Afternoon Update: Issued at 2:45pm local time 07-25-2023.
The biggest change to this outlook is the reflection of the modest increase in the tornado threat that will exist tomorrow, especially across southeastern portions of the WMIWX coverage area. The delineations on the map graphic remain largely unchanged however we have expanded the increased potential delineation (in red) to include the thumb region of lower MI and have slightly reduced the size of the same delineation in southwestern Michigan and eastern Illinois.
Model guidance is becoming more clear as the event draws closer. A strong shortwave trough and accompanying surface low will move eastward through the Great Lakes region as it exits the upper midwest. There is an increased potential for perhaps stronger or more widespread strong to severe thunderstorms across southern and southeastern portions of lower MI in the red delineation on the graphic map. Damaging wind gusts to 70 MPH, large hail, and isolated tornadoes are the primary threats.
Ahead of the surface trough, scattered to widespread convection in the form of rain showers and perhaps some thunderstorms will be ongoing across lower Michigan as a result of strong warm air flow into the region. As the morning progresses a low level jet should force a majority of this early morning convection east/southeast by about 11am local time.
Warm air advection will continue to stream into lower Michigan as we approach peak heating. Surface temperatures are forecasted to reach well into upper 70's and low 80's with locally higher readings possible. Surface moisture will be plentiful with surface based dew points forecasted to be in the 70's across the WMIWX coverage area. Additionally, models currently forecast anywhere from 1,000 - 4,000 J/kg of CAPE across much of the area.
Kinematics are also modestly favorable for the development and intensification of strong to severe weather though we will hold off on discussing this in more detail until there is more model agreement in terms of the placement of the low level jet and the strength of the modest westerly flow. Nonetheless, wind bards and curved hodographs do support some limited tornado potential as well as perhaps a slightly increased wind threat.
As aforementioned, morning convection may limit this threat to some degree. Overall intensity and coverage of the severe weather threat will be highly influenced by the evolution of the morning convection. Whether or not, and to what degree, the environment can recover behind the morning convection may increase or decrease the threat for severe weather.
Additional forecast changes for this threat are expected as the model guidance becomes more clear. Stay tuned to WMIWX and official sources for updates.
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