Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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777 FXUS62 KRAH 241725 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 125 PM EDT Thu May 24 2018 .SYNOPSIS... A weak cold front will settle across South Carolina this afternoon, and remain stationary through Friday. Meanwhile an area of high pressure will build into central NC from the northeast. This high will move offshore by the weekend, resulting in a return to a moist and unsettled weather pattern. && .NEAR TERM /THROUGH TONIGHT/... As of 1105 AM Thursday... A sfc cold front at 15Z had settle into South Carolina. With the best low level forcing to our south, the cluster of showers with heavy rain has temporarily ended across the southern counties. Later this afternoon, the moist air mass will become slightly unstable, and support the development of scattered convection, primarily along and south of a Laurinburg to Ansonville line. An area of high pressure extends aloft over the Carolinas, attributing to a very light wind flow. Since the steering flow will be less than 10 kts, the heavier showers and storms will be capable of dumping locally heavy/excessive rainfall, likely prompting the issuance of a few flood advisories. Farther north across the northern counties, northeasterly low level flow will advect a drier more stable air mass into this region. This has led to dewpoints in the upper 50s-lower 60s. The arrival of the stable drier air mass will prohibit the development of convection through early this evening. Afternoon temperatures will remain warm, with highs in the low-mid 80s. Tonight, scattered convection primarily over the southern Piedmont will diminish with the loss of heating. The presence of the lingering boundary immediately to our south and available moisture will maintain a small threat of a shower overnight. Overnight temperatures generally in the 60-65 degree range with a few upper 50s probable at the normally cooler locations in the northeast. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... As of 315 AM Thursday... The mid level ridge axis extending from NE of the Bahamas into the Southeast will start to be broken down by both a shortwave trough moving through the Upper Midwest into the W Great Lakes as well as by a weak but expansive mid level trough covering the Lower Miss Valley and Gulf of Mexico. Flow through the low and mid levels will strengthen from the SSE and S, drawing deepening moisture into S and W parts of central NC, with less influence over NE sections still within the scope of influence of the offshore-drifting low-level ridge. This will result in an increase in clouds, thickest over the S and W CWA, although precip chances won`t immediately increase substantially given the light winds through the column and lack of mechanisms to force ascent, as well as the clouds themselves which will decrease heating, thus limiting CAPE. Nevertheless, PW is forecast to rise well over 1.5" over the SW CWA, sufficient to keep chance pops in this area Fri through Fri night, with lower to no pops further NE. Expect highs to be similar to today, mostly lower to mid 80s. With the clouds and rebounding dewpoints, lows Fri night should respond accordingly, popping back up to above normal readings in the mid to upper 60s. -GIH && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 335 AM Thursday... Much of the long term forecast will be consumed by what could be our first tropical system of the year coming out of the Gulf of Mexico. The current tropical weather outlook from the National Hurricane Center gives the system a 70% chance of formation within the next five days. Regardless of if that happens or not, the result for central NC will be the same. That is, a lot more moisture over the area and rain chances through the long term forecast. This is the first hint we have seen at longer term deterministic models coming into better agreement on where the storm might end up. For Saturday, both simulations put the storm between Western Cuba and Southwest Florida with the EC solution further west. That is important because that scenario is mirrored through the forecast with the GFS bringing the system into the Florida Panhandle and into GA/AL before dissipating and being caught up in the northern stream flow. The EC solution stays west and brings the system into Louisiana on Monday evening before moving it north into Mississippi and spinning it there for several days. Both of these scenarios bring a wave of heavy rain through the Carolinas Sunday afternoon through Monday which could be our wettest period. Chances for rain and thunder will be present throughout the period but like recent afternoons, expect some breaks in the rain in time and space and that could leave some folks dry for periods of time. While rain will definitely be a concern for central NC given that we have already had an extended period of wet weather, wind is not expected to be a problem in this area. Temperatures through the period will top out in the 80s with lows in the upper 60s to low 70s making it very humid throughout the long term forecast. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... As of 125 PM Thursday... While VFR parameters will persist over the northern TAF sites through this evening, low end VFR/MVFR conditions are probable in vicinity of KFAY through this evening due to ceilings and scattered convection. Late tonight, VFR conditions appear likely at KRWI, KFAY and KRDU thanks to an area of high pressure. There may be a brief instance of MVFR/IFR ceilings at KFAY between 09Z-13Z Friday. Over the western Piedmont, including KINT and KGSO, circulation around the sfc high should advect low level moisture and cause a deck of low stratus to develop, mainly between 10Z-15Z Friday. This stratus deck should gradually lift into a scattered cu field by mid day. The weather pattern will become increasingly unsettled from Saturday through Tuesday across central NC, with a high probability of MVFR ceilings along with scattered-widespread showers and a few thunderstorms. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...WSS SHORT TERM...Hartfield LONG TERM...Ellis AVIATION...WSS

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