FXUS62 KRAH 270801 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 400 AM EDT Sat Jul 27 2024 .SYNOPSIS... High pressure will extend across the Middle Atlantic and Carolinas through the weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 350 AM Saturday... A shortwave trough in generally nly flow aloft, and preceding weak, 10-20 meter 500 mb height falls, will pivot across and offshore the srn Middle Atlantic through this evening. At the surface, ~1022 mb high pressure will build from the nrn Middle Atlantic swd and across the Carolinas. Multi-layered overcast this morning, including mid-level ceilings and patchy light rain associated with lift accompanying the aforementioned shortwave trough aloft, will gradually clear from northeast to southwest as drier air upstream advects swwd and ultimately to the surface with diurnal heating/mixing. With resultant afternoon surface dewpoints in the 60s, it will feel less humid than the 70s of recent days, with highs a few degrees below average and in the 80s. Clear and calm tonight will favor strong radiational cooling and lows mostly 60-67, with a few upr 50s possible in typically cooler areas. && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... As of 400 AM Saturday... High pressure over the Middle Atlantic and Carolinas Sunday will move east and offshore Sunday night. Dry air accompanying the ridge will result in afternoon/mixed surface dewpoints in the upr 50s-lwr 60s, with near average high temperatures in the mid 80s to around 90. Sunday night will be milder with lows mostly in the mid 60s to around 70, mildest west where mid-level ceilings and virga accompanying an approaching mid-level trough will arrive late. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 315 AM Saturday... A positively-tilted trough axis from the Great Lakes to the lower Ohio Valley is forecast erode the ridge axis over the Northeast and Mid-Atlantic while lifting the closed low off the northern Mid- Atlantic coast northeast towards New England. This will promote a surge of moisture (PWAT 1.75 to 2 inches) within the southwesterly flow and deposit a baggy trough situated from the Ohio Valley through the Mid-Atlantic and Southeast. At the surface, generally southwesterly flow east of the lee trough will steadily increase southerly moisture advection as the remnant front lifts north and through central NC by Tues night. Perturbed flow from upstream disturbances will bring back showers/storm chances maximized during the afternoon/evening of the diurnal cycle. Ensemble guidance continues to show the mid/upper level trough lingering over the area, but perhaps slowly shifting eastward through midweek and towards the Mid-Atlantic coast by Thurs afternoon, shifting the greatest coverage of convection towards the Coastal Plain Thurs into Fri. Temperatures will creep back to above normal as low-level thicknesses steadily rise through the extended forecast beyond Mon. Although forecast confidence is lower for Thurs/Fri, Ensemble guidance highlights 40-60% chances for 850mb temperatures to rise above 20C, which would favor the potential for mid/upper 90s for highs. Although this is heavily skewed by the GEFS and its members with EPS and GEPS closer to 20-40% chances by Fri afternoon. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... As of 200 AM Saturday... Lingering moist, nely low-level flow will favor the expansion and lowering of IFR-MVFR ceilings across cntl NC through early this morning. However, drier air just upstream across VA and nern NC will gradually advect swwd and cause the low ceilings to disperse from northeast to southwest (ie. first at RWI and RDU) between 08-14Z. Otherwise, a little light rain will also be possible this morning, especially at RWI, as a mid/upr-level trough and associated lift pivot across the srn Middle Atlantic. Outlook: High pressure will extend across cntl NC and favor VFR conditions through the weekend. A chance of mainly afternoon- evening showers and storms will return early-mid next week. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...MWS SHORT TERM...MWS LONG TERM...Swiggett AVIATION...MWS