Severe Storm Outlook Narrative (AC)
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Issued by NWS
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603 ACUS01 KWNS 130110 SWODY1 SPC AC 130108 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0808 PM CDT Sun May 12 2024 Valid 130100Z - 131200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF EASTERN TX INTO CENTRAL LOUISIANA AND SOUTHERN MISSISSIPPI... ...SUMMARY... Large hail and locally damaging winds are possible from southeast Texas into Louisiana and southwest Mississippi through tonight. Isolated large hail will remain possible this evening across the Edwards Plateau of Texas. Damaging winds and hail could still occur this evening across northeast Wisconsin toward the Lower Peninsula of Michigan. ...Synopsis... A mid-level trough is currently traversing the southern Plains as a second mid-level trough continues to graze the Great Lakes region through this evening. A surface cold front continues to drift southward across the northern Plains and into the central High Plains, serving as a source of convergence for scattered strong thunderstorms. Ahead of the surface front, a low-level jet will become focused over eastern TX into LA and MS, supporting increased lift and destabilization tonight due to warm-air advection. As such, isentropic lift over convective outflow left behind by earlier storms should encourage additional strong storms into tonight. ...Northern Plains... Scattered thunderstorms continue to percolate in intensity over portions of Wisconsin toward Lower Michigan. SBCAPE around 1000 J/kg may support additional strong storms capable of wind and hail (perhaps briefly reaching severe limits) for at least a few more hours. However, nocturnal cooling should result in boundary-layer stabilization, limiting the severe risk to very brief and isolated occurrences. ...Central Plains into the southern High Plains... Strong multicellular storms continue to develop along or near the stationary portion of the surface front across KS into the TX/OK Panhandles. Adequate low-level CAPE colocated with abundant vertical-oriented surface vorticity has supported stronger cells with a history of occasional severe hail and isolated landspouts. The landspout risk should gradually diminish through the evening as diurnal heating wanes and convective overturning from the many ongoing storms reduces buoyancy. Given modest lapse rates over the Plains though, at least an isolated severe wind/hail risk should persist for at least a few more hours. ...Portions of central Texas... An isolated supercell continues to progress south over Irion/Tom Green Counties in central TX, and this storm may continue for a few more hours given the presence of 7+ C/km mid-level lapse rates and 60+ kts of effective bulk shear. Deep-layer ascent should remain weak through the remainder of the period, with convective coverage expected to remain isolated. However, surface temperatures around 90 F amid low 70s F dewpoints, beneath 8 C/km mid-level lapse rates, will support over 3000-4000 J/kg MLCAPE to linger over central and southern TX through the evening. Furthermore, strong mid-level flow overspreading this regime support elongated hodographs and 70 kts of effective bulk shear. Should an additional storm develop and become sustained, a supercell with large hail could result, warranting the continuation and expansion of severe probabilities into the evening. ...Eastern Texas toward southern Mississippi... Earlier storms have reinforced a surface baroclinic zone immediately north of the Gulf coast, which will be overspread by a developing low-level jet overnight. Warm-air advection atop this boundary will foster over 2000 J/kg MLCAPE amid 70+ kts of effective bulk shear, which may support multicells and transient supercells capable of producing severe wind and hail through tonight. ..Squitieri.. 05/13/2024 $$