Marine Weather and Tide Forecast for Jacksonville, IL

DISCUSSION
Issued at 311 AM CST Sun Nov 8 2026

08z/2am surface analysis shows a 998mb low over northern Ontario with a weak cold front/trough axis extending southwestward into the Upper Midwest. A band of high clouds associated with this feature will stream into central Illinois today: however, the thin cloud cover will do little to mitigate warming courtesy of W/SW winds of 10-15mph. Afternoon high temperatures will top out in the lower 60s. Once the boundary passes, winds will become NW and decrease substantially after sunset. High pressure will build into the region and should be positioned directly overhead by 12z Mon...resulting in good radiational cooling conditions and early morning lows bottoming out in the lower to middle 30s. Fog development will be possible as well, although confidence remains low at this point. The RRFS continues to suggest widespread visibility restrictions by dawn Monday, while the HRRR/RAP focus pockets of fog primarily along/west of I-55. Meanwhile the 00z NBM features just a 20-25% chance of visibilities less than 5 miles. Since it has not rained recently and the ground is dry, am skeptical widespread fog will be able to form even under ideal radiational cooling conditions. The more likely scenario would be fog along rivers and streams and in a few low-lying rural spots. Have therefore opted to leave fog mention out of the forecast until stronger evidence for impactful visby reductions materializes.

With zonal flow in place across the CONUS, temperatures will continue to moderate as readings climb well into the 60s for both Monday and Tuesday. After that, a short-wave trough ejecting eastward from the Rockies and another wave diving southward out of Canada will phase over the Midwest/Great Lakes, eventually forming a significant long-wave trough east of the Mississippi River by the end of the week. GFS precipitable water values have risen from previous runs, with the 00z Nov 8 iteration now showing 1-1.25 ahead of the phasing system. Given strong upper dynamics and an uptick in moisture, the latest NBM has increased PoPs to 20-30 by Wednesday afternoon. All models show the deep trough shifting east of Illinois by Thursday: however, a strong fetch of colder air flowing over the warmer waters of Lake Michigan will lead to one or more bands of lake- effect showers Thursday and Thursday night. Based on the initial N/NE flow trajectory, some of the showers could potentially impact locations east of I-57 on Thursday before shifting further E/NE by Thursday night into Friday. The main weather story for the end of the week will be the temporary shot of much cooler air. The chilliest day will be Friday when highs only reach the middle to upper 40s. Once the trough shifts further eastward and upper heights once again begin to rise, temps will climb back into the lower 60s by next Sunday.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/
Issued at 540 AM CST Sun Nov 8 2026

VFR conditions will prevail through the entire 12z TAF period.
Patchy fog has formed well south of the terminals early this morning...particularly south of the I-70 corridor. KDEC has been reporting reduced visbys throughout the night: however, with a temp/dewpoint spread of 3-5F, a SW breeze of 5-10kt, and local webcams showing unrestricted visbys...think this may be a sensor error rather than fog. SCT-BKN high clouds will stream across the sky today ahead of an approaching surface trough. SW winds will become W and gust 15-20kt from mid-morning through the afternoon. Once the trough passes, winds will veer to NW and decrease to less than 10kt toward sunset.

ILX WATCHES/WARNINGS/ADVISORIES
None.