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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.

Friday, August 4, 2023

SPC Aug 4, 2023 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Fri Aug 04 2023 Valid 041200Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE NORTHEAST AND CENTRAL PLAINS... ...SUMMARY... Severe thunderstorms are possible across parts of the Northeast and also the central High Plains this afternoon and evening, with a threat of damaging wind and isolated hail. Additional strong storms are possible along a broad arc from the central Plains to the Southeast. ...Northeast... A mid/upper-level cyclone is forecast to remain centered over Quebec today, as small-scale vorticity maxima move through the attendant trough across parts of the Northeast. A weak cold front will move southeastward across the region this afternoon and evening. Moderate destabilization will support scattered thunderstorm development along/ahead of the front through the afternoon, with moderate mid/upper-level flow resulting in sufficient effective shear for some storm organization. Initial semi-discrete storms will be capable of producing at least isolated hail and damaging gusts, with some tendency for clustering and a transition to primarily a damaging-wind threat by late afternoon/early evening. Some threat may approach near-coastal areas before storms weaken later tonight. ...MO/AR into parts of the Southeast... Multiple clusters of thunderstorms will likely be ongoing later this morning from parts of MO/AR into the Southeast, as a west to west-northwesterly low-level jet impinges upon an outflow-reinforced baroclinic zone. These clusters may pose at least an isolated damaging-wind threat as they move southeastward during the day, with a somewhat greater coverage of wind damage possible in areas where stronger preconvective diurnal heating/destabilization can occur. Isolated hail also cannot be ruled out, especially where buoyancy is stronger across parts of MO/AR. Storms may also intensify near a remnant MCV across northern MO this afternoon and spread southeastward this evening, with at least an isolated severe wind/hail threat. In general, rather weak deep-layer flow/shear will tend to limit storm organization, and the most favored corridors for somewhat greater damaging-wind potential (and possible eventual upgrade from 5% wind probabilities) will be dependent on mesoscale details that remain unclear at this time. ...Central Plains... Thunderstorm development is again expected across portions of the central High Plains late this afternoon into this evening, within a moderately unstable and modestly sheared environment. Storm coverage may be somewhat greater from southwest SD into western NE, in closer proximity to a persistent mid/upper-level trough, though isolated to widely scattered development will be possible into parts of eastern CO and western KS. With modest westerly flow aloft, effective shear will likely remain in the 25-35 kt range (higher where winds are locally backed), sufficient for a few strong multicells and perhaps a marginal supercell or two. Large hail and localized severe gusts are expected to be the primary threats. Guidance varies regarding the extent (if any) of nocturnal low-level jet intensification later tonight across the central Plains, which will impact the potential for any organized upscale growth, but some threat for isolated severe gusts could spread eastward somewhere across the central Plains late tonight. ..Dean/Moore.. 08/04/2023 Read more CHECK UPDATE ZOOM GRAPHIC