SPC May 1, 2025 0600 UTC Day 1 Convective Outlook
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Thu May 01 2025 Valid 011200Z - 021200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON THROUGH TONIGHT ACROSS PARTS OF WRN NY...WRN PA...WRN WV...MUCH OF OH...SERN IN...CNTRL AND ERN KY...MIDDLE TN...CNTRL/SRN MS...NRN/CNTRL LA...SRN AR...SRN OK...NRN TX... ...SUMMARY... Lines and/or clusters of strong to severe thunderstorms are likely to impact parts of the Ohio Valley into lower Great Lakes, parts of the lower Mississippi Valley, and the southern Great Plains this afternoon through tonight. ...Discussion... It appears that an amplifying mid/upper flow regime across the northern mid-latitudes of the eastern Pacific into North America will undergo further amplification while continuing to develop inland through this period. This will include a prominent ridge overspreading the Canadian Rockies and northern U.S. intermountain region later today through tonight, perhaps with an embedded high evolving to the east of the Cascades. Downstream, a notable short wave trough is forecast to continue digging to the lee of the northern U.S. Rockies, preceded by a short wave trough which has recently emerged from the Southwest. Models suggest that the lead perturbation will undergo shearing, but it may still provide support for modest deepening of a surface low northeast of the middle Mississippi Valley through lower Great Lakes region by late tonight. To the southwest of this low, conglomerate outflow from extensive convective development of prior days will at least initially precede and obscure any trailing surface front. By 12Z this morning, it appears that the leading edge of this outflow will be in the process of advancing eastward through the lower Ohio Valley, while stalling and weakening across the lower Mississippi Valley through upper Texas coastal plain. It remains a bit unclear the extent to which the surface outflow, residual cloud cover and rain will impact destabilization and convective potential later today. It is possible that this could impact a sizable area centered across parts of the Mid South. ...Ohio Valley into lower Great Lakes... Uncertainty exists concerning the possible influence of convective outflow and cloud cover on destabilization, and spread is evident among the various model output concerning the synoptic evolution. However, broad surface troughing overspreading the region during the day may provide the focus for the highest probabilities of vigorous thunderstorm development. Boundary-layer moistening (including mid 60s F surface dew points) and warming may become sufficient to support mixed-layer CAPE on the order of 1000-2000+ J/kg, in the presence of 30-50 kt south to southwesterly flow in the 850-500 mb layer. This environment may become conducive to organizing lines or clusters of storms, and perhaps a few supercell structures, posing a risk of severe wind and hail, with at least some potential for tornadoes, during the afternoon and evening. ...Lower Mississippi Valley vicinity... Large-scale forcing for ascent to support convective development remains unclear, on top of the possible lingering influence of convective outflow, cloud cover and rain. However, the NAM and Rapid Refresh suggest that a zone of strengthening differential heating may develop across the Ark-La-Tex into lower Mississippi Valley during the day, providing a focus for strong destabilization beneath steep-lapse rates associated with remnant elevated mixed-layer air. Aided by boundary-layer moisture characterized by surface dew points near 70F, large CAPE on the order of 2000-3000+ J/kg is forecast beneath modest westerly mid-level flow. Perhaps aided by lift associated with low-level warm advection, organizing convection posing a risk for large hail and damaging wind gusts appears possible. This may include supercell structures, at least initially, and eventually an upscale growing, east-southeastward propagating cluster. ...Raton Mesa into southern Great Plains Red River vicinity... Models indicate another zone of potentially strong convective development may evolve late this afternoon into tonight, as the boundary layer moistens and heats beneath the northern periphery of a plume of elevated mixed-layer air. It appears that this will advect east/east-southeast of the southern Rockies, near the southern periphery of the mid-level troughing digging to the lee of the northern Rockies. Models suggest that a smaller-scale embedded perturbation may be accompanied by increasing convective development across and east-southeast of the Raton Mesa vicinity by early this evening. Aided by updraft inflow of increasing instability across the Texas Panhandle into areas near/north of the Red River, there appears potential for the evolution of an upscale growing cluster. The 01/00Z NAM, in particular, generates a convective perturbation that would appear to include 70+ kt westerly rear inflow (in the 850-700 mb layer) across Oklahoma by late tonight. Based on other output, this appears an outlier, but the evolution of a convective cluster posing a risk for severe hail and wind appears possible. ..Kerr/Weinman.. 05/01/2025 Read more
