172 FXUS61 KRNK 111408 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1008 AM EDT Thu Oct 11 2018 .SYNOPSIS... Tropical Storm Michael will move across the central Carolinas today then off the Virginia coast tonight. Cooler high pressure builds in to start the weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 1000 AM EDT Thursday... Heaviest rainfall continues across the western sections associated with banding to the north of Michael and within convergence into the surface cold front now along the Appalachians. Latest short term models gradually shift bands east as the front to the west also starts to undercut via winds becoming more north to northwest from west to east this afternoon. This should act to decrease rainfall rates over the mountains early this afternoon while heavier rain heads into the piedmont sections before exiting by sunset. However given efficiency of the tropical rainfall, bumped up QPF amounts over the west to start and a bit over the southeast where guidance shows a period of stronger lift before deeper moisture exits. Other concern could be with isolated spinup tors far southeast pending the degree of any heating and given appearence of lightning in spots added more thunder mention southeast. Otherwise winds remain elevated and given that are not seeing much mix down will keep the wind advisory timing going for this afternoon with adjustments likely needed later to cover the post Michael gustiness. Left temps close to previous with only a slow rise into the 70s expected. Also tornado watch 409 until 9 pm just issued for a few eastern counties. Previous discussion as of 300 AM EDT Thursday.. High confidence forecast for flooding and wind threat. Looking at another busy day as TS Michael tracks from eastern GA to central NC by mid afternoon, then off the VA Tidewater by midnight. We currently are in a holding pattern in terms of moderate to heavy rainfall, although scattered showers are still moving from south to north across the forecast area, especially over the mountains/adjacent foothills. Regional radar showing northern edge of rain band with Michael pushing into Southwest NC. There is also a ribbon of rainfall from eastern Ohio south into the Smokies associated with a front. Higher-resolution models showing the moderate to heavier bands from Michael reaching our NC mountains by 6am, then progressing northeast into southern VA by mid morning, while frontal forcing moves a band of showers into the WV mountains by mid-late morning as well. Tropical moisture/higher PWATs stay along/east of the Blue Ridge, and per coordination with WPC will see higher rainfall set up along/east of the Blue Ridge with another 2 to 5+ inches expected today into this evening, with the higher amounts in southside VA into the NC piedmont. West of the Blue Ridge amounts will stay mostly under 2 inches. Given where it rained hardest yesterday with flooding, will keep the flash flood watches in the mountains to account for the fact that not much rain will likely lead to more flooding. We will see the rain shield exit the mountains by mid-late afternoon and the piedmont this evening. Winds though sub-tropical storm force will gust as high as 40 mph at times today across the southern half of the CWA. With wet ground it will not take as much wind to down trees, and thus possibly create issues with power outages. Therefore, wind advisories have been posted for the southern half of the CWA for this afternoon into Friday morning. Post storm gradient and pressure rises will keep winds gusty into Friday morning along the Blue Ridge. Another issue to watch later this morning into the afternoon will be for isolated spin-up tornadoes. SPC has a marginal risk in the piedmont but confidence is low, per lack of decent banding features so far. However, not out of the question to see some, as models depict 200-300 SRH in the 0-2km layer pushing across the NC piedmont into southside VA by 18z, then weakening after 21z. Will highlight this in the HWO. As we head through the night tonight, dewpoints will drop off into the 40s. You will definitely notice a change when you head out the door Friday morning. As for temps did not go too warm today given clouds and rain, so basically tacked on 5-8 degrees to lows this morning with highs ranging from the mid 60s to around 70 in the west, to mid to upper 70s. Expect cooler lows tonight, with 40s in the mountain to 50s east. Wet ground and mixing may keep temps from falling as far as they could. