Monday, December9, 2019
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Marine Weather and Tides
Sleepy Hollow, IL

Version 3.4
NOTICE
10/9/2019 Updated the Marine Zones.
9/4/2019 Fixed the weather maps due to NOAA moving them.
7/25/2019 New feature in the Airports section gives a link to 5 minute updates for data reports.
6/2/2019. Many thanks to a user for reporting an error on one of the Edit pages. The switch to PHP 7.2 caused many pages that previously worked to quit working. I fixed many but I still depend on users to report ones I missed. Please report errors HERE or send an email to me at L-36.com. Allen

Sunrise 7:07AMSunset 4:22PM Monday December 9, 2019 11:42 AM CST (17:42 UTC) Moonrise 4:02PMMoonset 5:16AM Illumination 95% Phase: Waxing Gibbous; Moon at 13 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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LMZ740 Winthrop Harbor To Wilmette Harbor- Wilmette Harbor To Northerly Island- Northerly Island To Calumet Harbor-calumet Harbor To Gary- 901 Am Cst Mon Dec 9 2019
.small craft advisory in effect from 4 pm cst this afternoon through Tuesday morning...
Rest of today..Southwest winds 10 to 20 kt becoming west to 30 kt toward Sunset. Areas of fog in the morning. Rain and drizzle in the morning, then a chance of drizzle and rain this afternoon. Waves 1 to 3 ft building to 3 to 5 ft near Sunset.
Tonight..West winds to 30 kt. Occasional gale force gusts in the evening. Chance of rain in the early evening. Waves 4 to 6 ft occasionally to 8 ft subsiding to 3 to 5 ft after midnight.
Tuesday..West winds 20 to 25 kt diminishing to 15 to 20 kt by late morning. Partly Sunny in the morning then clearing. Waves 3 to 5 ft subsiding to 2 to 4 ft in the afternoon.
Tuesday night..West winds 10 to 20 kt. Mostly clear. Waves 1 to 3 ft.
LMZ740 Expires:201912092300;;094053 FZUS53 KLOT 091501 NSHLOT NEARSHORE MARINE FORECAST National Weather Service Chicago/Romeoville IL 901 AM CST Mon Dec 9 2019 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>743-092300-


7 Day Forecast for Marine Location Near Sleepy Hollow, IL
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location: 42.1, -88.29     debug


Area Discussion for - Chicago, IL
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FXUS63 KLOT 091735 AFDLOT

Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 1135 AM CST Mon Dec 9 2019

SHORT TERM. 314 AM CST

Through Tonight .

The next 18-24 hours will feature a fairly harsh temperature change and gusty winds, especially late this afternoon into this evening. But in terms of high impact weather the period looks mainly free of that. Of note are some wind gusts that could exceed 35 mph between 4-9 p.m. Because of these winds being onshore for Porter County, Indiana, conditions overnight will be near Lakeshore Flood Advisory.

Early morning surface analysis indicates the entire CWA is within the warm sector of a broad 999 mb surface low over the central Plains into central Iowa. The system warm and nearly stationary front is draped basically over the Wisconsin stateline. Along this boundary, low-level moisture convergence is maximized and areas of less than one mile visibility in fog/drizzle have developed across Iowa into southern Wisconsin, with some patchy dense fog within that. This surface warm frontal zone is somewhat broad, so do have some concerns some of that low visibility could still build back, or just the low stratus could settle to the ground, into Winnebago, Boone, and possibly Ogle, McHenry, and Lake Counties this morning. Will continue to monitor observational trends and webcams closely for any need of a Dense Fog Advisory in far northern Illinois.

The warm sector over the CWA early this morning is characterized by mid to upper 40s, which is ten degrees warmer than normal highs this time of year. The warm sector will remain over the entire area through the early afternoon and eastern locations through the entire daytime period with only a slight climb, though that will result in a few lower 50s. A sheared short wave evident on water vapor imagery early this morning has provided a 40 kt moisture transport low-level jet corridor into our eastern CWA which has been responsible for areas of showers, while elsewhere much shallower and weaker isentropic ascent is resulting in areas of drizzle from lowering stratus. Expect after daybreak this morning that it will be mainly drizzle with only scattered showers, with the showers primarily along/east of I-55 or north into Wisconsin.

