FXUS62 KRAH 111731 RRA AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 1230 PM EST Mon Dec 11 2023 .SYNOPSIS... A strong cold front will push off the North Carolina coast this morning. Behind the front, surface high pressure will build into the Southeast today through Tuesday. A dry secondary cold front will cross the area early Wednesday, and will be followed by another high pressure area late Wednesday into Friday. && .NEAR TERM /TODAY THROUGH TONIGHT/... As of 940 AM Monday... With the morning update, needed to increase sky cover across both the northwest and southeast portions of the forecast area. Lower clouds have held on a bit longer than expected, and the new forecast may still be a little optimistic when it comes to clouds clearing out. Made some minor tweaks to hourly temperatures, and overall reduced highs by a couple degrees in the locations with cloud cover. Previous discussion follows. As of 255 AM Monday... The strong cold front has pushed just E of the forecast area in the last hour, designated by a sudden wind shift and sharp drop in temp and dewpoint (as much as 10-15 deg F in around 10 min). The heavier showers persist just behind the front, noted by cool cloud tops and a period of enhanced gusts up to 30-40 mph, although the deepest convection has blossomed off the Carolina coast (and this is on track to pass over the Outer Banks in the next several hours). Trailing stratiform rain extends back through the E Piedmont and Sandhills at this hour, having exited the W Piedmont. (The threat of a little wet snow mixed in at the end is not zero but is low in our area, as we're likely to see drying in the mixed phase region aloft prior to temps dropping into the mid 30s or lower, meaning little to no ice in the cloud.) Satellite imagery and surface obs show strong gravity wave action behind the front (the saturated stable layer conducive to ducting is depicted on the 00z FFC sounding at 850-600 mb), and this has led to a period of surface winds over the Piedmont from the NE (when CAMs suggest we should be seeing NW winds). The potent mid level shortwave trough and strong upper level divergence helping to support the post-frontal rain will continue a gradual eastward shift, with a clearing-out of both low and mid level cloudiness from W to E through daybreak, although the Coastal Plain may retain some clouds through mid morning. Surface high pressure will build into the Southeast from mid-late morning through tonight, and as we'll be on the subsidence side of the mid level wave, skies will be generally clear. But some stratocu banked up along the W slopes may sneak through and into the Triad today, as we'll stay within a fast cyclonic mid level flow. Very warm thicknesses of 1370 m at GSO this past evening (around 50 m above normal) are expected to plunge to 15-30 m below normal by morning, suggesting highs in the mid 40s to lower 50s, despite plentiful sunshine, with brisk gusty winds diminishing throughout the day. Radiational cooling conditions will be decent, although perhaps not textbook as a light breeze may hold through the night as the surface high builds in further. Lows 23-32 under clear skies. -GIH && .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... As of 330 AM Monday... One last weak shortwave trough will cross NC early Tue morning, with flattening and still-swift mid level flow in its wake, as the split- flow longwave pattern features a large polar low over SE Canada and another low near Las Vegas. Low PWs around a quarter inch will persist through Tue, with a stable column, thus expect plenty of sunshine as the surface high settles over the Carolinas. This air mass will likely have undergone some modest modification, so expect highs to be slightly higher than today but still cool, in the upper 40s to mid 50s. Tue night, the upper level moisture currently seen upstream over the Four Corners region (including orographic enhancement of high clouds off the S Sangre de Cristos) will spread into our area, yielding an incoming veil of high clouds over NC Tue night. Expect lows of 25-36. -GIH &&. .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 301 AM Monday... Dry and cooler conditions are expected for much of the longterm period. Aloft, wnwly will dominate the period as mid-level ridging builds upstream across the central US. The ridge will slowly move east and eventually over central NC by Friday. At the sfc, cold high pressure originating in Canada will ooze down into the southeast through Friday. This feature will promote dry and cooler conditions Wednesday through Saturday as highs struggle to reach the lower 50s (Thursday in particular looks quite cool with highs in the upper 40s). Latest ensemble guidance has delayed the next chance for rain until at least Saturday night/Sunday associated with a developing trough and sfc low over the Gulf of Mexico. The GEFS continues to be a bit quicker bringing associated precipitation into our area compared to the CMC and ENS solutions. As such, leaned moreso on the CMC/ENS for introducing slight to chance POPs early Sunday morning into the afternoon period. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... As of 1230 PM Monday... TAF period: VFR conditions are expected through the TAF period. RDU/FAY are likely to waver between SCT/BKN clouds, while RWI should keep a ceiling through the afternoon. So far all cloud heights have remained VFR, but an isolated MVFR cloud observation cannot be ruled out. These clouds should fade after sunset. Wind will be out of the northwest 10G20kt, with gusts ending at sunset and wind becoming light. Outlook: Dry VFR conditions are expected through the outlook period. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Green/Hartfield SHORT TERM...Hartfield LONG TERM...Luchetti AVIATION...Green