Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 140953 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 553 AM EDT Thu Sep 14 2017 .SYNOPSIS... Low pressure over the Ohio Valley will track northeast into Pennsylvania today, then push into New England tonight. High pressure will cover much of the Mid Atlantic region tonight into Friday. A cold front will approach the region from the northwest on Monday and Tuesday. && .NEAR TERM /THROUGH TONIGHT/... As of 300 AM EDT Thursday... The upper level low will weaken and fill as it moves northeast this morning into tonight. The Hiresw-arw-east, HRRR and 3-km NAM develop a band of light showers along A subtle convergence axis across the Piedmont. SPC Mesoscale analysis at 07z showed most unstable CAPE from 500 to 1000 j/kg east of the Blue Ridge. Forecasted LIs placed the better instability to our east this afternoon. A couple of shortwaves on the southern side of the upper low will pivot east across our region. In general, this will result in clouds and scattered showers. High temperatures this afternoon will range from the upper 50s in the northwest mountains to the upper 70s in the piedmont. High pressure will build east across the region tonight into Friday. Added some patchy fog tonight into Friday morning. Low temperatures will vary from the lower 50s in the west to the lower 60s in the east. && .SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/... As of 340 AM EDT Thursday... A summerlike pattern will dominate the region during this period with deep trough developing in the western U.S. and a broad subtropical ridge extending from Texas northeast to New England. A pocket of relatively cool 850mb temps will linger over central Appalachians through much of the period, but moderate a bit each day from around +14C to +18C. Moisture levels will be fairly high through the period with dewpoints hovering in the lower to mid 60s as residual moisture from Irma is left lingering across the eastern U.S.. With no sign of any Canadian or Arctic air mass to scour this out within this time frame, the pseudo-tropical air mass is likely be hanging around for while. Given the synoptic pattern in place, the only mechanism to produce precipitation will be differential heating and perhaps a few very weak upper troughs drifting across the northern part of the CWA. Activity will be diurnally driven and focused mainly across the mountains. Lingering troughing across the northeastern U.S. may help trigger a tad more activity across northern areas as well. Will keep pops in the 20-30 percent range and focus mainly on afternoon/evening. An isolated thunderstorm cannot be ruled out any of these days, but Sat and Sun appear to off the best chance for such. After below normal temperatures at the end of the August and so far much of September to this point, a change to above normal temperatures can be expected through this period. Max temperatures will average 5-10 degrees above normal in the mid 70s west to the lower 80s east, with lows mainly in the 50s to lower 60s. && .LONG TERM /MONDAY 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 the west edge of the 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 Hurricane Jose 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. A weak backdoor also appears in several models drifting southwest into the area Monday, which could slightly enhance shower activity. In addition, should Jose meander closer to the coast as a few models suggest, this would result in 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 little to no impact on our weather, but of course we will continue to monitor its track should later models follow a more westward track toward the Mid-Atlantic. Otherwise, with this pattern we can expect 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 /10Z THURSDAY THROUGH MONDAY/...
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As of 552 AM EDT Thursday... VFR conditions with pockets of MVFR/IFR and isolated LIFR in showers, drizzle and fog this morning. The taf site with the best chance of MVFR/IFR is Bluefield. In general, intervals of unrestricted showers will overspread from west to east this morning. Some pockets of fog are possible this morning. However, high cloudiness has hindered fog development this morning. There may be a few patches of fog this morning mainly in the foothills. Winds will remain mainly south under 6 kts becoming light and 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 could 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. Expect diurnal isolated showers and thunderstorms across the terrain. 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...KK NEAR TERM...KK SHORT TERM...RAB LONG TERM...RAB/SK AVIATION...AL/KK

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