SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1257 AM CDT Wed Jun 02 2021 Valid 021200Z - 031200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE SOUTHERN PLAINS...AND ALSO FROM THE MID-SOUTH INTO PARTS OF THE OHIO VALLEY... ...SUMMARY... Isolated severe storms capable of large hail and strong wind gusts are possible from eastern New Mexico into much of Texas, mainly this afternoon and evening. Isolated strong to severe storms are also possible from the Mid South into parts of the Ohio Valley. ...Synopsis... A mid/upper-level trough extending from the Great Lakes into the southern Plains is expected to gradually move eastward today. A weak surface low is forecast to move from the mid-MS Valley toward the lower Great Lakes. A surface boundary, which has been reinforced by days of prior convection, will trail generally southwestward from the surface low into central TX, then west-northwestward into southeast NM. ...Mid South into the OH Valley... A broad area of rain with embedded thunderstorms will be ongoing this morning from portions of the Mid South to the OH Valley, in conjunction with moisture transport associated with a southerly low-level jet. While the primary low-level jet will become focused further north with time over the OH Valley, convection will likely persist within a moist low-level environment across portions of TN/MS and northern AL. Diurnal heating will result in moderate destabilization along the southern and western fringe of ongoing convection by afternoon, while midlevel 30-40 kt southwesterlies will support sufficient effective shear for some updraft organization. Ongoing storms may intensify by afternoon, with additional development possible to the west of earlier convection along the weak surface boundary from northern MS into western TN/KY. Organized multicells and perhaps a supercell or two will be possible from afternoon into early evening. Damaging wind will likely be the primary hazard, though buoyancy may be sufficient to support some hail despite weak midlevel lapse rates, and a tornado cannot be ruled out with any sustained supercell. ...Southern High Plains into the TX Hill County... Some airmass recovery is expected across portions of central/south TX into the southern High Plains, due in part to relatively limited prior-day convective overturning and the potential for somewhat stronger diurnal heating this afternoon. Moderate to locally strong instability is forecast to develop near and south of the surface boundary that is forecast to be draped from just north of the Upper TX Gulf Coast westward into the Hill Country, and then northwestward into southeast NM. With the primary upper trough gradually moving away from the region, large-scale ascent may be subtle at best, with initiation largely tied to the surface boundary, higher terrain across NM/west TX, and any other boundaries that are not yet evident. Midlevel flow will remain modest, but a gradual shift from westerly to northwesterly flow aloft with time may provide sufficient effective shear for a few organized clusters and/or supercells from late afternoon into the evening. Large hail would be the primary threat with any supercell, while locally severe wind gusts may accompany any well-organized cluster. Uncertainty is too high at this time to specify areas of greater threat within the larger Marginal Risk, but some portions of the area may require an increase in probabilities (and associated risk category) as details become clearer. ..Dean/Squitieri.. 06/02/2021 Read more LIVE: spc.noaa.gov
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