SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1237 AM CDT Thu Aug 15 2024 Valid 151200Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN KS INTO PARTS OF THE MID MS VALLEY AND MIDWEST... ...SUMMARY... Scattered severe thunderstorms are possible across parts of the Midwest, mid Mississippi Valley, and central Plains on Thursday. Damaging winds and large hail should be the main threats, but a couple tornadoes may also occur. A few strong storms may also develop across parts of the Northeast. ...Central Plains to the Mid Mississippi Valley... Weak mid-level height falls will spread across the mid Mississippi Valley today ahead of a short-wave trough that will approach western IA/northwest MO by early evening. Early in the period, a weak short-wave trough will be responsible for inducing multiple thunderstorm clusters across the Midwest, aided by LLJ that will translate into Lower MI by late afternoon. This early-day convection will be an extension of ongoing thunderstorm clusters that currently extend from central IA into eastern KS. This activity will propagate downstream as the LLJ shifts into the Great Lakes ahead of the weak disturbance. While locally severe gusts and hail could accompany this activity, considerable amount of precip and modest lapse rates do not favor widespread severe. Of more concern, strong boundary-layer heating is expected across much of the Plains into portions of the mid MS Valley. As a result, strong buoyancy will develop along the eastern edge of this steeper lapse-rate plume. Latest model guidance suggests very strong instability (MLCAPE >3000 J/kg) will materialize by mid afternoon from portions of eastern KS/MO into southeast IA. High-level diffluent flow will favor storm-top venting and scattered robust thunderstorms are expected to develop ahead of the short wave. Thunderstorms should concentrate along a synoptic front that will arc from southeast MN-eastern IA-northern MO-southeast KS-northern OK by late afternoon. Deep-layer shear should be adequate for supercells and wind/hail can be expected with the most robust updrafts. High-based thunderstorms are also expected to develop along the trailing boundary into the southern Plains where surface temperatures will easily rise through the upper 90s to near 100F. Dry adiabatic 0-3km lapse rates favor strong downdrafts as PW values will be seasonally high (1.5-1.75 inches). ...New England region... Upper troughing will hold across New England today with cool mid-level temperatures and modest northerly flow at 500mb. Strong boundary-layer heating will allow convective temperatures to be breached by 19z and scattered convection is expected to develop within a sheared environment that favors robust multi-cell updrafts. Some of this activity could generate strong gusts and marginally severe hail. Convection will be diurnally driven and should weaken with loss of daytime heating. ..Darrow/Halbert.. 08/15/2024
