Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 221128 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 728 AM EDT Thu Sep 22 2016 .SYNOPSIS... Low pressure along the coast of South Carolina slides slowly north along a front through Friday with high pressure shifting over the Southern Appalachians. A backdoor front edges into the area by late in the weekend, then shifts south as strong high pressure works in across the northeast Monday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 715 AM EDT Thursday... Bumped pops up some over southside VA into the NC piedmont per radar trends showing a better concentration of showers. Previous discussion from early this morning... Surface low situated off the Georgia/South Carolina will start to slide back north through tonight, while the upper low weakens and opens up. For our area, will still see some isolated to scattered showers today over the southside portion of Virginia into the piedmont of North Carolina. Should stay mostly cloudy here through the day while the rest of the area that experiences some clouds this morning see a clearing trend this afternoon, with better subsidence. Temperatures should be close to yesterday, maybe a degree or two warmer in the southeast with some partial clearing possible. Most will have highs in the upper 70s to lower 80s. Tonight, the threat of showers will shift further southeast but cloud cover may hold into areas southeast of Lynchburg to Martinsville while clear skies occur in the west. The 00z nam shows possible upslope of stratus/stratocu in the southern Blue Ridge late, but overall keeping it mostly clear/partly cloudy there. With less mixing and clear skies, patchy fog will form in the river valleys. Temperatures should also drop a few more degrees with lows in the mid to upper 50s west to mid 60s east where clouds and higher dewpoints linger.
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&& .SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/... As of 330 AM EDT Thursday... The upper pattern will be undergoing significant changes through the end of the workweek and into the weekend as it evolves into a high amplitude blocky configuration with a steep ridge building in the east and a large closed low developing over the upper midwest. This will allow Canadian high pressure at the surface to move into the Great Lakes region and wedge down the east side of the Appalachians. As the high surges southward it will push a backdoor cold front into the region from the northeast late on Saturday. BUFKit soundings indicate a good amount of low level moisture behind the front and the low level west to southwest flow will create isentropic lift as it rides up over the wedge with boundary layer winds gradually veering from northeast to southeast. The end result will be clouds and a chance for rain for most of the region for Sunday and into the first part of next week. Temperatures will continue running about 10 degrees above normal for Friday and Saturday with highs well into the 80s. Then, temperatures will cool considerably behind the front in the cool wedge with low to mid 70s for most locations on Sunday, a bit warmer far west of the Blue Ridge on the fringe of the wedge. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... As of 330 AM EDT Thursday... Lots of uncertainty to take shape early next week as model spread remains large in just how fast a second cold front to the west will be able to slide east given eastern ridging in place. Latest 12Z GFS has continued to make a shift toward the slower ECMWF from overnight in keeping this slow moving front west of the mountains through midweek. However these solutions remain much slower and stronger than the GEFS which looks too weak/fast in lifting support out to to the north, while spilling the front quickly east. Overall the slower scenario would keep the area in more or less a more stable low level wedge formation per high pressure to the north under ridging aloft. Tendency in this setup likely to lead to more clouds and spotty showers/drizzle including much cooler temperatures into midweek. Therefore have trended in this direction with highs below Mos, but still mostly 70s and lows 50s- mid 60s, although highs by early week could be only in the 60s if more widespread low clouds do materialize. && .AVIATION /12Z THURSDAY THROUGH MONDAY/...
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As of 723 AM EDT Thursday... Will see -shra impact DAN at times til 15z with IFR ceilings possible. Mainly MVFR east to VFR west through late morning with conditions improving at LYH by 15z and DAN by 18z to VFR. Clouds should linger in DAN all day with clearing elsewhere by dusk. Still VFR. Fog was not as much a factor at LWB/BCB this morning. Given drier weather think fog potential will stay low late tonight so none added to the terminals. Extended aviation discussion... VFR conditions will prevail through Saturday with high pressure in place. A back door front passes across late in the weekend into early next week which may bring sub VFR ceilings as an easterly flow sets up. Rainfall chances will stay low however.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...WP NEAR TERM...WP SHORT TERM...MBS LONG TERM...JH AVIATION...AMS/KK/WP

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