SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1218 AM CDT Wed Aug 03 2022 Valid 031200Z - 041200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS LOWER MICHIGAN INTO THE MIDDLE MISSISSIPPI VALLEY... ...SUMMARY... Scattered storms, some severe, are most likely from Lower Michigan into the Mid Mississippi Valley, with at least isolated severe possibly extending southwestward across Missouri and into eastern Kansas. ...Great Lakes to Mid-MS Valley Vicinity... A shortwave trough over the upper MS Valley this morning will shift east across the Great Lakes vicinity through early evening before shifting into southern Ontario and Quebec. At the surface, a cold front will extend south/southwest from a low near James Bay into southeast MN and then western KS. Ahead of the front, mid 60s to low 70s F dewpoints will reside beneath modest midlevel lapse rates. This will contribute to the development of moderate to strong instability (2500-4500 J/kg MLCAPE). While stronger large-scale ascent will be focused across the Great Lakes, the southeastward-advancing cold front will provide focus for thunderstorm develop from WI/MI into IL/MO. Vertical shear will remain fairly modest across the entire region, though somewhat better over MI. Modest shear and steep low-level lapse rates will generally favor outflow dominant storms, and organized clusters will pose a threat for damaging gusts, with some sporadic marginally severe hail also possible. Forecast guidance has a consistent signal among various CAMs and ML output indicating some organized forward-propagating cluster/MCS could develop across parts of MO and shift south while building westward into eastern KS. Given rather poor shear across this area, confidence is low in how intense or well-developed any thunderstorm clusters may be across this area. The Marginal risk has been expanded southward across southern MO with some southwest expansion to the Slight risk. If confidence increases that a well-organized MCS could develop via cold pool development, severe probabilities may need to be increased in coming outlooks. ...AZ... Moderate vertical shear will develop as mid/upper easterly flow increases atop northwesterly low-level flow. Modest midlevel lapse rates will support weak instability up to around 1000 J/kg while strong heating aids in a well-mixed boundary-layer. Thunderstorms will initially develop over higher terrain before moving westward into lower elevations. Outflow dominant storms producing strong gusts will be possible, with some potential for a forward propagating cluster across the lower desert of southeast AZ. ..Leitman/Weinman.. 08/03/2022
