Subj : DAY3SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jan 22 2023 08:29:18 ACUS03 KWNS 220829 SWODY3 SPC AC 220828 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0228 AM CST Sun Jan 22 2023 Valid 241200Z - 251200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TUESDAY EVENING THROUGH TUESDAY NIGHT ACROSS MUCH OF SOUTHEASTERN LOUISIANA...SOUTHEASTERN MISSISSIPPI...SOUTHERN ALABAMA AND THE WESTERN FLORIDA PANHANDLE... ....SUMMARY... Severe thunderstorms are possible, perhaps near mid to upper Texas coastal areas early Tuesday afternoon, but more likely across southeastern Louisiana and Mississippi through southern Alabama and the western Florida Panhandle Tuesday night. These may become capable of producing tornadoes and locally damaging wind gusts. ....Synopsis... Models suggest that an initially prominent mid-level high over the southern mid-latitude eastern Pacific will weaken, with a new high beginning to form in higher latitudes, within persistent larger-scale ridging. This ridging is forecast to continue to build north-northeastward across British Columbia, Yukon and parts of the Northwest Territories through this period, with amplified troughing being maintained downstream, along and east of the Rocky Mountains. The most prominent embedded short wave perturbation within this regime, initially in the base of this troughing, is forecast to accelerate east-northeastward out of southwest Texas by early Tuesday. Aside from the NCEP SREF (with the 22/03Z run remaining a notable slower outlier), most model output indicates that the perturbation will rapidly progress across the southern Great Plains into the Mid South by late Tuesday night, accompanied by significant surface cyclogenesis near mid/upper Texas coastal areas into and through the lower Mississippi Valley and Mid South. As this occurs, an intense west-southwesterly mid/upper jet (including 90-100 kt around 500 mb) is forecast to develop across the lower Mississippi through Tennessee Valleys by 12Z Wednesday. In association with the developing cyclone, a southerly low-level jet may include speeds increasing in excess of 50-70 kt to the east of the lower Mississippi Valley during a period of more rapid deepening Tuesday evening. A similar earlier period of cyclone deepening and wind field intensification is also appearing increasingly probable near mid/upper Texas coastal areas early Tuesday afternoon. ....Texas coastal areas through central Gulf Coast states... Given the synoptic forcing, the presence of an initially cool/stable boundary layer across much of the Gulf Coast region is the primary limiting factor to the development of a more substantive risk for severe thunderstorms Tuesday through Tuesday night. The boundary layer across much of the northern Gulf of Mexico will also still be in the process of modifying from prior frontal intrusions, but it does appear that mid/upper 60s F surface dew points may rapidly advect toward northwestern through north central Gulf coastal areas. Boundary-layer destabilization near, if not inland of, mid into upper Texas coastal areas may contribute to an environment conducive to supercell development around midday into early afternoon. Thereafter, boundary-layer moistening within at least a narrow inland corridor across southeastern Louisiana into south central Alabama still seems probable Tuesday evening through Tuesday night. Beneath a plume of modestly steepening lapse rates, this is expected to contribute to a corridor of boundary-layer destabilization sufficient to support organized convective development. This may include a developing line of storms along a pre-frontal confluence zone, perhaps preceded by more discrete supercells. While it appears possible that moist adiabatic to more stable near-surface lapse rates could tend to minimize the number of potentially severe storms, even with only somewhat better boundary-layer modification than currently forecast, a more substantive severe weather threat may still develop. Very large and clockwise-curved low-level hodographs forecast to develop within the warm sector will contribute to wind profiles potentially supportive of strong tornadoes in supercell storms. ...Kerr.. 01/22/2023 $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .