textproduct: Chicago

KEY MESSAGES

- One more seasonably cool day before temperatures start warming Sunday into early next week.

- Elevated fire weather conditions today and possibly again on Sunday. - Stormy weather pattern returns towards the middle of next week.

DISCUSSION

Issued at 315 AM CDT Sat Mar 28 2026

Through Sunday Night:

A surface high continues to drift overhead early this morning which is setting up a clear but chilly start to our Saturday. Temperatures will rebound this afternoon under mostly clear skies and increasing warm advection, though highs look to only top out around 50 degrees at best which is around average for late March. That said, dew points today are expected to remain in the mid to upper teens (lower teens in northwest IL) which will generate afternoon humidities around 25-30%. Couple these conditions with the breezy southwest winds gusting around 20-25 mph and conditions look favorable for an elevated risk for grass and brush fire spread. However, with fuel moistures on the more marginal side (around 10-15%) the set up today looks a bit too marginal to warrant the issuance of a Special Weather Statement at this time. Nevertheless, anyone planning to be burning today should use caution especially during the period of strongest winds this afternoon.

While the strongest winds will diminish this evening, the continued warm advection looks to keep the atmosphere at least loosely mixed which may allow occasional 15-20 mph gusts to linger. Though, temperatures will be more mild tonight as some increasing cloud cover and the warm advection hold readings in the upper 30s to around 40.

Sunday will feature similar conditions to today but with notably warmer temperatures (highs in the low to mid-60s). Winds will once again become breezy during the afternoon with gusts around 20-30 mph, however, these winds will begin to advect in higher dew points throughout the day. Therefore, the afternoon humidities look to be a bit better (in the 25-35% range) which should limit the fire weather concerns. Though, if dew points are slower to rise than forecast then another period of elevated fire conditions could materialize Sunday afternoon. Otherwise, expect another mild night Sunday night with lows in the upper 40s and lower 50s.

Monday through Friday Night:

The extended period continues to look active as a deepening shortwave trough is forecast to begin moving onshore across the Pacific Northwest on Sunday followed by broader troughing that will drift eastward during the later part of next week. The aforementioned shortwave is still expected to traverse across the northern Plains and Upper Midwest Monday into Tuesday with a weaker secondary wave expected to eject out of the southern Plains and into the Great Lakes Monday night. As the southern wave approaches, a warm front is expected to move through northern IL and northwest IN on Monday. While the warm front will gradually moisten the lower levels of the atmosphere, forecast soundings do show a notable mid-level dry layer that looks to keep the atmosphere capped as the front moves through. Therefore, dry conditions should prevail through the daytime hours on Monday. Temperatures on the other hand will be on the rise Monday with highs forecast to be back into the lower to mid-70s for most. However, as is typical with warm fronts this time of year the cooler waters of Lake Michigan may limit its northward progress and result in onshore winds and notably cooler temperatures along the IL shore.

Heading into Monday night, the mid-level dry layer is progged to gradually wane as a slug of Gulf moisture is advected into the area. This diminishing of the cap in combination with the subtle forcing from the weak shortwave and warm advection may allow for a few scattered showers and/or thunderstorms to develop. The latest 00z guidance suite seems to still favor a drier forecast, however, likely due to the cap being too strong to fully erode especially without the aid of diurnal heating. Based on this, I suspect that the chances for showers/storms Monday night is more on the order of 20-30% as opposed to the 40-50% offered by the NBM. Since there is still some uncertainty as to the cap's strength opted not to make any adjustment to the NBM POPs just yet.

A better coverage of showers and thunderstorms is expected to occur on Tuesday as the northern stream shortwave and its associated surface low push a cold front through northern IL and northwest IN. The environment ahead of the front continues to look unstable with steep mid-level lapse rates and over a 1000 J/kg of CAPE noted in forecast soundings which in combination with the 40-45 kts of deep layer shear present may support a few strong to possibly severe storms as well. Overall, guidance has remained in good agreement for Tuesday but there continues to be some differences as to the exact timing the cold front will push through. If the later timing (which seems to be favored in the 00z guidance suite) persists, then the northern extent of any stronger storms could be limited. Additionally, the later solutions would also mean that more locations see highs in the mid to upper 70s Tuesday afternoon but if the faster solutions verify than some could see notably cooler conditions. For now our official forecast will lean towards these later solutions with the better coverage of showers/storms Tuesday afternoon and evening and warmer temperatures areawide. Though, we will continue to keep a close eye on this period and adjust as trends support.

Guidance has started to trend into better agreement that the cold front will push through the area and stall closer to the Ohio and Tennessee River Valleys Tuesday night into Wednesday. Therefore, it appears that Wednesday and Thursday may be actually dry as a surface high pivots over the Great Lakes. As a result the latest NBM/WPC POPs for Wednesday and Thursday have come down, but still maintain a 20-30% chance due to some guidance members being slower and further north with the front. Beyond Thursday forecast confidence continues to be low as guidance varies on the timing and intensity of trailing shortwaves that will be traversing the broader Pacific troughing. So while our official forecast does have higher precipitation chances returning as early as Thursday night, there is a signal that precipitation could hold off until Saturday when a more notable system moves through the region. Regardless, temperatures behind Tuesday's cold front will be much cooler with highs in the 40s and 50s to close out the week.

Yack

AVIATION /12Z TAFS THROUGH 18Z SUNDAY/

Issued at 605 AM CDT Sat Mar 28 2026

There are no significant aviation weather concerns anticipated through the period.

A rather stout surface high will slide across the region early this morning. This will foster a period of light and variable winds for a couple hours this morning. However, directions will quickly settle into a south-southwesterly direction by mid to late morning following the eastward departure of the surface high. Later in the day, as diurnal mixing maximizes, expect some gusts up to 20-25 kt to develop for a period before abating this evening.

KJB

LOT WATCHES/WARNINGS/ADVISORIES

IL...None. IN...None. LM...Small Craft Advisory until 10 AM CDT this morning for the IN nearshore waters.