477 FXUS62 KRAH 250007 AFDRAH AREA FORECAST DISCUSSION National Weather Service Raleigh NC 810 PM EDT Sat Aug 24 2019 .SYNOPSIS... A mid level disturbance interacting with abundant low level moisture will cause widespread cloudiness and areas of showers through this evening. Cool high pressure will continue to build into the region through Monday. && .NEAR TERM /THROUGH TONIGHT/... As of 330 PM Saturday... While the sfc cold front has pushed south of our region, a trailing trough at 925-850mb was drifting swd across central NC this afternoon. Meanwhile, a weak mid level vorticity maxima was crossing central NC. This feature interacting with the low level trough and the abundant moisture in the lowest 15000 ft of the atmosphere has triggered a band of moderate, briefly heavy, showers in vicinity of the I-40 corridor between the Triad and the Triangle. As the afternoon wears on into early evening, expect the bulk of the showers to occur along and east of highway 1, with a decreasing coverage after 00Z as the mid level wave exits the region. After 00Z, while the shower coverage will be waning, could still see patchy light drizzle into the overnight hours. Cool northerly low level flow has advected a notably cooler air mass into central NC with temperatures this afternoon averaging a solid 20 degrees cooler than Friday afternoon. Skies will remain overcast tonight in the wake of the departing mid level wave. The low level nly flow will persist as the parent high over the Great Lakes drifts east into southern Quebec with the ridge axis extending swd into the southern Appalachians. Overnight temperatures pleasantly cool for late August, ranging from near 60-lower 60s NW to the mid-upper 60s SE. && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... As of 330 PM Saturday... Main forecast challenge Sunday into Sunday night will center around the amount of cloud cover that will occur. A cool and relatively moist air mass will likely remain trapped below a mid level subsidence inversion Sunday morning. Thus, feel fairly confident that skies will remain overcast through mid day with brief instances of spotty drizzle or light rain occurring. As the sun climbs higher in the sky Sunday afternoon, mixing of drier air aloft will commence, gradually eroding the low clouds from above. The GFS and the ECMWF appear too aggressive with its projected clearing trend NE- SW late Sunday morning through Sunday afternoon. Am leaning toward the more pessimistic NAM which typically handles CAD sky coverage better. RH cross sections of the NAM depict a layer of stratus maintaining a presence over central NC through Sunday night. Using a blended approach suggest some partial clearing mainly across the Coastal Plain and eastern Piedmont Sunday afternoon, and less so over the NW and southern Piedmont. If the skies remain overcast Sunday afternoon, highs Sunday may end up 4-5 degrees cooler over the eastern half of the forecast region. Conversely, if the GFS is correct, Sunday afternoon highs will end up much warmer, particularly over the western Piedmont. Plan to advertise highs Sunday in the mid-upper 70s, with lower 70s over the NW Piedmont. Still expect some residual cloud cover Sunday night which should moderate temperatures. Will lean lows toward the lower-middle 60s. If clouds do depart Sunday afternoon and it remains mostly clear overnight Sunday night, then potential for several spots across the northern Piedmont and northern Coastal Plain to dip into the upper 50s, with lower 60s common across the south. && .LONG TERM /MONDAY THROUGH SATURDAY/... As of 245 PM Saturday... Weak upper-level ridging to begin the work-week will quickly transition back into a broad-scale troughing pattern, likely to hold tough through the end of the period. At the surface, the CAD type regime will slowly weaken, likely requiring the passage of a fairly robust mid level shortwave and associated surface cold front mid week to become completely dislodged. A series of shortwaves will slide east of the Appalachians as we progress into next weekend, with a front likely to stall in or just south of the area by Saturday evening. Early Week: CAD type conditions with persistent northeasterly flow will continue across central NC, with the likely remnants of the tropical disturbance progged to remain safely offshore. Temperatures will begin to warm slightly, as drier air begins to work into the mid levels of the atmosphere, and a few breaks in the rather persistent mid level cloud deck will become more likely. Expect temperatures to warm into the upper 70s/low 80s on Monday, with a 4 to 5 degree warming trend likely each afternoon Tuesday and Wednesday. POPs will remain extremely limited, especially Monday afternoon, with only some patchy drizzle/light showers possible across most of the central NC zones. POPs will increase Tuesday afternoon and evening as a shortwave begins to dig southeast out of the Ohio Valley, likely to progress west to east Tuesday night/early Wednesday across central NC. We could also see an enhanced area of showers with a few low topped storms possible across the northeastern zones Tuesday afternoon and evening as northeasterly flow is maximized thanks to the positioning of both the CAD high and tropical low to our east. As we progress into Wednesday, the shortwave trough and associated surface front will help dislodge the CAD as well as usher the remnant tropical low further northeast into the Atlantic. Late Week: A secondary, likely a bit stronger, shortwave will round the base of the trough later in the period helping to propel a reinforcing cold front through central NC Thursday evening into Friday. Behind this boundary, there remains some hint of a much quieter area of surface high pressure filtering overhead early next weekend, although, models continue to diverge with the eventual progression of the surface front. Temperatures should remain seasonable mid to late week, with afternoon highs in the mid to upper 80s and lows in the middle 60s. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... As of 810 PM Saturday... Passage of a disturbance aloft and deep moisture rooted in the low levels has produced widespread rain and drizzle over central NC over the last several hours, along with sub-VFR conditions, mainly over S and E sections, SE of RDU. As the disturbance shifts to our E, and as drier air works into central NC from the N, the rain and drizzle will gradually taper off from NW to SE, and cigs will continue to improve, with mostly dry weather overnight through Sun. MVFR to VFR conditions will dominate at INT/GSO/RDU tonight, although a short period of IFR cigs and MVFR/IFR vsbys in drizzle can't be ruled out 08z-12z tonight. VFR conditions are then likely from mid morning Sun onward at these sites. RWI/FAY will see mostly MVFR to IFR conditions lasting through much of tonight and into Sun morning, followed by an improvement to MVFR then VFR through mid to late Sun morning. Surface winds will remain out of the northeast at 6-10 kts, with infrequent gusts to 12-15 kts, mainly Sun afternoon. Looking beyond 00z Sun, dry weather will hold through Mon night, with mostly VFR conditions, although pockets of sub-VFR fog are possible 09z-12z both Mon and Tue morning. An approaching trough from the west will bring a return to rain chances and sub-VFR conditions Tue afternoon through Wed night, followed by a return to mostly dry VFR conditions behind a cold front on Thu. -GIH && .Climate... Greensboro's record low Maximum Temperature for August 24 is 74 degrees set in 1985. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...WSS NEAR TERM...WSS SHORT TERM...WSS LONG TERM...JJM AVIATION...Hartfield CLIMATE...Badgett