Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
066 ACUS02 KWNS 120558 SWODY2 SPC AC 120557 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1257 AM CDT Fri Jun 12 2026 Valid 131200Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERN KANSAS INTO WEST-CENTRAL ILLINOIS... ...SUMMARY... One or two evolving thunderstorm clusters appear possible across parts of the central Great Plains and lower Missouri Valley vicinity Saturday afternoon through Saturday night, accompanied by potential for strong, damaging wind gusts. Large to very large hail may also occur early in storm development from Kansas into Iowa. ...Mid-MS Valley into KS/OK... Generally low-amplitude mid/upper flow will extend across the central/southern Plains to the Mid-MS Valley area initially Saturday morning as the region is sandwiched between an upper trough over the Upper Midwest and the northern periphery of upper ridging across the Southeast. As the Upper Midwest trough modestly deepens and pivots east, some strengthening of mid and upper westerly flow is forecast. At the surface, southerly low-level flow will transport rich boundary layer moisture northward across OK/KS into the Mid-MS Valley ahead of northeast to southwest oriented cold front. Steep midlevel lapse rates atop this moist airmass will support a corridor of moderate to strong instability (2500-4000 J/kg MLCAPE) across KS, MO into southern IA and perhaps IL. Some uncertainty remains regarding possible ongoing convection across parts of northeast OK/southeast KS early Saturday morning in the form of a decaying MCS from the Day 1/Friday period. It is possible an MCV associated with this feature could move across MO during the day and pose some severe risk toward the MS River by afternoon. However, confidence in this scenario is low given low predictability of mesoscale feature at this time scale. Confidence is somewhat higher that convection will develop during the afternoon in the vicinity of the surface front from eastern KS into IA. Initial supercells appear possible. Low-level shear will be modest, but given rich boundary layer moisture and strong instability, a couple of tornadoes are possible. More likely, a large to very large hail risk will be possible with initial supercells given steep midlevel lapse rates, strong instability and elongated/straight forecast hodographs. As the surface front develops southeast during the late afternoon into the evening, one or more bowing MCSs are expected to develop, posing a risk for scattered severe/damaging winds (isolated gusts to 70-80 mph will be possible). This activity should continued southeast across the Lower MO Valley toward the Ozarks vicinity through evening/overnight. The northward extent of greater severe potential is uncertain, and this portions of the outlook may need further refinement in subsequent outlooks. ...Lake Michigan Vicinity... Isolated thunderstorms are expected during the afternoon and early evening along the advancing cold front. Cool temperatures aloft will support steep midlevel lapse rates atop low 60s F boundary layer moisture. This will foster MLCAPE values around 1500-2000 J/kg. Isolated hail and gusty winds will be possible with these storms. ...Southern Plains vicinity... A surface dryline will extend from southwest KS into eastern NM on Saturday. Forecast guidance depicts a shortwave impulse ejecting across the southern Rockies ahead of a western U.S. upper trough. As this occurs, isolated to scattered storms will develop near the surface boundary. This activity will likely be higher-based given deep mixing and strong heating into the 90s. Isolated strong wind gusts will be the main hazard with this activity, though a few instances of hail also are possible. ..Leitman.. 06/12/2026 $$