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LMZ742 Expires:202312092215;;170767 Fzus53 Klot 091429 Nshlot
nearshore marine forecast national weather service chicago/romeoville il 829 am cst Sat dec 9 2023
for waters within five nautical miles of shore on lake michigan
waves are provided as a range of significant wave heights, which is the average of the highest 1/3 of the waves, along with the average height of the highest 10 percent of the waves which will occasionally be encountered.
lmz740>743-092215- winthrop harbor to wilmette harbor il- wilmette harbor to northerly island il- northerly island to calumet harbor il- calumet harbor il to gary in- 829 am cst Sat dec 9 2023
.small craft advisory in effect through this evening...
Rest of today..Southwest winds to 30 kt this morning becoming west 20 to 25 kt this afternoon. Isolated showers ending by noon. Waves 1 to 3 ft.
Tonight..West winds 20 to 25 kt. A few sprinkles and flurries in the evening. Waves 1 to 3 ft.
Sunday..Northwest winds 15 to 25 kt diminishing to 10 to 20 kt. Mostly cloudy. Waves 1 to 3 ft.
Sunday night..Northwest winds 10 to 15 kt. Partly cloudy in the evening then clearing. Waves 1 to 3 ft.

LMZ700
No data

FXUS63 KLOT 091206 AFDLOT

Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 606 AM CST Sat Dec 9 2023

SHORT TERM
Issued at 250 AM CST Sat Dec 9 2023

Through tonight...

Key Messages:

* Showers gradually ending after daybreak this morning.

* Gusty SW winds (potentially up to 40 mph) develop ahead of cold front early this morning (mainly E of I-55).

* Spotty showers/flurries possible (15% chance) late this afternoon into the early evening.

A band of showers is currently progressing northeast across the area early this morning. A few embedded lightning strikes had been observed along the leading edge but have since dissipated.
Showers will continue to lift northeast through daybreak with any lightning remaining mainly south of the the area across portions of central Illinois. A trailing axis of rain behind the front extending from northwest Missouri into central Wisconsin will be slower to lift northeast, likely resulting in precipitation lingering into the daylight hours, especially across far northern Illinois.

Winds remain gusty ahead of the line of showers early this morning but observations have yet to reach 35 mph. The potential remains for gusts to gradually increase up to 40 mph out of the southwest in advance of the surface cold front over the next few hours as it progresses across the area in response to slight pressure falls. Winds then turn westerly behind the front after daybreak, remaining gusty through the day across the area around 20-30 mph.

Only change to the short term forecast was to introduce slight chances (20%) for spotty showers late this afternoon and evening when cloud depths becomes deep enough to support precipitation coincident with a mid-level vort max pivoting overhead as it rounds the upper low. Cloud temperatures may become just cold enough to squeeze out a few flurries as well early in the evening (6-8pm).

Temperatures remain fairly steady through the daylight hours as weak cold advection matches the diurnal warming of the day.
Temperatures then steadily decrease after sunset with overnight lows in the upper 20s to lower 30s.

Petr

LONG TERM
Issued at 245 AM CST Sat Dec 9 2023

Sunday through Friday...

Key Messages:

* Turning cooler though still seasonable the first half of next week then moderating midweek.

* Mainly dry conditions are forecast for much of next week.

Amplified upper troughing will be translating across the area on Sunday as the associated surface low races northeast across eastern Canada. Another trailing vort max will bring the potential for a few flurries and spotty snow showers during the day on Sunday (currently 10% chance) with lake effect rain/snow showers grazing northern Porter County. This may need to be added to the official forecast with later updates if confidence in more widespread snow showers/flurries increases.

Cooler (albeit seasonable) and dry weather then prevails through the majority of the week as high pressure sets up over the region and upper troughing remains northeast of the region. Temperatures begin to moderate mid-late week with highs in the 40s as mid- level ridging expands overhead. Precipitation chances (30%) return later in the week heading into the weekend as a Central Plains closed upper low approaches the region.

Petr

AVIATION
For the 12Z TAFs...

* Rain should be tapering off shortly after sunrise, or by mid- morning at the latest.

* South winds switch to west after 13Z and remain gusty through early Sunday morning.

A cold front which brought rainfall to the area overnight will push through the region early this morning, bringing an end to the showers and turning winds westerly through the remainder of the forecast period. Gusts into the mid to upper 20s appear likely, but so far the upstream observations have not been showing much above that. IFR ceilings should yield to MVFR for most of the period, but with a broad area of VFR presently observed behind the front, elected to carry several hours of better conditions despite the concern that some of the lower level cloudiness will start filling back in.

Lenning

LOT WATCHES/WARNINGS/ADVISORIES
IL...None.
IN...None.
LM
Small Craft Advisory
Winthrop Harbor IL to Gary IN until 10 PM Saturday.

Small Craft Advisory...Gary to Michigan City IN until 4 AM Monday.

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