Marine Weather and Tide Forecast for Elmhurst, IL

DISCUSSION
Issued at 221 PM CDT Mon Jul 14 2025

Through Tuesday Night:

A few showers have developed across the far southern cwa early this afternoon, likely in the vicinity of a differential heating boundary leftover from the fog this morning. With very little wind through the column, these showers are just drifting. While they are tiny, there may be some brief heavy rain. These will dissipate later this afternoon into early this evening.

A weak wave will move across central IL and central IN Tuesday into Tuesday evening bringing a low chance (20%) for showers and a few thunderstorms, mainly for areas south of I-80. A lake breeze is expected to being moving inland Tuesday afternoon and this may allow for a few showers across the Chicago metro area but for now have remained dry north of I-80 Tuesday. Whatever does form Tuesday afternoon, which is expected to be isolated, should be on a slow downward trend Tuesday evening. Depending on how fast this wave departs, its possible a few showers may continue Tuesday night into early Wednesday morning across the southeast cwa, but confidence is fairly low.

High temps this afternoon will likely top out in the mid 80s for most locations with dewpoints in the 50s for parts of the Chicago metro area. Highs on Tuesday are expected to reach the upper 80s to lower 90s with increasing low level moisture.
Dewpoints look to get back into the upper 60s/lower 70s in the afternoon, which would push heat index values into the mid 90s for most areas with perhaps a few locations reaching the upper 90s. cms

Wednesday through Monday:

Toward the middle of the week, the upper-level pattern is expected to be characterized by zonal flow along the US/Canadian border. Within and along the southern extent of the zonal flow will be embedded shortwaves, which will likely be influenced by convective episodes in the northern Plains. A broad low-level frontal boundary will slowly slip south through the Great Lakes and act as a highway for episodic clusters of showers and storms. Taken together, a quintessential July pattern is shaping up for the middle of the week.

There remains a signal that the first convectively-augmented wave and associated surface MCV will move into the Lower Great Lakes region sometime in the Wednesday to Wednesday night timeframe. Exactly when and where it arrives/goes will be subject to refinement as we get closer. Regardless, augmented flow/shear along the periphery of the circulation and PWATs climbing toward 2" may spell trouble for both severe weather and flash flooding wherever the MCV tracks on Wednesday. Our gridded database will feature mid-range chances (40-60%) for storms Wednesday afternoon and evening, which seems appropriate at this point in time. WPC and SPC-advertised level 1/5 threats for both flash flooding and severe weather in our general region remain fair as well, though certainly can envision embedded corridors where (much?) higher probabilities/threat levels will be needed in later forecasts. If convective coverage ends up maximized after peak heating Wednesday, daylight hours will be stuffy with the combination of heat (highs in the lower 90s) and humidity (dew points in the mid 70s) making it feel like the upper 90s to lower 100s.

Another shortwave is poised to move into the general region on Thursday, presenting another opportunity for showers and storms.
As is typical in these patterns, the placement of the broad frontal boundary by then will dictate the threat zone for the next round of storms. For now, will feature mid-range chance PoPs (40-60%) along/south of both I-55 and I-80 keeping in mind adjustments are all but likely once we get an idea of the convective footprint on Wednesday evening/night. Outside the threat for thunderstorms, our area may be bisected by relatively comfortable temperature/humidity levels north of the front and continued hot and humid conditions to the south. We'll also have to watch for a quick uptick in wave heights Thursday evening as a surface high builds into the region and reinforces northerly flow down the spine of Lake Michgian.

The front should be well south of our area on Friday, leading to a much quieter and more comfortable day. Depending on the strength of northerly winds Thursday night, beach conditions may remain choppy through much of Friday. If planning to head to the beach toward the end of the week, stay up to date on the forecast.

Looking toward the weekend and into next week, ensemble model guidance is exhibiting an unusually strong signal for building heat and humidity levels as well as episodic (severe) MCSs in the broad Midwest region. Stay tuned.

AVIATION /00Z TAFS THROUGH 06Z TUESDAY/
Issued at 617 PM CDT Mon Jul 14 2025

A weak surface ridge to the southeast of the terminals will result in light and generally VRB winds through tonight. A weak lake breeze currently struggling to make inland progress (had actually retreated earlier) may wash out over ORD/MDW mid- evening, but speeds should be 5 knots or less. SSW winds up to around 10 knots are favored on Tuesday, with some variability in direction between 160-220 during the afternoon and evening.
Otherwise, expect VFR conditions through the period with a low (<20 percent chance) of nocturnal MIFG at DPA/RFD/GYY toward sunrise.

Kluber

LOT WATCHES/WARNINGS/ADVISORIES
IL...Air Quality Alert until midnight CDT Tuesday night for ILZ005- ILZ006-ILZ012-ILZ013-ILZ020-ILZ021-ILZ103-ILZ104-ILZ105- ILZ106-ILZ107-ILZ108.

IN...Air Quality Alert from midnight tonight to midnight CDT Tuesday night for INZ001-INZ002-INZ010-INZ011.

LM...None.