Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 130441 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1141 PM EST Thu Jan 12 2017 .SYNOPSIS... A cold front will approach the region from the west late tonight into early Friday, then stall across northern North Carolina Saturday before returning north as a warm front late Saturday night. This front will then oscillate north and south across the region into early next week keeping an unsettled and wet weather pattern in place. && .NEAR TERM /THROUGH FRIDAY/...
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As of 945 PM EST Thursday... Showers associated with the slowly approaching front are taking just a bit longer than forecast to reach the far northwest portion of the forecast area. Have delayed arrival by approximately two hours. After arrival, the general distribution of precipitation focused along the western quarter of the forecast area is still expected through the remainder of the night into early Friday morning. Have made some small tweaks to overnight low temperatures. There is quite a bit of variation across the region between areas with gusty winds and those without. Boone recently has been reporting calm winds and temperatures in the low to mid 40s. Have lowered forecast lows in this area to similar readings. Temperatures the remainder of the night will depend upon how much wind the area receives. Even a small breeze could easily ramp temperatures back to around 50 degrees. As of 640 PM EST Thursday... A slow moving cold front continues to make headway towards the forecast region through the Ohio Valley. We are still anticipating arrival in the western sections of the area around or a little before midnight. The associated showers are not expected to make much progress eastward into the forecast area. The eastern extent is expected to be near a Alleghany, VA to Radford, Va to Boone, NC line by daybreak Friday. Have adjusted hourly temperatures, dew points and winds to reflect the latest observations and expected trends through the evening. As of 230 PM EST Thursday... A quasi-stationary cold front over the Ohio Valley will track to the southeast through the period. This front is expected to move and stall across southeastern West Virginia Friday morning. Farther north, this front is expected to move east of the Appalachian Mountains then slides south across the central Virginia Piedmont in the afternoon, possibly into northern North Carolina by the evening. With the front mostly staying out of the forecast area for the next 24 hours, we will continue to see warmer than normal temperatures. tonight and tomorrow. Overnight temperatures will run 3F to 8F warmer than normal with readings in the mid 40s to lower 50s. Friday`s highs will vary from the upper 40s to lower 50s near the front in southeastern West Virginia to the mid to upper 60s across Southside Virginia. These temperatures are 15F to 20F warmer than normal. Precipitation chances will be limited to the vicinity of the frontal boundary with a few stray showers coming across the mountains in westerly flow. The best chances for showers will be along western slopes of southeastern West Virginia tonight through early Friday morning and southwestern Virginia Friday morning to early afternoon. No rain is expect to fall east of the Blue Ridge. Since the region is expecting warmer than normal temperatures through the period, all precipitation will fall as rain. Breezy conditions this afternoon are in response to a wave of low pressure tracking along the front in the Ohio Valley. These winds will decrease starting this evening evening as this wave tracks northeast into New England this evening.
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&& .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... As OF 243 PM EST Thursday... Lift increases over the top of the wedge Friday night. This brings an increasing chance for precipitation, and as the cold wedge continues to build some freezing rain and possibly sleet is expected to develop from the mountains of SE WV north of I-64 east to the Blue Ridge north of Roanoke. Still looks like a low qpf event, so no more than advisory impact will occur and mainly on the east/northeast sides of slopes into valleys. Will continue to highlight in the HWO. Will see cold air slowly erode Saturday with all places seeing plain rain, though higher percentage will be west of the Blue Ridge. Another weak wave moves across the southern Appalachians Saturday night with weak wedge, so rainfall still around for the west with less chance east. Another strong high will wedge in for Sunday and Sunday night. At this time it looks like just a chance of rain for everyone but temperatures trends will be monitored closely. && .LONG TERM /MONDAY THROUGH THURSDAY/... As OF 220 PM EST Thursday... Wavy front across the area Monday morning lifts north into New York Tuesday as strong upper low moving across the central U.S. amplifies ridge downstream. Will see less threat of showers Monday but still looks cloudier, though some sunshine should peek out. Warm air will stick around into midweek with models slowing the front moving into the CWA until late Thursday into Friday. Decided to keep pops low Tuesday with mainly dry in the foothills/piedmont then chance pops start Wednesday with better threat Thursday. Highs running about 10- 20 degrees above normal Tue-Thu. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/...
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As of 1130 PM EST Thursday... Deeper moisture with its associated lower cloud canopy continues to affect the far western sites tonight but having a hard time crossing the mountains given the deep westerly flow in place. This will continue to support MVFR cigs at KBLF/KLWB overnight and perhaps KBCB/KROA during the early morning hours. Narrow band of showers along the front may also work into the southeast West Va sites as well but given going diminishing trends may only see spotty light showers or sprinkles at best overnight, so only including a VFR mention. Still appears that strong westerly flow aloft will allow for less deeper moisture to push across the Blue Ridge. Therefore maintaining VFR cigs to just scattered clouds farther east at KLYH/KDAN overnight for now. However latest ensembles including the HREF show some fog development in the east where clouds will be less and winds lighter. This primarily around KDAN but cant totally rule out at KLYH late tonight into early Friday as the front arrives. Cold front pushes to the south during Friday with strong high pressure slowly building in from the north. This may allow for some drying and improvement in conditions to take place espcly along the KLWB-KLYH corridor in the morning before moisture starts to return across southwest sections later in the day. Otherwise most recent guidance suggesting that most will stay locked into MVFR cigs for much of the day with potential pockets of fog around if clouds lock in sooner so something to watch. This looks moreso around KBLF given upslope flow where could bounce around in IFR at times, while KDAN/KLYH may stay VFR before lowering to MVFR later in the afternoon. Do expect cigs to once again lower to more widespread sub-VFR by Friday evening with some spotty showers/rain possible near KBLF and over the rest of the mountains overnight. Medium confidence in cigs throughout the TAF valid period. Medium to low confidence in vsbys throughout the TAF valid period. Medium to high confidence in wind dir/spd throughout the TAF valid period. Extended Aviation Discussion... Low level moisture will then arc back north Friday night into Saturday, maintaining the threat for additional sub- VFR in low cigs/fog, along with light rain and/or drizzle, including possible patchy freezing rain across the northern Blue Ridge. Unsettled weather will continue into Sunday with some slow improvement in conditions as high pressure weakens to the north leaving the residual weak front near the area. However given uncertainty appears mainly MVFR to prevail under passing showers as the boundary likely oscillates across parts of the region. Southerly flow aloft will develop Monday ahead of a frontal system in the Central Plains with continued MVFR as the low level wedge redevelops while helping keep low clouds in place. Appears enough warm advection just ahead of the front at this time to help return much of the area to mainly VFR Tuesday with perhaps spots across the northwest clinging to sub-VFR a while longer.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...RCS NEAR TERM...DS/RCS SHORT TERM...WP LONG TERM...WP AVIATION...JH/RCS

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