SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Sat May 29 2021 Valid 291200Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL/SOUTHERN HIGH PLAINS... ...SUMMARY... Widely scattered severe thunderstorms capable of large hail and severe wind gusts are possible this afternoon and evening for parts of southeast Colorado, eastern New Mexico, and the Texas and Oklahoma Panhandles. ...Synopsis... Stronger westerlies aloft will be relegated to the northern Plains and the Eastern Seaboard. An upper trough will progress eastward over the Canadian prairies today and tonight, with strengthening westerlies and height falls occurring over the Upper Midwest. A positive tilt upper trough over the Great Lakes/Midwest will gradually take on a more neutral tilt as it slowly progresses eastward over the Ohio Valley toward the Appalachians. A southward-progressive cold front will relegate richer low-level moisture to the Carolinas and Southeast coastal areas as well as South Texas and the southern High Plains. ...Central and Southern High Plains... Although upper-level ridging and only modest-strength westerlies will generally be prevalent across the High Plains, a subtle mid-level disturbance noted in water vapor imagery over the southern Great Basin late Friday night will likely reach the south-central High Plains by around peak heating. In response, lee cyclogenesis will be focused across southeast Colorado, and to some extent across east-central/northeast New Mexico. Air mass modification/recovery in the wake of Friday night storms will gradually occur, with middle/some upper 50s F surface dewpoints likely to become reestablished west/northwestward toward the New Mexico/Texas border vicinity into southwest Kansas/southeast Colorado by late today. Effective shear will generally be between 30-40 kt, although slighter stronger and more supercell-supportive values of 35-45 kt are plausible across southeast/east-central Colorado and far northeast New Mexico/western Oklahoma Panhandle vicinity. Initial storm development and intensification should occur by around 20-21Z, potentially including the Palmer Divide vicinity, southeast Colorado/Raton Mesa area, and possibly near/east of the Sacramento Mountains in southeast New Mexico. Large hail will be the most prevalent hazard during the first few hours of storm development/maturation, although a brief tornado or two could also occur, perhaps especially in vicinity of the Palmer Divide and east-central toward southeast Colorado. A nocturnally increasing southerly low-level jet coincident with the instability axis may be favorable for upscale quasi-linear growth and forward propagation (east-southeastward) by evening, particularly from southeast Colorado/northeast New Mexico into the Oklahoma/Texas Panhandles. A somewhat more organized/sustained severe wind risk may evolve for a few hours within this corridor before storm intensity wanes overnight. ...Carolinas and far southeast Virginia... Thunderstorm development and intensification will likely be focused across the Carolinas into far southeast Virginia in vicinity of a southeastward-spreading front and near/east of a surface wave that will likely be focused near the North Carolina/South Carolina border vicinity. Low to mid 60s F surface dewpoints within the warm sector will contribute to as much as 1000-1500 J/kg MLCAPE. While a few transient supercells could occur immediately near the southwest/northeast-oriented frontal, multicells capable of isolated wind damage should be the most common mode/risk this afternoon through early evening. ...South Texas/Rio Grande River vicinity... Although forecast confidence is limited, there is some potential that storms occurring late Friday night across the Permian Basin toward the Hill Country may persist southeastward in a semi-organized/strong fashion into a residually moist/unstable air mass, which could include some early day severe hail/wind risk. Have opted to include low severe probabilities across the region to account for this potential. ..Guyer/Squitieri.. 05/29/2021 Read more LIVE: spc.noaa.gov
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