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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, July 8, 2023

SPC Jul 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 Sat Jul 08 2023 Valid 081630Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE FRONT RANGE ACROSS THE TX/OK PANHANDLES AND INTO OK...AND THE MID-SOUTH VICINITY... ...SUMMARY... Scattered strong to severe thunderstorms, and one or two organized thunderstorm clusters, are possible east of the Front Range and Sangre de Cristo Mountains through the Texas and Oklahoma Panhandles and Oklahoma. Additional strong to severe thunderstorm development is possible across parts of the lower Mississippi into Ohio Valleys. ...Front Range of the Central Rockies into TX Panhandle and OK... A moist air mass is already in place across the Front Range, with recent surface observations sampling upper 50s to low 60s dewpoints. Southeasterly low-level flow will help maintain this moist air mass throughout the day. Steep mid-level lapse rates are in place atop this low-level moisture, with recent mesoanalysis estimate max 2-6 km AGL lapse rates around 8 to 8.5 deg C per km. Convective initiation appears most likely first across the high terrain of north-central CO (and maybe adjacent southern WY), with these storms then moving into the destabilizing air mass across the Front Range. Long hodographs, created by moderate low-level southeasterlies veering to moderate northwesterlies aloft, will combine with moderate to strong buoyancy to support supercells capable of all severe hazards, including very large hail greater than 2" in diameter and a tornado or two. These supercells will likely persist into the evening, when a strengthening low-level jet should help promote upscale growth into one or more linear clusters. The resulting convective lines are then expected to progress southeastward across the TX/OK Panhandles into OK overnight and into Sunday morning. Some potential for significant wind gusts exists with these clusters, but uncertainty regarding overall evolution (mostly the strength of the rear-inflow jet) and most likely location for significant gusts precludes delineating any areas in this outlook. ...Mid-South Vicinity... Surface observations show mid-70s dewpoints are already in place across the region, downstream of an MCV related to last night's thunderstorms across OK. As discussed in recently issued MCD #1461, greater thunderstorm strength and coverage is possible as the MCV continues eastward and interacts with the destabilizing air mass over the Mid-South. Mid-level flow throughout the region will be generally modest, contributing to a predominantly multicellular mode. Even so, some localized enhancement of the flow is possible near the vorticity maximum, resulting in the potential for a few more organized updrafts. Storm mergers could also help briefly augment overall updraft strength. These factors, combined with ample moisture and steep low-level lapse rates, result in the potential for a few water-loaded downbursts. ...Middle/Upper OH Valley... Surface analysis places a pair of weak lows over southern Lower MI and western IN. A weak cold front extends between these two lows, and extends back farther southwestward from the western IN low. An area of showers and thunderstorms currently ongoing ahead of this front over western OH. Expectation is for this ongoing activity to continue eastward while gradually weakening over the next few hours. Associated cloud cover may temper daytime heating across IN and OH, but there should be a window for some limited heating/destabilization between the early cloudiness and the approaching cold front. Instability will still be modest, but this region will be on the southern periphery of the cyclonic flow covering eastern Canada, leading to slightly enhanced westerly flow aloft. The resulting combination of instability and shear could support a few stronger storms or bowing segments capable of damaging gusts. ..Mosier/Supinie.. 07/08/2023 Read more CHECK UPDATE ZOOM GRAPHIC
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