Marine Weather and Tide Forecast for Shipman, IL

SHORT TERM
(Through Late Friday Night)
Issued at 155 PM CST Thu Mar 5 2026

A quasi-stationary front continues to wobble around the Mid- Mississippi Valley, bringing with it ample stratus, fog, and on-and- off showers and thunderstorms. As of 17z, the boundary extends from about Fort Leonard Wood, MO northeastward to Vandalia, IL and beyond. The bulk of showers have remained within the warm sector to the south of this line, creating a relatively dry day today.
Tonight, however, the front is expected to buckle northward as cyclogenesis ramps up near the Front Range of the Rockies. This will open the CWA up to warm sector convection yet again. A strong 40-50 kt low-level jet developing in the evening will promote the development of scattered showers and thunderstorms overnight. These thunderstorms will be elevated and unlikely to produce anything more than small hail and beneficial rainfall for our northern CWA who missed out on the previous rain this week.

The real focus of the late week is the potential for severe weather Friday evening through night. The daytime hours on Friday are expected to be quite spring-like as the full CWA is encapsulated by the warm sector. Temperatures are expected to rise into the 75 - 80 degree range despite broken cloud cover. Dewpoints will rocket as well, with the HRRR probabilities of 60+ degrees being 50-100% for the vast majority of the CWA If KSTL is able to achieve a 61 degree dewpoint, which it is currently forecast to do, this will be a new record high dewpoint for March 6th. Needless to say, with this amount of warmth and moisture instability will be easy to come by.
However, a lack of forcing and lift will render this instability useless during the afternoon.

To our west, this instability will be utilized during the late afternoon and evening as thunderstorms fire up along and ahead of a cold front. Bulk shear fairly perpendicular to the cold front will result in supercells with all hazards possible before thunderstorms congeal into a QLCS. Latest high-res guidance is converging on the QLCS being nearly if not fully formed by the time it reaches central and northeast Missouri at around 07-08z. If this holds true, damaging winds and a brief tornado will be the primary hazards initially before the QLCS weakens below severe limits for good.

How quickly this occurs is still uncertain. HRRR, GFS, and RAP guidance both show SBCAPE/MUCAPE maximums of ~1000 to ~1500 J/kg occurring around 21z and dropping off after. By the time the QLCS makes it into the CWA, these values are expected to drop substantially to maybe 500 J/kg of SBCAPE and under 1000 J/kg of MUCAPE. The highest values are also expected to be along the line and not ahead of it, so the ongoing convection will be continually entering a less favorable environment. This is amplified given the potential for pre-frontal convection moving into southeastern Missouri from the southwest at around 05z. These thunderstorms are expected to be elevated and likely non-severe given the time of day and that they'll also be moving into a less favorable environment.
Being that these thunderstorms will be ahead of the QLCS, it's entirely possible that they scour out the environment of any remaining instability and cause the QLCS to degrade at a faster rate. It's also possible that the two complexes merge and weaken each other, and it's possible again that the pre-frontal complex feeds on the remaining instability and ends up being favored for severe weather. All of this to say, although confidence is increasing on timing, there is still plenty of variability concerning how the situation evolves Friday night. Given the trends we've been watching over the past several days, we're leaning toward the faster decay scenario.

Jaja

LONG TERM
(Saturday through Next Thursday)
Issued at 155 PM CST Thu Mar 5 2026

The cold front will be slow moving, not clearing the area completely until late Saturday morning/early Saturday afternoon. Despite being a cold front, most areas won't notice any appreciable cooldown.
Temperatures Saturday through early next week will only increase, with highs near if not achieving 80 degrees by Monday. This warmth will be paired with dry and breezy weather each day, making this a wonderful weekend for outdoor activities. The peace won't last, however. The chance of showers and possibly severe thunderstorms re- enters the forecast Tuesday into Wednesday as a cutoff low over the southwest CONUS ejects vorticity lobes into the Mid-Mississippi Valley. However, there is still ample uncertainty regarding the evolution and timing of the feature to extrapolate much further than that.

Jaja

AVIATION
(For the 18z TAFs through 18z Friday Afternoon)
Issued at 1133 AM CST Thu Mar 5 2026

Fog is forecast to persist through early this afternoon, and IFR ceilings will continue through tonight for the majority of the area. Brief breaks to MVFR are possible and are expected in portions of central MO where the stratus is breaking. Tonight, scattered showers and thunderstorms will develop and move northeastward through the area. Any direct impacts to terminals are uncertain. Light winds will increase from the south Friday morning and become gusty.

Jaja

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