SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0741 PM CDT Thu Sep 21 2023 Valid 220100Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND SOUTHERN PLAINS... ...SUMMARY... Widely scattered strong to severe thunderstorms remain possible this tonight across parts of the southern and central Plains. ...01z Update... High-level diffluent flow aloft has established itself across the Great Plains as a slow-moving upper low settles into the northern Great Basin, and broad upper ridging remains anchored over northeast Mexico/deep south TX. One weak disturbance has suppressed the height field over the southern Plains and is now turning southeast across the Arklatex region. A cluster of thunderstorms has developed in advance of this feature but this activity is beginning to propagate toward a region of notably weaker buoyancy. 00z sounding from SHV exhibits steep lapse rates through 6km but PW values are not that high immediately downstream, and MLCAPE is less than 500 J/kg. Sounding from FWD is notably more unstable, but weak inhibition is observed near 850mb. Additionally, LLJ will refocus across the High Plains later this evening so convection may struggle to back-build along the southwestern flank of the complex. Later tonight elevated thunderstorms may increase across northeast OK as LLJ strengthens into this region by daybreak. Farther north across the central Plains, slow-moving thunderstorm clusters continue across central/southern NE into extreme northern KS. Some increase in the LLJ over the next few hours may encourage additional development across the High Plains as an axis of greater buoyancy continues from central KS into the Panhandle of NE. Latest MRMS data suggests the most robust updrafts are generating very large hail, possibly around 2 inches in diameter with the supercell along the NE/KS border (Red Willow/Decatur County). 00z sounding from DDC supports this potential with MLCAPE around 2500 J/kg, but very steep lapse rates (9 C/km) through 6km. Shear remains favorable for supercells and while large hail should remain the primary severe risk, some tornado potential continues. ..Darrow.. 09/22/2023
