Saturday, October23, 2021
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Marine Weather and Tides
Lake Forest, IL

Version 3.4
NOTICE
3/30/2021 -- ANZ330 has been split into ANZ331 and ANZ332. Click EDIT in Marine Forecast and select your new zone.
1/26/2021 -- The West Coast Satellite images havd been updated. They now use GEOS-17.
1/1/2021 -- The 7 day forecast are now working well. Thank you NOAA for your support.

Sunrise 7:12AMSunset 5:58PM Saturday October 23, 2021 4:21 PM CDT (21:21 UTC) Moonrise 7:40PMMoonset 10:09AM Illumination 91% Phase: Waning Gibbous; Moon at 18 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- 248 Pm Cdt Sat Oct 23 2021
.gale warning in effect from Sunday afternoon through Monday evening...
Tonight..Northeast winds around 5 kt becoming east 10 to 15 kt in the late evening and overnight. Becoming mostly cloudy. Waves 1 to 3 ft .
Sunday..East winds 10 to 20 kt increasing to 30 kt in the afternoon, then to 35 kt gales by evening. Chance of showers in the morning, then rain in the afternoon. Waves 2 to 4 ft building to 4 to 7 ft occasionally to 9 ft in the afternoon.
Sunday night..East gales to 45 kt. Rain and slight chance of Thunderstorms. Waves 8 to 12 ft occasionally to 16 ft building to 10 to 14 ft occasionally to 18 ft after midnight.
Monday..Northeast gales to 45 kt. Slight chance of Thunderstorms in the morning. Rain showers through the day. Waves 10 to 14 ft occasionally to 18 ft subsiding to 6 to 9 occasionally to 12 ft.
LMZ740 Expires:202110240330;;152229 FZUS53 KLOT 231948 NSHLOT NEARSHORE MARINE FORECAST National Weather Service Chicago/Romeoville IL 248 PM CDT Sat Oct 23 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. LMZ740-741-240330-


7 Day Forecast for Marine Location Near Lake Forest, IL
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location: 42.24, -87.86     debug


Area Discussion for - Chicago, IL
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FXUS63 KLOT 232002 AFDLOT

Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 302 PM CDT Sat Oct 23 2021

SHORT TERM. 235 PM CDT

Through Monday .

Synopsis:

A powerful autumn storm system will take shape over the next 24 hours and eventually bring a multitude of inclement and potentially hazardous weather to the area Sunday into Monday. Water vapor imagery early this afternoon depicts a powerful Pacific jet stream beginning to crash onshore the west coast. This strong jet stream (130-150kt at 250mb) will translate eastward into the central Plains tonight resulting lee cyclogenesis in the left exit region of this jet. This cyclone will intensify and close off a mid-upper level circulation as it moves east toward the mid Mississippi Valley Sunday night into early Monday.

Southerly winds are already transporting moisture northward from the Gulf of Mexico north into the southern and getting into the central Plains. Strong low level jet (>50kt @ 850mb) will develop tonight in response to the developing lee cyclone and help accelerate the northward transport of moisture in advance of the system.

Early this afternoon, a warm front at the surface extends from central Kansas east to downstate IL. As the cyclone develops tonight, look for warm front to begin lifting northward with strengthening low level jet resulting in significant low level theta-e advection into strengthen low-mid level frontal system. The strengthening low-mid level frontogenesis combined with the strong theta-e advection should result in a blossoming area of showers and thunderstorms to the north of the sfc warm front. This activity will lift north into the our CWA late tonight into tomorrow morning, with this likely to be the first of multiple rounds of showers and some thunderstorms as the system moves rather slowly eastward across the region.

Hydrology:

Models continue to advertise near record levels of moisture availability with precipitable water values near or above 1.5 inches pooling near and north of the quasi-stationary boundary. The slow moving nature of the east west boundary combined with at least waves of strong forcing, at first via theta-e advection and frontogenesis and eventually from the DCVA with the cyclone itself, should be quite effective at translating this abnormally moist atmosphere into effective heavy rainfall production.

Higher resolution models continue to advertise narrower swaths of well over 4" inches of rain in spots mainly south of I-80. Even the lower resolution guidance has widespread 2-3"+ rainfall amounts south of I-80 and one inch plus over most of the CWA. While exact locations in the various models vary, the idea of swaths of >4" of rain is a pretty consistent and concerning signal in the convective allowing guidance. SREF probabilities of 2" of rain in 6 hours are in the 30-80% range over a sizable portion of our southern CWA Sunday evening, which is close to the 6 hourly flash flood guidance (which isn't taking into account antecedent rainfall during the day Sunday).

A preponderance of the evidence supports issuing a flash flood watch for our southern CWA. Not uncommon for warm sector convection to our south to sometime retard the northward moisture transport in these strong systems, reducing rainfall totals to the north. In this case, round one of will occur tonight and into Sunday, prior to any meaningful convection in the warm sector. Widespread convection is expected to develop tomorrow afternoon/evening across Missouri, however backing low-mid level flow owing to the closing off of the mid-level low should actually drive the weakening remnants of the Missouri convection north into our CWA.

Latest runs suggest the rainfall with the trowel on the back side of this system later Sunday night into Monday will probably be mostly north of the areas most likely to see heavy and potentially flooding rainfall on the "front" side of the storm. However, thermodynamics would suggest a potential for a lake enhancement to the rainfall over northeast Illinois Sunday night into Monday. So while during and intensity of the rain stands a lower probability of producing substantial flooding in northeast IL north of I-80, could still see problems with standing water, particularly in poor drainage areas. Probably a flood advisory type situation, if anything.

