FXUS62 KRAH 040800 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 300 AM EST Wed Dec 4 2024 .SYNOPSIS... Arctic high pressure over the region will move offshore this afternoon, with onset of southerly return flow allowing a brief warm- up before a reinforcing arctic front crosses the region Thursday. && .NEAR TERM /TODAY AND TONIGHT/... As of 300 AM Wednesday... Reloading of the upper trough gets well underway as a deep upper low and associated upper trough swing southeast through the Upper Midwest, Upper Great Lakes, and Ohio Valley through tonight. Under quasi-zonal flow aloft, heights will steadily decrease with 30-50 meter height falls overspreading the area tonight. At the surface, Arctic high pressure will move off the SE US coast during the afternoon, ahead of a cold front that will be on our western doorstep by daybreak Thursday. Despite the synoptic forcing moving into the area, the lack of substantial moisture transport into the area will result little in the way of cloudiness with mostly sunny/clear skies prevailing. Onset of southerly winds will result in a modest moderation of the cA in place. Highs ranging from mid 40s north to near 50 south. Winds will gradually increase with gustiness developing as a 40-50kt LLJ overspreads the area during the late afternoon and into the overnight hours. A well mixed BL with steady SSWLY winds of 10 to 20 mph will keep temps up overnight. Not as cold with lows in the lower to mid 30s. && .SHORT TERM /THURSDAY AND THURSDAY NIGHT/... As of 300 AM Wednesday... ...Reinforcement of Arctic Air Thursday Night... ...Wind chills in the single digits to lower teens at the bus stop Friday morning... The upper trough will move through the region in clipper fashion and will propel a dry, reinforcing Arctic cold front through the area during the morning and early afternoon hours. Frequent pre and post frontal gustiness of 25 to 35 mph is expected through the afternoon the early evening, before subsiding Thursday night. The NW to SE timing of the frontal passage will govern daytime highs and will feature a sharp temperature gradient across the area. Highs ranging from mid 40s north to upper 50s/near 60 across the SE. Strong CAA Thursday night will bring very cold temps and low wind chills. Lows in the mid/upper teens to lower 20s, with wind chills in the single digits to lower teens. && .LONG TERM /THURSDAY THROUGH TUESDAY/... As of 230 PM Tuesday... Broad northwesterly flow aloft will continue Friday through the weekend, eventually veering and becoming southwesterly on Sunday. At the surface, a sprawling 1030+mb high will position itself over the Ohio Valley on Friday and off the NC coast Sunday. Friday will be quite chilly with highs in the upper 30s to lower 40s, gradually moderating into the mid 40s and mid 50s Saturday and Sunday respectively. Lows will follow a similar trend, with teens Friday night, mid 20s Saturday night, and upper 30s Sunday night. There is general ensemble agreement in a southern stream trough developing on Sunday with mid level moisture and forcing for ascent overspreading the area early next week. Unfortunately, there remain differences with respect to the trajectory that this trough will take, with some scenarios taking the trough northward into the Great Lakes with minimal precip across NC, while others take a more southern track with more widespread rainfall. I will maintain NBM PoPs in the 40-50 percent range Monday into Tuesday, but this remains a low confidence portion of the forecast. At this point it looks like temps should be sufficiently warm for an all-liquid precip forecast, given antecedent surface high pressure migrating offshore (southeasterly surface winds) vs holding strong over eastern Canada (northeasterly surface winds). && .AVIATION /06 WEDNESDAY THROUGH SUNDAY/... As of 125 AM Wednesday... TAF period: High confidence in VFR conditions through the TAF period. Light and variable winds will become SWLY after daybreak and will increase with gusts of 15-20 kt by the afternoon. SWLY Winds will stay up Wednesday night, with some intermittent gustiness as a strong ~45-50kt LLJ overspreads the area, resulting in LLWS at all TAF sites. Outlook: Gusty conditions will continue on Thursday, ahead of a dry cold frontal passage, with a period of NWLY post frontal gustiness Thursday evening/night. Otherwise, VFR conditions should continue through the weekend. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...CBL NEAR TERM...CBL SHORT TERM...CBL LONG TERM...Leins AVIATION...CBL