419 FXUS62 KRAH 092118 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 518 PM EDT Tue Oct 9 2018 .SYNOPSIS... High pressure centered to our northeast will extend into the area through tonight. Hurricane Michael is forecast to move northward over the Gulf of Mexico through tonight, before making landfall over the Florida panhandle Wednesday. The storm will then move quickly northeast over the Southeast states and Carolinas Wednesday night through Thursday night. High pressure will build in from the northwest on Friday. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... As of 250 PM Tuesday... The threat of shallow showers, driven by low level destabilization prompted by heating, will continue for a few more hours, with the greatest coverage over E and N sections along a band of slightly higher PW and accelerating low level moisture transport from off the Atlantic. This activity should translate to our NW and wane during the early to mid evening with loss of heating. Higher level moisture over the region as noted on GOES water vapor channels is expected to continue lifting north tonight, and the temporary reduction in high clouds will likely facilitate radiational cooling and fog/stratus development overnight. But the low level water vapor channel also shows some relative drying, with models depicting steady or slightly lower moisture influx in the low levels, so the extent of any such fog/stratus is uncertain. The latest HRRR runs are pretty timid, showing little or no fog/stratus for much of the night. Toward morning, however, the band of higher moisture transport/PW now oriented from just NE of the Bahamas northwestward into SE GA will translate northward, getting into our far S sections late tonight. Pops will depict the downward trend this evening, then a return to higher pops late arriving from the S, along with a trend to overcast skies. Muggy lows of 66-71. -GIH && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... As of 330 PM Tuesday... Hurricane Michael is expected to make landfall over the FL Panhandle or Big Bend on Wed, then accelerate to the NE, crossing the Carolinas Thu/Thu night, as it gets picked up by the mean SW steering flow. The ECMWF remains one of the slower solutions, still over NE NC at 12z Fri, with the latest GFS not far behind and the latest NAM faster, in line with the official forecast track. The band of enhanced moisture now streaming into SE GA will translate N through central and E NC Wed, bringing high pops and an initial round of moderate to briefly heavy rainfall. This presents a problem in terms of messaging (letting people know that this first bout of rainfall is indirectly, not directly, associated with Michael) as well as service (some spots may get enough heavy rain Wed to warrant flood advisories or perhaps warnings). At this time, the threat of very heavy rain on Wed should not present a widespread flooding threat, so will not start a flood watch this early, but this potential will be monitored closely through tonight. Expect a trend to categorical pops from SSW to NNE as this band shifts through the area Wed. Highs mostly in the mid 70s to lower 80s. A short relative lull is expected Wed evening between this rain band and the rain shield directly associated with Michael. Heavy rain is expected to shift into our SW sections prior to daybreak Thu, then overspread the area through Thu evening before tapering down late Thu night. General model consensus indicates rainfall potential of 3- 6" over the forecast area during this time, and will go ahead with a flash flood watch for the entire area, starting at 6 am Thu (although this may need to be started earlier in the far SW), running until 5 am Fri. Based on the latest track and wind decay, sustained speeds are likely to be in the 15-25 mph range over the W (W of highway 1), with gusts of 25-30, while sustained speeds in the 20-30 mph range and gusts of 30-40 mph are expected from highway 1 E. We may need a tropical storm warning at some point across the SE sections, and this will be evaluated over the next day. Expect lows of 69-74 Wed night, highs in the mid 70s to around 80 Thu, and lows in the upper 50s to mid 60s Thu night as the post- Michael cooler air begins to roll in. -GIH && .LONG TERM /THURSDAY THROUGH TUESDAY/... As of 335 PM Tuesday... Based on the official forecast track, TS Michael will be tracking quickly NE away from the N NC coast Fri morning. So while there may be a lingering rain and gusty wind threat in the NE early in the day, we should see improving conditions. Models indicate dry air moving into the area, so expect plentiful sunshine. Michael will leave a 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. A shortwave trough moving through the N-central CONUS early Fri will progress eastward across the Northeast through Fri/Sat, allowing a cool surface high centered over the central CONUS to shift eastward and push the cold front SE/SSE into our area. After a dip to near normal temps Fri, the secondary front will initiate a further drop in thicknesses by Sat morning, with perhaps just a few clouds to start the weekend, including indications of terrain-enhanced cirrus early Sat morning in our NW. The surface high will shift E off the Mid Atlantic and Northeast coast Sun, sending a broad coastal inverted trough westward into the Carolina coastal sections, causing a rebounding of thicknesses and increased cloud cover for the latter half of the weekend. We'll get into a more active pattern for the Sun-Tue time frame, with broad and fast WSW steering flow across NW Mexico and the southern and SE CONUS bringing greater cloudiness. This pattern will include the remnant moisture and energy from Sergio, which will cross OK/N TX Sat/Sat night before tracking quickly NE and shearing out to our N. While it's not clear that we'll see rainfall from this system, at the very least it will help draw the frontal zone back northward as a warm front Sun through Mon, although lingering in situ CAD on Sun should keep cloud cover elevated and temp rises muted. Thicknesses will rise back to near normal readings Mon, holding into Tue, although another broad northern stream shortwave that will drop through MT/WY and the Dakotas over the weekend will push a cold front into NC by Tue. As a result, the forecast will show an increase in rain chances Tue with frontal passage expected. This should bring temps back below normal for midweek. -GIH && .AVIATION /21Z TUESDAY THROUGH SUNDAY/... As of 136 PM Tuesday... 24 hour TAF period: SCT to BKN VFR ceilings are the general rule across central NC this afternoon. However, isolated to widely scattered showers with short lived CIG and VSBY restrictions are developing and spreading inland to the northwest. These showers should diminish around sunset before period of sub-VFR conditions develops late tonight, with more wide spread MVFR/IFR conditions mostly in CIGS, with some LIFR conditions possible, mainly across the Triad. Light northeast to easterly winds are expected through the period at 10kts or less. Looking further ahead: A band of showers and a few thunderstorms will lift northward across central NC on Wednesday afternoon and evening followed by a lull before for most of Wednesday night. More widespread showers and thunderstorms along with windy conditions associated with Hurricane Michael will spread across the area from the southwest on Thursday and continues into Thursday night. Weather conditions will improve significantly and dramatically on Friday and continue into the weekend. -Blaes && .RAH WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch from Thursday morning through late Thursday night for NCZ007>011-021>028-038>043-073>078-083>086-088-089. Tropical Storm Watch for NCZ028-042-043-077-078-085-086-088- 089. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield SHORT TERM...Hartfield LONG TERM...Hartfield AVIATION...Blaes