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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, August 23, 2023

SPC Aug 23, 2023 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0750 AM CDT Wed Aug 23 2023 Valid 231300Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE GREAT LAKES... ...SUMMARY... Thunderstorms associated with damaging wind gusts and hail are expected tonight across parts of the lower Great Lakes and upper Ohio Valley. Isolated large hail and/or severe wind gusts may also occur across parts of the northern Plains late this afternoon and evening. ...Great Lakes/Upper Ohio Valley... Initially, isolated large hail potential exists early today with elevated storms ongoing mostly across northern/eastern Michigan. These storms are focused near the terminus of a moderately strong low-level jet, to the north of the prominent anticyclone centered over the Lower Missouri Valley/Ozarks. Any such isolated severe potential is expected to wane into late morning/midday as the low-level jet weakens. A moist/very unstable air mass is otherwise expected to quickly advect east-northeastward across the region today in tandem with a warm front, with surface dewpoints in the low/mid 70s F becoming more prominent into sizable portions of Lower Michigan and Ohio. Storms are expected to develop, perhaps as early as near/just after sunset, especially near a weak surface wave/triple point and warm front vicinity, and become more prominent regionally into late evening/early overnight. This corridor of convective development includes central/southern Lower Michigan into Ohio/northwest Pennsylvania, although there is some west/east spatial uncertainty related to capping aloft. This activity may grow upscale and evolve into an MCS tonight that spreads southeastward across the region, fueled by ample source-region buoyancy. Isolated instances of large hail are possible, but damaging winds should become the more common hazard. ...North Dakota/Northern Plains... In the wake of a decayed convective cluster and remnant MCV moving into southern Manitoba this morning, height falls will continue to occur with multiple convectively augmented mid-level disturbances glancingly influencing the region later today. A moist boundary layer will exist across much of North Dakota and nearby parts of South Dakota/Minnesota, along and north-northeast of a wavy surface front. Isolated deep convective development will be possible by late afternoon/early evening, particularly across northern North Dakota near this boundary, with other storms development potentially moving into the region from southern portions of Saskatchewan/Manitoba. Where sustained storms do occur, relatively strong wind profiles (40-45 kt effective shear) will support some semi-organized and sustained storms. This may include a few supercells, in the presence of modestly steep mid-level lapse rates and moderate buoyancy, which will be weaker and rooted above the surface with eastward extend into eastern North Dakota/northern Minnesota. Some severe hail will be possible regionally along with the possibility of localized severe-caliber wind gusts. ..Guyer/Goss.. 08/23/2023 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)