SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1139 PM CST Sat Dec 04 2021 Valid 051200Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST OKLAHOMA/ARKANSAS TO MIDDLE TENNESSEE... ...SUMMARY... Scattered thunderstorms, some severe, are expected from southeast Oklahoma/Arkansas to the Mid-South and lower Ohio River Valley. ...Discussion... Low-latitude short-wave trough over AZ/northwest Mexico is expected to drift southeast later today as more dominant northern stream shifts south across the CONUS. Early this morning, moist warm sector had established itself across east TX where mid-upper 60s were noted as far north as TRL. With time this air mass should advance northeast across southeast OK into AR as the weak front draped across this region lifts north over the next 12-18hr. At 0530z, isolated thunderstorms have developed just north of the front over southeast OK within strengthening low-level warm advection and additional convection should evolve prior to sunrise. Early day thunderstorms may struggle to organize but could produce some hail/wind as they spread/develop northeast in response to the aforementioned retreating boundary. Forecast shear is not particularly strong early, but likely adequate for weak supercells. Mid- and high-level flow will increase during the latter half of the period and shear profiles will be more supportive of organized rotating updrafts. As mid-level heights fall across the mid MS Valley a strong cold front will surge across the Plains and extend from central MO-southeast KS-northern OK at 06/00z, then from central IN-southeast MO-northern AR-southeast OK at 06z. While convection should be mostly isolated during the day, extensive frontal convection is expected to develop during the evening. A forced band of thunderstorms will advance southeast during the overnight hours, possibly stretching from eastern KY-middle TN-northwest MS-southern AR-northeast TX by daybreak Monday. Damaging winds will likely be the main threat with this forced line but a few discrete supercells early in the convective cycle may generate large hail. A few tornadoes may also develop, especially embedded along the QLCS. ..Darrow/Wendt.. 12/05/2021 Read more LIVE: spc.noaa.gov
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