Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 192005 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 305 PM EST Thu Jan 19 2017 .SYNOPSIS... High pressure centered over our region this afternoon will shift east to the coast tonight as a warm front lifts north from the Gulf Coast states into the southern Appalachians. The warm front will swing north across Virginia and into the mid-Atlantic Friday, before stalling. Another storm system moving across the southern U.S. will impact our region Sunday into Monday. && .NEAR TERM /THROUGH FRIDAY/... As of 200 PM EST Thursday... Upper Ridge over our region this afternoon will slide east tonight into Friday. Warm advection high clouds this afternoon will be followed by increasing mid clouds starting to roll into the southwest by dusk. Low pressure over western Tennessee this afternoon will lift northeast into the Ohio Valley tonight and reach Lake Erie by Friday afternoon. A warm front trailing from the low will lift northward tonight into Friday. Isentropic lift increases this evening across the mountains of North Carolina and shift to the rest of the forecast area overnight. With a dry airmass in place, slowed down the onset of the rain this evening. Used a blend of HRRR and HiResW-arw-east for pops this evening, then utilized a mix of NAM and Continuity with pops tonight into Friday. The best chance for rain is in the mountains with lower threat in the Piedmont. Lower dewpoints in the evening combined with increasing moisture may allow for temperature drop once the rain starts to fall tonight. However, it should remain mild with low temperatures ranging from the upper 30s in the Alleghanys and portions of the Greenbrier Valley to upper 40s to about 50 degrees in Mountain Empire. On Friday, the best lift will push quickly northeast through the region. An upper level shortwave ridge will build over the Mid- Atlantic region. The bulk of the rain will have moved northeast of the area by the early to mid afternoon. Added the mention of fog to isc grids. Lowered high temperatures a few degrees especially in the north Friday with clouds and rain. High temperatures Friday will vary from the upper 40s in the mountains to the lower 60s in the south. Rainfall amounts overall will average around a quarter inch with locally higher in the western mountains of Southwest Virginia and North Carolina. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... As of 300 PM EDT Thursday Even with limited sunshine on Saturday the air mass will be unseasonably warm, 15 to 25 degrees above normal. Deep moisture begins to arrive back into the area from the southwest on Saturday afternoon. But Bufkit not showing a saturated sounding until closer to Sunday morning. Models forecasting good lift Sunday with a strong vorticity maximum crossing the central and southern Appalachians along with upper diffluence. Winds at 850MB back to the southeast by 12Z/7AM Sunday with good upslope and increasing inflow off the Atlantic first along the Appalachians in northern North Carolina on the Sunday morning gradually shifting north of Roanoke by the end of the day. More significant differences in the guidance in the amount of instability across southern Virginia and northern North Carolina on Sunday all related to the location of the warm front. 12Z NAM/GFS and latest RAP indicating enough of a secondary low developing over eastern North Carolina that with the precipitation there should be strong in-situ wedging. Large spread in location of heaviest rain also so will lean toward WPC guidance. Wedge and precipitation will keep temperatures on the cool side/or below guidance for Sunday. Have added slight chance of thunder from extreme southern Virginia into northern North Carolina but confidence is low. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... As of 200 PM EDT Thursday Precipitation will remain in the area through Monday with the highest rain amounts on Sunday night and Monday, mainly along and east of the Blue Ridge. Experimental Hydrologic ensembles showed a least a small potential for 1 to 3 inches of rain. Localized minor flooding is possible is this amount of precipitation is realized. Once the surface low is off the coast on Monday night and Tuesday, precipitation will be confined to favored western upslope areas. Enough colder air comes in Monday night that will have snow in the forecast from southeast West Virginia into northwest North Carolina. Winds will also increase Monday night and Tuesday. There may be enough of a low level jet. cold air advection and pressure rises for wind gusts in the 40 to 50 mph range. By Wednesday and Thursday a long wave positively tilted upper trof will extend from the Great Lakes across the central United States. Prevailing deep southwest flow over the Mid Atlantic region this time frame differences in the models on how fast any front will progress east. For now WPC has surface front crossing the region on Wednesday and Wednesday night. Behind this system is a much colder air mass. More upslope snow showers in the mountains are possible. At this time the models are showing any snow showers on Thursday night. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... As of 101 PM EST Thursday... Low clouds eroded out of the Greenbrier valley this afternoon, returning KLWB to VFR conditions. Under Mid and High clouds VFR conditions will continue into this evening. As the high pressure center shifts east tonight, a warm front will lift north in the the southern Appalachians. As moisture increases ceilings will lower from the Southwest tonight into Friday morning. Looking at rain moving into BLF/LWB/BCB/ROA in the 08-12z time frame with MVFR cigs. Heavier bands of rain could produce IFR conditions. Rain will spread east across the region Friday with MVFR ceilings and local IFR/LIFR conditions in low clouds,fog and rain. Medium confidence in ceilings,visibilities and winds during the taf period. Extended Aviation Discussion... Rain moves out Friday afternoon with some improvement expected briefly but next system will bring more lower cigs in Saturday into Sunday with rain. This continues into Monday with poor flying conditions expected across the Mid-Atlantic and Southeast. Gusty northwest winds and mountain MVFR showers are expected for Tuesday. && .CLIMATE... As of 305 PM EST Thursday... Record warm Mins for January 21 Blacksburg....42 in 1954 Bluefield.....47 in 1999 Danville......56 in 1954 Lynchburg.....51 in 1927 Roanoke.......51 in 1959 Record highs for January 21 Blacksburg....59 in 1954 Bluefield.....60 in 1999 Danville......68 in 1959 Lynchburg.....72 in 1932 Roanoke.......74 in 1932 && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...KK NEAR TERM...KK SHORT TERM...AMS LONG TERM...AMS AVIATION...KK/WP CLIMATE...AMS is the U.S. government's official web portal to all federal, state and local government web resources and services.