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SPC Jun 15, 2023 2000 UTC Day 1 Convective Outlook

2 years 1 month ago

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Thu Jun 15 2023 Valid 152000Z - 161200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM SOUTHWESTERN KANSAS SOUTHEASTWARD TO NORTH TEXAS... ...SUMMARY... Widespread severe storms associated with giant hail (larger than 3-4 inches in diameter), intense wind damage (greater than 80 mph) and a few tornadoes are expected this afternoon into tonight across western and southern Oklahoma into north and northeast Texas. ...Discussion... Aside from minor line adjustments, no substantive changes appear necessary to the ongoing outlook in this update. Severe weather is ongoing across eastern portions of the SLGT risk area -- i.e. the Gulf Coast states eastward to the southern Georgia/northern Florida coasts, where watches remain in effect. Farther west, severe weather is ongoing across the southeastern Colorado/southwestern Kansas area, with gradual expansion of storms -- and high-end severe-weather potential -- likely to occur southeastward across the eastern Texas Panhandle and parts of Oklahoma, and eventually into North Texas this afternoon and evening. Giant hail, strong/destructive wind gusts, and a few tornadoes are expected. ..Goss.. 06/15/2023 .PREV DISCUSSION... /ISSUED 1130 AM CDT Thu Jun 15 2023/ ...Southern Plains this afternoon through tonight... A midlevel shortwave trough is moving east-northeastward across northern NM as of late morning, and in response to this wave weak lee cyclogenesis is underway across northeast NM/southeast CO. This will help draw rich low-level moisture northwestward through the afternoon, with mid-upper 60s boundary-layer dewpoints reaching western OK/eastern TX Panhandle, and low-mid 70s farther southeast into northwest and north TX. The moistening is occurring beneath very steep midlevel lapse rates near 9 C/km, which will contribute to extreme buoyancy (MLCAPE in excess of 4000 J/kg) this afternoon/evening along the warm front and east of the dryline. Severe storm development is expected by early-mid afternoon along the dryline from the TX Panhandle into southwest KS, with subsequent development on the dryline into northwest TX. The extreme buoyancy, steep lapse rates and very long hodographs will all be quite favorable for intense supercells capable of producing giant hail (3-4 inches in diameter or greater). Despite modestly high temperature-dewpoint spreads (20 to 25 F) initially, a gradual increase in low-level shear/hodograph curvature will support some tornado threat late this afternoon/evening. As storms spread eastward this evening, upscale growth into one or more clusters appears likely, with an increasing threat for swaths of intense gusts in excess of 80 mph. The corridor of the most intense storms is expected across western/southern and parts of central OK, as well as north TX. Thus, the ENH/MDT risk areas have been expanded southward and southeastward into TX to reflect both the high-end hail threat with the initial supercells, and a high-end wind threat with any late evening/overnight storm clusters. ...Southeast through this evening... Clusters of severe storms are ongoing, along with a few supercells, in a broken band along a residual/composite outflow boundary from south GA to southern MS. An embedded mid-upper speed max is moving east-southeastward over the lower MS Valley in concert with the diurnal heating cycle, which will support continued storm development along this corridor through this afternoon/evening. Large CAPE and strong deep-layer vertical shear will favor large hail (some of which could exceed 2 inches in diameter) and damaging gusts (60-70 mph) as the primary severe threats. A couple of tornadoes may also occur with supercells interacting with the residual outflow boundary, primarily across southeast AL/southwest GA/FL Panhandle. ...OH area this afternoon/evening... An embedded shortwave trough is rotating southeastward over Lower MI/Lake MI as of late morning, and the zone of ascent preceding this trough will affect southeast Lower MI and northern OH later this afternoon/evening. Some increase in midlevel flow and steepening of low-level lapse rates will support thunderstorms capable of producing strong outflow gusts, and perhaps marginally severe hail. Read more