Marine Forecasts

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7 Day Forecast for Marine Location Near Lincolnwood, IL

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Area Discussion for - Chicago, IL

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FXUS63 KLOT 271201 AFDLOT

Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 701 AM CDT Sun Sep 27 2020

SHORT TERM. 340 AM CDT

Through Monday .

Main questions for the near term involve temperature and precipitation trends with an approaching frontal passage today. Have continued to slow down arrival of precipitation with this system despite the surface boundary working its way into far northwest IL by daybreak. Presently the parent surface low sits north of the central Great Lakes and sfc obs show the front approaching the Dubuque area. There are some very light radar returns trailing this boundary where dewpoint depressions are not quite as pronounced, but generally the dry lower levels and diffuse nature of the surface boundary are expected to limit precip development along the front itself. Instead, development is expected to be tied more to midlevel fgen forcing where moisture is more plentiful and upper level support also is greater.

If these trends hold, local precip chances would increase toward the RFD area by early afternoon with likely POPs by late afternoon. In the Chicago suburbs chance POPs would increase by late afternoon and likely POPs would overspread the area by early evening. This timing would also describe the expected temperature trends, falling from the 70s into the 60s as rainfall chances increase.

Behind the front, temperatures Monday look to top out in the low to mid 60s with breezy northwest winds. Lower rain chances hang out through the day under the deep upper trough swinging through but any showers that do develop would likely be spotty in nature and not expected to contribute to significant additional accumulation.

Lenning

LONG TERM. 340 AM CDT

Monday night through Saturday .

The big story later this week will be the shot of unseasonably chilly air for early October behind a strong cold front passage. This could set the stage for the frost and possibly even near/below freezing temperatures outside of Chicago to close out the week. Prior to this frontal passage, we'll have a fair but seasonably cool day on Tuesday with highs in the lower to mid 60s after a cool start to the day. Forecast soundings suggest we should develop fair weather Cumulus/strato-Cu in the afternoon as lapse rates steepen. Warm advection ahead of the front on Wednesday will lead to the mildest temps of the work week, with highs in the mid to upper 60s, if not warmer (near to a bit above 70), especially with southward extent and/or the frontal passage is slow enough.

In the wake of the cold front on Wednesday a much stronger push of chilly air will work in over the area for the later half of the week as a large upper trough digs over the area. This looks to result in breezy conditions, especially on Thursday, with daytime highs in the 50s for Thursday through Saturday. There will also be a good chance for showers on Thursday, and lake effect showers may continue into Friday for areas near the lake in parts of northwest Indiana as northwest/NNW winds set up over the lake. In fact, with such a chilly air mass aloft (850 mb temps below 0C) moving over the still mild lake, impressive lake induced instability, in addition to the lake effect rain shower generation, could be supportive of waterspouts. Exact low level wind orientation will determine whether parts of our northwest Indiana counties or points farther east are more favored. Expect overnight lows outside the city to drop into the 30s in this pattern late in the week. Timeframe of highest concern for temperatures near to even below freezing for possible sensitive vegetation impacts would be late Friday night into Saturday morning. This will depend on cloud cover, though it does appear a surface high will be over the region, bringing light winds otherwise favorable for strong radiational cooling. While there's plenty of uncertainty this far out, some of the guidance for next weekend indicates a short-wave trough and associated surface low could bring a chilly rain to the area later Saturday/Saturday evening if not Sunday, which is just beyond day 7 in the current long term forecast period.

Castro/KJB

AVIATION. For the 12Z TAFs . 700 AM CDT

The concerns include: * Chance for a period of MVFR CIGs this morning * Wind shift to northwest/north-northwest this afternoon with gusts to around 20 kt * Rain developing late afternoon into evening with periods of moderate rain possible/likely * MVFR CIGs/BR likely during the rain, especially late evening- Monday morning, with IFR CIGs probable late Sunday night/early Monday and MVFR to IFR VSBY

Winds will shift to west and then northwest with a cold front today. There's concern that direction could get close to due north for a period late afternoon/early evening closer to the lake, including ORD and MDW. In addition, gusts should be up to about 20 kt, possibly higher at GYY being downwind of the lake. Winds should then shift back to west or even southwest in the evening or overnight, especially away from the lake.

