609 FXUS62 KGSP 110554 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 154 AM EDT Thu Oct 11 2018 .SYNOPSIS... Heavy rain and gusty winds associated with Hurricane Michael will impact the area tonight and Thursday. Cool high pressure will build in Friday and bring seasonably cooler and drier air into the region through the weekend. A cold front will impact the area early next week with a chance of showers. && .NEAR TERM /THROUGH TODAY/... Showers associated with the outer bands of Matthew and upslope flow are spreading back into the area from the SW. Very heavy rainfall rates expected to redevelop overnight. There will be a window from 06-ish to 15-ish Z in which ingredients will be sufficiently aligned to produce a tropical tornado concern south and east of I-85, although the higher threat will certainly be south of the forecast area, which will be more solidly in the right front quad/ favorable hodograph environment. In terms of the winds, being that Michael has made landfall as a category four storm, there is some concern that the traditional model guidance may be spinning the storm down too quickly, thus under-doing the inland winds. This is always a very tough forecast, and the Tropical Storm Warning that was issued earlier for our southern tier of zones was mainly done to accommodate the tropical storm wind probability info from NHC. The other wind-related concern is the potential for hybrid convective gusts associated with any intense rain bands, which could easily produce occasional 50 mph (or greater) winds. Thus, while our official forecast doesn't really support the headlines, the uncertainty regarding the intensity of the cyclone and the potential for occasional higher end wind gusts warrants continuation of the Tropical Storm Warning. Of course, the primary concern going forward will be the heavy rainfall, flood/flash flood potential. As the cyclone experiences increasing environmental shear on its northeast track, it will take on more in the way of extra-tropical characteristics, with the axis of heaviest rainfall becoming increasingly concentrated in a relatively narrow (i.e., ~75 mile) axis along and to the left of the cyclone center associated with intense deformation zone. Thus, the track of the storm will be critical in determining which areas just get heavy rain, and those that get intense/excessive rainfall. 3-5 inches, with locally higher amounts of as much as 7 inches will be possible within this axis. Being that the bulk of that would fall in < 10 hours, flash flooding is certainly a concern, with the most likely area of concern being across the lower/eastern SC Piedmont, and the southern NC Piedmont, including much of the Charlotte metro area. A secondary enhanced area of concern will be along the eastern Blue Ridge escarpment, where additional amounts of 2-4 inches appear likely, on top of the 1.5-2.5" that have already occurred. No changes are necessary to the Flash Flood Watch at this time. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... As of 130 AM Thu: Surface high pressure will filter into the Southeast Friday bringing a dry northwesterly flow across the CWFA and the return of temps very close to normal. However, a fast-moving shortwave will move all the way from the central Plains to New England between Friday afternoon and Saturday afternoon, with a cold front in tow. While the best lift will be north of our area, a brief chance of precip will accompany these features as they cross the mountains early Saturday. Another, cooler sfc high will move in behind the front, bringing temperatures a little below climo for Saturday afternoon. This front will weaken and stall across the Southeast Saturday night. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 230 PM Wednesday: A series of troughs will drop into the central part of the county during the early to middle part of next week. A surface cold front will bring the chance of showers to the mountains on Sunday and the entire forecast area on Monday. High pressure will build in for Tuesday and Wednesday leading to seasonably cool and dry conditions. Temperatures will be autumn-like with morning lows in the 30s and 40s in the mountains and 50s in the Piedmont. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... At KCLT and elsewhere: Widespread IFR across the area at TAF time will see little improvement until later this morning. SHRA overspreading the Upstate and will continue to lift north. Cannot rule out isolated thunder but not enough to include in TAFs at this time. Should see rapid clearing from the W generally starting around or just after 18z with cigs lifting through MVFR and to VFR by this evening. Winds will also be on the increase out of the E through the early morning hours with pretty steady gusts to 30kt or thereabouts today with continued LLWS concerns, but as the center of Michael passes to our south today, winds will shift rapidly N to NNW. Winds will diminish after midnight for all but KAVL, where 20-25kt gusts will continue through the end of the period. Outlook: Fair conditions develop for the weekend, but restrictions will be possible again early next week as a cold front approaches the area. Confidence Table... 06-12Z 12-18Z 18-24Z 00-06Z KCLT High 94% Med 69% High 91% High 100% KGSP Med 65% Med 76% High 100% High 100% KAVL Med 66% High 83% High 96% High 100% KHKY Med 65% High 82% High 94% High 100% KGMU Med 79% Med 78% High 100% High 100% KAND High 81% High 82% High 100% High 100% The percentage reflects the number of guidance members agreeing with the scheduled TAF issuance flight rule category. Complete hourly experimental aviation forecast consistency tables and ensemble forecasts are available at the following link: www.weather.gov/gsp/aviation && .GSP WATCHES/WARNINGS/ADVISORIES... GA...Flash Flood Watch through this evening for GAZ028-029. Tropical Storm Warning for GAZ029. NC...Flash Flood Watch through this evening for NCZ033-049-050-053- 064-065-501>510. Flash Flood Watch from 6 AM EDT this morning through this evening for NCZ035>037-056-057-068>072-082. Tropical Storm Warning for NCZ082. SC...Flash Flood Watch through this evening for SCZ002-003-005>007- 010>013-019. Flash Flood Watch from 6 AM EDT this morning through this evening for SCZ008-009-014. Tropical Storm Warning for SCZ009-011>014-019. && $$ SYNOPSIS...SW NEAR TERM...JDL/RWH SHORT TERM...SW LONG TERM...DEO/SW AVIATION...TDP