Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 131953 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 353 PM EDT Fri Oct 13 2017 .SYNOPSIS... High pressure will continue to wedge southward along the eastern slopes of the Blue Ridge tonight before eroding by Saturday afternoon. A cold front will arrive during Sunday night into Monday. High pressure should return to provide cooler and drier weather for most of next week. && .NEAR TERM /THROUGH SATURDAY NIGHT/... As of 220 PM EDT Friday... While high pressure wedges southward along the eastern slopes of the Blue Ridge, the resulting cold air damming pattern has kept skies cloudy with patchy drizzle and isolated showers for the afternoon. Temperatures are sluggishly moving upward, and highs will pretty much be in the 60s for most locations. Locations west of the wedge like far southwest Virginia and southeast West Virginia could reach the mid 70s where more sunshine will exist. By tonight, moisture will remain trapped below the subsidence inversion. Expect patchy fog and drizzle to persist through the night into Saturday morning. Lows should mainly be in the 50s. The moisture near the surface should lessen enough to stop the drizzle and fog around 10 AM. Temperatures will struggle to rise at first under cloudy skies, but the wedge should erode after midday. A rapid clearing and warming will take place from west to east. High pressure and considerable ridging aloft will allow high temperatures to jump into the 70s by the late afternoon. The timing of when this jump occurs does make the prediction of the highs a little uncertain as there will be a sharp gradient between sunshine and cloud cover. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
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As of 340 AM EDT Friday... With the wedge out of the area and a strong subtropical ridge building back over the area from the south, increasing southwest flow in advance of an approaching front/upper trough, unseasonably warm temperatures will return to the area. Maximum temperatures Sunday will likely run 15-20 degrees above normal with 80s across much of the forecast area, 70s in the higher elevations. A frontal system will approach the area from the northwest late in the day, possibly moving into the western mountains before sunset. Even with limited moisture, strong forcing should support a narrow line of showers with the front, largely behind the front. While the front appears on all models to be about 6 hours slower than earlier thought, still expecting all areas to see some showers, mainly west of the Blue Ridge overnight and into Monday morning across the Piedmont. QPF will be light and largely less than 1/4 inch. The remainder of the forecast period will trend much more toward typical fall weather as compared to our recent period of extended summer. 850mb temperatures will drop down into the single digits by Tuesday, allowing low temperatures to drop into the 30s in the mountain valleys and 40s across the Piedmont. While this is not particularly unusual for mid-October, it is much cooler than anything we have seen for a while. Locations such as Burkes Garden will likely see a light freeze and frost is a possibility as well, especially with greater moisture in the ground compared to cool spells in October. Will include patchy frost around Burkes Garden on the coldest morning, Tuesday morning. Other than the chance of rain Sunday night/Monday morning, look for abundant sunshine and dry conditions through the period. Temperatures trending from well above normal at the beginning to below normal at the end.
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As of 350 PM EDT Friday... High pressure at the surface and aloft will remain and build over the area through the entire period. Only the GFS hints at a possible upper-low pressure off the coast late in the period. Even if that occurs, the moisture will remain well east of our area. Otherwise, a very dry air mass with strong subsidence will prevail through the period. 850mb temperatures will slowly recover back into the +15C range by the end of the period allowing temperatures, below normal at the beginning, to be near to slightly above normal by the end of the period. Have kept pop values at 0% through the entire period.
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&& .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... As of 200 PM EDT Friday... Poor flying conditions will prevail through this afternoon and tonight. High pressure should continue to wedge southward along the eastern slopes of the Blue Ridge during this timeframe. The easterly component of the wind will keep skies cloudy, and drizzle should persist into the night before subsiding after midnight. While ceilings should improve to MVFR this afternoon, confidence is high that ceilings and visibilities should plummet to IFR/LIFR later tonight with calm winds and moisture trapped near the surface. Fog will be quite prevalent, especially at BCB and LWB. On Saturday morning, conditions will slowly improve with the fog dissipating and the ceilings lifting toward IFR/MVFR. Moisture trapped near the surface should begin to lessen toward the late morning. Expect a rapid change in ceilings from west to east toward the end of this forecast period as the high pressure wedge erodes and conditions return to VFR. Winds should turn around to the southwest by that time. Extended Aviation Discussion... VFR conditions will persist during Saturday afternoon into Sunday. A cold front will arrive by Sunday night to bring a chance of showers with accompanying MVFR/IFR ceilings and visibilities into Monday. The cold front should head offshore on Monday night, which will allow conditions to improve to VFR by Tuesday. High pressure will return to provide good flying weather through the rest of the week. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...PW NEAR TERM...PW SHORT TERM...RAB LONG TERM...RAB AVIATION...PW is the U.S. government's official web portal to all federal, state and local government web resources and services.