729 FXUS61 KRNK 091805 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 205 PM EDT Tue Oct 9 2018 .SYNOPSIS... A warm and moist southeast flow will continue over the region through midweek as high pressure stays well off the east coast. Hurricane Michael is expected to move out of the Gulf of Mexico through the southeastern US by Wednesday night into Thursday, with a cold front shifting across Thursday into Thursday night. && .NEAR TERM /THROUGH TONIGHT/... As of 205 PM EDT Tuesday... No substantial change needed at this point. Mostly cloudy skies still continue, largely a mix of scattered cumulus underneath a layer of cirrus. Still have some upslope component contributing to scattered showers along the southern Blue Ridge, though rain amounts to this point have not been anything to write home about. Conditions to remain more or less steady state through the afternoon with only modest warming expected into the 70s to a few low 80s east of Highway 29 where best chance of greater clearing exists. Earlier discussion from 320 AM: Satellite showing extensive lower clouds across the area this morning with higher clouds streaming up from the south associated with tropical moisture east of the Bahamas, as well as from Michael. These two factors are limiting fog development, but still some lower cigs allowing for fog along the ridgetops. Radar fairly quiet but some light returns along the southern Blue Ridge resulting in light rain/drizzle from Boone to Fancy Gap. Going with high-res solutions this morning yields chance pops from Mabry Mill southwest to the NC High Country with slight chances either side. A southeast flow continues today as upper high moves further east away from the coast. A few impulses in the southeast flow will work into the southern Appalachians, and upslope flow will allow for a scattering of showers mainly along and east/southeast of I-81 into the piedmont with higher pops across the Blue Ridge in NC. Expect limited instability so no thunder mentioned in the forecast. Clouds will be more extensive today though southeast flow may allow for some breaks across WV west of Lewisburg and Bluefield. With a warm start, should see temps rise around 10 degrees except limited 2 to 5 degrees rises into the Blue Ridge southwest of Fancy Gap. So, expect highs in the mid to upper 60s across the Boone to Fancy Gap corridor, with lower to mid 70s elsewhere in southwest VA into Southeast WV, with upper 70s to around 80 east of the Blue Ridge including Roanoke. Upper 70s also anticipated southwest of Tazewell to Marion. Tonight, southeast flow persists and winds increase around 30 to 40 kts at 8h into the TN Valley and southern Appalachians. Will see an increasing coverage of showers across the North Carolina High Country northeast along the Blue Ridge to Floyd with shower chances increasing elsewhere as well. Shower coverage will be less northwest of Tazewell to Hinton in WV per strong downslope component. Rainfall amounts during this time will average less than quarter inch, but would not be surprised to see half inch or more amounts near Boone/Blowing Rock as precipitable water increases to 1.5 inches, which is close to record values for early October. Low temps again running 15 to 20 degrees above normal, with most in the 60s. Forecast confidence is above average this period for all elements, though moderate on rainfall amounts and wind gusts over the higher terrain of the west. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... As of 235 AM EDT Tuesday... We are still anticipating a very wet forecast for at least the Wednesday through Thursday time period. The area will be in a deep and moist southeast flow trajectory between the departing upper high in the western Atlantic, and an approaching upper trough to our west, and what is expected to be Tropical Storm Michael heading northeast through the Carolinas. First, the southeast flow will advect a generous amount of moisture into our area that will head upslope with rainfall maximizing along the crest of the Blue Ridge Wednesday into early Wednesday evening. By late Wednesday night, and during the day Thursday, we are expecting the approaching upper trough and moisture associated with Tropical Storm Michael to provide around a 12 to 18 hour window of moderate to heavy rain across the region before quickly ending Thursday night. The challenge is when that end will be. While in reality that ending should be fairly prompt, and coincide when the axis of the upper trough shifts east through the area. The forecast however will reflect a slower ending of the precipitation during Thursday night to better reflect the uncertainty in the ending. Rainfall totals during the Wednesday through Thursday night time period are forecast to be greatest across parts of Southside Virginia and neighboring sections of north central North Carolina. The latest forecast for the area is on the order of three to four inches. Heading northwest across the forecast area, precipitation totals are generally expected to decrease