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 300 AM EDT Thursday... Remnants of Hurricane Michael will be tracking off the northeast coast while high pressure covers the forecast area. Cooler drier air will grace the area as Friday's highs will range from the upper 50s to lower 60s across the mountains to the upper 60s to lower 70s east of the Blue Ridge. A northern stream disturbance will track across the Ohio Valley Friday night into Saturday morning. This system will bring a chance for showers, mainly across southeastern West Virginia. A cold front will follow this disturbance keeping temperatures cool with Saturday's highs in the 50s across the mountains to 60s east. High pressure will bring a re-enforcing shot of cooler air Saturday night with a few mountain locations dropping into the 30s. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 400 PM EDT Wednesday... October finally feels like, October. A large scale upper trough is forecast to reside over the eastern 2/3rds of the country the entire week, amplifying by mid-week as series of short waves digging south from Canada resulting in a fairly extensive cold intrusion to much of the central and eastern CONUS. Model consensus is for some unseasonably cold air (yep summer to winter) to overtake areas which were basking in unseasonable warmth, and in some cases extreme enough to permit the frozen form of precipitation across the upper Mid-West and Great Lakes into parts of New England where 850 mb temps plunge low enough to support snow. For the central Mid-Atlantic it will certainly feel like October, if not favor some November sort of temperatures which would be permissible for frost formation for parts of the forecast area...especially the mountain valleys. Precipitation chances appear somewhat limited, but there will be opportunities for showers associated with each passing shortwave trough, Monday favoring a day for showers, and then again toward mid week. Monday might actually turn out to be a little wetter than forecast, models trending toward some over-running associated with a frontal passage. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... As of 130 AM EDT Thursday... Looking at poor flying conditions through at least late afternoonuntil TS Michael and attendant front move across. Heavier rain bands moving up from NC into southwest VA will overspread much of the region through the morning. Winds will pick up from the east to northeast, then shift to the northwest this afternoon. Some gusts 30 to 35 kts possible near DAN this afternoon. As we head toward 00z, will start to see drying out from the southwest to northeast and expect all taf sites to improve to VFR. Confidence is above average for sub-VFR most of the period, but lower how strong winds are and clearing to VFR. Extended Discussion... Strong northwest winds will be common Friday morning in the mountains in the wake of Michael along with areas of mountain turbulence. VFR on Friday along with diminishing winds Friday night. Generally VFR anticipated over the weekend. Another front arrives Monday with possible sub-VFR cigs/vsbys with showers. && .HYDROLOGY... As of 450 AM Thursday... 3 to 7 inches of rain fell across upper portions of the New River basin Wednesday afternoon/evening. As Michael moves in with another 1 to 3 inches of rain in this basin, plus 2 to 6 inches across the Dan River, some river flooding is possible. In the near term, convective elements with tropical moisture with PWATS at records highs (as 06z sounding showing 1.88" at RNK and normally we should be at 0.69" for October 11th), will lead to flash flooding threat over the southern half of the forecast area. As we work into the afternoon and after the rain ends, main stem rivers will already be responding. Some minor flooding, possibly moderate flooding along the New River and Dan River is likely. As for other rivers, such as the Yadkin and Roanoke, will see how much occurs in the headwaters and downstream and gage that later this morning for flood potential. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...Wind Advisory from 2 PM this afternoon to 11 AM EDT Friday for VAZ010>018-022-032-033-043. Flash Flood Watch until 8 PM EDT this evening for VAZ009-012- 015. Flash Flood Watch through late tonight for VAZ013-014-016-017- 022-032-033-043-044-058. Flash Flood Watch through late tonight for VAZ023-024-034-035- 045>047-059. Wind Advisory from 2 PM this afternoon to 2 AM EDT Friday for VAZ044-058-059. NC...Wind Advisory from 2 PM this afternoon to 11 AM EDT Friday for NCZ001>003-018>020. Flash Flood Watch until 8 PM EDT this evening for NCZ001-002- 018-019. Flash Flood Watch through late tonight for NCZ003>006-020. Wind Advisory from 2 PM this afternoon to 2 AM EDT Friday for NCZ004>006. WV...None. && $$ SYNOPSIS...AL/WP NEAR TERM...JH/WP SHORT TERM...RCS LONG TERM...PM AVIATION...PM/WP HYDROLOGY...PM/WP