Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 180245 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 945 PM EST Sun Dec 17 2017 .SYNOPSIS...
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A trough will move rapidly east and offshore overnight. A warm front will move north into southern sections of NC Monday night and Tuesday. Low pressure will approach from the west Tuesday night and Wednesday.
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&& .NEAR TERM /THROUGH TONIGHT/...
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As of 945 PM Sunday... The light rain and sprinkles are moving rapidly east with the weakening trough mid to late evening. Clearing has yet to show up even in the Appalachians in the rear of the trough. It appears that clearing will not occur until late tonight in the west, with lingering clouds all night in the east. If we do get clearing, the top of the ground may be just wet enough for the development of patchy fog due to the expected nearly calm conditions. Lows generally 35-40 NW and 40-45 SE.
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&& .SHORT TERM /MONDAY AND MONDAY NIGHT/... As of 355 PM Sunday... Low amplitude, mid level perturbations are forecast to be steered around the nwrn and nrn periphery of the sub-tropical ridge over the Caribbean. These will result in periods of mainly high level cloudiness throughout cntl NC on Mon, while the area of low clouds forecast to expand into srn NC later tonight will likely linger over RAH`s srn counties for much of the day. The air mass will have warmed, characterized by a rise in low level thickness values by 12- 15 meters over those of Sun; and this will support high temperatures in the upr 50s to lwr to middle 60s. It will also become more humid, as the lead warm front now over the cntl Gulf coast states retreats nwd into srn NC and causes surface dewpoints to surge into the middle to upr 50s there during the afternoon, with 40s elsewhere. The influx of low level moisture will also support the development of areas of fog and low overcast late Mon night-Tue morning, particularly in the richer low level moisture across the srn Piedmont, Sandhills, and srn Coastal Plain. Some fog may become dense there, which is consistent with what the pattern of a retreating warm front would suggest. As such, if the fog signal remains in subsequent model guidance, it will be worthy of mention in the HWO later tonight or tomorrow. && .LONG TERM /TUESDAY THROUGH SUNDAY/... As of 305 PM Sunday... Frontal zone south of the area will be lifted north as a strong mid level wave over the southwest US ejects eastward across the southern plains on Tuesday. High cloudiness will be prevalent with an initially dry and mild airmass in place over the area benefiting from zonal flow to allow highs to reach the mid 60s. A moisture plume off the western Gulf will be aimed east along the frontal boundary, which will be in the vicinity of the NC/SC border, producing increased cloudiness rapidly ahead of the mid level system Tuesday night. Expect to see light rain spreading into the western Piedmont by Wednesday morning and across the remainder of the area Wednesday into Wednesday night. PoPs will peak on Wednesday, graduated from 40% north to 70% across the south, and may wind up being bumped considerably higher if we see see continued model consensus on the timing and precip distribution. Mins Tuesday night will be mild, mostly mid and upper 40s, with highs on Wednesday in the mid and upper 50s. The upper wave and associated cold front will move offshore Wednesday night, with drier but only modestly cooler air ridging down the Atlantic seaboard from the northeast. High temperatures will take a short-lived tumble to near seasonable levels as the CAD builds in, topping out mostly in the lower 50s Thursday. The surface high associated with the CAD will be progressive, allowing the airmass to begin scouring out Thursday night as low level veers easterly, with highs edging back to the mid and upper 50s Friday ahead of our next cold front, which will move into the area and stall over the weekend. Seasonable temperatures in the 50s are expected Saturday and Sunday, with at least chance (30%) PoPs through the weekend. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... As of 740 PM Sunday... 24 Hour TAF Period: A weak mid level disturbance moving across the area this evening/early tonight will allow for some very light rain and low end VFR cigs. Any associated precip should exit by 06Z at the latest. Cigs will begin to scatter out across northern portions of the area later tonight. However, we may see some sub-VFR cigs (MVFR) develop across southeastern portions of central NC late tonight into Monday morning (KFAY). Confidence in how long any sub- VFR cigs will last at KFAY remains low, as some guidances shows the potential for MVFR cigs to last into early to mid afternoon. Otherwise, VFR conditions are expected. Outlook: The nwd retreat of a warm front, and leading edge of a more humid air mass, will result in a medium chance of advection fog, and/or VLIFR stratus, Mon night-Tue morning, particularly at FAY. There will then be a high chance of rain and sub-VFR conditions, heaviest and lowest at FAY, late Tue night through Wed night, with the passage of a low pressure system across the sern U.S. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Badgett NEAR TERM...Badgett SHORT TERM...MWS LONG TERM...mlm AVIATION...BSD/MWS

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