####018006476#### FXUS62 KRAH 030452 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 1250 AM EDT Fri May 3 2024 .SYNOPSIS... An upper level high pressure ridge extending over the area this morning will shift to our southeast later today, as a surface backdoor front drops into northeast North Carolina, before stalling out and holding over the state through Saturday. A series of weak upper level disturbances will move through the region from late today through Sunday, bringing periods of unsettled weather. && .NEAR TERM /THROUGH TONIGHT/... As of 845 PM Thursday... Little change to the going forecast for the rest of tonight. The Mid- level ridge will remain anchored in place, although some energy from the Mid-Mississippi valley and OH valley will reach portions of eastern TN, increasing some high clouds toward daybreak. The main forecast challenge will be if we see fog like we did yesterday, and if so, where. Dewpoints mixed out into the low to mid 50s in most places, indicating the dry air in place. However, observations and model forecasts indicate these dewpoints rising into the low to mid 60s overnight with the inland sea-breeze. Dewpoints are already in the mid 60s over some parts of the southern Coastal Plain. So there could be some potential for some shallow fog beneath the drier air and inversion that develops. However, most guidance keeps the best chance over far SE NC. The best chance appears over the eastern Sandhills to southern Coastal Plain, where dewpoints are expected to be higher. Lows were raised a degree or two given the expected weak moist advection. Lows to range from 57 to 64. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... As of 230 PM Thursday... A convectively enhanced disturbance over the Ohio Valley Fri morning will largely remain to our west and north as it rides through the western periphery of the high amplitude ridging along the East Coast through the Great Lakes. At the surface, a lobe a high pressure will ridge south through the Northeast and down the Mid-Atlantic coast during the daylight hours. This should effectively push a shallow backdoor cold front combined with the seabreeze through southeastern VA into the northern Coastal Plain of central NC Fri evening before stalling overnight. 12z Hi-Res guidance hints at some isolated shower potential early Fri afternoon over the Piedmont, but limited instability, dry air aloft, and a deeply mixed boundary layer will likely prevent much outside of towering cumulus and an isolated shower. Otherwise, a very similar airmass will be in place with marginally cooler 850mb temperatures compared to Thurs and would result in highs in the upper 80s to around 90. Thickening mid/high clouds and bubbling cumulus during the afternoon may keep temperatures in the Triad closer to low/mid 80s. Underneath a blanket of cloud cover overnight, lows will be more uniform across the area with lows in the low/mid 60s. && .LONG TERM /SATURDAY THROUGH THURSDAY/... As of 220 PM Thursday... The first half of the extended forecast will feature an unsettled pattern. A weak surface low will be over the Ohio River Valley Saturday morning, slowly move to the east over Virginia by Sunday morning, then dissipate. A cold front will extend to the south from the low, and the front will be the primary rain-maker over the weekend. Extended likely pops a bit farther to the east both Saturday and Sunday. Rainfall amounts will range from a quarter inch in the southeast to nearly an inch in the northwest - needed rainfall, but not enough to change the drought status (almost all of which is D0 - abnormally dry - in our area). All locations will have at least a slight chance of thunderstorms, although instability values will be a little higher in the west. After the upper 80s and lower 90s of today and tomorrow, highs will be more seasonable for the weekend, ranging from the upper 70s the mid 80s. An upper level trough will approach the area Monday and move overhead Tuesday, bringing a chance of showers and thunderstorms to all locations. The forecast should then generally dry out for the middle of the week. However, an upper ridge will build across the Carolinas, and with southwesterly surface flow, temperatures will rise above normal again. By Wednesday and Thursday, highs should be in the lower 90s with lows around 70, values more typical of July and August than early May. