints stuck in the 20s and evening soundings showing PWATS of below two tenths of an inch under a very dry column aloft. This would again support colder lows espcly in the valleys given such dry ground pending just how fast high clouds seen advecting in from the west associated with a weak upper disturbance thicken up. Latest model cloud fields do show a decent canopy by late tonight espcly west as high level moisture works through the mid level ridging but expect somewhat overdone given dry air. Therefore opening up the range of lows to more 20s valleys/outlying areas to closer to 40 along the higher ridges where will get into a bit more return southwest flow under deepening warm advection aloft after midnight. Otherwise beefed up cloud cover some to reflect more of an increasing high cloud flavor overnight with perhaps the far west becoming mostly cloudy under thinning high clouds over the next few hours. Previous discussion as of 230 PM EST Sunday... High pressure will linger over the coastal piedmont of Virginia and North Carolina into Monday morning, then move offshore during the afternoon. While this ridge is in the vicinity, overnight temperatures will cool off into the 20s across mountain valleys and rural areas east of the Blue Ridge. Warm air advecting in aloft will keep ridgetops mild with lows in the lower 30s. High clouds will enter after midnight and become thicker through the day Monday. These clouds will insulate the area and keep temperatures from warming to normal values Monday afternoon. If the atmosphere saturates quickly, a few light showers may move over the North Carolina Highlands by late afternoon. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 310 pm EST Sunday... Not too much change with this forecast period. Exceptions are limited if any thunder threat Tuesday and QPF totals from both events sliding down some, but still overall looks like at least an inch to 2 inches most locations. The rain showers start to shift rapidly up the Blue Ridge and either side into early Tuesday morning and most locations will see rain Tuesday as a strong southwest low level jet sends a plume of moisture from south to north. Winds will also be increasing especially in the higher ridges of WV to NC. The pattern is conducive for wind advisory level winds at least near Burkes Garden to Mt. Rogers and the ridges along the TN/NC border. Coverage should be isolated enough and will hold off on advisory headlines for winds since its mainly Monday evening. Will continue to mention in the HWO. As the low level just pushes into the mid-Atlantic Tuesday morning the winds should start to wind down, though still seeing enough gradient to keep some gusts to 30 mph across the higher ridges into the afternoon while valleys and piedmont will see 10-15 mph with gusts to 20 mph. Expect a potential for a line of heavier showers Tuesday sliding across then looks like a lull in the rain Tuesday evening before next wave and associated front track to the Central Appalachians Wednesday. This next batch seems to have better upper support with 150 kt jet moving across the MS valley into the Great Lakes putting us in the right entrance region Wednesday. Instability still looks best south and east of us Wednesday afternoon so mainly seeing showers, though there could be some thunderstorms southeast of Danville. Will see cooler air work in late Wednesday night with drying taking place. Models differ on how fast moisture moves out so will lean toward slower per collaboration with surrounding offices. As far as temps, still looks mild Tuesday and Wednesday, despite the showers with mainly 60s. Lows will be above normal during the period with 40s Monday night, upper 40s mountains to mid 50s piedmont Tuesday night, and lower 40s mountains to upper 40s piedmont Wednesday night. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 115 pm EST Sunday... Bulk of the showers will be lifting out as we head through Thursday as upper low weakens across the Great Lakes and cold front moves to the coast. Colder air pours in for Friday-Saturday as northwest flow sets up. Appears enough moisture to have slight chance of snow or rain showers Thu night into Friday night for western Greenbrier. Shortwave ridging sets up by Saturday-Sunday and another wave shows up in the area Sunday-Sunday night with small chance of rain/snow showers. Highs Thursday close to normal will drop to 5 to 8 degrees below normal Friday-Sunday with highs in the 40s west to lower 50s east. Low temperatures should be at or slightly below normal through the period. && .AVIATION /04Z MONDAY THROUGH FRIDAY/...
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As of 1130 PM EST Sunday... VFR conditions including light winds to prevail under high pressure overnight with a thickening canopy of high clouds continuing to increase from the west through dawn Monday. Moisture should continue to slowly increase on Monday as the surface high exits offshore allowing the flow to veer more south and southwest by the afternoon. Expect this to moisten things enough to allow the development of some cumulus /strato-cu Monday afternoon with this cloud field beneath sheared mid/high clouds arriving from the west. Some potential for spots near the Blue Ridge to lower to near high end MVFR levels by late Monday but iffy given dry air in place. Otherwise keeping it VFR for now with any lower canopy mainly above 4k feet under lowering mid deck above. Winds should also bump up a bit with speeds increasing to 8-15 kts, with a few gusts to 20-25 kts possible on the ridges as the low level jet picks up under increasing warm advection aloft. Flying conditions will deteriorate Monday night as moisture deepens ahead of a band of showers that should arrive from the west around midnight and continue into early Tuesday morning. Expect this combined with upslope flow along the Blue Ridge to result in conditions lowering to MVFR across most sites during the evening, and possible IFR in low cigs and restricted vsbys in rain/fog espcly mountains after midnight into the early morning hours of Tuesday. Since appears most of the rainfall will be just south and west of the TAF sites Monday evening, will only include a shower mention in the far western locations for now ending 06z/1AM Tuesday. In addition, strong southeast winds with gusts to 30-40+ kts may occur around KBLF Monday night as well as some of the higher ridges along the western slopes through dawn on Tuesday before diminishing. Extended aviation discussion... Initial wave of rainfall will exit later Tuesday with leftover sub-VFR conditions in place before a more significant batch of rain arrives later Tuesday night and continues into Wednesday evening. This likely to keep widespread sub-VFR ceilings and visibilities in place until a cold front passes through the region early Thursday. Drier air behind the front should result in a return to VFR east of the mountains while upslope sub- VFR cigs likely linger across the southeast West Va locations, where rain or snow showers appear possible. Broad northwest flow looks to keep this scenario in place on Friday as well with upslope driven sub-VFR cigs western mountains and mainly VFR to the east.
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As of 800 PM EST Sunday... Humidity slowly recovering across the valleys and east of the Blue Ridge but remains very dry on the ridges where values remain below 30 percent early tonight. However winds are quite light most spots so expect moisture to continue to edge up espcly valleys as temps cool, while may take most of the night for the ridges to recover above 50-60 percent per latest arid evening soundings. Better push of moisture advection to take shape Monday with the low level southerly jet pushing into the area by Monday night. This should help lift dewpoints up enough to alleviate the ongoing low humidity although some of the ridges may still stay below 30 percent until later Monday afternoon. Winds will pick up after dark Monday night and gusts to 40 mph or more over the higher ridges of southern WV to NW NC are likely. At the same time RH will be rising into the 40s and 50s as rain starts to initiate over the mountains Monday night. Still looking for two good rain events, though amounts are trending lower, but still in the 1-2 inch range Tuesday-Wednesday.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...JH/RAB/WP NEAR TERM...JH/RCS SHORT TERM...WP LONG TERM...WP AVIATION...JH/RCS FIRE WEATHER...JH/RAB is the U.S. government's official web portal to all federal, state and local government web resources and services.