Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 190738 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 238 AM EST Sun Nov 19 2017 .SYNOPSIS... Much colder air on blustery winds will arrive today, with clearing skies across the Piedmont, but with abundant clouds over the mountains along with some upsloping snow showers across the western flanks of the Appalachains. High pressure builds in from the southwest late tonight into Monday. && .NEAR TERM /THROUGH TONIGHT/... As of 220 AM EDT Sunday... 500MB trof deepening over the eastern United States this morning. GOES16 water vapor loops showed a well defined short wave crossing into Virginia early this morning. A second vorticity maximum will track across the area late this afternoon into early this evening. Colder air aloft will provide some instability today and strong upslope northwest wind behind the cold front will result in a prolonged period of showers along the west slopes of the Appalachians. No change needed to wind advisory at this time. Expecting strong cold air advection this morning and 6hr pressure rises of 14 to 18 mb. By this evening pressure rises slacken but the second short wave will bring another brief increase of the low level jet which will extended the gusty conditions. Will be leaning toward NAM Nest and MET guidance for lows tonight. Temperatures will be in the 50s ahead of the front this morning then drop behind the cold front today. High temperatures for most locations in southwest Virginia, southeast West Virginia and northwest North Carolina will be in the morning. Much of the HiRes guidance has the pre-frontal showers into central Virginia and North Carolina by 09Z/4AM, leaving only showers in the mountains for the rest of the day. Models diminish upslope flow and low level moisture after 03Z/10PM this evening. Snow showers will taper off to flurries by midnight but cloud cover will take until around sunrise to dissipate. && .SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/... As of 218 AM EST Sunday... Upper pattern stays transitory this period, with a shortwave ridge Monday over the west side of the mountains, then next trough digs into the upper Great Lakes with broad troughing southward into the lower Mississippi Valley, early Tuesday. At the surface high pressure moves from overhead Monday to off the NC coast Monday night. Will see some increasing moisture in southwest flow but models overall keep us dry, with main surge of deeper moisture passing over the southeast Tuesday. Cannot rule out a few showers as we head into Tuesday night across the east, and with the next front over the west, but looks marginal. Models are showing a split flow regime midweek with northern stream trough over the Northeast-Mid-Atlantic with west southwest flow aloft over our forecast area, with a digging shortwave moving into the mid and lower MS Valley Wednesday-Wednesday night. At the moment models are keeping the deeper moisture and showers well south going during this time across the Gulf Coast states, but may bear watching if the the shortwave stays further north, which could push some rain toward our southern forecast area Thanksgiving. Overall, temperatures will be close to normal for lows and at or below normal for highs. May see some uptick in winds from the northwest as northern wave pushes across Wednesday per latest ECM. && .LONG TERM /THURSDAY THROUGH SATURDAY/... As of 300 PM EST Friday... GFS ensemble indicates a 500 mb pattern resembling a cold season positive Pacific-North American (PNA) teleconnection regime centered around the Thanksgiving holiday period. This often translates to mean troughiness at 500 mb into the central and eastern US, as repeated shortwave troughs round the top of a large ridge across the Pacific Coast and dig/reinforce cyclonic flow aloft. Overall an unsettled holiday period but nothing that would significantly hamper travel plans attm. Kept highs for the Thanksgiving holiday only in the 40s with partly cloudy skies and dry conditions. Looks to be a warming/moderating trend to temperatures Friday into the holiday weekend and will likely trend temperatures to near/above late-November normals. Weather pattern then turns more unsettled after the holiday weekend with a larger degree of guidance solution spread. && .AVIATION /08Z SUNDAY THROUGH THURSDAY/... As of 1235 AM EST Sunday... Local radar showed a pre-frontal band of showers from eastern West Virginia into western North Carolina. Winds ahead of these showers were from the southwest with gusts up to 20 knots. Winds shift to the west behind the showers with gusts to 30 knots. Ceilings were generally VFR with this precipitation with a few spots of MVFR ceilings with the heavier rain. An intense cold front extended from Lake Erie to northwest Georgia early this morning. The front was moving rapidly east and will turn the winds to the northwest with gusts of 30 to 45 knots through the rest of the morning. Clouds will clear out east of the Blue Ridge this afternoon, but MVFR ceilings are expected in the mountains for much of the day. Strong upslope winds will also result in MVFR rain or snow showers on the western slopes of the Appalachians, including at KLWB and KBLF. Any snow accumulation at these airports will be light. High confidence on the winds and ceilings and visibilities during the taf period, but medium confidence on the timing. Extended Discussion... Higher pressure and a weakening pressure gradient should allow for northwest winds to slowly abate by late tonight, along with decreasing clouds across the western flanks of the Appalachians. Widespread VFR conditions are expected thereafter from Sunday night into Friday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...Wind Advisory until noon EST today for VAZ007-009>020-022>024- 032>035. NC...Wind Advisory until noon EST today for NCZ001-002-018. WV...Wind Advisory until noon EST today for WVZ044-507-508. && $$ SYNOPSIS...WERT/WP NEAR TERM...AMS SHORT TERM...WP LONG TERM...AL AVIATION...AMS/KK is the U.S. government's official web portal to all federal, state and local government web resources and services.