523 FXUS62 KRAH 080641 AFDRAH AREA FORECAST DISCUSSION National Weather Service Raleigh NC 235 AM EDT Fri Oct 8 2021 .SYNOPSIS... Surface high pressure centered over New England and the Canadian Maritimes will extend south into the mid-Atlantic and Carolinas through mid-week. A coastal trough will evolve into a meandering low pressure area off the Carolina coast through the weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 905 PM Thursday... Most of the showers have dissipated this evening. However, there continued to be some light showers and drizzle particularly in the Triad region. Lower cloudiness was seen over the western Piedmont into the mountains, with breaks in the cloudiness in the east. A 1023 mb surface high pressure was located over western VA with cool moist advection into our region from the NE. Low overcast conditions are favored to develop over much of the region overnight. Some patchy drizzle in the increasingly stable low level environment is also possible. Lows generally in the upper 50s to mid 60s. Previous discussion as of 330 PM Thursday... Water vapor imagery depicts a closed mid/upper low currently centered over central Illinois, which will slowly lift NE into northern Illinois tonight. The attendant trough will begin to deepen southward to the northern Gulf Coast as a jet streak pumps up the ridge over the Intermountain West. Water vapor imagery also clearly depicts a couple of upper disturbances near our region: one just off the NC coast and another over the Appalachians. These disturbances are resulting in a couple areas of showers: one over the NW Piedmont and another across the far SE. As the disturbance off the coast continues to lift NE, a band of heavier showers should move into the southern Coastal Plain and Sandhills this afternoon/early evening, so continue some likely POPs there. Farther to the north over the Piedmont, drier air and a lack of forcing will limit precipitation later this afternoon and evening. As the upper disturbance moves away from the NC coast tonight and daytime heating is lost, shower coverage will lessen but patchy light rain and drizzle are again possible overnight. There is again a chance for some patchy fog to develop by early tomorrow morning, mainly in the north, but persistent light northeasterly winds will limit this threat. Widespread stratus will keep low temperatures well above normal again, ranging from lower-to-mid-60s north to upper-60s south. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... As of 345 PM Thursday... The mid/upper low will continue to lift NE into the Great Lakes on Friday and Friday night. After a lull in precipitation Friday morning, as the associated sharpening trough continues to move east and approach the region, forcing for precipitation will increase late Friday and especially Friday night. At the surface, the pattern will remain very similar to today's, with a low pressure system sitting off the SC coast and high pressure over New England, resulting in moist northeasterly flow and plenty of low cloud cover. Thus instability again looks limited, with only 500-1000 J/kg at most to work with, and the best forcing and PW values don't move in until after dark. So while a few storms are possible, there is no severe threat. The WPC does have much of our area in a marginal risk for excessive rain tomorrow/tomorrow night, with QPF generally in the half inch to inch range and locally higher amounts possible. But again, given the relative lack of instability, and relatively dry antecedent conditions, rainfall amounts are not expected to be heavy enough for any significant flooding concerns. Very similar low-level thicknesses will keep high temperatures similar to today's, generally in the 70s, with lows tomorrow night dropping into the 60s. && .LONG TERM /SATURDAY THROUGH THURSDAY/... As of 300 PM Thursday... The upper trough associated with the former closed low over the MS Valley will move east through the SE US, where it will begin to interact with a weak area of low pressure meandering off the Carolina coast. With the upper trough directly overhead to start the day, the first half of Saturday should be fairly wet. The passage of the upper trough during the second half of the day should result in decreasing rain chances west to east through the afternoon/early evening. Depending on rain/shower coverage, highs Saturday across northern portions of the forecast area could hold into the upper 60s. Elsewhere, expect highs in the lower to mid 70s. Widespread clouds and rain will also deter destabilization and thunderstorm probability. By Sunday-Monday, deterministic and ensemble model guidance show significant divergence/spread wrt to the evolution and location of the coastal low. Given, proximity to land and interaction with the upper trough, potential for tropical development will remain limited. Regardless of the classification, this system could result in some lingering rain chances over eastern NC Sunday and possibly again on Monday. The associated NELY flow will also result in a continuation of extensive low cloud shield across the area, which will keep temps seasonable. Once the coastal low moves away and/or dissipate, the residual low- level moisture will scour under strengthening high pressure aloft. Sunshine will return with daytime highs warming well above normal(7 to 10 degrees). Highs in the 80s. Lows in the 60s. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... As of 235 AM Friday... 24-hour TAF period: Widespread IFR and some MVFR conditions are noted across central NC early this morning. These are primarily associated with low ceilings in stratus and some fog. Ceilings will continue to lower through the daybreak hours and then will be slow to improve through the day, with some locations becoming VFR during the afternoon, with the best chance of better conditions across the Coastal Plain, especially the northern Piedmont and northeast Piedmont. An approaching upper trough will lead to the development of showers and some thunderstorms across southern areas later this morning and especially this afternoon that will lift north across central NC late this afternoon and this evening with associated visibility and ceiling restrictions. A mainly light northeast wind at 5 to 10kts is expected through the period. Looking beyond 06Z Saturday: A continuation of a moist northeasterly low-level flow and an upper level low that will linger across the region will result in a period of unsettled weather through early next week. Sub-VFR ceilings are expected during the late night/early morning period through Monday. Unsettled weather with a good chance of showers is expected into Saturday across the area with a lingering but decreasing chance from Sunday into early next week. -Blaes && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Blaes NEAR TERM...Badgett/Danco SHORT TERM...Danco LONG TERM...CBL AVIATION...Blaes