249 FXUS62 KRAH 031024 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 624 AM EDT Thu Apr 3 2025 .SYNOPSIS... A warm front will retreat very slowly westward through the western Carolinas and central VA this morning, then dissipate by this afternoon. Unseasonably strong and warm, sub-tropical high pressure will otherwise extend westward across the South Atlantic states through Sunday. && .NEAR TERM /THROUGH TONIGHT/... As of 425 AM Thursday... A sub-tropical high over the swrn N. Atlantic will continue to strengthen and remain the dominant feature and influence for cntl NC. Surrounding anticyclonic flow will extend throughout the South Atlantic states. At the surface, an in-situ damming/wedge front extended this morning in the lee of the srn Appalachians from n-cntl GA, newd and across the Upstate of SC, the Foothills and nw Piedmont of NC, and cntl VA. This boundary retreated through KINT around 05Z but has made little additional progress since; and it remains over w-cntl Forsyth Co. per home weather stations from Clemmons to Stanleyville and points wwd. It will continue a very slow nwwd retreat throughout the morning, then dissipate, with following unseasonably strong and warm, sub-tropical high pressure that will extend from near and south of Bermuda wwd and throughout much of the Southeast, including all of cntl NC. A separate differential heating boundary/zone will also likely develop and retreat across cntl NC today, with a southeast to northwest erosion of the now widespread, mostly MVFR stratus, and with associated cloudy or mostly so conditions that will linger longest and into early to mid-afternoon over the nw Piedmont. Temperatures throughout cntl NC will warm mostly into the 80s and well above average (~ +15F), except upr 70s possible where the aforementioned low clouds take longest to erode. After patchy light rain and drizzle through mid-morning, a few showers and storms will be possible in the vicinity of the differential heating zone as it retreats across the srn and nwrn NC Piedmont. The airmass there will moderately destabilize with diurnal heating of the unseasonably moist airmass characterized by mid/upr 60s F surface dewpoints, beneath a plume of modestly steep lapse rates (~6.5 C/km) accompanying a remnant, contaminated EML plume around the periphery of the sub-tropical ridge. Unseasonably muggy conditions, with lows in the mid-upr 60s, will follow tonight, with likely late redevelopment of low overcast by Fri morning. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... As of 445 AM Thursday... Hot, sub-tropical ridging at the surface and aloft will continue to extend across the South Atlantic states. A backdoor cold front may dip to near the VA/NC Fri evening, then retreat nwd across s-cntl VA Fri night. Shallower/thinner than recent days stratus Fri morning will favor a quicker cloud erosion and following longer and stronger diurnal heating. As such, temperatures will warm mostly into the upr 80s throughout cntl NC, to around 90 F in the typically hotter locations from FAY and AFP to RDU. That stronger heating and associated deeper mixing will likely cause surface dewpoints to mix out into the lwr 60s, via vertical advection of drier air aloft, so heat index values will be comparable to ambient air temperatures. The FV3 is alone in depicting any convection over cntl NC on Fri, and even that just an isolated cell over the srn Piedmont. Given continued influence from the sub-tropical ridge as it strengthens perhaps another decameter, and a lack of a low-level forcing mechanism, the forecast will remain dry Fri. A slight chance of an evening storm will exist near the Roanoke River, however, when the aforementioned backdoor front makes its closest approach to cntl NC. Low temperatures, with late night stratus possible, are expected to be mostly in the mid 60s. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 420 AM Thursday... The weather pattern across central NC on Saturday will continue to be controlled by a subtropical high aloft that remains anchored east of FL and ridges up the Eastern Seaboard for one more day. Meanwhile a 1025-1030 mb surface high centered east of GA/SC and SW of Bermuda will slowly drift east. A cold front initially extended from eastern TX to the mid-MS Valley and Lower Great Lakes early Saturday will reach the TN Valley and northern Mid-Atlantic by early Sunday, as a wave of low pressure associated with a mid-level shortwave over the Southern Plains rides along the front. This will help to push Friday evening`s backdoor front well to our north, and with high pressure to our SE resulting in capping/subsidence aloft, Saturday looks dry and partly to mostly sunny. High temperatures will again be quite warm, mainly in the upper-80s to lower-90s, which is 15-20 degrees above normal and near the daily record highs for April 5 at GSO, RDU and FAY. Skies will turn mostly