Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 212257 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 657 PM EDT Thu Sep 21 2017 .SYNOPSIS... High pressure will cover the region into the weekend. A cold front will approach the Mid Atlantic region the middle of next week. && .NEAR TERM /THROUGH FRIDAY/... As of 325 PM EDT Thursday... An upper level ridge will remain stationary over the Midwest but will expand in areal coverage to include the south-central Appalachains tonight into Friday. As this ridge expands, it will nudge an upper level trough south into North Carolina tonight. While this trough remains in our vicinity, scattered afternoon showers are possible, mainly across the mountains south of hwy 460 and along western slopes of southeastern West Virginia. These showers will fade with loss of heating this evening. Surface high pressure will build in overnight and remain through the day Friday, decreasing chances and areal coverage of showers Friday afternoon to the North Carolina High Country. Any afternoon showers today and Friday will remain light with less than a tenth of an inch of rainfall. Patchy dense fog is highly likely in mountain valleys for Friday`s morning commute. Area remains under high pressure with very little change in air mass. Temperatures will stay above normal tonight and Friday. Highs Friday will range from the upper 70s to lower 80s west of the Blue Ridge to the mid 80s east. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... As of 142 PM EDT Thursday... Upper ridge will remain just to our northwest through the weekend. The center of the ridge will build northeast and be located over Pennsylvania. At 17Z, Hurricane Maria was located near 20.4 N, and 69.4 W. Maria was moving toward the northwest near 9 mph. Data from an Air Force Reserve reconnaissance aircraft indicate that maximum sustained winds remain near 120 mph with higher gusts. Maria is expected to turn toward the north-northwest Friday, then northward into the weekend. Summerlike conditions will continue into the weekend with 850mb temperatures around plus 16 to plus 18. It will be a real nice weekend for outdoor activities with mild temperatures and comfortable humidity levels. Any isolated shallow convection Friday afternoon will diminish quickly Friday evening with the loss of solar heating. Clear to partly cloudy conditions will result in good radiational cooling. Added some patchy valley fog to ISC grids. Low temperatures Friday night will range from the lower 50s in the mountains to the lower 60s in the Piedmont. Under plenty of sunshine, High temperatures Saturday will vary from the mid 70s in the west to the mid 80s in the east. Mostly clear conditions will continue Saturday night with lows from the the lower 50s in the mountains to the lower 60s in the piedmont. Sunday will feature bright sunshine with high readings from the mid 70s in the mountains to the mid 80s in the piedmont. A good night to keep the window open Sunday night with low values from the lower 50s in the west to the lower 60s in the east. && .LONG TERM /MONDAY THROUGH THURSDAY/... As of 142 PM EDT Wednesday... Models showed good large-scale agreement across CONUS through medium range. The amplified weather pattern continues across the country with an active tropics in the western Atlantic ocean. Model ensembles and consensus from NHC keep Maria east of the mainland. See latest NHC advisory for position and track. The trough across the central U.S. and associated cold front will slowly travel eastward. The strong upper level ridge should hold across our area. Operational models showed the potential for some clouds and possible showers to flirt with our piedmont counties Tuesday afternoon with Maria interacting with coastal front and trough. Hard to tell how far west any moisture really pushes. 12z run looked less impressive with moisture and qpf. Interesting to note the weak shortwave rotating around the upper ridge across southeast portions of forecast area. A cold front will weaken as it moves east and travel through the eastern U.S. Thursday into Friday. Temperatures remain above normal during extended period with lows generally in the upper 50s to around 60 in the west, to lower to mid 60s in the east. High temperatures will range from the mid 70s to around 80 in the west, to lower to mid 80s in the east. The strength of the subsidence with Maria and amounts of cloud cover will greatly impact the temperatures. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... As of 645 PM EDT Thursday... Isolated convection lingers across the southwest sections, mainly southwest of KBCB/KLWB attm. Expect coverage to linger a while longer before dissipating shortly after sunset with loss of heating. May still need to include a VCSH mention at a few western locations pending release trends, otherwise maintaining overall VFR into the evening. Weak upper level trough should push farther south overnight allowing clearing to take place. Just like the last several mornings, patchy dense fog is highly likely in mountain river valleys as supported by fog stability and latest HREF output. Expect this mainly to affect KLWB/KBCB with a period of IFR/LIFR late, although KBLF may drop into sub- VFR after earlier rainfall, as well as KDAN where low level moisture is greater. Any fog/stratus should lift by 14Z/10A making for mainly VFR under light east to northeast winds as high pressure aloft starts to build in. Extended Aviation Discussion... Overall persistence forecast to prevail this weekend into early next week as strong high pressure aloft builds in from the northwest keeping tropical moisture offshore. This should also maintain good flying conditions along with mostly dry weather, outside of any late night/early morning fog from Saturday through Tuesday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...RCS NEAR TERM...RCS SHORT TERM...KK LONG TERM...KK AVIATION...JH/RCS

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