Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 140545 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 145 AM EDT Thu Sep 14 2017 .SYNOPSIS... Low pressure will track into Pennsylvania by Thursday morning. High pressure will cover much of the Mid Atlantic region for Thursday night and Friday. A cold front will approach the region from the northwest on Monday and Tuesday. && .NEAR TERM /THROUGH TODAY/... As of 1130 PM EDT Wednesday... Keeping current forecast similar to previous with isolated/scattered showers in two distinct areas early per radar depiction. One over southside VA into the NC piedmont, and the other over WV into the Alleghany, south toward the NC mountains. Overall light amounts expected. Clouds will be plentiful overnight which should limit fog, though some of the higher-res models show some clearing after 5am, and if this occurs, fog will become dense in spots, but overall confidence is low in this occurring, per upstream satellite showing clouds stretched all the way back into northern Alabama. Previous discussion from early evening... Mid-level height falls associated with weakening/filling upper low over northeast KY continue to overspread the region. Regional radar and METARs show intervals of showers still to our west and southwest in eastern KY into eastern TN. Finer- resolution guidance has slowed a bit on the eastern advancement of the showers into areas west of the Blue Ridge, opting for a mid to late evening start time. HRRR and 3-km NAM also are keying on development of steady light showers along subtle convergence axis across the Southside of VA into the north- central NC Piedmont after midnight. Outside of these areas, look for at least an increase in clouds areawide - though a slower increase in our northeastern VA counties. No changes to lows attm - in the middle 50s to lower/mid 60s. Previous near-term discussion issued at 215 PM Wednesday follows... Guidance brings the filling upper low out of the Tennessee Valley tonight, with the short wave on the southern and eastern side of the low reaching southwest Virginia, Northwest North Carolina, and southeast West Virginia close to 00Z/8PM. Best probability of precipitation remains on western slopes of the Appalachians. Will also be adding a chance of rain tonight into the piedmont of Virginia and North Carolina, which is another area that will have moisture increasing from the surface through mid levels. Several of the ensembles showing only a small rise in temperatures on Thursday. Relatively coolest 850MB temperatures,around +10, will be over the Ohio Valley 12Z/8AM Thursday morning. && .SHORT TERM /TONIGHT THROUGH SATURDAY/... As of 215 PM EDT Wednesday... Expecting high pressure and lighter winds on Thursday night and Friday. Temperatures rebound on Friday but cloud cover will be the determining factor reguarding the eventual highs for the day. Models show lingering moisture at low levels so not looking for a lot of sun. A broad upper ridge builds through the end of the week. On Saturday a weak wave moves will cross the Mid Atlantic area. Will keep chance of precipitation in the forecast for this time frame. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... As of 130 pm EDT Wednesday... Late this weekend through mid next week is expected to be dominated by an upper ridge with the axis on west edge of Appalachians. This is within a fairly stationary large scale pattern with a deeper trough remaining over NW U.S., which will help with the extreme fire situation there, and what is likely to be Tropical Storm Jose well off the mid-Atlantic and New England coasts. The ridge just to our west and tropical system in the western Atlantic will keep a light north or northeasterly flow over the Appalachian region, and models suggest just enough low level convergence for a very small chance of isolated showers each day, most likely in afternoon with some heating and not lasting long. Not a great deal of confidence this far out in those overall precip chances but it is likely that most areas on any one of these days will remain dry. Also, should Jose meander closer to the coast, which only a few out of dozens of model ensemble members suggest is even possible, this could do two things: 1) create more subsidence over our region to actually reduce any precip chances, and 2) increase the northerly breezes in the Piedmont. At this point there is fairly high confidence Jose will remain far enough offshore to have essentially no impact on our weather, but of course we will continue to monitor its track. Otherwise, with this patterns expect seasonable to even slightly above normal temperatures through this period, with highs in the mid to upper 70s mountains and lower 80s Piedmont, and lows in the 50s to lower 60s. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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As of 145 AM EDT Thursday... VFR conditions with pockets of MVFR in showers and fog. The taf sites with the best chance of MVFR are Bluefield and Lewisburg. In general, intervals of unrestricted showers will overspread from west to east this morning. Some pockets of fog are possible this morning. However, Lower-confidence fog forecast as won`t radiate quite as well though did indicate a temporary MVFR mist after 09z as moisture levels rise. Winds mainly south under 6 kts becoming light/variable. Upper low and associated cold pool aloft continues to overspread the TAFs into this afternoon . Expect a continuation of MVFR/VFR ceilings along with spotty/hit-or-miss light showers. Really couldn`t discount chance of showers pretty much at any TAF but any showers unlikely to yield visibility restrictions. Improvement in ceilings likely to be quite slow today. Winds variable initially but should trend light southwest around 5 kts this afternoon. Medium confidence in ceilings,visibilities and winds during the taf period. Extended Aviation Discussion... Scattered showers may continue into Friday. Some MVFR showers are possible on Saturday with another short wave. The chance of precipitation remains low for Sunday and Monday. Aside from valley fog in the early morning, conditions overall should be VFR. Tuesday may feature some isolated MVFR showers in the west.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS/WP NEAR TERM...AL/AMS/WP SHORT TERM...AMS LONG TERM...SK AVIATION...AL/KK

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