cloudy on Saturday night, and with southerly flow ahead of the approaching cold front, lows will be very warm and near record high minimums, only dropping to the mid-to- upper-60s. The Bermuda high will finally begin to break down and shift away from us on Sunday, in response to the mid-level southern stream wave pushing east and a broad northern stream trough digging into the Great Lakes. This will help push the cold front east through our region, as a wave of low pressure tracks along it. The frontal passage looks slow due to the SW flow aloft, and while the GFS is a bit faster than the ECMWF, both models are in pretty good agreement that it will gradually move east across central NC Sunday night into Monday, maybe even stalling out for a time. So continue likely to categorical POPs from Sunday afternoon into Monday. Precipitation may not completely clear our far SE until late Monday night if the ECMWF and many of its ensembles are correct. Some storms can`t be ruled out on Sunday and Monday, but at this time instability looks marginal, with CAPE on the ECMWF and GFS generally less than 500 J/kg, and their ensembles depicting very low probabilities of exceeding that. So despite strong winds aloft, the severe threat looks fairly limited at this time. Even outside of convection, GFS point soundings on BUFKIT indicate gusts of 25-35 mph will be possible during the day on Sunday. The bigger threat at this time looks to be heavy rain, and WPC has our region in a marginal (level 1 of 4) risk of excessive rainfall on Sunday/Sunday night, which lingers in our far SE on Monday. WPC total QPF for the event is in the 1-2 inch range, but the deterministic ECMWF and GFS both have stripes of 2-3 inches across a portion of central NC, and the 90th percentile QPF of their ensembles is in a similar range, indicating potential for isolated totals that high especially where any storms train. At the same time, this would provide some welcome drought relief as much of central NC is currently in D0 or D1 conditions. Sunday looks a bit cooler from cloud cover and precipitation chances, but still very warm with highs in the mid-80s to 90, which could still approach some records. Sunday night`s lows will again be quite mild (upper-50s to mid-60s) before we turn much cooler and close to normal on Monday (highs mid-60s to lower-70s, lows in the 40s). We finally dry out on Tuesday and skies turn sunny, as Canadian high pressure builds in from the NW and westerly flow aloft around the mid/upper low over the Great Lakes and New England pushes the cold front well to our east. A reinforcing cold front on Tuesday will bring a shot of even cooler, drier air with highs both Tuesday and Wednesday only in the upper-50s to mid-60s and dew points in the teens and 20s. As the surface high settles near the Appalachians on Tuesday night, went on the cooler side of guidance for temperatures as decent radiational cooling conditions and 1000-850 mb thicknesses only in the 1280-1295 m range will support widespread lows in the lower-to-mid-30s. Upper-20s will even be possible in outlying areas. This will result in some frost and freeze concerns. && .AVIATION /10Z THURSDAY THROUGH MONDAY/... As of 620 AM Thursday... Widespread MVFR ceilings throughout cntl NC this morning may lower to IFR and be accompanied by light rain or drizzle mainly at INT/GSO in the few hours centered around 12Z. Ceilings should then gradually lift and/or scatter to VFR at FAY, RWI, RDU by early this afternoon, while IFR-MVFR ceilings will be slower to lift and disperse, likely not until mid to late afternoon, at GSO/INT. Sswly surface winds will strengthen and become frequently gusty to 20-25 kts by ~12-13, then remain so until diminishing around sunset. The exception may be at FAY, where an inland-moving sea breeze may maintain a little sly to ssely gustiness there until ~02-03Z this evening. IFR-MVFR ceilings will likely redevelop Fri morning, amid continued unseasonably moist/humid low-level flow. Outlook: IFR-MVFR ceilings will probably redevelop Sat morning, amid continued unseasonably moist/humid low-level flow. A strong cold front will be accompanied by a band of convection and flight restrictions, as it moves slowly east across cntl NC Sun night and Mon, possibly as early as late Sun afternoon at INT/GSO. && .CLIMATE... Record High Temperatures: April 3: KRDU: 91/1967 KFAY: 90/1934 April 4: KGSO: 86/1934 KRDU: 88/1934 KFAY: 93/1910 April 5: KGSO: 87/1942 KRDU: 90/1942 KFAY: 91/1942 April 6: KGSO: 89/2010 KRDU: 93/1967 KFAY: 91/2010 Record High Minimum Temperatures: April 3: KGSO: 64/1946 KRDU: 62/2000 KFAY: 65/1977 April 4: KGSO: 62/1999 KRDU: 63/2017 KFAY: 63/2017 April 5: KGSO: 60/2023 KRDU: 64/1910 KFAY: 64/2008 April 6: KGSO: 65/2023 KRDU: 69/2023 KFAY: 69/2023 && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...MWS SHORT TERM...MWS LONG TERM...Danco AVIATION...MWS CLIMATE...NWS