583 FXUS62 KRAH 301944 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 245 PM EST Fri Dec 30 2022 .SYNOPSIS... High pressure centered offshore will bring a warm southerly flow into the area through tonight. A storm system will move through the region Saturday morning through Saturday night, before pushing offshore Sunday morning. Mild high pressure will build into the area Sunday through Monday. && .NEAR TERM /THROUGH TONIGHT/... As of 245 PM Friday... Today's very pleasant, warm, and (mostly) sun-filled weather is slated to deteriorate tonight. Precip will be very spotty and light for much of tonight, but chances will ramp up late tonight. The stratiform/overrunning light rain and drizzle has thus far held just W and SW of the CWA, over the far W Piedmont into the Foothills, while in our SE within the moist onshore flow, we're just in the last couple of hours seeing some vertical extent to the convective clouds along and NW of an inland-tracking sea breeze. Coverage over the W Piedmont is being enhanced just ahead of the passage of a mid level perturbation NNE-ward through the Carolinas, but moisture remains shallow over the region with ACARS soundings in the Triad and current WV imagery showing lots of dry air in place through the mid and upper levels. So once this mid level wave passes to our N this evening, we should be in a relative lull of precip chances in our W until late tonight, however steady moist upglide around 290- 300K over the far W Piedmont will keep a risk of light drizzle over W sections. Further E, an isolated sprinkle is possible over the far E coastal plain for a few more hours, although low level moisture here is even less abundant below the dry mid-upper levels with limited forcing for ascent closer to the ridge axis aloft, which should keep coverage low. Dry weather will continue between these two features, over the E Sandhills through the central and E Piedmont, through much of tonight. But moisture will steadily increase and deepen over central NC late tonight as the mid level shortwave trough tracks NE through TX/LA/AR with a sharpening SWrly upper jet to its ENE inducing strengthening upper divergence over the Carolinas to accompany the gradual mid level height falls, although the majority of this forcing for ascent will hold off until after 12z Sat, when PW climbs quickly well over 1". Will gradually draw pops up to 15-25% areawide late tonight, with the higher end of these values over the far W and far E. The current very warm temps in the 60s to mid 70s will fall off toward sunset but should level off with steady WAA overnight and overspreading clouds. Expect lows in the upper 40s to mid 50s. -GIH && .SHORT TERM /SATURDAY AND SATURDAY NIGHT/... As of 410 AM Friday... A shortwave trough will lift northeast and glance the srn mid Atlantic late Sat and Sat night, during which time a surface warm front will retreat north across GA and the ern and cntl Carolinas. Despite the nwd retreat of that warm front, convection and diabatic cooling across the Deep South, and a lack of more-prolonged maritime- modified air, will cause the richer low-level theta-e and instability to hold mainly to the south of cntl NC through the forecast period. Nonetheless, modest steepening of mid-level lapse rates to around 6-6.5 C/km will support a risk of weak destabilization (up to a few hundred J/kg) across cntl NC during the afternoon through evening, during which time an area of showers and isolated storms are expected to blossom and track northeast across the forecast area. Given a relative split between the stronger forcing for ascent passing to the northwest and only glancing cntl NC, and the reservoir of stronger instability holding to the south and more south just offshore, rainfall amounts are expected to only range from around a half to three quarters of an inch. And while strong, generally unidirectional flow aloft will overspread the region through the evening, including ~50 kts in the mid-levels, the aforementioned lack of instability suggests any severe threat will be low, and conditional upon greater instability being realized. It will otherwise be cloudy, mild, and slightly more humid as surface dewpoints increase through the 50s, with high temperatures ranging from the upr 50s across the nw Piedmont to the upr 60s in the ern Sandhills and srn Coastal Plain. The brunt of the convection will move east and out of cntl NC before midnight, except for perhaps in the Coastal Plain, but a lack of stronger low level flow and drying suggests areas of low stratus and fog will linger and/or redevelop overnight-Sun morning. Some fog may become dense; and this threat will be included in the Hazardous Weather Outlook. Lows in the mid 40s to mid 50s. && .LONG TERM /SUNDAY THROUGH FRIDAY/... As of 157 PM Friday... Not much change in the extended forecast with today's 12Z suite of model data. Sunday will see the surface trough/decaying front shifting off the Mid Atlantic coast with weak surface ridging building in throughout the day across the Piedmont. Any lingering morning cloud cover should dissipate through the day as flow aloft takes on a more zonal configuration. All in all, New Years Day should be quiet and dry with above normal highs in the mid/upper 60s and lows in the upper 30s/lower 40s. The trend of above normal temperatures will continue through much of the upcoming week. Mid/upper level ridging will set up across the Southeast US early next week in response to a deepening low moving through the Desert Southwest, and 500mb heights across the region will range from 579-582dm Monday into Tuesday. Eventually the aforementioned low will move into the Plains and track through the Ohio Valley by the middle of the week, importing even warmer temperatures and moisture into the area. Highs early in the week should range from the mid 60s in the NW Piedmont to the mid 70s in the southern Coastal Plain. While Monday should remain mostly sunny, clouds will be on the increase by the time we get to Tuesday but decreased insolation should be offset by increased warm advection at the surface and aloft ahead of the approaching low. Overnight lows during this period will also be mild, with Wednesday morning being particularly warm with lows only bottoming out in the upper 50s to low 60s (would threaten record warm minimum temperatures for January 4 if they verify). The exact track and intensity of this low has wavered a bit among the deterministic models over the last day and some differences remain in today's 12Z guidance. However the 100 member GFS/EC/CMC cluster analysis still favors increasing chances for precip across the region by the middle of the week regardless of where the upper level (and surface) lows end up tracking. Still going with anywhere from 70-80 percent chances of rain on Wednesday when moisture transport and isentropic forcing for ascent should be maximized across the area. Wednesday will also see breezy southwest winds ahead of the approaching front with speeds in the 15-25mph range, with locally higher gusts within any embedded convective elements. Eventually the low will drag a cold front through the area but this may not actually happen until Thursday. Lots of spread among the ensembles with respect to how quickly this front moves through the area (and consequently - when precip will taper off from west to east). Will hang on to at least some mention of showers into Thursday before drying things out entirely Thursday night/Friday. Post-frontal temperatures to close out the week will be much closer to early January normals with highs in the low 50s. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... As of 100 PM Friday... Current VFR conditions across central NC will remain dominant through mid evening, but confidence is high in deteriorating conditions tonight. Wind flow from the S in the lowest few hundred ft AGL will continue ahead of an approaching storm system moving in from the WSW, aided by the circulation around offshore-centered high pressure to our E. Increasing moisture at multiple levels, including near the ground, will foster development of widespread low stratus and fog mainly after midnight tonight, helped by very weak surface winds, as cigs/vsbys drop quickly through MVFR to IFR. Some improvement in vsbys is possible at FAY after 14z with cloud breaks leading to improve vsbys, but elsewhere the IFR conditions should persist through Sat morning, with the onset of rain after 14z in the western terminals. Poor aviation conditions will prevail at INT/GSO/RDU/RWI through early afternoon. Looking beyond 18z Sat, an area of steady rain with embedded storms and sub-VFR conditions will continue moving eastward across central NC through mid Sat evening, then push to our E Sat night, although the threat of low vsbys in fog will linger overnight. Trends to VFR are expected roughly 06z-09z western terminals and 09z-13z Sun eastern terminals, and these conditions will hold through early Tue, although patchy fog is possible early Mon morning. Sub-VFR conditions are expected with rain and storms Tue afternoon through Wed night. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield SHORT TERM...MWS LONG TERM...Leins AVIATION...Hartfield