SPC 1300Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0751 AM CDT Tue Sep 29 2026 Valid 291300Z - 301200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN ARIZONA/NEW MEXICO TO WEST TEXAS... ...SUMMARY... Isolated severe thunderstorm wind gusts and possibly a tornado or two could occur this afternoon into tonight from southern and eastern New Mexico into west Texas, and across southeast Arizona. ...Synopsis... A mid/upper-level low and attendant trough will move across the Desert Southwest through the period. In response to the approaching deep trough, Hurricane Polo is forecast to move from the Gulf of California into Sonora this morning. While the tropical cyclone is forecast to weaken over the mountainous terrain of northern Mexico later today, a phasing of the mid-level remnants of Polo with the approaching deep mid/upper-level trough will result in a consolidating surface low that is forecast to deepen and move across eastern New Mexico and west Texas tonight. ...Southern/eastern New Mexico to west Texas... Widespread convection is ongoing and expected to generally continue into this afternoon and tonight from southern/eastern New Mexico to west Texas, as increasing large-scale ascent overspreads a very moist environment. The influence of the remnant tropical system will result in poor mid-level lapse rates, but increasing deep-layer flow/shear and enlarging low-level hodographs will favor some storm organization, especially later this afternoon and evening. The widespread storm coverage will result in a tendency toward complex or linear storm modes with time, though a few/episodic supercells will also be possible. The weak lapse rates and modest buoyancy are expected to limit the overall magnitude of severe potential, but a localized tornado and severe-gust threat could accompany any organized storm structures, particularly this afternoon and evening, influenced by a nocturnally strengthening low-level jet. ...Southern Arizona... A moist environment resides in close proximity to the Southwest Deserts mid/upper-level low, with a belt of very strong deep-layer winds sampled in available 12z upper-air data and regional WSR-88D VWPs. Scattered thunderstorms are common this morning, and while this convection/related cloud cover will generally hinder overall destabilization, modest diurnal heating will probably lead to some convective intensification during the day. The strong nature of the wind profiles could support a few at least weak/transient supercells, and potentially more organized convective bands later today, with at least some potential for strong thunderstorm winds and mostly sub-severe hail. ..Guyer/Bentley.. 09/29/2026 Read more