SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1246 AM CDT Mon May 31 2021 Valid 311200Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TODAY INTO TONIGHT ACROSS PARTS OF SOUTHEASTERN NEW MEXICO AND SOUTHWESTERN TEXAS... ...SUMMARY... A few strong to severe thunderstorms are possible today across parts of the Permian Basin vicinity of southeastern New Mexico and southwestern Texas, into parts of the southern Great Plains. ...Synopsis... Models indicate that positively tilted mid-level ridging, on the leading edge of an amplified belt of westerlies across the mid-latitude Pacific, may build inland across the Pacific Northwest and Canadian Rockies during this period. Downstream of this feature, it appears that one short wave perturbation, within large-scale troughing over the Southwest, will gradually emerge from the Colorado Plateau vicinity. This will be preceded by at least a couple of other perturbations, one convectively enhanced across the western Oklahoma vicinity at 12Z this morning, as another approaches the Guadalupe and Davis Mountains vicinity of southern New Mexico and southwest Texas. All the perturbations will make only generally slow eastward progress, embedded within initially modest to weak west-southwesterly flow extending from the Southwest through the middle/lower Mississippi Valley. In the wake of the trailing perturbation, it appears that mid-level troughing will be maintained across the Southwest into the subtropical eastern Pacific, with an embedded cyclonic circulation forming near northern Baja. As the trailing perturbation progresses east of the southern Rockies by late tonight, and another short wave impulse digs to the lee of the northern Rockies, larger-scale mid-level troughing may begin to consolidate across the Great Plains. Downstream, broad troughing may also gradually consolidate across the lower Great Lakes into the Canadian Maritimes, as one short wave trough accelerates northeast of the northern Mid Atlantic coast, ahead of another digging southeast of the Upper Midwest. In association with this regime, seasonably cool and stable conditions will persist across most areas east of the Rockies, with warm and generally dry conditions across much of the west. However, it will remain seasonably moist across the lower Rio Grande Valley and parts of the southern Great Plains into the southern Rockies, ahead of the Southwestern mid-level troughing, as well as across the Florida Peninsula. ...Guadalupe/Davis Mountains vicinity into southern Great Plains... The southern of a couple of convective generated cyclonic vortices (currently near Lubbock, TX) may slowly reach western portions of northern Texas by 12Z this morning, before continuing east-northeastward across the Red River vicinity during the day. This will be trailed to the west-southwest by a convectively reinforced baroclinic zone, which could become a focus for additional developing clusters of storms through the period. It appears that this may extend from north central Texas into southeastern New Mexico by late this afternoon, when daytime heating may contribute to the development of moderately large CAPE along and to its south. Steepest lower/mid tropospheric lapse rates and largest CAPE (2000+ J/kg) may become focused across the eastern slopes of the higher terrain of southwest Texas into southern New Mexico. The evolution of the developing conglomerate convective outflow boundary to the north and northeast remains a bit more unclear, with early day thunderstorm development possible to the northeast of the Guadalupe and Davis Mountains. However, where substantive boundary-layer destabilization does take place, it does appear that modestly strengthening mid-level flow (around 30-40+ kt at 500 mb) across this region will contribute to potential for isolated supercells (where storms are not undercut by outflow) and evolving/organizing clusters. This activity will pose a risk for large hail and locally strong surface gusts, before diminishing late this evening or overnight. ...North central/northeast Wisconsin into Upper Michigan... Beneath the cold core of mid-level troughing initially over the Upper Midwest, at least some model output (NAM in particular) suggests that there may be sufficient moistening and daytime heating within a narrow pre-frontal corridor to support mixed-layer CAPE on the order of 500-1000 J/kg by late this afternoon. Perhaps aided by forcing for ascent associated with an elongating mid-level cyclonic vorticity center forecast to pivot across the region, this may support the evolution of a small cluster of storms. Low-level wind fields are forecast to remain generally weak, and deep-layer shear may be modest, at best. However, it might not be out of the question that relatively cool thermodynamic profiles (including relatively steep lapse rates) could support small to marginally severe hail and a few strong surface gusts before activity diminishes while spreading southward this evening. ..Kerr/Squitieri.. 05/31/2021 Read more LIVE: spc.noaa.gov
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