Stratus is less extensive to the south/southeast than it was yesterday morning. However, have seen some develop into eastern Illinois and northwest Indiana. Opted for TEMPO mention at GYY, but confidence was too low for ORD and MDW, so will need to monitor observations. Rain will eventually develop behind the frontal passage today. Trends continue to suggest that the rain will start a later than previous forecasts, although some spotty showers are possible out ahead of the front. Kept similar onset time to the previous TAFs, late afternoon at RFD and this evening for the Chicago terminals. Forecast soundings suggest that the rain could come down at a moderate clip at times, causing MVFR VSBY along with BR. CIGs will start out at VFR but should gradually deteriorate, though timing of deterioration to MVFR is uncertain along with whether CIGs will be prevailing. As the rain gradually lightens up after midnight/early Monday, CIGs could lower to prevailing low MVFR with a period of IFR probable along with MVFR/IFR BR. The light rain should eventually end some time Monday morning, followed by isolated to widely scattered showers Monday afternoon, beyond current ORD/MDW TAF.

Castro

LOT WATCHES/WARNINGS/ADVISORIES. IL . None. IN . None. LM . Small Craft Advisory . IN nearshore waters until 9 AM Sunday.

Small Craft Advisory . LMZ743-LMZ744-LMZ745 . 7 PM Sunday to 4 AM Monday.

Small Craft Advisory . IL nearshore waters until 7 AM Sunday.



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Weather Reporting Stations

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Stations	Dist	Age	Wind	Air Temp	Water Temp	Waves	Pressure	DewPt
FSTI2	2 mi	84 min	WNW 6	74°F
OKSI2	3 mi	84 min	Calm G 1.9	74°F
CHII2 - Chicago, IL	4 mi	34 min	SSW 8 G 8.9	72°F				64°F
CNII2	7 mi	24 min	SW 5.1 G 11	73°F				58°F
45174	13 mi	34 min	SW 3.9 G 5.8	64°F	53°F	1 ft	1006.1 hPa	58°F
CMTI2 - 9087044 - Calumet, IL	16 mi	54 min	SW 5.1 G 8	74°F			1006.7 hPa	63°F
WHRI2 - Waukegan Harbor, IL	30 mi	94 min	W 5.1 G 6
45187	38 mi	24 min	S 3.9 G 5.8	58°F	50°F	1 ft
MCYI3 - Michigan City, IN	41 mi	34 min	W 8 G 8.9	69°F				62°F
KNSW3 - Kenosha, WI	45 mi	24 min	SE 4.1 G 6	69°F			1006.4 hPa (+0.3)

Wind History for Calumet Harbor, IL

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Last 24hr

S12 G17

S13 G20

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S10 G18

S15 G20

S12 G16

S12 G18

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S13 G20

S15 G22

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S13 G19

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S12 G18

S14 G20

SW11 G18

S12 G18

SW7 G16

SW8 G14

SW6 G12

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1 day ago

SE9 G12

S10 G13

S6 G14

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S7 G12

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2 days ago

S8 G11

SW6 G10

S8 G14

SW7 G12

SW4 G8

S5 G8

S4 G7

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S5 G10

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Airport Reports

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Airport	Dist	Age	Wind kt	Visibility	Sky/Weather	Temp	DewPt	Humidity	Pressure
Chicago, Chicago Midway Airport, IL	13 mi	31 min	N 0	10.00 mi	Mostly Cloudy	74°F	59°F	60%	1005.7 hPa
Chicago, Chicago-O'Hare International Airport, IL	14 mi	33 min	WSW 5	10.00 mi	Overcast	73°F	60°F	64%	1006.3 hPa
Chicago / Wheeling, Pal-Waukee Airport, IL	18 mi	32 min	Var 3	10.00 mi	Fair	73°F	62°F	69%	1006.6 hPa

Link to 5 minute data for KMDW

Wind History from MDW (wind in knots)

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Last 24hr

SW15 G25

S15 G24

S14 G22

S17 G26

S13 G25

S13 G23

S14 G24

S18 G27

S17 G27

SW14 G26

S18 G27

SW16 G25

SW16 G24

SW13

SW11 G22

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Calm

1 day ago

S11 G18

S11 G22

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SW13 G21

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2 days ago

SW12 G16

SW9 G19

SW12 G19

W11 G17

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S9 G19

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Tide / Current Tables for

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Weather Map

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GEOS Local Image of    EDIT
NOTE: East coast views moved to GEOS-16. They are experimental and not well supported by NOAA so they may not be correct so be warned. This change required redoing a large amount of the GOES code. If the image you are expecting is not showing, please let me know. You may need to use the EDIT function to update your location.
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Other links: Northern Pacific     Contential US     Full GOES-East

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Ground Weather Radar Station Chicago, IL

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