Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Apr 24 2023 12:42:18 ACUS01 KWNS 241242 SWODY1 SPC AC 241240 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0740 AM CDT Mon Apr 24 2023 Valid 241300Z - 251200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF CENTRAL AND SOUTHERN FLORIDA... ....SUMMARY... Thunderstorms over the central and southern Florida Peninsula today may produce isolated severe hail and gusts. ....Synopsis... In mid/upper levels, amplified northern-stream flow will trend more zonal with southward extent, away from a large, complex, persistent cyclone covering much of ON, the Great Lakes and adjoining states, with a net eastward drift. To its south, a convectively induced vorticity banner and shortwave trough are evident in satellite imagery over the central and south-central Gulf, as a residual effect of the severe MCS that moved off the TX Coast yesterday. The northern part of this perturbation should move over FL during the midday to mid-afternoon time frame. At 11Z, surface analysis showed a frontal zone extending from the east-central FL coastline eastward across the Atlantic, and southwestward over the FMY area, then westward across the north- central Gulf. This boundary should move diffusely, erratically and slowly northward over southwestern and central FL into this afternoon, before being obscured by convective processes. ....FL... Scattered to locally numerous thunderstorms are expected to develop over much of the central/southern FL Peninsula today, on a combination of sea-breeze, frontal, outflow, and perhaps differential-heating boundaries. Isolated severe gusts and damaging subsevere gusts are possible, along with isolated large hail. Though it should be thinning and breaking up somewhat, extensive mid/high cloud cover left from Gulf convection will spread over the peninsula through the remainder of the morning, slowing but not prohibiting favorable diurnal heating. Meanwhile, as the frontal zone drifts northward, rich low-level moisture (characterized by surface dewpoints in the upper 60s to mid 70s F) should spread into more of the central/southern peninsula. These factors will reduce already weak MLCINH (per the MFL 12Z sounding) at the same time large-scale DCVA/ascent from the Gulf trough reaches the area. A deep troposphere, seasonally steep midlevel lapse rates between modest stable layers, and favorable boundary-layer theta-e, should support areas of 1500-2000 J/kg preconvective MLCAPE today. Although strong veering of flow with height is expected in low/middle levels -- especially along and east of the East Coast sea-breeze boundary -- weak speeds will keep hodographs small. Still, these profiles, beneath strong flow above 500 mb, will lead to 35-45-kt effective-shear magnitudes -- locally/briefly stronger around favorably aligned boundaries. Forecast soundings also suggest strong anvil-level winds contributing to around 80-100 kt cloud-layer (LCL to EL) shear. As such, the main mode should be multicells, with the best-organized offering isolated severe potential, a few briefly exhibiting supercell character to aid in local hail/wind potential. A combination of expanding outflow air and diabatic cooling will diminish convection late this afternoon through evening. ....Four Corners States... Moisture-channel imagery reveals a compact cyclone over western WA, anchoring a strong shortwave trough that extends southward to near the CA/OR/NV border junction. The cyclone should deepen, enlarge, and dig southeastward, with its center reaching the SLC area by 12Z tomorrow. Isolated general thunderstorm potential will spread across a large part of the Rocky Mountain States in an expansive field of DCVA/destabilization and difluent flow aloft, preceding that low/trough. Isolated strong gusts may occur over lower desert elevations of UT, eastern AZ, western CO, or western/central NM this afternoon, where any high-based/low-topped diurnal convection (with meager but sufficient moisture aloft) overlaps a well-mixed, deep boundary layer. However, severe potential appears too isolated, conditional and nebulously focused for an outlook area at this time. ...Edwards/Leitman.. 04/24/2023 $$ = = = 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) .