SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0649 PM CST Wed Nov 17 2021 Valid 180100Z - 181200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for severe thunderstorms appears negligible across the U.S. through tonight. ...01Z Outlook Update... Strongest southerly low-level return flow is now focused across the lower Ohio Valley into lower Great Lakes region and Northeast, with low-level flow across the northwestern Gulf coast region into the Ozark Plateau generally modest to weak. However, latest model output continues to suggest that a corridor of pre-frontal low-level moistening which has occurred across the Ozark Plateau vicinity into the lower Ohio Valley will be sufficient to contribute to scattered thunderstorm development overnight. Warm mid-level temperatures are still contributing to inhibition above the corridor of most substantive low-level moistening, but as a significant short wave trough continues to gradually turn southeast/east of the middle Missouri Valley and central Great Plains, mid-level height falls and cooling should support the initiation of thunderstorm activity. Large-scale ascent is already aiding increasing convection rooted in increasingly elevated moisture return to the northwest of the surface frontal zone, across northwestern Arkansas and southern/eastern Missouri into the Great Lakes. It appears that strengthening lift in closer proximity to the front (but still to the cool side of it) will yield thunderstorm initiation within the next hour or two, which should tend to gradually spread southward with the advancement of the front. Otherwise, isolated thunderstorm development still appears possible near the front as it advances into Deep South Texas overnight, perhaps aided by weak forcing associated with an impulse within weak troughing across the northern Mexican Plateau and Rio Grande Valley. Further moistening on continuing southerly low-level flow, coupled with weak mid-level cooling, may also contribute to isolated thunderstorms overnight near or inland of the Louisiana Gulf coast. A weak perturbation migrating northeast of the western Caribbean may contribute to additional thunderstorm development along a remnant frontal zone, mostly south and southwest of the Florida Keys, overnight. ..Kerr.. 11/18/2021 Read more LIVE: spc.noaa.gov
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