The cold air mass is well-defined upstream under a digging upper trough, and this trough will be responsible for maturing of the aforementioned surface low. As that occurs this afternoon into tonight, the process will usher that cold air into the area. Model guidance the past 12-24 hours has steered the cold front through the area quicker and see no reason to go against that, with an arrival time of 3-4 pm toward I-39, 5-6 pm into the Chicago metro, and 6-8 pm for northwest Indiana. This cold front will support a drop from mid to upper 40s right before passage to 20s areawide by midnight to mid teens to lower 20s by daybreak Tuesday. Those temperatures are certainly not that bad for December, but this will be accompanied by stout winds, thus providing wind chills 30-35 degrees cooler than air temperatures this morning. These winds will be especially gusty in the immediate several hours after fropa, with the combination of 1.) cold advection and steepened low-level lapse rates, 2.) unidirectional west-northwest winds within the deepening boundary layer, and 3.) a strong isallobaric component with the surface low deepening and quickly pulling away. This is why some gusts could approach 40 mph in that 4-9 p.m. window.

With the system still maturing, there is limited wraparound moisture and deformation at our latitude, so precipitation chances in the cold air look brief with the cold front and in the immediate wake of it. If materializing, these should be rain or maybe a poor quality snow shower or two. While there does continue to be a signal through the evening for stratocumulus (matching upstream satellite conditions) the depth looks shallow, and thus the potential for any cold advection- driven freezing drizzle looks quite low. Even in the low chance it were to briefly occur, pavement temperatures will lag the falling air temperatures. Also on that note, any "flash freeze" type concern will be minimized too due to lack of any appreciable rainfall today and wind speeds sufficient for drying conditions.

Otherwise, some lake effect snow showers are likely to move into northern parts of Porter County overnight. Some of these could be moderate in intensity at first but with quickly strengthening subsidence, these should taper in intensity into the pre-dawn hours of Tuesday. This lakeshore area too is likely to see some waves of 9+ ft for a period late evening into overnight hence some concern for minor lakeshore flooding.

MTF

LONG TERM. 338 AM CST

Tuesday night through Sunday .

Cold weather Tuesday and Wednesday remains the main concern in the extended with temps around 10 degrees below normal for early December.

Blustery conditions continue into Tuesday as chilly northwest winds remain quite gusty through much of the day. Little warming should occur during the day due to continued cold air advecting into the region, limiting highs to the 20s. Mostly clear skies beginning Tuesday night should allow temps to drop quickly into the teens and single digits across the area. Increasing cloud cover from an approaching weak clipper system early Wednesday morning could limit additional cooling. Despite this, northwest winds will likely result in wind chills values in the single digits to just below zero.

There is a brief period where we could see some flurries/light snow across the area Wednesday morning as the aforementioned weak clipper system moves through. The combination of strong 850 baroclinicity and associated isentropic lift/frontogenesis could support a brief period of light snow, although uncertainty remains on the overall intensity/coverage due to model variability and being under a fairly dry airmass. Currently have a mention of flurries across most of the area by Wednesday morning. If confidence increases, it may be necessary to include some light snow accumulations given that ground temperatures will be sufficiently cold to limit melting. Highs Wednesday will again be in the 20s and lows drop into the teens.

Temperatures begin to rebound Thursday as the surface high and cold air shift to the north and east and southerly flow returns. Highs on Thursday will be near normal in the mid 30s, and slightly above normal by Friday and Saturday with highs in the upper 30s to 40s. The overall pattern remains active during this period, with slight precip chances Friday night through Sunday. Multiple weak upper level disturbances track across the area and appear to blend together in the forecast due to model variability. Will continue to monitor trends as this gets closer to better determine timing of rain/snow potential.

Petr

AVIATION. For the 18Z TAFs .

