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Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.

Wednesday, October 13, 2021

SPC Oct 13, 2021 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0255 PM CDT Wed Oct 13 2021 Valid 132000Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE EASTERN DAKOTAS/MINNESOTA AREA...CENTRAL/SOUTHWEST MISSOURI...AND FROM THE TX HILL COUNTRY INTO NORTHEAST TX... ...SUMMARY... Marginal severe-weather potential (in the form of thunderstorm wind and tornado threat) is apparent today over parts of the eastern Dakotas/Minnesota area, and from south/central Texas and Missouri. ...Discussion... No appreciable change was made to the previous convective outlook. ..Smith.. 10/13/2021 .PREV DISCUSSION... /ISSUED 1129 AM CDT Wed Oct 13 2021/ ...Synopsis... A mid-latitude cyclone continues to mature as it gradually moves northeastward toward the northern Plains. Recent surface analysis places the occluded low associated with this cyclone over south-central SD. An occluded front extends southeastward from this low to the triple point over southeast NE, with a cold front extending from the triple point southward across eastern KS and then back south-southwestward through central OK and northwest TX into the TX Permian Basin. A decaying convective line/outflow boundary precedes this cold front, currently extending from far southeast IA southwestward across MO and eastern OK into western north TX. Given the narrowing warm sector and anticipated northward shift in the stronger low to mid-level flow, reinvigoration appears unlikely along the majority of this outflow as it transitions to more of an anafrontal character. The only exception is from north TX into the TX Hill County (discussed in more detail below). Potential exists for additional thunderstorm development along the occluded front as it moves through the western Dakotas and into MN as well as along the cold front across a portion of MO. ...TX Hill Country into Northeast TX/Southeast OK... Widespread showers and thunderstorms are expected across the region as an influx of mid-level moisture associated with TC Pamela spreads northeastward. This increased moisture in the presence of the frontal boundary should contribute to continued regeneration of showers and thunderstorms. While much of this activity will likely be elevated behind the front, vertical shear supports supercells with any surface-based development. A somewhat messy storm mode is likely, but the potential for bowing line segments and a brief tornado exists with any surface-based development that persists ahead of the front. ...Eastern Dakotas/Western MN... An arc of low-topped showers and thunderstorms is still expected this afternoon just ahead of the deep-layer cyclone. Cool mid-level temperatures will result in modest buoyancy despite limited diurnal heating while backed low-level flow will enlarge hodographs in a narrow corridor near the arc of strongest low-level lift. This will support some potential for storm-scale rotation and perhaps a few stronger storms capable of damaging wind gusts and maybe even a brief tornado. The limiting factor will be amount of low-level destabilization and result buoyancy. Even with relatively cool surface temperatures in the upper 50s to near 60 F in forecast soundings, a narrow area of 200-700 J/kg MLCAPE may develop. ...MO... Recent convection-allowing guidance continues to show the potential for isolated thunderstorms along the front as it moves through MO this afternoon/evening. Heating will be limited but the air mass is expected to remain moist and modestly buoyant. This area will remain within the southern extent of the stronger low to mid-level flow. These conditions could result in the development of a strong storm or two, with damaging wind gusts as the primary threat. Read more LIVE: