Subj : DAY3SVR: Nws Storm Predic To : All From : Mike Powell Date : Thu May 11 2023 15:31:00 ACUS03 KWNS 110722 SWODY3 SPC AC 110721 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0221 AM CDT Thu May 11 2023 Valid 131200Z - 141200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE IOWA VICINITY...AND ACROSS THE SOUTH TEXAS AREA... ....SUMMARY... A few severe storms are forecast to develop across parts of Iowa and vicinity, and diminishing in coverage southeastward across the lower Ohio Valley. Scattered severe storms are also forecast across parts of South Texas, with isolated risk across a broader portion of the central Plains. ....Synopsis... An upper-level blocking pattern will continue to evolve across western North America Saturday, as a broad/weak upper low over the West retrogrades westward, shunting the western U.S. ridge northward into western Canada. Meanwhile, cyclonic northwesterly flow aloft will persist across the Northeast. Across the central U.S., a pair of weakening upper lows will continue to fill -- one drifting east-northeastward across Nebraska and southern South Dakota, and the other moving slowly north-northwestward across western Texas and eastern New Mexico. At the surface, a backdoor-type cold front extending from Nebraska eastward across the Midwest to southern New England will sag southward across the Ohio Valley, while lingering over the Mid-Missouri through the end of the period. ....Southern Plains... As the remnant upper low drifts across West Texas, isolated thunderstorms are forecast across portions of Oklahoma and Texas. With enhanced southerly mid-level flow persisting across the southern Plains east of the weakening low, shear will be sufficient to support organized storms, and attendant threat for hail/wind locally. The greater severe risk appears likely to reside over South Texas. Here, enhanced low-level southeasterly flow is expected, beneath south-southwesterlies at mid levels. While questions exist regarding location of early-day/ongoing convection, at least some heating is forecast across the area -- resulting in ample afternoon destabilization. At this time, is appears the redevelopment/reintensification of convection will occur during the afternoon, and shift eastward/southeastward across the southern portion of the state through the evening and possibly overnight. Damaging winds and hail are expected, with a couple of tornadoes also possible given the amply strong/favorably veering flow with height. ....Iowa vicinity into the Midwest... As the Nebraska upper low weakens while drifting eastward, a small area of still-favorable shear is forecast across the Iowa vicinity -- particularly near a weak surface front progged to lie northwest-to-southeast across this area. Low-level southeasterlies near and to the cool side of the front beneath remnant/enhanced mid-level southwesterlies will result in shear favorable for rotating updrafts. Given ample afternoon destabilization forecast near the boundary, a few severe storms are expected to evolve, possibly extending in a more isolated manner southeastward across Illinois and the lower Ohio Valley area. Along with potential for locally damaging winds and hail with a few of the stronger cells, a tornado or two would also be possible across portions of Iowa near the front. ...Goss.. 05/11/2023 $$ --- SBBSecho 3.14-Linux * Origin: Ilink: CCO - capitolcityonline.net (454:1/105) .