Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 242339 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 737 PM EDT Sun Mar 24 2024 .SYNOPSIS... Cool and dry high pressure will extend southward through the region through Tuesday. This high will weaken and give way to warmer air starting late Tuesday, ahead of a storm system that will impact our area Wednesday through Thursday night. && .NEAR TERM /THROUGH TONIGHT/... As of 255 PM Sunday... Quiet but cold night ahead. A very dry and stable column will persist, as the surface high centered over Quebec will continue to nose southward through central NC, while aloft, the axis of the strong mid level shortwave ridge will settle overhead. A few wispy high clouds riding atop the ridge will spread into W sections, but otherwise skies will stay clear tonight. As the height gradient between the deep NW-Atlantic low and the low level ridge continues a gradual decrease through tonight, surface winds and gusts should slowly decline, with nearly calm or very light NE winds after decoupling takes place toward sunset. These excellent radiational cooling conditions combined with low dewpoints should culminate in low temps tonight within a few degrees of 32F, particularly across the Piedmont and W Sandhills through the heart of the low level thermal trough where winds will be lightest. Expect lows across the area of 28-34, coldest in the rural and far N Piedmont. These lows line up well with the existing frost advisory and freeze warning, and will maintain these alerts as is. -GIH && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... As of 315 PM Sunday... Another dry day but with increasing clouds. The surface ridge will remain in place but slowly modify as its center drifts ENE to the Canadian maritimes, although some degree of CAA will persist as the flow around the deep low parked offshore continues to reinforce the low level NNE winds in our area. As the large longwave trough over the western CONUS edges eastward, the increase in southwesterly upper level flow will bring increasing high clouds, esp across the Piedmont, through Mon night, while the mid levels remain very dry and stable. After a cold start, expect highs in the 60s. Lows will be 36-41 with a much lower risk of frost compared to tonight. -GIH && .LONG TERM /TUESDAY THROUGH SUNDAY/... As of 145 PM Sunday... The main forecast impacts in the extended continue to revolve around a potent system in the Wed to Thu night period, with impacts largely centered around late Wed through Thu. Tue-Wed: A shortwave over the Mid/upper Mississippi Valley will track NE into the Great Lakes and Canada, while a ridge over the Carolinas slowly slides east off the coast. At the surface, a CAD wedge will slowly erode but likely remain over the northern and northwest Piedmont to some extent. High pressure will slide off to near Delmarva by late-day Wed. A cold front will approach into the TN valley, while an area of low pressure forms over southern GA. Most of the energy with the upper-trough still appears to glance our area, but isentropic ascent will aid rain/showers as early as Tue evening across the far west, but the best chance appears to be overnight Tue night into Wed afternoon. Precipitation may have a hard time remaining together over the Coastal Plain as the ridge holds steady here, such that highest PoPs will be over the Piedmont. Below normal temps are expected, with a wide range possible Wed in the in-situ wedge with near 60 NW to low 70s SE. Wed night-early Fri: The suite of ensemble guidance still suggests a high likelihood of rain from late Wed night through Thu, with decreasing chances late Thu night to early Fri. Probabilistic data shows a range of 1-1.5 inches of rain possible for this period, with a 30-40 percent chance of over 2 inches. While there are still varying model solutions, with the GFS about 6-12 hours faster with the surface low, the top two ensemble cluster solutions would favor a slower onset/end time than the GFS. This would put the highest rainfall chances overnight Wed into Thu eve. A southern stream wave will track up into the Carolinas, setting up a surface low development from GA to somewhere along/off the coast of the Carolinas. Model spread is still evident with the low track, but the suite of solutions favor strong lift east of the trough with strong upper divergence, anomalous PWs, and frontogenetical forcing on the NW side of the low. It is no surprise WPC has us in a marginal risk of excessive rain, which could increase in later updates if the trend continues in this manner. Gusty winds are also possible Thu into Fri as the gradient strengthens with the low offshore. Fri-Sun: NW flow builds in as the trough departs on Fri. High pressure will set up over the NE Gulf, bringing in return SW flow and aiding highs rising above normal int the 70s by Sat to possibly 80 in spots Sun. Some guidance suggests a back door cold front Sat night or Sun with a chance of rain, but most ensemble members are dry so have kept the forecast in this manner until better agreement can be reached. && .AVIATION /00Z MONDAY THROUGH FRIDAY/...
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As of 737 PM Sunday... VFR conditions expected over the next 24 hours. Light northeast surface winds overnight with mostly clear skies. A few high clouds expected to slowly move in from the west late afternoon tomorrow. Outlook: Dry and VFR conditions will continue Monday. Early morning stratus appears possible Monday night into Tuesday morning. Rain showers and sub-VFR conditions then appear likely Wednesday into Thursday.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... Freeze Warning from midnight tonight to 9 AM EDT Monday for NCZ007>011-021>027-038>040-073>076. Frost Advisory from midnight tonight to 9 AM EDT Monday for NCZ028- 041>043-077-078-083>086-088-089. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield SHORT TERM...Hartfield LONG TERM...Kren AVIATION...CA/Luchetti

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