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... As of 1250 AM Friday... Except for a chance of MVFR vsbys/cigs in the SE including FAY 08z- 12z this morning, VFR conditions are likely to hold through at least this afternoon across all central NC terminals, but with gradually increasing high and mid clouds. Starting after 21z, an upper level disturbance along with daytime heating will prompt isolated to scattered showers and a few storms pushing into the west (INT/GSO), with these chances lasting through the overnight hours, however VFR conditions will still be dominant. However, starting after 04z tonight, a backdoor front dropping into far N and NE sections will bring a good chance for IFR cigs and MVFR to IFR vsbys into northern areas, along and behind the front. However, these adverse aviation conditions should hold N of the primary terminals until after the end of the TAF valid period at 06z Sat. Looking beyond 06z Sat, as the backdoor front settles southward well into central NC, sub-VFR cigs/vsbys are expected to spread south through most of the area 06z-12z Sat. As the front slowly lifts back north and washes out, conditions will slowly improve back to VFR Sat from SE to NW, with the Triad (INT/GSO) remaining sub-VFR well into the afternoon. But the chance for sub-VFR conditions within scattered to numerous showers and storms will be high, especially at INT/GSO/RDU, Sat through Mon, particularly each afternoon and evening, with locally gusty winds in and near storms, and a chance for patchy early-morning fog areawide. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Kren SHORT TERM...Swiggett LONG TERM...Green AVIATION...Hartfield ####018003784#### FXUS63 KILX 030452 AFDILX Area Forecast Discussion...Updated Aviation National Weather Service Lincoln IL 1152 PM CDT Thu May 2 2024 .KEY MESSAGES... - Concern remains for some strong to locally severe storms through sunset, primarily west of I-55. - While some quieter periods are expected during the weekend, an active weather pattern re-establishes itself early next week. && .UPDATE... Issued at 930 PM CDT Thu May 2 2024 Storms have diminished in intensity and coverage across central Illinois late this evening with loss of daytime heating and the severe threat has ended. Outflow boundaries from earlier severe storms have gusted to near the I-57 corridor as of 925pm but the synoptic cold front is still off to our west, likely near the Mississippi River, but not well defined in surface obs due to the earlier convection. A few storms remain possible over the next several hours but mainly expect light showers through the overnight hours. Deubelbeiss && .DISCUSSION... Issued at 251 PM CDT Thu May 2 2024 Isolated convection has begun to fire early this afternoon near Peoria, along a subtle surface boundary. Latest SPC mesoanalysis shows close to 1500 J/kg of surface based CAPE across much of central Illinois, with steep low level lapse rates of around 8.5 C/km. Already have received some pea size hail reports with the Peoria cell. On a broader scale, numerous thunderstorms continue to develop over central Missouri and are traveling northeast. A general expansion northeast along the Illinois/Iowa border is expected over the next few hours, with storms becoming numerous over west central Illinois. Area remains in a Level 1 severe risk this afternoon and early evening, with some brief wind/hail risks. High-res models show some general weakening after sunset, though PoP's will remain high over the eastern half of the forecast area through about 3-4 am. Timing of the overall system appears to have sped up though, and rain chances on Friday were significantly lowered and primarily limited to near/east of I-57. Overall, the upper air pattern over the coming days has not changed in the morning model suite. As the upper low over southern Saskatchewan lifts northeast, a larger low will track into northern California/Nevada this weekend, before ejecting into the Plains on Monday. The international models keep the closed low more or less intact through the period, while the GFS opens it up for a time. Net effect of this will be periods of showers and thunderstorms into the middle of next week. There are some signs of extended drier periods Friday night, and again later in the weekend, with more of an increase in PoP's as the low moves into the Plains and gets more wound up. Tuesday remains a period of concern for potential for strong storms, with a number of European ensemble members featuring CAPE values upwards of 1500 J/kg. Overnight CSU machine learning probabilities also highlight Tuesday as a concern. Geelhart && .AVIATION... (For the 06z TAFs through 06z Friday Night) Issued at 1152 PM CDT Thu May 2 2024 Light rain and a couple isolated storms will accompany a cold front overnight. Winds will be a bit variable due to outflow from earlier storms, but will eventually set up out of the NW/NNW overnight as the synoptic cold front moves through. Precip will diminish behind the front but MVFR ceilings will overspread the terminals for several hours. Winds will veer to the NE Friday with VFR conditions returning the remainder of the period. Deubelbeiss && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$