SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1221 PM CDT Tue Sep 19 2023 Valid 201200Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF EASTERN OK AND FAR WESTERN AR... ...SUMMARY... Isolated strong to severe thunderstorms are possible across the portions of eastern Oklahoma and far western Arkansas. ...Synopsis... Heights are expected to rise across the southern High Plains and central/southern Plains on Wednesday, as the overall pattern across the western and central CONUS begins to amplify. This amplification will primarily result from the deepening/maturating of a shortwave trough dropping across the Pacific Northwest towards the western Great Basin, although some secondary influence will result from a progressive, low-amplitude shortwave trough moving from southern CA across the Four Corners. Primary upper-level feature east of the Rockies will be a convectively augmented vorticity maximum forecast to centered over the Ozark Plateau early Wednesday morning. This feature is then expected to gradually drift northeastward across central MO throughout the day. Dry and stable conditions are anticipated for most of the CONUS east of the MS River, with the only exception being isolated thunderstorms early Wednesday morning over the Upper MS Valley, and near the aforementioned vorticity max as it moves across the Mid MS Valley. Highest thunderstorms coverage is anticipated in the OK/AR border vicinity, where some isolated severe is possible (discussed below), and over the Florida peninsula, where weak shear and poor lapse rates will limit severe potential. ...Eastern OK into Western AR... Showers and thunderstorms are expected across central and eastern OK tonight, continuing through Wednesday morning across eastern OK and far western AR. General expectation is that most of the severe potential associated with this cluster will occur before 12Z Wednesday, with this cluster then gradually weakening as it shifts eastward Wednesday morning. Outflow associated with these storms will likely form an effective warm front, extending from southeast OK into western central OK during the morning. Some northward progression of this boundary is possible throughout the day, although uncertainty exists regarding how far north it progresses. This uncertainty is largely a result of additional uncertainty regarding cloud cover across north-central and northeast OK north of the of the outflow/effective warm front. Given the lack of large-scale forcing for ascent, this boundary will likely act as the impetus for isolated thunderstorm development Wednesday afternoon/evening, with any open warm-sector development unlikely. Higher storm coverage appears more likely in the evening, as warm-air advection increases across the effective front. Shear is strong enough to support a few organized storms and some isolated hail appears possible. Additionally, there does appear to be just enough mid-level drying to potentially support a strong gust or two, even north of the boundary. ..Mosier.. 09/19/2023
