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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.


Saturday, August 5, 2023

SPC Aug 5, 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 0747 AM CDT Sat Aug 05 2023 Valid 051300Z - 061200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SOUTHEAST CO TO SOUTH KS/NORTH OK... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SEPARATELY OVER THE WABASH VALLEY TO CENTRAL IN... ...SUMMARY... The most concentrated area of severe thunderstorms with potential for destructive wind and hail is expected across parts of the south-central Great Plains from mid-afternoon through tonight. Potential for a few tornadoes will exist separately over the Mid-Missouri and Wabash Valleys during the late afternoon to early evening. ...South-central Great Plains to the Mid-South... A small MCS is ongoing along the southeast KS/northeast OK border area and may persist east-southeast across portions of the Ozark Plateau through midday. How it evolves into the afternoon across the Mid-South is uncertain given variation among CAM guidance that has adequately simulated the MCS so far (namely the 06/09Z RRFS and 00Z NSSL-WRF/10Z HRRR), as it progresses away from the more strongly sheared environment to its west-northwest but impinges on larger buoyancy over MO/AR. Have expanded the cat 2-SLGT risk some to account for potentially greater east-southeast progression and/or redevelopment later this afternoon with the remnant MCV. In the wake of this morning MCS, convective outflow arcs across central OK through the central TX Panhandle. Hot and deeply mixed thermodynamic profiles will develop to the south of this boundary amid full insolation, while capping to the north inhibits thunderstorm development until peak heating. Initial cells should develop off the Raton Mesa and Palmer Divide towards mid-afternoon within a low-level upslope flow regime and the left exit region of an intense upper jet from CA to CO. Potential will exist for regenerative supercells spreading east-southeast off the higher terrain. A few of these may become long-lived and capable of producing baseball to softball-sized hail centered on the southeast CO vicinity given highly elongated mid to upper hodographs and large buoyancy amid very steep mid-level lapse rates. A strengthening low-level jet over west TX during the evening will favor increasing convective development downstream and yield multiple clusters spreading across western and southern KS, the Panhandles, and western to northern OK during the evening. Severe wind gusts will become more prolific as this occurs, which should include potential for sporadic gusts from 70-90 mph. CAM guidance struggles to indicate a more prominent MCS evolving out of the clusters that should form, lowering confidence on where the most concentrated swath of significant severe wind gusts is likely to evolve tonight. But a broad region of at least scattered severe wind potential supports maintaining a cat 3-ENH risk. ...Mid-MO Valley vicinity... A mid-level low over central SD will drift east with stronger destabilization confined downstream of it from southeast SD to eastern NE and far western IA. Early afternoon convective development will initially be most pronounced across southeast SD and likely arc southward into at least northeast NE before spreading into northwest IA later. Weaknesses in the mid-level wind profile may yield a linear cluster type mode, but some enlargement to the low-level hodograph, especially in the SD/NE/IA border area, should foster low-level updraft rotation capable of producing a couple tornadoes. Otherwise, slow-moving linear clusters will yield a threat for isolated severe hail and wind persisting through the evening. ...IL/IN vicinity... An MCV over central IL will drift east into IN through tonight. Enhanced wind fields attendant to this MCV were sampled by the 12Z ILX sounding and will yield a spatially confined corridor of favorable low-level SRH overlapping the northeast extent of the surface-based instability plume in southern parts of IL/IN. This should support a few supercells developing during the mid afternoon to early evening, centered on the Wabash Valley into portions of central/southern IN. Any supercell will be capable of a tornado, and localized severe wind gusts will be the primary threat with convection that arcs southwestward towards larger buoyancy across the Lower OH Valley. ..Grams/Broyles.. 08/05/2023 Read more CHECK UPDATE ZOOM GRAPHIC
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