Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
547 ACUS02 KWNS 021703 SWODY2 SPC AC 021701 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1201 PM CDT Tue Jul 02 2024 Valid 031200Z - 041200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN AND CENTRAL PLAINS...AND FROM THE OZARKS TO THE LOWER OHIO VALLEY... ...SUMMARY... Severe thunderstorms are expected on Wednesday, particularly across parts of the Ozarks and Ohio Valley, and portions of the northern and central Plains. ...Ozarks to the Lower Ohio Valley... A modest shortwave impulse is forecast to develop northeast across the Midwest and Great Lakes vicinity on Wednesday. The bulk of strong mid/upper level southwesterly flow will remain over the Great Lakes vicinity, somewhat displaced from richer boundary-layer moisture and instability further south across the Mid-MS/OH Valley region. At the surface, a cold front will sag south/southeast across the Upper MS Valley/Great Lakes, perhaps stalling from northern MO/IL into Lower MI. The effective front will be augmented by early day clouds and perhaps showers over northern MO into northern IL. To the south, rich boundary-layer moisture with dewpoints in the 70s F and stronger heating across southern MO/IL into southwest OH, will foster a corridor of moderate to strong instability amid 25-35 kt effective shear magnitudes. Clusters/bands of strong to severe thunderstorms will mainly pose a risk for damaging wind gusts during the afternoon and early evening. ...Northern/Central Plains Vicinity... Modest height falls and strengthening midlevel westerlies are expected ahead of a deepening upper trough over the northern Rockies. As this occurs, a surface trough will sharpen over the High Plains. The western fringes of the Midwest cold front will be draped west to east near the NE/SD border. To the south of this boundary, south/southeasterly low-level flow will support low to mid 60s F dewpoints across much of KS/far southern NE westward into eastern CO, as well as across the adjacent southern Plains. Lower dewpoints are expected across the northern High Plains in the post-frontal airmass. Strong heating and steepening midlevel lapse rates will support moderate to strong destabilization. Vertically veering wind profiles with effective shear magnitudes greater than 40 kt will support initial supercell development near the surface trough from southwest SD/western NE southward into CO. This initial activity will pose a severe/damaging wind risk in additional to large to very large hail. Additionally, curved low-level hodographs and increasing SRH by late afternoon/early evening may support a few tornadoes near the surface trough. With time, consolidation of convection via outflow interactions and a modestly increasing low-level jet by early evening should result in more linear storm modes. Some potential exists for MCS development, shifting east across parts of far eastern CO into parts of southwest NE/northwest KS. If confidence increases in a bowing MCS developing, higher severe probabilities may be needed in subsequent outlooks. Convection will be more sparse with southward extent into NM and OK where large-scale ascent will be weaker and vertical shear overall more marginal. Nevertheless, a moist and unstable airmass will be present and any storms that develop could produce strong gusts. ..Leitman.. 07/02/2024 $$