Subj : DAY3SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue May 09 2023 18:56:59 ACUS03 KWNS 091856 SWODY3 SPC AC 091856 Day 3 Convective Outlook AMEND 1 NWS Storm Prediction Center Norman OK 0156 PM CDT Tue May 09 2023 Valid 111200Z - 121200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS... AMENDED FOR SEVERE POTENTIAL CENTRAL/SOUTHERN PLAINS ....SUMMARY... Strong/severe thunderstorms are forecast Thursday across the central Plains vicinity, where large hail can be expected along with locally damaging winds and possibly a couple of tornadoes. ....19z Update - Eastern CO/Western KS/OK... The Day 3 outlook for Thursday (May 11) has been amended for expected severe potential further west than previously forecast. Operational 09/12z NAM/GFS forecast guidance has trended slower/further west (and more in line with ECMWF and 12z NAM 3km/RRFS/FV3) with the progression of an ejecting mid/upper shortwave trough over the southern/central High Plains. This slower ejection of the shortwave trough is common in systems that tend to have a stronger meridional component. A surface low is expected to be located over southeast CO with a dryline extending south through the TX Panhandle and western TX Thursday morning. Convection will likely develop by late morning near the triple point over southeast CO and arcing east/southeast along the dryline through western KS. This morning activity will pose a risk for large hail initially. As the upper wave lifts northeast into the afternoon, convection is expected to shift north/northeast into a more unstable airmass. At the same time, additional development is expected south/southeast along the eastward-advancing dryline into central KS/OK. Supercells capable of all severe hazards will be possible from parts of western/central KS into OK. A second round of storms may impact parts of eastern CO and western KS behind morning convection and associated with the eastward meandering surface low. Large hail and strong gusts will be possible with any second round of convection that develops during the afternoon. ....Previous Day 3 Discussion (issued 0730z 09 May)... ....Synopsis... An upper low progged to lie over the central High Plains area early in the day is forecast to pivot slowly northeastward across Nebraska and into South Dakota through the period. At this occurs, a surface low is forecast to shift northeastward out of Colorado along roughly the same path, while a trailing trough/dryline reaches central Kansas/western Oklahoma by late afternoon. Elsewhere, ridging on the western and eastern flanks of the low will affect the West Coast, and the Southeast/Midwest, while northwesterly flow aloft prevails across New England. ....The Plains states from South Dakota to Oklahoma... Ahead of the advancing surface system, afternoon heating across the central Plains and vicinity will combine with a seasonably moist boundary layer to yield moderate destabilization -- particularly from central Nebraska southward. While a low-level capping inversion will limit convective coverage with southward extent, particularly given the northeastward advance of the upper system, isolated storms are forecast to develop along the dryline by late afternoon as far south as central Kansas and western Oklahoma. Here, steep lapse rates and veering/increasing flow with height will support supercells, with very large hail and a damaging gust or two expected, and possibly a tornado. Farther north -- into Nebraska and South Dakota, instability will decrease with northward extent. Still, with low-level southeasterly flow veering to a more southerly direction at mid levels will support organized/rotating storms, with risk for hail and locally damaging wind gusts along with a tornado or two. Storms may grow upscale overnight as the low-level jet increases, spreading across the Mid-Missouri Valley along with some hail/wind potential. ...Leitman.. 05/09/2023 $$ = = = 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) .