Marine Forecasts

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7 Day Forecast for Marine Location Near Hammond, IN

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Area Discussion for - Chicago, IL

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FXUS63 KLOT 031119 AFDLOT

Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 619 AM CDT Mon Aug 3 2020

SHORT TERM. 300 AM CDT

Through Tuesday .

The main weather focus today remains on building wave heights across the lake behind a fast-approaching cold front, and the potential for waterspouts mainly this morning and perhaps lingering into the early afternoon hours across the far southern tip of the lake.

Our latest much-advertised cold front is tough to discern in the surface fields early this morning, with a gradual theta-e gradient noted into portions of north-central and northwest Illinois. Eventually, this boundary will move through our entire region (by later this afternoon), injecting a much drier and cooler airmass across the CWA. Until then, near-surface moisture remains a bit elevated, especially across the southeastern half of the forecast area where dewpoint depressions have fallen to about a degree or less in spots. Clearing skies in the wake of yesterday afternoon's convection and also immediately ahead of the encroaching low- stratus deck north of I-80 should allow pockets of fog to develop through sunrise this morning. Have added some patchy fog wording to the gridded forecast roughly south of I-88 as a result with some locally dense pockets possible. This set up doesn't look like a Dense Fog Advisory situation, but we'll continue to keep an eye on trends this morning.

Watching our initial wind surge dropping down the lake, with buoy observations upstream indicating gusts increasing to 20 to 25 kts. Observations indicate what appears to be a mesovortex-like feature at the southwestern bowl of the lake--and this signal has been in hi-res guidance for the past few nights. Enhanced convergence associated with this feature, combined with an upstream approaching shortwave should continue to force convection near the land-lake interface the rest of this morning. While the coldest 850 mb temperatures are still north of our region, somewhat steep mid-level lapse rates combined with lake surface temperatures in the lower 70s are currently supporting lake- induced CAPE values approaching 1500 J/kg with equilibrium levels to almost 35,000 feet. In addition, area VWPs indicate about 30 kts of effective deep layer shear in place over the lake, which seems to be supporting transient supercellular structures with two recent impressive-looking cores tracking southeast across the lake (on the right-moving supercell vector). Conditions will remain favorable for the development of some stronger cells as well as an attendant waterspout threat this morning, especially for any showers/storms that are able to develop near the convergent axis associated with the aforementioned front-mesovortex intersection. Have greatly pared back PoPs inland today with crashing inversion heights and incoming subsidence likely to limit precipitation potential. In addition, have tried to limit the thunder wording to the immediate lake and lakeside locales today with instability really lacking elsewhere--save perhaps for our far southeast later this afternoon ahead of the cold front.

Hazardous swimming conditions and a threat for lakeshore flooding remain, and expected to ramp up today and late this afternoon and evening as the strongest winds surge down the lake. See the MARINE section below for further information.

Precipitation chances drop off tonight but low chances linger downwind of the lake into northwest Indiana. Lake parameters start to get a little less supportive by daybreak Tuesday, with things probably trending more towards just a broken-overcast lake-effect cloud deck during the day.

Carlaw

LONG TERM. 210 AM CDT

Tuesday night through Sunday .

With the upper-level jet stream well to our north and the trough responsible for our recent stretch of fall-like weather pivoting eastward by mid-week, the end of the workweek looks quiet and dry. Daily highs and lows will increase by a few degrees each day with ample sunshine and daily lake breezes. Longer-range forecasts call for a return to a more summer-like thunderstorm pattern from the weekend onward, with ensemble model guidance perhaps highlighting the Sunday through Tuesday timeframe for episodes of thunderstorms.

Borchardt

AVIATION. For the 12Z TAFs .

A stratus deck rooted between 800 and 1200 feet remains locked in place at all terminals with (lo and behold) prevailing IFR at DPA/MDW/ORD. As the daylight hours progress, would think cloud bases should respond to even modest low-level heating (via solar irradiance) and accordingly have offered a return to MVFR everywhere by 15Z. Should the IFR overstay its welcome, a secondary cold front this afternoon will afford a stronger push of wind that will mix cloud bases upward. Winds should also adopt a subtle easterly component behind the secondary front, as well.

