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SPC May 27, 2025 2000 UTC Day 1 Convective Outlook

2 months 3 weeks ago

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0255 PM CDT Tue May 27 2025 Valid 272000Z - 281200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF SOUTHWESTERN INTO DEEP SOUTH TEXAS...AND PARTS OF THE GULF COAST STATES... ...SUMMARY... Scattered strong to severe thunderstorms remain possible across parts of the southern Plains to the Southeast. Large to very large hail and severe winds should be the main threats across western and southern portions of Texas, with damaging winds the primary concern across the Southeast. ...20Z Update... The previous forecast remains on track. Consideration was given to trim the Slight Risk across portions of eastern LA into southern MS with the passage of an earlier QLCS. However, surface observations show temperatures reaching 90 F in spots, indicating robust enough modification of the boundary layer to support some organized severe potential with an expected second round of storms this evening. Severe wind and hail is still expected to accompany the stronger storms that form to the lee of the central/southern Rockies, with potentially 2+ inch hail possible with storms closer to the Rio Grande. ..Squitieri.. 05/27/2025 .PREV DISCUSSION... /ISSUED 1139 AM CDT Tue May 27 2025/ ...Southeast States... A modestly organized quasi-linear cluster persists at midday across east-central/southwest Alabama, with a trailing MCV near the Mississippi and Alabama border. These storms will continue generally eastward and potentially intensify along the composite outflow through the afternoon into areas along/south of a front across Georgia, with at least isolated damaging wind potential. While not certain, some short-term guidance suggests that a degree of air mass recovery and abatement of outflow could allow for strong/localized severe storm redevelopment near the synoptic front later today farther west across southern Mississippi and possibly nearby Louisiana. ...Southern Plains including West/South Texas... In the wake of last night's extensive storms and prominent outflow now over the western Gulf, substantial convective development should focus later today over portions of west/south Texas, as a weak mid-level shortwave trough moves from northwest/north-central Mexico into the Southwest and southern High Plains. Weak low-level upslope flow against the higher terrain in west Texas and northern Mexico may also aid thunderstorm development. Most guidance suggests that moderate to locally strong instability will exist by peak afternoon heating, with steep mid-level lapse rates once again overspreading the warm sector from higher terrain to the south/west. Mid-level westerly flow is expected to remain fairly modest, but veering and gradual strengthening with height through mid/upper levels should support around 30-40 kt of deep-layer shear. Slow-moving supercells posing a threat for large to very large hail (2+ inches) should be the main threat with initial development. A transition to one or more bowing clusters with a greater severe wind threat appears possible through the evening and overnight hours as convection spreads generally southeastward toward and across south-central/Deep South Texas including the Rio Grande vicinity. ...Central/Southern High Plains... On the back side of an upper trough/low over the north-central states, isolated/high-based thunderstorms should initially form over the higher terrain this afternoon before spreading southeastward over the adjacent High Plains. While instability should tend to remain fairly weak, steepened low-level lapse rates this afternoon/evening and sufficient deep-layer shear to support modest updraft organization may support occasional hail and severe wind gusts. Read more