Primary concerns for Chicago airports are:

- IFR ceilings and visibility early this afternoon in drizzle and light fog. Generally 500-800 ft, though LIFR persists west of Chicago early this afternoon.

- Strong west winds gusting as high as 35 kt this evening behind a cold front which will move through 22-23Z.

- Chance for scattered showers immediately along/behind the cold front early this evening. Mainly rain expected, though a few wet snow flakes may be possible, especially north/northwest of ORD.

Deepening low pressure was passing off to the northeast of the forecast area at midday, with a sharp cold front trailing along the Mississippi River. Ahead of the front, IFR/LIFR conditions persist in the warm sector into early afternoon, with the lowest conditions expected to remain generally west/northwest of metro Chicago terminals. A period of scattered rain or rain/snow showers is expected along/immediately behind the cold front, though coverage is expected to decrease south of ORD. Areas northwest of ORD are more likely to see some brief wet snow showers, with shallower moist layer further east into Chicago metro terminals less likely to support ice nucleation and snow. Showers should be fairly short lived, with precipitation finished by early this evening. Transition to MVFR ceilings/VFR visibility is then expected quickly behind the cold front, with a gradual lifting of ceilings and eventual scattering to VFR after midnight.

As for winds, will likely see some sporadic gusts 15-20 kts developing ahead of the cold front this afternoon from the southwest. Winds will turn westerly with the passage of the cold front, with a period of strong winds gusting as high as 35 kt this evening. Winds will generally remain in the 280-290 degree range tonight into Tuesday, with speeds and gusts gradually diminishing through the period.

Ratzer

MARINE. 500 AM CST

A Gale Warning has been issued for a portion of the northwest Indiana nearshore. Behind a strong cold front early this evening, winds will turn west-northwest and sharply increase. Gusts of 30-35 kt have high confidence. Gale force gusts are expected to be more sporadic in the Illinois nearshore but that will have to be re-evaluated through today as conditions will at least be close for a Gale Warning there too. Winds will gradually ease late tonight but high wave action will continue especially for parts of northwest Indiana.

MTF

LOT WATCHES/WARNINGS/ADVISORIES. IL . None. IN . None. LM . Gale Warning . LMZ744-LMZ745 . 6 PM Monday to 2 AM Tuesday.

Small Craft Advisory . LMZ744-LMZ745 . 2 AM Tuesday to 3 PM Tuesday.

Small Craft Advisory . LMZ740-LMZ741-LMZ742-LMZ743 . 4 PM Monday to 9 AM Tuesday.



VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK . TWITTER . AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
CHII2 - Chicago, IL 40 mi43 min SW 12 G 13 48°F 47°F
CNII2 40 mi28 min S 6 G 11 47°F 44°F
KNSW3 - Kenosha, WI 42 mi43 min WSW 6 G 11 46°F 998 hPa (-1.7)
CMTI2 - 9087044 - Calumet, IL 47 mi55 min SSW 6 G 11 47°F 999 hPa47°F

Wind History for Calumet Harbor, IL
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Chicago / West Chicago, Dupage Airport, IL12 mi51 minSW 125.00 miFog/Mist46°F44°F93%998.8 hPa
Chicago / Wheeling, Pal-Waukee Airport, IL21 mi51 minSW 8 G 1610.00 miOvercast48°F43°F83%998.8 hPa
Chicago, Chicago-O'Hare International Airport, IL22 mi52 minSW 85.00 miLight Drizzle Fog/Mist46°F45°F96%998.7 hPa

Link to 5 minute data for KDPA

Wind History from DPA (wind in knots)
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Last 24hrS11--SW12
G21
SW10SW10S4S4S3SE3S4S4S6S6S3S5S6SW7S9SW9SW7SW10SW11SW10SW12
1 day agoS9S12S10S10S9S7S5S7S8S9S8S9S10S8S9S12S11
G22
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2 days agoN9NW8N9N5N5N4CalmCalmCalmCalmCalmCalmS5S6S11CalmCalmSE5S4S6S6S7S6S10

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.
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Wind Forecast for Chicago, IL (12,3,4,5)
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Ground Weather Radar Station Chicago, IL
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