SPC Aug 18, 2024 1730 UTC Day 2 Convective Outlook
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 PM CDT Sun Aug 18 2024 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN A PART OF EASTERN CO... ...SUMMARY... Isolated severe thunderstorms with damaging winds will be possible across several areas of the Lower 48, mainly on Monday afternoon into the early evening. A more concentrated threat for large hail is evident over a portion of eastern Colorado during the late afternoon to early evening. ...Synopsis... A nearly full-latitude mid/upper trough will remain anchored over the East, with a ridge emanating north from the southern High Plains, and a trough near the BC/WA coast. Several impulses, influenced by D1 convection, should progress within the W-shaped mid-level flow regime across the CONUS. ...Central/northern High Plains to the Interior West... A predominately meridional flow regime over the Northwest should evolve to mainly southwesterlies, with westerlies downstream as the mid-level ridge flattens/drifts east over the central High Plains and Dakotas. Extensive convective activity is likely towards mid to late afternoon as storms develop off the higher terrain within a broad plume of adequate 700-mb moisture from the Four Corners to MT, and seasonably rich boundary-layer dew points across the northern/central High Plains. Within much of this regime, deep-layer shear should be relatively modest outside of western MT and eastern CO. This suggests loosely to semi-organized clusters should dominate with isolated severe gusts as the primary threat. Isolated severe hail is also possible, mainly from the central High Plains to the eastern MT owing to larger buoyancy. Consensus of guidance suggests a few slow-moving supercells should develop near/east of the I-25 corridor from the Cheyenne Ridge to the Palmer Divide. With some mid-level flow enhancement atop weak low-level easterlies expected, this setup could yield a more concentrated threat for large hail. Relatively warm upper-level temperatures may temper hail magnitudes to the 1-2 inch range. Bulk of severe potential should diminish after dusk. ...Lower Mid-Atlantic to New England... While severe potential appears to be relatively less than on D1, embedded shortwave impulses and boundary-layer heating of a still richly moist air mass should support scattered to numerous thunderstorms focused along a reinforcing surface trough/cold front. Effective bulk shear will be modest, largely from 20-25 kts, and MLCAPE should hold from 500-1500 J/kg to the north of eastern NC. Sporadic strong gusts will be capable of producing occasional tree damage, peaking in the mid to late afternoon. ...North FL vicinity... Despite relatively warm mid/upper-level temperatures, a plume of larger buoyancy should develop ahead of the trailing portion of the coastal Atlantic cold front. Modest mid-level west-northwesterlies near and to the backside of the amplified upper trough should support loosely organized multicell clusters during the afternoon. Isolated strong to localized severe gusts are possible. ...LA vicinity... A conditionally adequate environment for a few marginally severe storms remains apparent along the northwest/southeast-oriented arc of the baroclinic zone across the Gulf Coast States. Remnants of elevated thunderstorm activity may be ongoing at 12Z Monday in parts of AR to northern LA. Guidance mostly decays this activity as the downstream warm-moist sector maintains appreciable MLCIN until afternoon, but some suggest it may intensify towards the LA coast. There is also low-probability potential for storms to redevelop during the late afternoon to early evening along the baroclinic zone after differential heating is maximized. The western extent of moderate north-northwesterly mid-level flow would foster potential for an isolated severe wind/hail threat. ..Grams.. 08/18/2024 Read more
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 PM CDT Sun Aug 18 2024 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN A PART OF EASTERN CO... ...SUMMARY... Isolated severe thunderstorms with damaging winds will be possible across several areas of the Lower 48, mainly on Monday afternoon into the early evening. A more concentrated threat for large hail is evident over a portion of eastern Colorado during the late afternoon to early evening. ...Synopsis... A nearly full-latitude mid/upper trough will remain anchored over the East, with a ridge emanating north from the southern High Plains, and a trough near the BC/WA coast. Several impulses, influenced by D1 convection, should progress within the W-shaped mid-level flow regime across the CONUS. ...Central/northern High Plains to the Interior West... A predominately meridional flow regime over the Northwest should evolve to mainly southwesterlies, with westerlies downstream as the mid-level ridge flattens/drifts east over the central High Plains and Dakotas. Extensive convective activity is likely towards mid to late afternoon as storms develop off the higher terrain within a broad plume of adequate 700-mb moisture from the Four Corners to MT, and seasonably rich boundary-layer dew points across the northern/central High Plains. Within much of this regime, deep-layer shear should be relatively modest outside of western MT and eastern CO. This suggests loosely to semi-organized clusters should dominate with isolated severe gusts as the primary threat. Isolated severe hail is also possible, mainly from the central High Plains to the eastern MT owing to larger buoyancy. Consensus of guidance suggests a few slow-moving supercells should develop near/east of the I-25 corridor from the Cheyenne Ridge to the Palmer Divide. With some mid-level flow enhancement atop weak low-level easterlies expected, this setup could yield a more concentrated threat for large hail. Relatively warm upper-level temperatures may temper hail magnitudes to the 1-2 inch range. Bulk of severe potential should diminish after dusk. ...Lower Mid-Atlantic to New England... While severe potential appears to be relatively less than on D1, embedded shortwave impulses and boundary-layer heating of a still richly moist air mass should support scattered to numerous thunderstorms focused along a reinforcing surface trough/cold front. Effective bulk shear will be modest, largely from 20-25 kts, and MLCAPE should hold from 500-1500 J/kg to the north of eastern NC. Sporadic strong gusts will be capable of producing occasional tree damage, peaking in the mid to late afternoon. ...North FL vicinity... Despite relatively warm mid/upper-level temperatures, a plume of larger buoyancy should develop ahead of the trailing portion of the coastal Atlantic cold front. Modest mid-level west-northwesterlies near and to the backside of the amplified upper trough should support loosely organized multicell clusters during the afternoon. Isolated strong to localized severe gusts are possible. ...LA vicinity... A conditionally adequate environment for a few marginally severe storms remains apparent along the northwest/southeast-oriented arc of the baroclinic zone across the Gulf Coast States. Remnants of elevated thunderstorm activity may be ongoing at 12Z Monday in parts of AR to northern LA. Guidance mostly decays this activity as the downstream warm-moist sector maintains appreciable MLCIN until afternoon, but some suggest it may intensify towards the LA coast. There is also low-probability potential for storms to redevelop during the late afternoon to early evening along the baroclinic zone after differential heating is maximized. The western extent of moderate north-northwesterly mid-level flow would foster potential for an isolated severe wind/hail threat. ..Grams.. 08/18/2024 Read more
