Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
799 ACUS02 KWNS 180525 SWODY2 SPC AC 180524 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1224 AM CDT Tue Jun 18 2024 Valid 191200Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE SOUTHERN HIGH PLAINS...FROM PARTS OF IOWA INTO SOUTHERN WISCONSIN...AND OVER FAR SOUTHERN TEXAS... ...SUMMARY... Locally strong gusts may occur with storms over the southern High Plains, and from parts of Iowa into southern Wisconsin. A brief tornado cannot be ruled out over far southern Texas late Wednesday and Wednesday night in association with Potential Tropical Cyclone 1. ...Synopsis... The tail end of an upper trough will sweep across the northern Plains and upper MS Valley during the day, with primary speed max well into Ontario. Meanwhile, a strong upper ridge will extend from the OH Valley into the Northeast, with rising heights and subsidence developing over the Plains and south of the departing wave. At the surface, a cold front will decelerate into WI, becoming stationary during the evening westward into KS and toward northeast NM. While a moist air mass will exist ahead of this front, warming temperatures aloft and weakening lift will minimize severe potential across those areas. However, easterly upslope flow may result in a few strong storms into NM. Farther south, a very moist air mass will push west across the western Gulf of Mexico with upper 70s F dewpoints across southern TX. Overall wind fields are likely to increase as Potential Tropical Cyclone 1 develops, and possibly becomes a TS per NHC guidance. ...From southern WI to northeast NM... Areas of thunderstorms are likely to be ongoing Wednesday morning over parts of the central Plains, potentially producing strong outflow winds. This convection is expected to weaken during the day, with a rejuvenation along portions of the boundary during the afternoon. The most likely areas for isolated severe gusts appear to be over the IA to WI/IL portion of the boundary in closer proximity to the exiting upper wave, and in the upslope region over eastern NM. In both areas, neither shear nor instability will be particularly strong, but the front should provide a focus for development in a marginally unstable environment. In addition to gusty winds, cells over northeast NM into the OK/TX Panhandles may produce marginally severe hail as veering winds with height favor cellular storm mode. ...Far southern TX... Substantial convection with the potential tropical cyclone will move westward from the Gulf of Mexico and into southern TX, providing heavy rainfall and increasing winds. Official NHC guidance brings the system to tropical storm strength prior to landfall over Mexico early Thursday morning, which will maintain moist easterly winds across TX. Forecast soundings from various models depict upper 70s F dewpoints will favor sufficient SBCAPE for a few strong storms given 30-50 kt winds through the lowest few km AGL, veering with height. The combination of a very moist air mass with potentially strong low-level shear may favor a minimal tornado risk over the region, and low tornado probabilities have been introduced. ..Jewell.. 06/18/2024 $$