FXUS63 KLOT 200522

AFDLOT



Area Forecast Discussion

National Weather Service Chicago/Romeoville, IL

1222 AM CDT Fri Mar 20 2026



.KEY MESSAGES...



- Spring-like temperatures through the early weekend, though

  Lake Michigan will moderate temperatures along the shoreline.



- Cooler temperatures are expected early next week after a cold

  front passes on Sunday



&&



.DISCUSSION...

Issued at 211 PM CDT Thu Mar 19 2026



GOES-19 water vapor imagery shows moisture over the inner

mountain west riding over top of an upper level ridge located 

over the desert southwest. This ridge is expected to remain

mostly in place through Saturday, if not expand and slide

eastward slightly. Today, clear skies has cause temperatures to

over-achieve and climb into the lower 60s (inland areas) earlier

than expected. In contrast, onshore flow has capped max 

temperatures for the city of Chicago and other areas closer to 

Lake Michigan in the 40s. As the ridge expands, mid level warm 

air advection is projected to increase 850 mb temperatures to 15

to 18C. Temperatures will continue to warm up tomorrow and 

Saturday with highs in the 60s and 70s. Shoreline locations will

remain slightly cooler with the lake influencing the onshore 

flow. Moisture riding over the ridge and down the northwest flow

may allow periods of clouds at times through the weekend, but 

no precipitation is expected.



The upper level ridge will begin to flatten into Sunday with 

quasi-zonal flow projected to develop over the central CONUS 

ahead of the arrival of an upper level trough. This trough is 

expected to have a surface cold front associated with it that 

will pass over northern Illinois. Confidence lowers dramatically

in timing of the front and high temperatures for Sunday given 

the disagreement between models and even with the run-to-run

consistency of individual models. If later runs verify, the 

current high temperature could be underdone, whereas if that 

front comes racing down the lake, much cooler temperatures 

could arrive much sooner and drop temperatures substantially 

(especially along the lakefront). Lastly, the NBM is still 

showing a pool of moisture moving in with the front, so no 

changes to the slight chance PoPs that the blend gives; 

especially since amounts look fairly limited.



A cooler air mass is expected behind that front. Lows 

potentially could drop below freezing, while afternoon 

temperatures only climb into the 40s. Models are suggesting that

another ridge will move out of the southwest through the middle

of next week. That should help temperatures moderate and start 

to warm again back into the 50s. With northwest flow over the 

area, a stray impulse cannot be ruled out mid/late next week 

that could bring a chance for rain, but without any real model 

consensus, confidence is low.



DK



&&



.AVIATION /06Z TAFS THROUGH 12Z SATURDAY/...

Issued at 1222 AM CDT Fri Mar 20 2026



A cold front will move across the terminals this morning

resulting in a wind shift to northwest. In the wake of the front

look for winds to pick up to 10-15kt with a few gusts to around

20 kt possible late this morning into the afternoon. Lake breeze

is expected to develop and flip winds to northeast at GYY first

early-mid afternoon, then likely through MDW later in the

afternoon and eventually ORD by late afternoon/early evening.



VFR conditions are expected through the TAF cycle. 



- Izzi



&&



.LOT WATCHES/WARNINGS/ADVISORIES...

IL...None.

IN...None.

LM...None.



&&



$$



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