Marine Weather and Tide Forecast for Shipman, IL

SHORT TERM
(Through Late Wednesday Afternoon)
Issued at 256 AM CDT Tue Apr 14 2026

The overall weather pattern across the US consists of surface high pressure near the southeast US coastline with a rich plume of Gulf moisture (60+ dewpoints) circulating around this high from central Texas northeast to the Chicago area. The western edge of this moisture plume is bounded by a dryline, oscillating back and forth each day with daytime heating and the passage of shortwave troughs aloft. The northern extent is bounded by a quasi-stationary front/trough stretching from Nebraska to Michigan. Looking aloft, upper level ridging is centered over the Gulf with a trough over the Southwest US moving from around Las Vegas to the Four Corners during the day today. Between the Gulf ridge and the Southwest US trough exists a southwesterly jet with embedded shortwave troughs. The rich low level moisture on the edge of the upper level ridge has led to an axis of instability within which multiple patches of thunderstorms will continue to generate over the coming days.
Seasonably strong mid level flow combines with the instability to produce conditions favorable for supercell thunderstorms and occasional convective clusters where thunderstorms form.

Zooming in on our forecast area, although instability maximizes this afternoon with daytime heating (temperatures nearing 90!), the influence of the ridge aloft is expected to maintain capping through much of the day, inhibiting convective development. We'll be in between disturbances to our northeast and southwest leading to a local minimum in convective potential. The primary focus for development will be more toward the periphery of the ridge and along the surface boundaries: the warm/stationary front to the north and the dryline to the west. High resolution guidance is in good agreement that convection will be suppressed locally during the day today. That said, if we are able to get any local areas of lift along a local convergence zone or in an area of locally maximized low level moisture (reducing capping), then a storm or two could develop. The environment is primed for supercell thunderstorms if this occurs, with large hail and damaging winds the main threats.
The better chance for thunderstorms locally will be from leftover storms which formed to our west tracking into our area during the late evening or overnight hours. While wind shear will still be sufficient for organized thunderstorms, surface based instability will be on a downward diurnal trend by the time any such activity reaches our area, limiting the severe weather potential.

On Wednesday the southwest trough opens up and lifts northeast through the Plains. This leads to greater mid level lift supporting more widespread showers and thunderstorms across the instability axis including through our region. While we continue to see moderate to strong mid level flow sufficient for storm organization, more widespread cloud cover is expected to limit the development of surface based instability to just patches of stronger instability where cloud cover is less extensive. As a result, our confidence in the timing and location of the severe weather threat on Wednesday is lower, though the threat is likely to favor the afternoon hours when the potential for surface based instability is greatest during the heat of the day. We may not have greater clarity on these points until Wednesday morning when the effects of morning clouds and showers can be a bit better known.

Kimble

LONG TERM
(Wednesday Night through Monday)
Issued at 256 AM CDT Tue Apr 14 2026

The passage of the trough Wednesday into Wednesday night will also shove the front southeastward, pulling in some slightly drier air and shifting the instability axis southeastward. Showers and storms may still be ongoing Thursday morning, with the focus for convective activity shifting toward the Ohio Valley with time. Most of our area sees gradually clearing skies with continued warm temperatures near 80 degrees.

While ridging briefly builds back in behind Wednesday's departing trough, a stronger trough will be moving out of the Pacific Northwest and into the Plains on Friday. We'll see moisture return northward ahead of this approaching trough setting up the potential for another round of severe thunderstorms. Where that severe weather threat materializes depends on the speed of the front. At the moment, timing of the front favors a greater severe thunderstorm threat to our west as the front moves through our area mostly during the overnight Friday night into the first half of the day on Saturday. However, if the front speeds up a bit, this could shift the threat more into our area. Alternatively, if it slows down a bit, then another threat could develop during peak heating on Saturday. At this stage it's too soon to have much confidence in a severe weather threat locally given the current expected frontal timing, but it's a time period to watch for any changes that could shift the threat into our area.

The air mass behind this front is MUCH cooler than what we've been dealing with as of late. This air mass has origins in the Arctic which is still cold this time of year. There remains some uncertainty in how cold it will be by the time it reaches our area, but there is strong confidence that we'll see at least one day of below normal temperatures. NBM interquartile range for high temperatures on Sunday is around 10 degrees, with the warmer end of that range right around normal for mid April while the cooler end is several degrees below normal. Dewpoints also drop into the 20s suggesting that if we were to get a clear, calm night that temperatures could approach levels where a frost or freeze could develop. At this time, NBM probability of 32 degrees or colder is only 5 to 15 percent across the region as the likelihood of seeing the clear, calm conditions necessary to realize this air mass's full potential is low. We will begin to warm back up again early next week as amplified ridging rather quickly replaces this weekend's trough.

Kimble

AVIATION
(For the 18z TAFs through 18z Wednesday Afternoon)
Issued at 109 PM CDT Tue Apr 14 2026

A low chance (20%) for an isolated strong to severe thunderstorm exists for the area this afternoon/evening, but was not mentioned in the TAF because of the lower confidence of occurrence. Even though the chance is low, it is important to note, that if an isolated thunderstorm is able to form this afternoon/evening and directly impact a local terminal, IFR/below airport minimum visibilities along with damaging winds and hail would be possible. Confidence is higher in a remnant system of thunderstorms moving eastward out of KS/OK later this evening, potentially impacting local terminals by the late evening/overnight timeframe. If stronger thunderstorms persist with this system and directly impact a terminal, IFR/below airport minimum visibilities along with damaging winds and hail are certainly possible. Confidence is once again lower in conditions beyond the early morning with potential for some remaining showers/convection beyond what is indicated by the current TAF.
Otherwise, gusty (20-30kts) southerly winds continue into early tonight before slackening off tomorrow morning, possibly gusting again by tomorrow afternoon.

Peine

LSX WATCHES/WARNINGS/ADVISORIES
MO...None.
IL...None.