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LMZ740 Winthrop Harbor To Wilmette Harbor Il- Wilmette Harbor To Northerly Island Il- Northerly Island To Calumet Harbor Il- Calumet Harbor Il To Gary In- 949 Am Cst Mon Dec 11 2023
.small craft advisory in effect from 9 pm cst this evening through Tuesday afternoon...
Rest of today..Southwest winds 10 to 15 kt. Mostly cloudy. Waves 1 to 2 ft.
Tonight..Southwest winds 20 to 25 kt. Mostly clear. Waves 2 to 4 ft.
Tuesday..West winds 15 to 25 kt subsiding to 15 to 20 kt in the afternoon. Mostly Sunny. Waves 1 to 3 ft.
Tuesday night..West winds 10 to 15 kt becoming northwest. Partly cloudy. Waves 1 to 3 ft.

LMZ700
No data

FXUS63 KLOT 111747 AFDLOT

Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 1147 AM CST Mon Dec 11 2023

SHORT TERM
Issued at 235 AM CST Mon Dec 11 2023

Through Tuesday night...

Key Message

* Stratus clears out from the west and southwest today

Seasonably symbolic stubborn stratus sticking around this morning, though gradual clearing is expected today as low level flow backs and becomes anticyclonic. With stratus probably lingering into the early afternoon hours over the eastern CWA, did trim a couple degrees off of forecast highs today, but still in the ballpark of seasonal norms.

A south to southwesterly breeze will lock in tonight as the pressure gradient tightens a bit in advance of a cold front trailing south from a low over Canada. Despite mostly clear skies tonight, the south winds should temper the temperature fall a bit with lows mostly in the mid-upper 20s.

Cold front will move across the area Tuesday morning with very little fanfare, just a wind shift to the west-northwest. Brunt of the cold air should stay north of our CWA, so shouldn't see much of a temp drop with the front.

Temps Tuesday night will be a bit tricky. Assuming the encroaching mid-high level cloudiness doesn't put too big of a kibosh on temp fall, then the light/variable winds and ambient cold air mass would support lows in the teens across interior northern IL away from the Chicago metro urban heat island. Assuming those low temps verify, this will probably end up being the coldest night over the next 7-10+ days.

- Izzi

LONG TERM
Issued at 235 AM CST Mon Dec 11 2023

Wednesday through Sunday...

Key Message

* Return to warmer than average temps later this week through next weekend with minimal chances of precipitation

Wednesday will be one last cold (temps near average) day before mild Pacific air mass floods east across the country. Still seeing hints of potentially some small scale northern stream disturbance impacting the region this weekend, but guidance continues to vary from run to run and NBM pops are below mentionable, which is fine for now. Thursday through Sunday highs look to be in the 40s, with 50F not out of the question.

- Izzi

AVIATION
For the 18Z TAFs...

- Secondary stratus deck eroding over the next couple of hours, no significant impacts.

- Frontal boundary slides through Tuesday morning, bringing an increase of westerly winds to the region.

Some lingering MVFR ceilings across northeast Illinois will continue to erode heading into the afternoon. This will bring about VFR conditions across the region, lasting throughout the period. Winds remain s-sw this afternoon into the overnight, before a dry frontal boundary slides through the area Tuesday morning. Westerly winds increase Tuesday morning behind fropa, with gusts in excess of 18kts.

Baker

LOT WATCHES/WARNINGS/ADVISORIES
IL...None.
IN...None.
LM
Small Craft Advisory
Winthrop Harbor IL to Gary IN...9 PM Monday to 3 PM Tuesday.

Small Craft Advisory
Gary to Michigan City IN
9 PM Monday to 3 AM Wednesday.

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