Saturday, January16, 2021
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Marine Weather and Tides
Joliet, IL

Version 3.4
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8/26/2020 The 7 day forecast is taking about 5 seconds to load but it will eventually load. NOAA is still working on it.
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12/16/2019 NOAA is having trouble with requests that include wind gusts. I am posting graphs without wind gusts until it gets fixed.
10/9/2019 Updated the Marine Zones.
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7/25/2019 New feature in the Airports section gives a link to 5 minute updates for data reports.

Sunrise 7:14AMSunset 4:50PM Saturday January 16, 2021 1:48 AM CST (07:48 UTC) Moonrise 10:46AMMoonset 9:41PM Illumination 9% Phase: Waxing Crescent; Moon at 3 days in cycle
NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION.
Marine Forecasts
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LMZ742 Expires:202101161015;;984977 Fzus53 Klot 160332 Nshlot Nearshore Marine Forecast National Weather Service Chicago/romeoville Il 932 Pm Cst Fri Jan 15 2021 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>742-161015- Winthrop Harbor To Wilmette Harbor- Wilmette Harbor To Northerly Island- Northerly Island To Calumet Harbor- 932 Pm Cst Fri Jan 15 2021
.small craft advisory in effect from Saturday morning through Saturday evening...
Rest of tonight..Southwest winds 10 to 15 kt. Snow likely after midnight. Waves 1 ft or less.
Saturday..Southwest to west winds 10 to 15 kt early becoming northwest 15 to 25 kt in the late morning. Snow in the morning, then a chance of flurries in the afternoon. Waves around 1 ft building to 3 to 6 ft occasionally to 8 ft.
Saturday night..Northwest winds 15 to 20 kt becoming west 10 to 15 kt. Chance of snow. Waves 3 to 6 ft occasionally to 8 ft subsiding to 2 to 4 ft after midnight.
Sunday..West to northwest winds around 10 kt. Snow likely. Waves 1 to 3 ft.
LMZ742


7 Day Forecast for Marine Location Near Joliet, IL
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location: 41.52, -88.16     debug


Area Discussion for - Chicago, IL
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FXUS63 KLOT 160537 AFDLOT

Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 1137 PM CST Fri Jan 15 2021

UPDATE. 749 PM CST

Mostly clear skies continue to foster patchy shallow dense fog for areas mainly across the southern Chicago metro into the Kankakee River valley early this evening. This is especially true for open areas where bouts of heavy snow occurred during the afternoon. METARs and spotter reports suggest a higher prevalence (albeit still patchy) across western Will County into Kendall and Grundy counties where snow was heavier today (over 2" reported across west Joliet). While pockets of low stratus continue to develop in this area, the lack of any mid to upper-level clouds and several breaks in the low clouds will allow fog formation to continue through most of the evening.

Will continue to message this fog via an SPS (originally issued just prior to 6pm) and graphical forecasts given the patchy and generally shallow nature. However, if the areal extent of development continues to grow, a small targeted dense fog advisory may be needed for the aforementioned counties.

Kluber

SHORT TERM. 315 PM CST

Through Saturday Evening .

Focus shifts from the scattered snow showers this afternoon to a widespread round of light to at times moderate snow late tonight through Saturday morning. There could also be some lingering lake enhanced synoptic snow. Expecting accumulations of up to 1-2", highest probably west of I-355 and I-88 and north.

The snow showers have certainly performed as expected today, with intense cores able to produce sharp visibility reductions and quick localized accumulations up to an inch. Earlier there was even a cloud to ground lightning strike down in Benton County Indiana. As of the 3pm hour, starting to see highest snow shower coverage focus primarily south of I-88. Overall coverage should continue to wane toward and after sunset as instability wanes. Depending on radar and observational trends by 22z, may need to target one more SPS issuance.

Water vapor satellite imagery shows the large upper low circulation over the region, with very cold mid-level temps underneath it. At the surface, the original occluded surface low was north of STL with a secondary low over lower Michigan in the surface trough across the region. An area of snow associated with the deformation axis of the secondary low will pivot south- southeastward from Wisconsin and northeast Iowa this evening to far northern Illinois by about midnight and then spreading across the rest of the CWA. A 700 mb impulse wrapping southward around the departing upper level low gyre will yield an uptick in large scale ascent, in the presence of modest cold advection.

With the modest ascent showing sufficient overlap with the DGZ and cold advection increasing ratios to 11-13:1, up to 0.1 to 0.15 QPF should squeeze out snow totals of up to 1-2", again highest over interior far northern IL. Surface temperatures will range from a few degrees below to slightly above freezing during the light to occasional moderate snow rates, so treated main roads should fair okay. Nonetheless, would expect secondary roads to have some snow/slush on them making for slippery, slowed travel. Despite sub marginal lake effect parameters from a thermodynamics perspective, guidance indicating decent lake induced convergence that could enhance the synoptic snow into Porter County and keep it going a bit longer.

Behind the steadier snow, additional mid-level impulses should provide enough ascent through the lower-mid level saturated layer to wring out occasional flurries or light snow/snow showers into or through Saturday afternoon. Right on the heels of tonight- tomorrow's minor snow producer, our next one will move in on Saturday night. Could see light snow with this into parts of our western and northwestern counties just before midnight. Refer to the Long Term AFD below for full detail on this next round.

Castro

LONG TERM. 206 PM CST

Early Sunday through Friday .

The main focus in the long term portion of the forecast remains on the (increasing) potential for at least some lightly-accumulating snowfall on Sunday, with an additional chance for snow somewhere in the Monday night-Tuesday timeframe.

