Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 211736 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 136 PM EDT Thu Sep 21 2017 .SYNOPSIS... High pressure will cover the region today through Saturday. A cold front will approach the Mid Atlantic region the middle of next week. && .NEAR TERM /THROUGH TONIGHT/...
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As of 125 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 this afternoon 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 and south of hwy 460. These showers will fade with loss of heating this evening. Surface high pressure will build in overnight, 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 little to no change in air mass. Temperatures will stay above normal today and tonight.
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&& .SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/... As of 310 AM EDT Thursday... Anomalous 500 mb ridge over or just northwest of the western Appalachians projects to be the main driver of sensible weather conditions through the weekend. Synoptically quiescent conditions should be the rule for our area, with the focus for more active weather staying away from us - either in the intermountain west/northern Plains or along the Atlantic seaboard to about 70 degrees W longitude related to Jose and Maria. Summerlike warmth with good diurnal ranges looks to continue in this pattern, with at least mostly sunny skies and +16 to +18C 850 mb temperatures pushing high temps each day into the upper 70s to mid/upper 80s. Largely clear skies should permit good radiational cooling and lows in the mid/upper 50s to mid 60s. Precipitation chances are generally nil through the weekend, with the best chance being Friday along the NC high country and the southern Blue Ridge in conjunction with daytime heating and some weak/subtle easterly convergence. May see some showers or thunderstorms in this general area Friday, though convective development may be stunted to an extent by marginal CAPE values around 1000 J/kg and dry mid-level air. PWAT values then plummet to values under 1" by the weekend, and despite otherwise steep daytime PBL lapse rates, dearth of columnar moisture may keep even fair weather cumulus to a minimum. All in all, looking at a real nice weekend for outdoor activities with mild temperatures but with rather comfortable humidity levels. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... As of 310 PM EDT Wednesday... We will remain in an amplified pattern across the country with two storms in the western Atlantic to watch. Will see Jose continue to weaken this period. Will see Hurricane Maria head north to off the NC coast, with question remaining on how close and if Maria comes ashore. Model ensembles and consensus from NHC keep it east of the mainland. Meanwhile, the central U.S. will be active with deep upper trough and slow moving front. Will see this translate to upper ridge across our area but expect potential for some clouds and possible showers to flirt with our piedmont counties Tuesday per leftovers of Jose interacting with coastal front/trough. However, threat of any appreciable rain looks low for the next 7 days and even beyond the front washes out as it moves into the eastern U.S. by Thu-Fri next week. Temps remain above normal during this time frame with lows in the upper 50s to around 60 west, to lower to mid 60s east. Highs ranging from the mid 70s to around 80 west, to lower to mid 80s east, with some upper 80s not out of the question, especially if Maria stays strong and we get on the western subsidence side of the system without any mid/high clouds Tuesday. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/...
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As of 130 PM EDT Thursday... A departing upper level trough sinking south into North Carolina may generate scattered showers and an isolated thunderstorms this afternoon. Areal coverage will be too limited to add to the TAFS at this time and the best probability of precipitation will be south and west of KROA, KBCB, and KBLF. Just like the last several mornings, patchy dense fog is highly likely in mountain river valleys (KLWB/KBCB). Fog should lift by 14Z/10A. Extended Aviation Discussion... Overall persistence forecast to prevail for the rest of the week. Strengthening high pressure remaining in place between exiting Jose offshore and a weak cold front approaching from the west. This should maintain good flying weather outside of isolated diurnal showers and thunderstorms. Dry weather is expected Friday through Monday.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS NEAR TERM...RCS SHORT TERM...KK LONG TERM...KK AVIATION...RCS

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