Marine Weather and Tide Forecast for East Peoria, IL

DISCUSSION
Issued at 225 PM CDT Sun May 11 2025

Seasonably warm and dry conditions are in place this afternoon with just a few passing cirrus at times. Dewpoints have once again trended lower than most guidance, with minimum relative humidities around near 20% as of 2 pm.

An upper cutoff low located over the Gulf coast states will begin to open up and lift north toward the Ohio Valley the next couple of days. Cloud cover will increase ahead of this feature tonight with dewpoints expected to steadily climb, bringing a more humid airmass northward. Scattered shower and storm chances make a return by mid to late Monday morning with periodic chances continuing through Tuesday night as the upper cold-core system remains close enough nearby. 12Z guidance continues to show pockets of the Non-supercell tornado parameter >1 both Monday and Tuesday afternoons with any associated lobes of vorticity. This essentially means conditions would be favorable for cold air funnels to develop with any showers or storms.

By Wednesday the upper low will have shifted east of here with a brief period of ridging sliding overhead. Warmer and more active conditions develop by the end of the week as a strong upper low lifts into the upper Midwest states. Temperatures in the 80s will be common on Wednesday with upper 80s to low 90s looking increasingly likely by Thursday. The ECMWF extreme forecast index (EFI) has values approaching 0.7 west of the IL River, which implies that most members show high confidence in having an anomalous event.
High temperatures on Thursday will flirt with or even come close to breaking our records, which range from 90-93 degrees at Lincoln, Springfield, and Peoria.

In addition to the above normal temperatures, there is a conditional threat for severe thunderstorms Thursday afternoon into evening.
Although the parent upper wave will be displaced north of here, upper jet dynamics will be supportive for thunderstorm development over central Illinois. By Thursday afternoon, forecast guidance shows strong instability (2000+ J/kg of SBCAPE), sufficient deep layer wind shear (50-60 kt 0-6 km shear), and steep lapse rates (7-8 C/km). However, the main limiting factor is a capping inversion which will prevent anything from developing most of the day. A cold front approaching from the west should work to erode the CAP later on Thursday, but timing still remains uncertain. If the capping inversion is able to erode soon enough during daytime heating, robust thunderstorms could develop with all severe hazards possible.

The forecast going into the weekend remains uncertain with global ensembles remaining split between a wet or dry pattern. Let the National Blend of Models (NBM) handle this period for now which advertises warmer and dryer conditions for the start of the weekend followed by cooler and wetter weather for the second half.

NMA

AVIATION
(For the 00z TAFs through 00z Monday Evening)
Issued at 620 PM CDT Sun May 11 2025

Low pressure over the lower Mississippi Valley this evening will slowly lift north towards central Illinois through the period.
Winds will generally remain out of the east through the period, trending to a more ESE/SE direction during the latter part of the day Monday. A few pin-wheeling bands of showers will move east-to- west across central Illinois Monday afternoon but should taper off in coverage around sunset. MVFR ceilings will be possible mainly in or near the precip bands.

Deubelbeiss

ILX WATCHES/WARNINGS/ADVISORIES
None.