Full disk GOES-17 moisture channel imagery depicts a region of strong cyclonic shear stretching from Kodiak, Alaska and down into Vancouver and British Columbia with an embedded vort packet spiraling across northern Alberta. These features will eventually drop in tandem southeastward into the northern Great Plains later on Sunday before translating towards our longitude through midday. Coarse-resolution guidance has remained fairly consistent regarding this next feature's track, and we continue to note a good degree of clustering among the deterministic and ensemble output alike today. There's still some degree of uncertainty regarding precipitation start time, as well as the exact track of the upper vort, but confidence is high enough to warrant introducing likely (60-70%) PoPs Sunday morning and into the afternoon for areas roughly south of I-88.

Mid-level DCVA and warm advection look to force a respectable degree of large scale ascent--appearing to maximize at this time along and south of I-80 and through Sunday morning and early afternoon. Moisture will be somewhat limited with this disturbance, although PWATs near 0.3" are actually near or just above climatology for this time of year. While the strongest forcing looks to reside just above the dendritic growth zone, the DGZ depth will grow with time as the column cools, which, taken together, seems to support snow ratios probably near 15-16:1 or so. Liquid amounts should remain fairly modest given the lack of more appreciable moisture, but would not be surprised at all to see some pockets of 2-4" amounts given everything. For this forecast issuance, we've increased snowfall totals for the Saturday overnight through Sunday period towards 2" or so south of I-80, and closer to 1-2" farther north.

With cloud cover probably staying in place through Sunday night, did increase overnight low temperatures a bit above the blended offering. The next fast-moving wave approaches late Monday night and into Tuesday. On a run-to-run basis, deterministic guidance is waffling a bit with this feature's track, but ensemble output continues to indicate a general theme of once again focusing light precipitation across our southern locales. We'll show some low-end chance PoPs for this activity for the time being given model uncertainties. Our more active pattern does look to continue through the end of the week, with the next system within the wave train slated to arrive towards Thursday.

Carlaw

AVIATION. For the 06Z TAFs .

Aviation weather concerns for tonight and Saturday are:

- Shallow patchy fog near MDW through 09Z

- Accumulating snow and IFR visibility spreading over the area prior to daybreak and persisting through mid to possibly late Saturday morning before scattered light snow showers

- Light and variable winds becoming west and then gusty northwest Saturday morning

- More snow spreading over the area late Saturday night into Sunday morning

Areas of dense fog are present over the southern Chicago metro into far northwest Indiana into the overnight. The dense fog and IFR conditions will likely remain south of MDW with medium confidence, with GYY likely seeing occasional dense fog.

Attention then turns to snow moving southeast across the area by daybreak. This has the nature of 1-2SM visibility snow, with any visibility under 1SM looking to be brief. Confidence is somewhat lower on how quickly the snow becomes more off and on (light showery), as it could be as early as 14Z or as late as 17Z. The scattered light snow showers will continue into the afternoon. Total snow accumulation looks to be around one inch at ORD with the composition being near normal snow-to-liquid ratio.

During Saturday afternoon, there is uncertainty in whether the ceilings will remain IFR in the scattered snow shower activity or be more MVFR. Winds Saturday afternoon will be gusty from the northwest.

The next upper level disturbance will move into the region late Saturday night with a broad light to at times moderate snow spreading over the area. This will continue through Sunday morning with additional light accumulation.

MTF

LOT WATCHES/WARNINGS/ADVISORIES. IL . Dense Fog Advisory . ILZ020-ILZ021-ILZ023-ILZ105-ILZ106-ILZ107- ILZ108 until 3 AM Saturday.

IN . Dense Fog Advisory . INZ001 until 3 AM Saturday.

LM . Small Craft Advisory . LMZ740-LMZ741-LMZ742 . 10 AM Saturday to 9 PM Saturday.

Small Craft Advisory . LMZ743-LMZ744-LMZ745 . 10 AM Saturday to 9 AM Sunday.



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Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
CMTI2 - 9087044 - Calumet, IL 36 mi48 min SSW 7 G 8.9 29°F 1001.2 hPa (-0.4)29°F
CNII2 37 mi33 min WSW 8 31°F 28°F
OKSI2 39 mi108 min WNW 2.9 G 5.1 34°F
CHII2 - Chicago, IL 41 mi28 min SSW 11 G 12 32°F 32°F
FSTI2 42 mi108 min 32°F
BHRI3 - Burns Harbor, IN 54 mi68 min SSW 5.1 G 5.1 29°F 1002.7 hPa

Wind History for Calumet Harbor, IL
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Joliet Regional Airport, IL1 mi73 minN 01.00 miFog/Mist25°F24°F96%1002.7 hPa
Lewis University Airport, IL7 mi73 minSW 30.50 miFreezing Fog25°F25°F100%1002 hPa
Morris Muni-James R Washburn Field Airport, IL15 mi53 minW 30.50 miFreezing Fog26°F25°F99%1002.4 hPa
Aurora Municipal Airport, IL24 mi56 minSW 39.00 miOvercast26°F24°F92%1002.4 hPa

Link to 5 minute data for KJOT

Wind History from JOT (wind in knots)
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Last 24hrS10S7S7S8S4S5S5S4S5S7CalmSE6CalmCalmS3CalmCalmCalmCalmCalmCalmCalmCalmCalm
1 day agoCalmSE4SE4SE3SE5SE5SE5S6S5S7SE7SE5SE7S7S6S6SE6SW9
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2 days agoS4S3S4S4SW3SW4S4S5S6SW8SW5SW5SW7S8S7SW4S6CalmCalmS5S5S5S5SE3

Tide / Current Tables for
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Tide / Current Tables for
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Weather Map
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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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