SPC May 11, 2025 0730 UTC Day 3 Severe Thunderstorm Outlook
SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0228 AM CDT Sun May 11 2025 Valid 131200Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for severe thunderstorms currently appears negligible across the U.S. Tuesday through Tuesday night. ...Discussion... It appears that significant mid/upper-level troughing progressing inland of the U.S. Pacific coast may dig as far south as the lower Colorado Valley, and suppress ridging within a belt of westerlies emanating from the subtropical eastern Pacific, across the southwestern international border area. Thereafter, models indicate that the perturbation will turn eastward across the Intermountain West later Tuesday through Tuesday night, with intensifying difluent west-southwesterly mid/upper flow overspreading the southern Rockies by 12Z Wednesday. In lower levels, modestly deep surface troughing to the lee of the Rockies may continue to slowly shift eastward across the Great Plains. However, in the wake of broad, weak negatively tilted mid/upper troughing shifting east of the Mississippi Valley, toward the Atlantic coast at a slower pace than the upstream trough, strengthening low-level flow (up to 30-40 kt around 850 mb) is forecast to maintain a pronounced westerly component across the southern Great Plains into lower Mississippi Valley. This will continue to impede boundary-layer moisture return off the Gulf into the Great Plains, though evapotranspiration may contribute to moistening beneath the leading edge of a plume of warm elevated mixed-layer air advecting eastward across the central and southern Great Plains. Downstream, models indicate that there will be gradual further deepening of broad, weak surface troughing across much of the Southeast. However, the plume of seasonably high moisture content air emanating from the lower latitudes is forecast to generally shift east of the south Atlantic coast during the day Tuesday, though this may be slower to occur across southeast coastal areas of the Florida Peninsula. ...Intermountain West into Great Plains... Models suggest that destabilization beneath an elongated mid-level cold pool, trailing the surface cold front, may contribute to scattered, generally weak/diurnal thunderstorm activity across the northern Rockies and intermountain region, into the vicinity of the northern Sierra Nevada. Near the surface troughing across the Dakotas, it appears that a strongly heated and deeply mixed boundary may become characterized by 40-50 F surface temperature/dew point spreads, but with thermodynamic profiles still supportive of CAPE on the order of 500-1000 J/kg. High-based thunderstorm development appears possible near/after peak heating, which could pose some risk for locally strong surface gusts. However, the extent of this potential remains unclear, and too uncertain to introduce even low severe probabilities at the present time. ...Ohio Valley/Mid Atlantic/Southeast... Scattered, largely diurnal thunderstorm activity will again be possible beneath the weak/weakening mid-level troughing. Stronger convection may focus along the sea breeze near southeastern Florida coastal areas, and perhaps across parts of the mid and southern Atlantic Piedmont, where at least modest boundary-layer destabilization may occur. However, it is not yet clear that this will be accompanied by an appreciable risk for severe weather. ..Kerr.. 05/11/2025 Read more
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0228 AM CDT Sun May 11 2025 Valid 131200Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for severe thunderstorms currently appears negligible across the U.S. Tuesday through Tuesday night. ...Discussion... It appears that significant mid/upper-level troughing progressing inland of the U.S. Pacific coast may dig as far south as the lower Colorado Valley, and suppress ridging within a belt of westerlies emanating from the subtropical eastern Pacific, across the southwestern international border area. Thereafter, models indicate that the perturbation will turn eastward across the Intermountain West later Tuesday through Tuesday night, with intensifying difluent west-southwesterly mid/upper flow overspreading the southern Rockies by 12Z Wednesday. In lower levels, modestly deep surface troughing to the lee of the Rockies may continue to slowly shift eastward across the Great Plains. However, in the wake of broad, weak negatively tilted mid/upper troughing shifting east of the Mississippi Valley, toward the Atlantic coast at a slower pace than the upstream trough, strengthening low-level flow (up to 30-40 kt around 850 mb) is forecast to maintain a pronounced westerly component across the southern Great Plains into lower Mississippi Valley. This will continue to impede boundary-layer moisture return off the Gulf into the Great Plains, though evapotranspiration may contribute to moistening beneath the leading edge of a plume of warm elevated mixed-layer air advecting eastward across the central and southern Great Plains. Downstream, models indicate that there will be gradual further deepening of broad, weak surface troughing across much of the Southeast. However, the plume of seasonably high moisture content air emanating from the lower latitudes is forecast to generally shift east of the south Atlantic coast during the day Tuesday, though this may be slower to occur across southeast coastal areas of the Florida Peninsula. ...Intermountain West into Great Plains... Models suggest that destabilization beneath an elongated mid-level cold pool, trailing the surface cold front, may contribute to scattered, generally weak/diurnal thunderstorm activity across the northern Rockies and intermountain region, into the vicinity of the northern Sierra Nevada. Near the surface troughing across the Dakotas, it appears that a strongly heated and deeply mixed boundary may become characterized by 40-50 F surface temperature/dew point spreads, but with thermodynamic profiles still supportive of CAPE on the order of 500-1000 J/kg. High-based thunderstorm development appears possible near/after peak heating, which could pose some risk for locally strong surface gusts. However, the extent of this potential remains unclear, and too uncertain to introduce even low severe probabilities at the present time. ...Ohio Valley/Mid Atlantic/Southeast... Scattered, largely diurnal thunderstorm activity will again be possible beneath the weak/weakening mid-level troughing. Stronger convection may focus along the sea breeze near southeastern Florida coastal areas, and perhaps across parts of the mid and southern Atlantic Piedmont, where at least modest boundary-layer destabilization may occur. However, it is not yet clear that this will be accompanied by an appreciable risk for severe weather. ..Kerr.. 05/11/2025 Read more