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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.


Tuesday, August 8, 2023

SPC Aug 8, 2023 1630 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1630Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Tue Aug 08 2023 Valid 081630Z - 091200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL HIGH PLAINS... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL PLAINS AND SOUTHEAST... ...SUMMARY... Scattered severe thunderstorms are expected across parts of the central Plains during the late afternoon into tonight. Large to very large hail, severe gusts, and a tornado or two are possible. Scattered damaging winds and isolated severe hail will also be possible through early evening across parts of the Southeast. ...Wyoming/northern Colorado to Central Plains... A prominent summertime shortwave trough will continue to advance southeastward over southeast Idaho/northern Utah into Wyoming today, with downstream height falls influencing the High Plains by evening. This scenario will enhance lee troughing, aiding a north-northwestward surge of low-level moisture through late afternoon/evening toward much of the Colorado Front Range and southeast Wyoming/Nebraska Panhandle. Initial high-based thunderstorm development is expected over the mountains/higher terrain of northern Colorado/southern Wyoming by mid-afternoon, with a subsequent increase/eastward spread, along with additional development into the larger buoyancy environment across the central High Plains including northeast Colorado/southwest Nebraska/northwest Kansas. Strengthening late-day westerlies (35-45 kt) will contribute to elongated, nearly-straight hodographs, while buoyancy with 2500-3000 J/kg MLCAPE should be maximized across northeast Colorado and southwest Nebraska. Splitting supercells are expected with a north/south-oriented cluster likely evolving relatively quickly as outflows consolidate towards the Colorado/Nebraska/Kansas border vicinity. The potential for a longer-track discrete supercell or two appears greatest along the southern periphery of convective development owing to lack of interference from other storms. Very large hail, significant severe wind gusts, and a tornado or two are all possible. A strengthening nocturnal low-level jet and enhanced warm/moist advection near/above the surface could help maintain or even reinvigorate the MCS east-southeastward into central/eastern Kansas overnight, with damaging wind potential and possibly some hail risk. ...Lower Mississippi Valley/Southeast... The leading edge of a residual MCS is ongoing across the Lower Mississippi Valley at late morning, with a considerable amount of trailing stratiform precipitation. Much of this MCS will continue to interface with the cooler/more stable side of the front that arcs roughly west-to-east across Louisiana/Mississippi/Alabama and Georgia, with some of the MCS-related cloud canopy extending across the downstream warm sector. But even a glancing influence of the MCS/any MCV and related outflows should contribute to at least isolated/widely scattered thunderstorm development near the front this afternoon as the boundary layer becomes moderately to strongly unstable, with upper 70s F warm-sector surface dewpoints common. Upstream WSR-88D VWP data (such as Fort Smith AR and Little Rock this morning) does sample a seasonally strong 50+ kt belt of westerlies between 3-8 km AGL, with the stronger winds grazing the frontal zone/adjacent warm sector. This is likely to support sustained/relatively organized multicellular clusters with scattered damaging winds as the most common hazard. ...New England... A relatively short duration severe risk may briefly linger early this afternoon across coastal southeast New England in association with a narrow warm/moist sector ahead of a secondary surface low, including the possibly of a localized wind damage and/or a brief tornado. Otherwise, convective development this afternoon is anticipated over western New England where deep-layer shear will be weak in closer proximity to the trough axis, with the potential for organized severe thunderstorm development expected to remain low. ...Northern Minnesota/eastern North Dakota... A shortwave trough over northern Manitoba and northwest Ontario will continue to dig southeastward, with a cold front settling southward across North Dakota/northern Minnesota through tonight. Thunderstorms should be focused along the front particularly late this afternoon through early evening. An adequate combination of deep-layer shear and instability should support an isolated severe wind/hail risk. ..Guyer/Squitieri.. 08/08/2023 Read more CHECK UPDATE ZOOM GRAPHIC
SUNRISE AND SUNSET TIMES IN UTC (if you're not logged in to Google)
CHICAGO UTC-6 during CST (Central Standard Time, e.g., winter)
CHICAGO UTC-5 during CDT (Daylight Savings Time, e.g., summer)