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Thu May 01 2025 Valid 011200Z - 021200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON THROUGH TONIGHT ACROSS PARTS OF WRN NY...WRN PA...WRN WV...MUCH OF OH...SERN IN...CNTRL AND ERN KY...MIDDLE TN...CNTRL/SRN MS...NRN/CNTRL LA...SRN AR...SRN OK...NRN TX... ...SUMMARY... Lines and/or clusters of strong to severe thunderstorms are likely to impact parts of the Ohio Valley into lower Great Lakes, parts of the lower Mississippi Valley, and the southern Great Plains this afternoon through tonight. ...Discussion... It appears that an amplifying mid/upper flow regime across the northern mid-latitudes of the eastern Pacific into North America will undergo further amplification while continuing to develop inland through this period. This will include a prominent ridge overspreading the Canadian Rockies and northern U.S. intermountain region later today through tonight, perhaps with an embedded high evolving to the east of the Cascades. Downstream, a notable short wave trough is forecast to continue digging to the lee of the northern U.S. Rockies, preceded by a short wave trough which has recently emerged from the Southwest. Models suggest that the lead perturbation will undergo shearing, but it may still provide support for modest deepening of a surface low northeast of the middle Mississippi Valley through lower Great Lakes region by late tonight. To the southwest of this low, conglomerate outflow from extensive convective development of prior days will at least initially precede and obscure any trailing surface front. By 12Z this morning, it appears that the leading edge of this outflow will be in the process of advancing eastward through the lower Ohio Valley, while stalling and weakening across the lower Mississippi Valley through upper Texas coastal plain. It remains a bit unclear the extent to which the surface outflow, residual cloud cover and rain will impact destabilization and convective potential later today. It is possible that this could impact a sizable area centered across parts of the Mid South. ...Ohio Valley into lower Great Lakes... Uncertainty exists concerning the possible influence of convective outflow and cloud cover on destabilization, and spread is evident among the various model output concerning the synoptic evolution. However, broad surface troughing overspreading the region during the day may provide the focus for the highest probabilities of vigorous thunderstorm development. Boundary-layer moistening (including mid 60s F surface dew points) and warming may become sufficient to support mixed-layer CAPE on the order of 1000-2000+ J/kg, in the presence of 30-50 kt south to southwesterly flow in the 850-500 mb layer. This environment may become conducive to organizing lines or clusters of storms, and perhaps a few supercell structures, posing a risk of severe wind and hail, with at least some potential for tornadoes, during the afternoon and evening. ...Lower Mississippi Valley vicinity... Large-scale forcing for ascent to support convective development remains unclear, on top of the possible lingering influence of convective outflow, cloud cover and rain. However, the NAM and Rapid Refresh suggest that a zone of strengthening differential heating may develop across the Ark-La-Tex into lower Mississippi Valley during the day, providing a focus for strong destabilization beneath steep-lapse rates associated with remnant elevated mixed-layer air. Aided by boundary-layer moisture characterized by surface dew points near 70F, large CAPE on the order of 2000-3000+ J/kg is forecast beneath modest westerly mid-level flow. Perhaps aided by lift associated with low-level warm advection, organizing convection posing a risk for large hail and damaging wind gusts appears possible. This may include supercell structures, at least initially, and eventually an upscale growing, east-southeastward propagating cluster. ...Raton Mesa into southern Great Plains Red River vicinity... Models indicate another zone of potentially strong convective development may evolve late this afternoon into tonight, as the boundary layer moistens and heats beneath the northern periphery of a plume of elevated mixed-layer air. It appears that this will advect east/east-southeast of the southern Rockies, near the southern periphery of the mid-level troughing digging to the lee of the northern Rockies. Models suggest that a smaller-scale embedded perturbation may be accompanied by increasing convective development across and east-southeast of the Raton Mesa vicinity by early this evening. Aided by updraft inflow of increasing instability across the Texas Panhandle into areas near/north of the Red River, there appears potential for the evolution of an upscale growing cluster. The 01/00Z NAM, in particular, generates a convective perturbation that would appear to include 70+ kt westerly rear inflow (in the 850-700 mb layer) across Oklahoma by late tonight. Based on other output, this appears an outlier, but the evolution of a convective cluster posing a risk for severe hail and wind appears possible. ..Kerr/Weinman.. 05/01/2025 Read more