A convergent band of showers over Lake Michigan may meander west and east at times this morning leading to showers impinging on the 10 mile vicinity radius at ORD/MDW/GYY. Otherwise, current thinking is most if not all hours will be dry at the terminals.

After sunset, sufficient lake instability and low-level northeasterly flow will enable lake effect stratus to stream over all but RFD.

Borchardt

LOT WATCHES/WARNINGS/ADVISORIES. IL . Beach Hazards Statement . ILZ006-ILZ103-ILZ104 until 7 AM Wednesday.

Lakeshore Flood Advisory . ILZ006-ILZ103-ILZ104 until 4 PM Tuesday.

IN . Beach Hazards Statement . INZ001-INZ002 until 7 AM Wednesday.

Lakeshore Flood Advisory . INZ001-INZ002 . 1 PM Monday to 10 PM Tuesday.

LM . Small Craft Advisory . IL nearshore waters until 4 AM Wednesday.

Small Craft Advisory . IN nearshore waters until 4 AM Wednesday.



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Weather Reporting Stations

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Stations	Dist	Age	Wind	Air Temp	Water Temp	Waves	Pressure	DewPt
CMTI2 - 9087044 - Calumet, IL	8 mi	47 min	NNW 11 G 17	69°F			1016.3 hPa	65°F
JAKI2	12 mi	125 min	N 8.9 G 18	69°F
CNII2	17 mi	35 min	NNW 12 G 14	70°F				62°F
CHII2 - Chicago, IL	21 mi	35 min	NNW 18 G 20	67°F				65°F
OKSI2	21 mi	125 min	N 6 G 8	67°F
45170	29 mi	25 min	9.7 G 14	70°F	72°F	5 ft		64°F
MCYI3 - Michigan City, IN	32 mi	35 min	N 14 G 15	70°F				63°F
45174	37 mi	55 min	NNW 14 G 19	66°F	73°F	6 ft	1017.2 hPa	63°F

Wind History for Calumet Harbor, IL

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SW4 G9

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W7 G18

NE7 G11

NW5 G11

E8 G12

SE6 G10

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W3 G6

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NW6 G11

W3 G8

NW5

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NW8 G15

NW8 G12

NW10 G15

1 day ago

NE4 G7

N3 G7

N5 G8

N6 G9

N5 G9

N7 G11

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N7 G12

NE8 G11

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SW2 G5

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N8 G11

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NE10 G13

N9 G14

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N9 G17

N10 G13

N9 G14

N8 G11

N7 G10

N8 G11

N5 G9

N8 G11

N6 G10

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N8 G11

NE6 G9

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NE4 G7

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SE4 G7

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NE4

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Airport Reports

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Airport	Dist	Age	Wind kt	Visibility	Sky/Weather	Temp	DewPt	Humidity	Pressure
Gary Regional Airport, IN	4 mi	80 min	NNW 14 G 18	10.00 mi	Mostly Cloudy	72°F	0°F	%	1016.9 hPa
Lansing Municipal Airport, IL	7 mi	70 min	NNW 8	10.00 mi	Overcast	70°F	63°F	82%	1016.9 hPa
Chicago, Chicago Midway Airport, IL	18 mi	72 min	N 8	10.00 mi	Overcast	69°F	60°F	73%	1016.3 hPa

Link to 5 minute data for KGYY

Wind History from GYY (wind in knots)

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S4

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W12 G19

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N7

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E6

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NW14 G18

NW15 G18

1 day ago

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Calm

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N8

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Calm

E3

Calm

Calm

Calm

N6

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Tide / Current Tables for

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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.
Link to Loop

Other links: Northern Pacific     Contential US     Full GOES-East

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Wind Forecast for Chicago, IL (13,3,4,5)

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Ground Weather Radar Station Chicago, IL

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