Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 191815 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 115 PM EST Sun Feb 19 2017 .SYNOPSIS... An upper low will cross the region this morning before exiting to the southeast this afternoon. High pressure builds in from the north behind this system tonight and remains into Monday night. A weak frontal system will approach from the west by midweek. && .NEAR TERM /THROUGH TONIGHT/...
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As of 100 PM EST Sunday... The biggest adjustment to the forecast for this afternoon has been an adjustment of the forecast high temperatures. Have decreased by a couple of degrees readings over parts of the mountains from near Hillsville, VA, south into the Northern Mountains of North Carolina. Readings have been trending below forecast levels here, and cloud cover will slow any notable rise for another hour or two. Have increased forecast highs by a degree or two in the east where plenty of sunshine, and increasing northwest winds should help temperatures to continue to rise. Another adjustment based upon the latest observations includes a removal of mention of patchy drizzle and patchy light fog from the forecast this afternoon. The area between Richlands, VA and Bluefield, WV has seen an end to these features, and they are not expected to return this afternoon. As of 1000 AM EST Sunday... No major updates to the forecast this morning. We are still expecting cloud cover to persist across the western sections of the region through at least the remainder of the morning, and mostly likely some hours this afternoon. What remains a question is if areas near a line from Tazewell, VA to just west of Lewisburg, WV will see any breaks in the cloud cover today. From a look at regional weather observations and area web cams, looks like a good call to maintain some patchy fog and drizzle across this similar region into the afternoon, and also parts of the Northern Mountains of North Carolina. Have also tweaked hourly temperatures and dew points heading into the early afternoon based upon the latest observations and expected trends into the early afternoon. As of 215 AM EST Sunday... Upper low will continue to pivot across the region early this morning before exiting to the southeast by afternoon. Trailing deformation band currently producing a band of showers across the far northwest should also gradually shift east while slowly stretching/dampening out after daybreak as the associated upper support pulls away. However decent northwest flow in the wake of the upper system likely to keep low clouds trapped over much of the west to start with some showers northwest, and perhaps spotty light rain/drizzle elsewhere along the far western ridges early on. Subsidence to gradually increase this afternoon as ridging to the west starts to shift east and ongoing cool advection weakens. This should help to erode the low cloud canopy over the mountains with guidance profiles showing moisture pulling back to the west allowing for mainly sunny skies east and decreasing clouds west. Just how fast this occurs the key to high temps as MOS has trended cooler western sections while keeping things quite mild east per downslope under more insolation. Therefore edged highs from the Blue Ridge west down a little with some spots likely staying in the 50s espcly if clouds hold longer under a gusty northwest breeze. Strong upper ridging to build in overnight as surface high pressure bridges in from the north by daybreak. Models depict very strong warming aloft as the next round of warm advection to the west shifts east. Expect better subsidence to keep skies mainly clear although some potential for low clouds to again get trapped over the far west beneath the inversion aloft as warming comes in above. Otherwise appears a bigger range in low temps from 30s valleys to perhaps mid 40s at elevation likely with good radiational cooling outside of warming aloft.
