Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1129 AM CDT Sun Apr 12 2026 Valid 121630Z - 131200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF SOUTHWEST AND CENTRAL TX... ...SUMMARY... Isolated to scattered severe thunderstorms are possible today into evening mainly across parts of Texas and perhaps other nearby parts of the southern Plains. More isolated severe storms may occur across portions of the Upper Great Lakes and northern Rockies. ...Synopsis... Recent satellite imagery shows a pair of phased shortwave troughs over the Plains, one moving through the Dakotas and another moving through KS/OK. Both of these waves are forecast to continue northeastward through the day, with the northern wave reaching northwestern Ontario and the southern wave reaching the Great Lakes region. This evolution will take these waves east/northeast of the higher low-level moisture, which will remain in a corridor from the southern Plains northeastward into the Upper Midwest. Showers and thunderstorms are anticipated throughout much of this corridor today, with highest thunderstorm chances across central/east TX and from the Upper Midwest into the Great Lakes. Farther west, an upper low is slowly drifting eastward across northern CA. Guidance suggests this eastward drift will continue today, with several shortwave troughs rotating quickly through the base of this system and ejecting across the Great Basin and northern Rockies. Large-scale ascent and modest mid-level moisture associated with these waves will combine with cold temperatures aloft and associated buoyancy to support thunderstorms today from northern CA across the northern Great Basin and northern Rockies, and into the northern Plains. ...Southern/Central Plains... Much of this region will be displaced south and west of any notable large-scale forcing for ascent. This limited ascent, combined with the showers and isolated thunderstorms currently ongoing across central and east TX, complicates the overall forecast today, with mesoscale factors likely contributing significantly to when and where storms develop this afternoon and evening. General expectation is for development along the southern and western periphery on the ongoing storms (i.e. from southeast/south-central TX into southwest TX) later this afternoon and this evening. This redevelopment will be supported by a combination of moist advection, modest heating, and limited low-level convergence. Moderate to strong buoyancy amid moderate vertical shear could support supercells if the mode remains discrete. However, the weakness in the mid-level flow suggests storms may tend to cluster, a scenario that is supported by most CAM guidance. Buoyancy and shear are still strong enough to support rotating updrafts and large hail early in the convective cycle, but the trends towards a messy convective mode could limit the persistence and coverage of robust updrafts. Damaging gusts are possible even with the clustered storm mode, especially given there is some potential for slightly more organized bowing segments over time. Farther west, mid-level height rises/subsidence are anticipated coincident with the dryline from central Kansas south-southwestward across western Oklahoma and west/southwest Texas. The environment, characterized by 1500 to 2000 J/kg of MLCAPE and 30 to 40 kt of westerly deep-layer shear, is conditionally supportive of supercells capable of all severe hazards. However, the previously mentioned height rises and subsidence, combined with modest convective inhibition, are generally expected to preclude thunderstorm development. Even so, given the conditional risk, Marginal risk probabilities will be maintained. ...Minnesota/Wisconsin... Recent surface analysis places a low just west of FAR, with a warm front extending southwestward across central/southeast MN and southern WI. This low is forecast to move eastward today, while the warm front expands northward. A narrow corridor of surface-based buoyancy could develop from north-central MN into far northwest WI as dewpoints increase in the upper 50s (perhaps even low 60s). Thunderstorm initiation appears possible along the cold front within this corridor, although veered low-level flow and northward/westward displacement of the better forcing casts doubt to whether updrafts will be maintained. Any storms that do mature within this warm sector should become supercells capable of all severe hazards, including large hail and tornadoes. However, low confidence in storm development and maturity precludes higher probabilities with this outlook. ...Northern Rockies... Mid-level moisture will support another day of modest surface-based buoyancy ahead of the shortwave trough mentioned in the synopsis. Persistent 30-40 knot flow within the CAPE-bearing layer combined with somewhat deep boundary-layer mixing will support strong to severe downburst winds with the more robust convective cells, mainly this afternoon through early evening. ..Mosier/Squitieri.. 04/12/2026Read more
