080 FXUS63 KSGF 281035 AFDSGF Area Forecast Discussion National Weather Service Springfield MO 535 AM CDT Sun Apr 28 2024 .KEY MESSAGES... - Significant and dangerous flooding is ongoing in areas along and west of I-49 as training thunderstorms continue to impact the area. The flooding threat will slowly shift eastward through today and tonight. A Flood Watch is in effect until 1PM Sunday. - Severe weather threat continues through this morning as a line of storms moves through. Wind gusts up to 70 mph, a couple tornadoes, and hail up to the size of half dollars are all possible. A Tornado Watch is in effect until 7AM. - Severe weather is expected again this afternoon into tonight as another line of storms develops. The main threat will be wind gusts up to 60 mph with secondary marginal threats of quarter-size hail and a brief spinup tornado or two. - The unsettled pattern continues with additional storm chances mid to late next week. && .SHORT TERM /THROUGH TONIGHT/... Issued at 330 AM CDT Sun Apr 28 2024 Significant and dangerous flooding is ongoing: A large complex of severe thunderstorms is progressing eastward across the central/southern Plains. The complex is located on the east side of a 90-110 kt meridional jet streak associated with a potent negatively-titled shortwave. This synoptic wave is very slowly progressing to the NE. That, combined with straight N-S flow all the way down to the surface is forcing the MCS to move slowly eastward and train, bringing heavy rain to locations along the MO/KS border. Latest MRMS QPE estimates put out 5-7 inches of rain in the last 6-12 hours over Bourbon, Vernon, and Crawford counties, specifically around the Fort Scott, KS area. This is on top of 4-6 inches that have already fallen the past couple of days. With all this rain, rivers such as the Little Osage and Marmaton are approaching major flood stage. Several considerable flash flood warnings are currently out to address this threat. Observed PWATs of 1.25" (above 90th percentile) are allowing for rainrates of 1-2 inches/hr. These will produce an additional 1-1.5" in this area with localized values greater than 2-3 inches before the MCS exits the area. Please avoid traveling in this area if you can! If you cannot, make sure to turn around, don't drown. Keep up to date with alerts and have a plan in place. As mid-level ascent catches up to the complex and a better cold pool forms, the thunderstorm complex will pick up its pace and progress eastward through early this morning. HREF LPMMs suggest this will produce 1.5-3 inches of rain east of I-49 and along and west of Hwy 65, including Springfield. Within heavier training thunderstorms, localized values up to 3-5 inches are possible (10-30% chance). Once again, this will introduce an areal, river, and flash flooding threat for the Flood Watch area. After the first thunderstorm complex dissipates early this morning, airmass recovery/destabilization is expected to quickly occur given any frontal forcing will still be lagging west in KS/OK and high amounts of moisture will limit the depth and strength of the cold pool. Even with mild highs in the lower 70s, the appreciable dewpoints in the lower 60s will allow for enough MLCAPE (300-800 J/kg via RAP model soundings) for new thunderstorm development Sunday afternoon. All HREF models are depicting another thunderstorm complex to develop along and west of I-49 by 3-5PM. This complex should extend through the N-S extent of our CWA. The mid- and upper-level wave will finally kick out of the area to the NE this afternoon/evening, so this MCS will be more progressive than last night's. However, high PWATs above the 90th percentile still in the region will allow for high rainrates in the thunderstorm complex bringing an additional 0.5-1.5 inches of rain east of I-49 with localized values up to 2-4 inches suggested by HREF probs (30-40% chance). Severe weather threat continues through this morning: A Tornado Watch is in effect for portions of our forecast area through 7 AM this morning. This threat is mainly for 60-70 mph wind gusts and brief spin-up circulations within the line of storms progressing eastward. The threat becomes more marginal the further east you get, with the severe threat diminishing east of Hwy 65. A 06Z balloon sounding revealed 90-110 J/kg of SB/MLCIN with increased low-level and mid-level capping. Additionally, radar trends are suggesting that the line is becoming more outflow dominant as cells are beginning to advect rearward. Both these observations suggest the line