Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0401 AM CDT Thu Jun 22 2023 Valid 251200Z - 301200Z ...DISCUSSION... A shortwave trough is forecast to progress from the Mid/Upper MS Valley into the Upper Great Lakes/Lower OH Valley on D4/Sunday, before then continuing eastward through more of the OH and TN Valleys on D5/Monday. Thunderstorm development is expected across the Lower OH Valley during the afternoon, as cold front associated with the shortwave trough moves through. There is some uncertainty regarding the amount of destabilization that occurs prior to the frontal passage, but strong mid-level flow will be spreading into the region. This combination of ascent (both along the front and via the approaching shortwave trough), buoyancy, and shear should be enough to produce severe thunderstorms. Highest probability of severe is currently expected across central/southern IN, southwest KY, far southeast IL, and far northwestern TN. Guidance offers differing solutions regarding the progression of the shortwave on D5/Monday. A faster solution would take the wave and associated stronger flow into the Mid-Atlantic, with an attendant risk for severe thunderstorms. However, a slower solution favors weakening mid-level flow and a less progressive cold front. This variability limits forecast confidence, precluding the introduction of any outlook areas. Upper ridging is expected to build across the central CONUS from D6/Tuesday through D8/Thursday. A shortwave trough is expected to move through the northern periphery of this ridging during this time frame. Some severe potential exists with this wave, but guidance differs on its timing and location, limiting predictability.
