911 FXUS62 KRAH 101955 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 355 PM EDT Wed Oct 10 2018 .SYNOPSIS... Hurricane Michael will move quickly northeast over the Southeast states late today through tonight, before passing over the Carolinas as a tropical storm late tonight through Thursday. The storm will then track off the Mid Atlantic coast late Thursday night. High pressure will build in from the northwest on Friday. && .NEAR TERM /THROUGH TONIGHT/... As of 330 PM Wednesday... High rain chances will be continued as the broad area of strong water vapor transport and elevated PW pivots northward through the area, beneath a supporting area of upper divergence, although the loss of heating will result in a downturn in coverage and precip rates. A band of stronger convection now lifting northward over north central SC will encounter marginal to moderate CAPE values of 500-1500 J/kg (highest SE) within 25-30 kts of effective shear, so have added a mention of thunder through the evening hours. Despite the lowering coverage yielding a relative lull later tonight before Michael arrives, the amount of moisture streaming in remains above normal, and will leave in a chance of showers overnight. Pops will trend back up over the far SW toward morning as Michael's circulation tracks NE over GA into SC late tonight. With cloudy (W) to mostly cloudy (E) skies, expect muggy lows of 70-74. -GIH && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... As of 355 PM Wednesday... ...The most significant impacts associated with Michael are expected across central NC late Thursday morning into Thursday evening... The rain shield with Michael will move NE through the central Carolinas Thu. While the surface wind field will have weakened from its current hurricane status, this is a powerful storm with a lot of energy, and the storm's swift movement will allow far too little time for significant dissipation of this energy. Winds just aloft around the broad center of the storm will remain quite strong, with model projections showing 40-60 kts at 925 mb on either side of the center. And forecast soundings as well as model cross sections indicate sufficient low level mixing just behind the center, as the drier air dives in behind the departing storm, for a focused, particularly intense band of winds from the N. Will monitor for this potential closely through tomorrow. Irrespective of this occurrence, the potential gusts within this still-tropical cyclone warrant an areal expansion of the tropical storm warning, and this will take place after the next NHC forecast package is issued, barring any major track change (path or speed). The flash flood watch will remain as is. Today's rain will certainly help moisten the soils, especially across the S and W halves of the forecast area, although we did not see quite the rates that were initially feared. Concern remains for what some convection-allowing models depict as an intense rain band over the N circumference of the circulation center, which could generate heavy totals on the NW side of the storm as such a band pivots counterclockwise and leads to a longer duration of heavier rain over the Piedmont. This potential has led to a slight NW shift in the expected corridor of heaviest rain, although we still expect nearly 3" over SE sections ranging to 4-6.5" over much of the Piedmont. (A lowering of rain totals over the SE would certainly be helpful to those still recovering from Florence.) Following the official track and supporting model guidance, have shown a quick decrease in rain chances from WSW to ENE as the storm pulls away late Thu night. Breezy, gusty winds from the NNW will hold areawide through much of the night. Expect highs of 74-81 Thu, followed by lows of 55-64 Thu night. -GIH && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... As of 1235 PM Wednesday... Based on the official forecast track, TS Michael will be tracking quickly NE away from NC Fri morning. Models indicate dry air moving into the area, so expect plentiful sunshine, albeit with potential stray gusty winds in its wake. Michael will leave a broad trailing frontal zone off the SE coast, with a more substantial cold front sitting just to our NW, the coldest/densest air staying temporarily blocked by the mountains. So while a dip in temps is expected Fri, readings will be just slightly below normal initially. A shortwave trough moving through the N-central CONUS early Fri will progress eastward across the Northeast states late Fri into early Sat, allowing a cool surface high centered over the central CONUS to shift eastward and push the cold front SE/SSE into our area, initiating a further drop in thicknesses by Sat morning. We should see a few clouds to start the weekend, including potential terrain- enhanced mid clouds early Sat morning in the Piedmont. Thicknesses suggest highs about two categories below normal Sat. We'll start to see a more active pattern into early next week, with greater-than-usual day-to-day variability. The surface high will shift E off the Mid Atlantic and Northeast coast Sun, sending a coastal inverted trough northwestward into the Carolinas. This will cause a rebounding of thicknesses and increased cloud cover for the latter half of the weekend. With the increased moist upglide along the northward-shifting frontal zone, will bring in small chance pops (20-30%) Sun night into early Mon, with a rebound in temps Mon as brief warm air advection returns. Another broad but amplified shortwave trough swinging through the central CONUS early Mon will swing by to our N through early Tue, taking a cold front through the area, and expect good chances of showers and perhaps a storm late Mon through Mon night. The front will stall out just to our south for Tue/Wed, with cool high pressure building in from the W and NW. Expect quiet and dry weather to move in Tue, with increasing clouds Wed as the front begins to buckle back north into the area. -GIH && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... As of 215 PM Wednesday... Adverse aviation conditions will persist at INT/GSO (MVFR to IFR) as a band of showers moves through the area. VFR conditions should hold at RDU/RWI/FAY, although a brief period of MVFR conditions with rain is possible this afternoon. This rain will decrease in coverage and intensity as it tracks northward through this evening, and will be followed by a brief relative lull (low rain chances) from mid evening through much of the night. This will allow low clouds to develop areawide, with MVFR conditions expected (and likely IFR/LIFR at INT/GSO) after 03z. These poor conditions will hold through Thu, as Hurricane Michael tracks northeastward through our region as a tropical storm. While surface winds will have decreased somewhat, the winds just off the surface will remain very strong, resulting in considerable gustiness starting in the last few hours of the TAF valid period, along with a trend to very heavy rainfall. In short, starting tonight, conditions at all TAF sites will begin to deteriorate, with strong/shifting winds with height (and potential low level wind shear) making aircraft handling very difficult. Looking beyond 18z Thu, the low cigs/vsbys and strong/shifting winds will remain problematic through much of Thu night. Clearing skies and improving aviation conditions from W to E are expected Fri morning as Michael moves quickly NE away from the area, although winds may remain gusty for a longer time. VFR conditions are expected to dominate for much of the Fri through Mon period, with high pressure extending in from the NW, although sub-VFR stratus/fog is possible late Sat night into early Sun as a warm frontal zone briefly pushes northward into the region. A little rain is possible late Sun into Mon ahead of a cold front that will move in from the W late Mon. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... Tropical Storm Warning for NCZ028-042-043-073>078-083>086-088-089. Flash Flood Watch from Thursday morning through late Thursday night for NCZ007>011-021>028-038>043-073>078-083>086-088-089. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield SHORT TERM...Hartfield LONG TERM...Hartfield AVIATION...Hartfield