such that portions of southeast West Virginia are expected to receive three-quarters of an inch to one inch of rain. The exception to the decreasing amount pattern will be immediately along and near the crest of the Blue Ridge. Here along this relatively narrow section of the forecast area, two and one-half to three inches are forecast. This compares to an average of one to two inches immediately to the west of the crest and two to two and one-half inches immediately to the east of the crest. All guidance is in good agreement of the precipitation east of the area by Friday, with drier and cooler air working its way into the area on gusty northwest winds Friday into Friday night. The gusty northwest flow may yield some isolated upslope showers across far western Greenbrier County, WV Thursday night into early Friday. Temperatures will continue to remain well above normal for this time of the year through Thursday, with readings falling closer to normal for Friday. && .LONG TERM /SATURDAY THROUGH MONDAY/... As of 400 PM EDT Monday... Upper level pattern will deflate over the weekend and into the following week as the Bermuda high gives up the October ghost. One last surge of higher dewpoint air will try to work back into the area Sunday ahead of what will be the remnants of Hurricane Sergio which is expected to get drawn into the southwestern U.S Saturday and into the base of the central CONUS long wave trough. Attm it appears the energy associated with this feature will pass through the OH valley Sunday with showers primarily to our northwest. However, with the passage of this feature it will open the door for a pattern change with the northern jet stream making dive into the central and eastern CONUS, a feature that will favor below normal temperatures across much of the central and eastern U.S. by the middle of next week. As for the details, the upcoming weekend as a whole does not look that bad...featuring dry conditions and near seasonal temperatures. Near seasonal temperatures however, means temperatures at night will be in the 40s, so it will feel noticeably cooler compared to our extended summer-like nights. By Monday, showers associated with the deepening upper level trough to our northwest are expected to move across the area. After that...it dries out for the middle of next week, but the bottom drops out of the thermometer. Will there be frost for Wednesday or Thursday mornings of the 17/18th? Time will tell. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... As of 205 PM EDT Tuesday... Mix of VFR/MVFR based cumulus clouds atop a field of cirrus this afternoon. Occasional unrestricted showers in the upslope areas on the eastern edge of the southern Blue Ridge will continue but not affect any TAFs. Conditions to remain relatively steady- state through early evening, though some of these unrestricted showers may affect Roanoke or Danville through 00z Wednesday. Southeast winds to remain around 6-10 kts. For this evening, model guidance suggests that persistent upslope light rain or drizzle will continue, with a deterioration in ceilings to a more persistent MVFR at sites along or near the Blue Ridge. Do think VFR ceilings should prevail at Bluefield and Danville through the bulk of the overnight, with best chance at sub-VFR ceilings from Blacksburg, Lewisburg and Roanoke. It's possible MVFR ceilings may exist at Lynchburg as well though guidance shows mixed signals there which reduces confidence in ceiling forecast there. May see intervals of mist at times but likelihood of mixing from southeast winds would serve to limit visibility restriction to no worse than MVFR. Expect ceilings to at least partly obstruct the Blue Ridge ridgetops. Southeast winds again remain around 6-10 kts. Toward early morning, an increased southeasterly jet of 35-40 kts will likely contribute to development of choppy conditions and mechanical turbulence near ridgetop level along the southern Blue Ridge south of Roanoke, and into the hilltops of southeastern WV and the New River Valley. Worst flight category conditions anticipated on Wednesday. Guidance shows good consistency in progressing a band of what should be moderate to potentially heavy rain at times from south to north along the spine of the Blue Ridge between 11-18z (and continuing into the late-aftn hrs). Expect ceilings to lower to MVFR-IFR category with visbys largely VFR-MVFR, though will tend IFR at times in the steady and at times heavy rain. Confidence is average for the entire period, though is lower than average on ceilings for the overnight period. Extended Discussion... Showers are expected to increase in coverage by Wednesday and Thursday as tropical moisture shifts northward ahead of Hurricane Michael and a cold front moving in from the west. Rain may be heavy at times Thursday. Conditions will improve back to VFR on Friday behind the front, then VFR over the weekend. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AL/WP NEAR TERM...AL/WP SHORT TERM...DS LONG TERM...PM AVIATION...AL/WP