textproduct: Chicago

KEY MESSAGES

- Chance for periodic showers across the area tonight. Scattered strong storm chances at times late Friday through this weekend.

- Better shot at widespread showers and storms, some possibly severe, Monday into Tuesday.

- Temperatures trend warmer through the weekend and into early next week.

DISCUSSION

Issued at 215 PM CDT Thu May 14 2026

Surface high pressure centered over the region will keep conditions quiet through this evening. A subtle short-wave and push of mid-level WAA tonight will kick off a round of showers tonight (after 04Z). With a lack of instability tonight the risk for any thunderstorms is very low (less than 10%) and impacts should be minimal. Showers should depart to the east mid-morning Friday leaving the rest of the day dry with temperatures peaking in the low to middle 70s. Winds on Friday will increase as they become southerly, sustained winds of 15- 20 mph are expected through much of the day with wind gusts peaking around 25-30 mph. REFS shows a brief period of 20-40% probabilities for greater than 30 mph gusts during the late morning with diminishing probs through the afternoon as the pressure gradient slacks off.

CAMs are in general agreement that another short-wave will eject out of the southwest late Friday and pass through otherwise zonal flow aloft. This feature will bring the next chance for thunderstorms to the region late Friday into early Saturday morning. Ahead of the short-wave surface dew points are forecast to increase into the mid 50s which along with an EML causing steepening mid-level lapse rates (7-8 C/km) will result in elevated instability values of 1000-1500 J/kg. 0-6km shear values of around 50 kts are also expected during this timeframe as a 45-60kt jet streak passes over central WI. This will create a parameter space capable of supporting a few marginally severe elevated thunderstorms across the western half of the forecast area with large hail the main threat, however, sporadic damaging wind gusts are also possible.

A quasi stationary boundary is expected to set up somewhere across the region Saturday which may provide the focus for another round of thunderstorms Saturday afternoon/evening, however, exactly where this boundary sets up will in part be tied to how the early morning convection plays out. South of this boundary low-level moisture transport will continue throughout the day Saturday with dew points increase into the low to mid 60s and temperatures warming into the mid to upper 70s resulting in 1000-1500 J/kg of surface based instability which would support at least another round of stronger thunderstorms. However, mid- level capping and the lack of a stronger forcing mechanism may lead to more isolated storm coverage.

A trough digging into the intermountain west later into the weekend and early next week will result in prolonged period of southwesterly flow bring more summer like conditions (high temperatures in middle 80s to low 90s) to the region. Along with the warmth there will be a chance for thunderstorms each day through Tuesday as a series of short-waves move across the region. Sunday the best storm chances will come during the morning on the leading edge of an area of middle level WAA before the area becomes capped during the afternoon. Monday the region is forecast to be well into the warm sector with dew points in the upper 60s and temps in the 80s leading to impressive surface instability, however, the lack of a clear forcing mechanism leads to low confidence in convective evolution Monday. At this point the timeframe with the most areal coverage of storms is late Tuesday as a well defined cold front is forecast to swings across the forecast area.

Kaiser

AVIATION /18Z TAFS THROUGH 00Z SATURDAY/

Issued at 1230 PM CDT Thu May 14 2026

Surface high pressure will pass to the east through the afternoon with winds trending southerly at KRFD while an easterly onshore component develops at KORD/KMDW. However, winds will remain mainly at or below 10 kts this afternoon. Winds will become southeasterly overnight with south to southwesterly winds increasing on Friday, gusting 20 to 25 kts at times by mid-morning.

There's a small chance (20-30%) for a shower early Friday, but higher chances will be south of the area terminals. Mainly VFR conditions will continue through Friday, although there is a low probability (20-40%) for a brief period of MVFR ceilings Friday morning.

NWS Chicago

LOT WATCHES/WARNINGS/ADVISORIES

IL...None. IN...None. LM...None.