076 FXUS63 KLSX 080658 AFDLSXArea Forecast Discussion National Weather Service Saint Louis MO 158 AM CDT Wed Oct 8 2025
.KEY MESSAGES...
-Near normal temperatures will continue into Thursday before warming back above normal over the weekend and into next week.
-Dry conditions are favored through the end of the week.
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.SHORT TERM... (Through Late Wednesday Afternoon) Issued at 157 AM CDT Wed Oct 8 2025
Morning satellite imagery shows the region caught in between a mid- level trough over the Great Lakes region and a weak ridge over the Southern Plains. The axis of the trough has exited the region, and at the surface yesterday`s cold front is now south of the forecast area. In its wake relatively cooler, dry air has moved into the region with a surface high. While the new airmass is cooler than we`ve experienced lately, temperatures will peak near normal for this time of year with highs in the low 70s areawide under a clear sky.
The surface high will stick around, and radiational cooling and light winds overnight will allow temperatures to cool well below normal across the area. Temperatures will reach their minimums in the 40s, with some localized areas in the hollows and across west- central Illinois closest to the high reaching into the upper 30s. The mid-level ridge strengthens over the Central Plains Thursday, leaving the mid-Mississippi Valley within northwesterly mid-level flow. The surface pattern will remain unchanged, and after a chilly start, temperatures will be similar to Wednesday with highs in the low 70s.
Delia
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.LONG TERM... (Wednesday Night through Monday) Issued at 157 AM CDT Wed Oct 8 2025
The mid-level ridge will continue to strengthen Friday, while a mid- level cut off low will move southeast into the Great Lakes region. At the surface a low will quickly develop over the Great Lakes region in response, but the system will quickly occlude and the associated surface fronts are expected to stay to the north of the forecast area. Instead, southwesterly low-level flow across the mid- Mississippi Valley will kick off a warming trend that will last through the end of the forecast period.
The southwesterly flow will deepen as the axis of the mid-level trough shifts east over the weekend, and will last through next week. This will open the region back up to shortwaves, though confidence in moisture return and the timing of any one disturbance is low at the moment. However, confidence is high that temperatures will warm above normal over the weekend and into next week as the interquartile range has continued to narrow over the past several days. Now the range is only 6-8 degrees heading into next week, with the 25th percentile above normal for this time of year.
Delia
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.AVIATION... (For the 06z TAFs through 06z Wednesday Night) Issued at 1143 PM CDT Tue Oct 7 2025
Under clear sky and light northerly winds most TAF sites are at VFR flight conditions. The exception is KSUS, where fog has developed and is bouncing the site between IFR and MVFR conditions. Dry air is moving into the region and will erode the fog, though its uncertain how fast this will occur. The best timing for VFR conditions to return to the site is around 07Z given observations at nearby sites, which is reflected in the TAF.
Delia
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.LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. &&
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WFO LSX
NWS LSX Office Area Forecast Discussion