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&& .SHORT TERM /MONDAY THROUGH WEDNESDAY/... As of 208 AM EST Sunday... An upper level ridge and lots of sunshine will allow Monday`s temperatures to reach into the upper 60s to lower 70s. These temperatures are 20F-25F warmer than normal. Records could be broken at Bluefield and Blacksburg Monday. A light east wind will keep Roanoke, Lynchburg and Danville from reaching their records. The upper level ridge will slowly exit the region Tuesday. This ridge is stubborn and has, by model standards, been slowing the arrival of our next chance for rain, now set for Tuesday night. Dew points recover quickly into the 40s Tuesday night, however, dry prefrontal environment and the lack of lift will limit rainfall to under a quarter of an inch. The front that will bring the rain is weak and will likely washout over North Carolina Wednesday. A reinforcing shot of cool easterly flow and increasing cloud cover will keep temperatures in the low to mid 60s Tuesday. Despite Tuesday being cooler than Monday, temperatures will still be 15F warmer than normal. Temperatures will rebound Wednesday as the washed out front gives way to warm southerly flow. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... As of 230 AM EST Sunday... Residual moisture with the weak front across the region looks to dry up Wednesday night into Thursday as ridging re- establishes over the southeast states. This leads to a more amplified 500 mb pattern for the end of the week with a deepening trough moving across the central United States and more spread showing up in the models by that time frame. Increasing southwest winds Thursday into Friday will increase moisture and keep temperatures way above normal ahead of the front with 60s to near 70 likely west and well into the 70s east. Timing of the frontal passage across the Appalachians looks to be on Saturday morning with precipitation along and ahead of the boundary at this point. Colder air comes in behind the front for the end of the weekend but again not overly impressive and likely limited in duration per latest warmer 19/00z ECMWF. However the combination of a modest low level jet and strong cold air advection will result in strong gusty winds behind the front into late Saturday with a brief return to more normal temps to start the weekend. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/...
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As of 1240 AM EST Sunday... VFR conditions currently prevail east of the crest of the Blue Ridge. As high pressure continues to build into the region, this pattern is expected to continue through at least the duration of the valid TAF period. Winds in this region will be close to 10 kts this afternoon from the northwest, with some gusts in the 15 to 20 kt range. Anticipate calm or light and variable winds overnight through Monday. Across the mountains, most areas were experiencing decreasing coverage of ceilings that ranged from LIFR to MVFR. Drying from aloft will help to continue to the trend of decreasing coverage as the afternoon progress with ceiling levels increasing mainly to MVFR and low end VFR. As the night progresses, moisture that becomes trapped under the nocturnal inversion will allow ceilings to redevelop and spread eastward. Levels again will return to LIFR to MVFR levels. However, drier air will eventually win with clouds decreasing in coverage towards daybreak. VFR conditions are expected across the mountains on Monday. Winds this afternoon in this region will be generally from the northwest around 10 kts with gusts in the 15 to 25 kt range. Overnight and on Monday, anticipate calm or light and variable winds. VFR visibilities are expected for much of the region. Some late night valley MVFR fog is possible in areas near and south of KBLF. No low level wind shear is expected during the TAF period. No precipitation is expected during the TAF period. Confidence levels of forecast parameters during the TAF time period include the following. Visibility...High. Ceiling...Moderate to High. Weather...High. Wind....High. Low Level Wind Shear...High. Extended Aviation Discussion... High confidence of VFR conditions Monday afternoon through Tuesday morning. Moderate to high confidence of patchy MVFR conditions across the mountains Tuesday afternoon into Wednesday with the passage of a cold front. East of the Blue Ridge, mainly VFR conditions will prevail. Thursday into Thursday night, moderate confidence of patchy light rain returning to the area, with ceiling and visibilities remaining mainly VFR. Some patchy MVFR is possible. Friday, moderate to high confidence of precipitation trending more showery, as low level jet increases in advance of a strong cold front. Expect a mix of MVFR and low end VFR ceilings and mainly VFR visibilities with isolated, brief sub-VFR visibilities under heavier showers. Surface wind gusts of 20 to 30 kts possible across the higher terrain.
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&& .CLIMATE... As of 307 PM EST Saturday... Record High Temperatures and Year of Occurrence Feb 19 Blacksburg, VA..65 in 1994 Bluefield, WV...66 in 1994 Danville, VA....73 in 1981 Lynchburg, VA...76 in 1939 Roanoke, VA.....77 in 1939 Feb 20 Blacksburg, VA..68 in 1984 Bluefield, WV...67 in 1986 Danville, VA....74 in 1971 Lynchburg, VA...76 in 1930 Roanoke, VA.....75 in 1939 && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...JH NEAR TERM...DS/JH SHORT TERM...RCS LONG TERM...AMS/JH AVIATION...DS CLIMATE...DS

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