will weaken as it moves eastward. Nevertheless, increased synoptic ascent and a nocturnal enhanced 45-55 kt low-level jet could make use of the 700-1000 J/kg of SB/MLCAPE and >400 m2/s2 of SRH to produce severe wind gusts and perhaps a spinup tornado or two before 7 AM. The MCS is then expected to dissipate to lingering stratiform rain as it crosses the Hwy 65 corridor after 7 AM or so. Severe weather/flooding expected again this afternoon/evening: As mentioned above, the morning thunderstorm complex will only produce modest stabilization in its wake. Lower to mid-60 dewpoints still in place will allow for 300-800 J/kg of MLCAPE ahead of the upper-level wave (as depicted by the mean HREF values). 0-6 km bulk shear values will increase to 40-50 kts as the mid-level jet core overspreads the area. This will set the stage for a low-CAPE, high-shear severe weather event. Surface frontal and mid-level jet forcing will enter our CWA Sunday afternoon and force more storms within the warm/moist sector. With low-CAPE, high-shear events, these storms will quickly grow into a line/MCS. Shear vectors strictly parallel to the forcing adds confidence to this storm mode. The MCS will start just east of I-49 and progress eastward. This will create mainly a damaging wind threat with gusts up to 60 mph. An Enhanced (3/5) risk is in place along and south of I-44 to capture mainly this wind threat. However, with RAP forecast soundings depicting 200-300 m2/s2 background SRH and mid-level lapse rates nearing 7 C/km, a brief spinup tornado and/or quarter-size hail cannot be ruled out. The MCS should exit our CWA to the east by the late evening hours. A cold front following the MCS will drops lows Monday night into the 50s with cooler temperatures toward the MO/KS border. && .LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 330 AM CDT Sun Apr 28 2024 The upper-level wave will finally exit our area Monday night, bringing a brief period of drier and warmer weather Tuesday with highs in the lower 80s. Additional storm chances mid to late next week: The dry weather won't last long, though, as a longwave trough sets up over the northern CONUS, allowing for multiple shortwaves to clip through our region. The first of which looks to lift through NE/IA Tuesday night. The positive vorticity advection and associated surface front may produce some showers/thunderstorms that would impact areas NW of I-44 (20-40% chance). The wave/front should stay NW of the area allowing lows Tuesday night to stay in the lower 60s. The next shortwave looks to be deeper, but also slower. This will allow S'ly low-level flow to persist through Wednesday and Thursday bringing highs into the mid-80s Wednesday and lows in the mid-60s Wednesday night. The conceptual model here depicts an amplified mid-level trough above a warm/moist sector with strong S'ly flow, and a dryline over central KS/OK. This could bring a severe threat Wednesday and Thursday, with the greatest chance Thursday. Details are too far out to give any details, but the conceptual model is there. CIPS/CSU algorithms are also hitting this timeframe with 15% contours in our area. This will continue to be monitored. Nevertheless, chances for showers/thunderstorms Wednesday are in the 20-50% range and 70-90% range Thursday. The system that clears through after these storm chances will bring in cooler air with highs in the lower 70s and lows in the lower 50s through the weekend. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 530 AM CDT Sun Apr 28 2024 A decaying thunderstorm complex is currently making its way through the area. Leftover stratiform rain and perhaps a few lightning strikes will keep visbilities, ceilings, and winds in flux until around 15Z. Once the complex dissipates, southerly 10-15 kt winds (with gusts between 20-25 kts) will return and a brief period of VFR conditions will prevail. Another line of thunderstorms will develop after 21Z and impact JLN first, then SGF and BBG. There is the potential for heavy rain and wind gusts up to 40-50 kts with this line of storms. The complex is then expected to clear by 04Z or so. A wind shift will occur towards the end of the TAF period as a front passes through. SE'ly winds will weaken to 3-8 kts and shift to WNW'ly by the end of the TAF period. && .SGF WATCHES/WARNINGS/ADVISORIES... KS...Flood Watch until 1 PM CDT this afternoon for KSZ073-097-101. MO...Flood Watch until 1 PM CDT this afternoon for MOZ055-056- 066>069-077>081-088>096-101>105. && $$ SHORT TERM...Price LONG TERM...Price AVIATION...Price