Marine Weather and Tide Forecast for Lake Petersburg, IL

DISCUSSION
Issued at 217 PM CDT Sat Mar 14 2026

Surface analysis early this afternoon shows surface high pressure centered over lower Michigan/Ohio with breezy east-southeast winds across central Illinois. Mostly cloudy skies have kept temperatures a few degrees cooler than originally anticipated with highs expected to top out in the upper 40s to middle 50s. A deepening surface low will track from the central Plains into the Great Lakes Region on Sunday, bringing a period of impactful weather Sunday through Monday.

Strong southerly winds will develop out ahead of an approaching cold front on Sunday with high probabilities for gusts to exceed 40 mph through Sunday night. A warm, moist airmass will advect northward during the day with high temperatures expected to climb into the 60s to low 70s. Periods of showers and thunderstorms will begin as early as mid to late morning, though the threat for strong to severe storms increases later Sunday afternoon/evening with the arrival of the cold front. The latest suite of CAMs shows a line of thunderstorms developing in west-central Illinois between 19-21Z as a strengthening mid-level jet begins rounding the base of a trough, further increasing deep layer shear. Although dewpoints in the 50s will limit instability (<1000 J/kg MLCAPE), robust deep layer shear and strong kinematics will favor a squall line/QLCS event, with damaging winds and tornadoes being the primary hazards through the evening. The highest threat will be east of I-55 where an Enhanced risk for severe storms (level 3 of 5) is in place.

Behind the front, strong cold air advection will transition precipitation to snow Sunday night within the lows deformation zone. Accumulating snow continues to be a possibility with about a 50-70% chance for seeing at least 2 inches near and west of the Illinois River, with lesser amounts further east and southeast.
Strong west- northwest winds on the backside of the departing low will significantly reduce visibility where snow is falling, resulting in hazardous travel conditions. A winter weather headline may be needed for counties near and west of the Illinois River where the highest accumulations are forecast.

Much colder air filters in behind the system for Monday and Tuesday with ECMWF EFI showing values around -0.8, which indicates an unseasonably anomalous event. Temperatures will be coldest Monday night with values falling into the single digits to teens. Breezy winds during this period will send wind chills below zero for western parts of the state Monday morning and for most Tuesday morning.

A quick hitting clipper system may bring another shot of wintry precipitation Tuesday night, possibly resulting in minor snow accumulations. Temperatures will moderate by midweek then surge well above normal late in the week into next weekend as upper ridging over the western CONUS amplifies, allowing mid-level heights to quickly rise over the Midwest states.

NMA

AVIATION
(For the 00z TAFs through 00z Sunday Evening)
Issued at 654 PM CDT Sat Mar 14 2026

Two rounds of convection are anticipated over the next 24 hours.
Scattered showers/thunder will develop between 14z and 17z, primarily impacting KPIA/KBMI. Later in the period, a more significant line of thunderstorms will develop along an advancing cold front. Based on growing confidence and latest HRRR/RRFS timing, have opted to include a TEMPO group for thunder with winds gusting 45-50kt between 20z and 23z at KPIA/KSPI and further northeast to KCMI between 22z and 24z/00z. Gradient winds this evening will be E with gusts over 20kt. The winds will gradually become SE overnight, then will veer to S and increase markedly by mid-morning. HRRR suggests strong winds from a low-level jet will mix to the surface by 14z, then remain strong/gusty for the rest of the day. Peak gusts will generally range from 35-40kt outside of storms.

Barnes

ILX WATCHES/WARNINGS/ADVISORIES
Wind Advisory from 10 AM Sunday to 7 AM CDT Monday for ILZ027>031-036>038-040>057-061>063-066>068-071>073.