Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 241800 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 100 PM EST Sat Feb 24 2018 .SYNOPSIS... Warm and deep high pressure centered off the Southeast coast will extend over the Carolinas today, before weakening tonight as a cold front approaches the Appalachians from the west. This front will move slowly east across the area Sunday night and into Monday. Cooler high pressure will build in from the north Monday night and Tuesday. && .NEAR TERM /THROUGH TONIGHT/... As of 1010 AM Saturday... Deep ridging centered off the SE coast will continue to rule today. It`s looking like any appreciable shower activity today will hold just to the NW and N of the forecast area, closer to the 850 mb speed max, given the otherwise lack of any kinematics or dynamic forcing for ascent. But moisture will be increasing, as noted by the 12z GSO sounding compared to upstream soundings such as FFC, and as seen on model output with rising PWs through the day. Given the increase in moisture, have left in a mention of isolated showers over the extreme NW and N through the day as a weak 700 mb trough passes through. Morning stratus is hanging firm over the southeast CWA but has started to break up elsewhere, allowing at least some insolation amid passing mid and high clouds. Very warm highs in the mid 70s to around 80 still seem achievable, and will make only minor tweaks to temps through the rest of today. -GIH Earlier discussion from 330 AM: Latest surface analysis shows a stationary front draped across central North Carolina separating a rather significant N/S dewpoint and temperature spread. Currently, dewpoints/temps near the VA/NC border reside in the mid to upper 40s while those along the NC/SC border are in the lower 60s. Intermittent fog formation is ongoing across much of the area, with additional fog formation likely, especially between 4am and 10am on Saturday. Little in the way of movement with the boundary has been witnessed thus far tonight, but guidance continues to indicate a slow retreat northward likely after sunrise. This should allow temperatures to steady to even slightly increase through dawn, with intermittent mid to upper level clouds overspreading from west to east associated loosely with the cold front draped west of the Appalachian Mountains. -JJM && .SHORT TERM /SATURDAY AND SUNDAY/... As of 330 AM Saturday... Sub-tropical ridging will remain centered in the vicinity or just northeast of the Bahamas, with associated surface high pressure extending from just south of Bermuda, westward into the southeaster U.S. This pattern will maintain unseasonably warm and relatively humid conditions across central North Carolina both Saturday and Sunday. Expect afternoon temperatures in the mid 70s to low 80s each day under intermittent cloud cover, with mild overnight low temperatures in the lower 60s expected Saturday night into Sunday. Cloud cover will be thickest across the western Piedmont Counties, where intermittent shower chances will be possible Saturday afternoon and evening, and again Sunday afternoon as the front pushes into the western portion of the state. Southwesterly winds will accelerate Sunday ahead of the approaching cold front, with sustained winds 10 - 15mph with gusts up to 30mph possible. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... As of 345 AM EDT Saturday... Sunday night through Monday night: Models are starting to come into better agreement with the timing of the cold front through the area Sunday night/early Monday, that is forecast to slow down and briefly stall along coastal areas on Monday before finally pushing south and away from the area Monday night. While a decent area of showers is expected to accompany the front Sunday evening/night , the better rain chances and higher QPF amounts will likely occur post-frontal on Monday, in response to the approach of a well- defined/significant shortwave trough that will spur the development of multiple waves tracking NE along the quasi-stationary frontal zone. Current model timing indicates, rain chances will taper off NW to SE during the late afternoon/evening hours. Widespread rainfall amounts of a half inch to three quarters of an inch can be expected. Calendar day highs in most locations will occur before daybreak, prior to fropa, with widespread rain and clouds keeping daytime temperatures in the mid/upper 50s NW to lower 60s. Clearing and CAA on the leading edge of a 1030ish mb high building into the area will result in some of the coolest overnight lows that we`ve seen for some time. Lows in the lower to mid 40s, which is still a good 5 to 7 degrees above normal. Tuesday through Friday: Expect dry, slight above normal temperatures on Tuesday as a progressive surface high builds across the mid Atlantic states briefly on Tuesday, only to quickly shift off the southern Mid-Atlantic Coast Tuesday night. The later half of the work week is setting up to be wet and unsettled, with widespread showers expected Wednesday through Wednesday night, within the warm conveyor feed on the cyclonic side of the shortwave trough ejecting east out of the southern Rockies. At this time, model spread is high wrt to the eastward evolution of the this system, more specifically, when/where this system will phase with northern stream energy as it progresses into the Eastern US. Eventually this system and it`s attendant cold front will bring another round of showers and possibly some thunder to the area Thursday/Friday. Will continue to monitor. Continued mild, with highs in the 60s on Wednesday, warming into the 70s ahead of the front. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/...
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As of 100 PM Saturday... Passage of a mid level trough and increasing moisture generated patchy light precip in the Triad late this morning, however these have moved to the NE, and any further chance of impactful showers will hold well north of the central NC terminals through the next 24 hours. This morning`s sub-VFR cigs have broken up to scattered, and VFR conditions will hold through this evening. There is a chance for development of MVFR or high-level IFR cigs after 09z tonight, however a steady SW wind overnight will keep the low levels stirred, such that confidence in the occurrence of sub-VFR cigs late tonight is low. And vsbys are likely to remain VFR regardless. Any sub-VFR cigs will start to lift and break up by 16z Sun. Looking beyond 18z Sun, a trend to sub-VFR conditions will begin Sunday night as a cold front moves slowly SE through the area, settled across SE NC Mon morning. Sub-VFR conditions with showers and isolated storms will be the most likely and the longest lasting over the SE (FAY), lasting through much of Mon, while at other sites, high pressure will start to build in behind the front, leading to a trend to mostly VFR conditions Mon at INT/GSO/RDU/RWI. VFR conditions will dominate Tue/Wed under high pressure. The next chance for sub-VFR conditions will be Wed evening/night into Thu as the front heads back northward into the area as a warm front, bringing a chance for showers. -GIH
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&& .CLIMATE... RDU Records: Date | High Year | High Min Year ------------------------------------------ 02/24 81 1982 58 1985 GSO Records: Date | High Year | High Min Year ------------------------------------------ 02/24 79 1982 55 1985 FAY Records: Date | High Year | High Min Year ------------------------------------------- 02/24 83 1930 60 1975 && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield/JJM SHORT TERM...JJM/MWS LONG TERM...CBL AVIATION...Hartfield CLIMATE...RAH is the U.S. government's official web portal to all federal, state and local government web resources and services.