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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 25, 2023

SPC Aug 25, 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 1242 AM CDT Fri Aug 25 2023 Valid 251200Z - 261200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS...LOWER TO MID MISSOURI VALLEY...MID MISSISSIPPI VALLEY...OHIO VALLEY...SOUTHERN AND CENTRAL APPALACHIANS...AND MID-ATLANTIC... ...SUMMARY... Isolated to scattered thunderstorms associated with strong wind gusts and hail will be possible this afternoon and evening from the central Plains eastward to the Ohio Valley and Mid-Atlantic. ...Mid Mississippi Valley/Ohio Valley/Mid-Atlantic... A mid-level cyclonic flow pattern will be in place today from the north-central U.S. east-southeastward into the Great Lakes. At the surface, a moist airmass will be located across much of the eastern U.S., with an axis of maximized low-level moisture extending from southeast Iowa into the Ohio Valley. Some model forecasts develop a cluster of strong thunderstorms along and near this axis of instability. Although low-level lapse rates are forecast to become steep near this axis during the late afternoon, deep-layer shear will remain weak. For this reason, any wind-damage potential should remain marginal. Further to the east into the southern and central Appalachians, and Mid-Atlantic, mid-level flow will be divergent and from the northwest. As surface temperatures warm during the day, isolated to scattered thunderstorms are expected to develop in the central Appalachians. Although low-level lapse rates will become steep across much of the region, deep-layer shear will remain weak. This suggests that any severe threat will be marginal late this afternoon and early this evening. A few strong wind gusts will be the primary hazard. ...Central Plains/Lower to Mid Missouri Valley... A mid-level anticyclone will remain over the south-central U.S. today as flow remains west-northwesterly across the north-central and northeastern states. At the surface, a cold front will advance southeastward into the central plains and mid Missouri Valley. A narrow corridor of maximized low-level moisture will be in place near the front, with surface dewpoints generally in the 60s F. This will contribute to moderate instability by afternoon. As the airmass destabilizes, scattered thunderstorms are forecast to develop in the central High Plains, where large-scale ascent will likely be maximized near and ahead of a shortwave trough. In addition to moderate instability, RAP forecast soundings at 21Z from eastern Colorado into northwest Kansas have 0-6 km shear peaking in the 25 to 30 knot range. This, combined with 700-500 mb lapse rates near 7 C/km could be enough for a few severe storms. Marginally severe wind gusts and hail will be the primary threats. Further east into the lower to mid Missouri Valley, isolated thunderstorm development will be possible during the late afternoon and early evening. However, large-scale ascent and deep-layer shear will remain weak. This suggests any severe threat that develops should be marginal and isolated. Hail and a few strong wind gusts will be the primary threats. ..Broyles/Thornton.. 08/25/2023 Read more CHECK UPDATE ZOOM GRAPHIC
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