BBS: TELESC.NET.BR Assunto: DAY2SVR: Nws Storm Prediction Center Norman Ok De: COD Weather Processor Data: Sun, 26 Apr 2026 05:45:30 +0000 ----------------------------------------------------------- ACUS02 KWNS 260545 SWODY2 SPC AC 260543 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1243 AM CDT Sun Apr 26 2026 Valid 271200Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS MONDAY AFTERNOON THROUGH MONDAY EVENING ACROSS MUCH OF THE MIDDLE MISSISSIPPI VALLEY...INCLUDING PORTIONS OF SOUTHEASTERN IOWA...SOUTHERN WISCONSIN..EASTERN MISSOURI...MUCH OF ILLINOIS...AND PORTIONS OF NORTHEASTERN ARKANSAS...NORTHWESTERN TENNESSEE AND WESTERN INDIANA... ...SUMMARY... Widespread strong to severe thunderstorm development appears probable across the middle Mississippi into lower Ohio Valleys Monday afternoon through Monday evening, accompanied by potential for a few strong tornadoes, damaging wind gusts and large hail. ...Discussion... Models suggest that the northern periphery of a prominent subtropical high, centered near the Mexican Gulf coast, may build a bit further northward through the southern Great Plains and Gulf Coast states through this period. This is forecast to occur downstream of a digging mid/upper trough and embedded low across the southern mid- to subtropical latitudes of the eastern Pacific, while broad, larger-scale troughing to its north progresses eastward through much of the interior of North America. Near the leading edge of the latter regime, it appears that a significant short wave perturbation will accelerate northeast of the lower Missouri Valley through the Upper Midwest/Great Lakes region, accompanied by a notable (sub-1000 mb) deepening surface cyclone. A trailing low may migrate from east central Kansas through eastern Iowa during the day Monday, trailed by a dryline just ahead of a cold front, which may gradually overtake the dryline across eastern Iowa through southwestern Missouri late Monday afternoon into evening. It appears that this may be preceded by one or two clusters of storms maintained by forcing for ascent associated with lower/mid-tropospheric warm advection, which may still be ongoing across northern Missouri/southern Iowa into parts of northern and central Illinois at the outset of the period, before shifting eastward into the Ohio Valley during the day. The impacts of this potential activity on subsequent destabilization and convective development remains unclear, and a significant source of lingering forecast uncertainty. However, most guidance continues to indicate moderate to strong warm sector boundary-layer destabilization will occur with low-level moisture return and insolation beneath an initially northeastward advecting plume of capping elevated mixed-layer air, ahead of the dryline. Substantive destabilization still appears possible to the cool side of an outflow boundary generated by the early day convection, which may retreat northward through parts of southeastern Iowa and central through northern Illinois by late afternoon, as an effective warm frontal zone to the east of the southern surface low. ...Middle Mississippi into lower Ohio Valleys... Aided by mid/upper forcing for ascent to the poleward side of a 70+ kt southwesterly, cyclonic 500 mb jet streak, it appears that the triple point low/dryline may become the focus for strongest storm development by late Monday afternoon across parts of northeastern Missouri/southeastern Iowa into northwestern Illinois. Given the environment, including sizable clockwise-curved low-level hodographs beneath 40-50 kt southerly 850 mb flow, this probably will include discrete supercells initially, with potential to produce large hail and strong tornadoes. Gradually, it is probable that this will grow upscale along the remnant outflow boundary and along the dryline as it begins to be overtaken by the southward surging cold front, into the lower Ohio Valley by late Monday evening. As this occurs, embedded supercell structures may continue to pose a risk for strong tornadoes, with evolving meso-vortices along developing gust fronts of convective outflow also posing a risk for brief tornadoes and/or damaging wind gusts. The extent of the tornadic threat remains a bit unclear, and will probably be dependent on how long discrete supercells are maintained along/ahead of the dryline. However, depending on how the modifying initial convective outflow evolves across southeastern Iowa into central Illinois, this boundary could become a focus for heightened tornado potential, with a few strong, and particularly damaging, tornadoes possible. Categorical and severe probabilities could still be upgraded further in later outlooks for this period. ..Kerr.. 04/26/2026 $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.28-Linux * Origin: Capitol City Online (1:2320/107) ----------------------------------------------------------- [Voltar]