Convection:

Some thunderstorms are likely very late tonight into Sunday morning in the warm air advection regime over mainly our southern CWA, though weak instability should result in mainly a heavy rainfall threat. It appears very likely that our CWA will remain safely north of the warm front with minimal severe weather threat in our area. As the sfc low track east near I-80 the warm sector could briefly make it into the southern portions of our CWA later Sunday night, but instability is likely to be too weak that time of day for a meaningful severe weather threat. However, could see a bit of an uptick in lightning activity later Sunday night as upper low approaches and we briefly poke into the warm sector.

Winds/Waves/Lakeshore Flooding:

Tightening pressure gradient in advance of the surface low will result in gradually increasing easterly winds, particularly starting late Sunday afternoon into Sunday evening. Over land, mixing is not expected to be particularly efficient in the easterly flow, but given the strong pressure falls and tightening gradient it should be breezy/windy Sunday night over northern IL.

Of greater concern, relatively chilly air mass in place north of the warm front flowing over the record warm Lake Michigan water will result in very efficient mixing of the higher momentum air to the surface over the lake and along western shores of the lake. Bufkit forecast soundings from most models suggest sustained winds over the lake of around 30kt Sunday night into Monday morning with deep mixing in the marine boundary layer likely to transport down gusts of 40-45kt.

These strong easterly winds will should result in large battering waves along the Illinois shore Sunday night into Monday. While the wind direction initially will not be favorable for a big storm surge, the magnitude of the winds should result in some response in lake levels which combined with the large waves will result in a lakeshore flood threat. Winds will back to northerly and begin to slowly ease, but likely continue at gale force until later Monday afternoon. So while the winds may begin to ease slowly Monday, the wind direction will result in a more favorable fetch probably continuing the lakeshore flood threat. Will be hoisting a lakeshore flood advisory for this time frame.

- Izzi

LONG TERM. 300 PM CDT

Monday Night through Saturday .

The main concern in the medium-long range is the potential for another period of wet weather Thursday into Friday, though confidence is very low. Temperatures will average near normal.

On Monday night, 850 mb temps will cool to near or below 0C, which will set up respectable lake induced thermodynamics with 850 mb to lake deltas up to 17C, equilibrium levels of 6-7kft, and a couple hundred J/kg of CAPE. Drying and subsidence should push in from the west later overnight or Tuesday morning, but before that, think some lake effect showers are a decent bet. Unidirectional brisk north-northeast flow from the surface to well aloft entails very little wind shear and decent inland penetration of lake effect showers. Introduced lower chance PoPs for this.

Weak high pressure ridging will bring a quiet and seasonable Tuesday and Tuesday night. Attention then turns to the next strong short-wave trough ejecting across the high Plains area, with lee cyclogenesis Tuesday. Global guidance is in good agreement in sharp short-wave ridging across the western Great Lakes on Wednesday in response to the digging trough to the west, and continued dry surface high pressure influence. As such, there has been a decided drier trend on Wednesday, so continued to trend PoPs downward.

Model variance grows substantially after the Wednesday daytime period, greatly lowering confidence and predictability. The southern Plains short-wave is forecast to close off at the mid and upper levels over the Mid South on Wednesday, with strong secondary cyclogenesis possible over the lower-mid MS Valley. Key word here is possible cyclogenesis, as the operational ECMWF is much farther south and slower with the key mass fields than the GFS and CMC. There are some ECMWF ensemble members still similar to the much more robust GFS and CMC suites, though the mean generally supports the operational. While vice versa is true for the other guidance, spread is massive.

What this all entails is that greatly disparate outcomes remain plausible for later Wednesday night through Friday, ranging from another wind driven soaking rain (GFS and CMC) to a period of lighter rain later Thursday into Friday and much less wind (ECMWF operational). Trended PoPs lower Wednesday evening when model consensus is primarily dry, but then maintained NBM thereafter, with PoPs peaking at likely on Thursday PM. Coming off the significant rain event tomorrow into Monday, another soaker would increase hydro concerns. Suffice to say, it will take some time to resolve the model variance, so stay tuned. Turning ahead to Halloween weekend, medium-long range guidance trends point toward seasonable to slightly above normal temperatures and drier conditions, with a surge of chilly air possibly waiting in the wings to start November.

Castro

AVIATION. For the 18Z TAFs . 1254 PM CDT

The concerns for the Chicago area TAF sites include:

* Rain developing on Sunday with CIGs deteriorating to IFR or possibly lower and reduced VSBY in steady to heavy rain * Gusty east to northeast winds on Sunday

The quiet VFR conditions will continue through tonight, followed by a long duration of aviation impacts starting Sunday morning. Variable winds will shift to easterly this afternoon and then start to increase late tonight. A slow moving low pressure will approach the mid MO Valley by mid day Sunday, with rain overspreading the local region well in advance of the system.

Expect a steady light rain to commence by the mid morning into the Chicago area, earliest at GYY, while RFD on northern edge may see spotty -SHRA initially. Confidence is high in a steady moderate rain Sunday afternoon, with occasional heavier rates probable. ORD/MDW extended TAFs indicate prevailing lower MVFR VSBY, though IFR VSBY is certainly possible by the mid afternoon. CIGs will deteriorate from MVFR to IFR from south to north into the early afternoon. At least temporary LIFR CIGs are possible mid to late Sunday afternoon. East winds will become gusty during the morning and then shift to more east-northeast during the afternoon, with peak gusts generally in 20-25 kt range. Even stronger winds are in store beyond the current TAF period.

Castro

MARINE. 235 PM CDT

Upgrading the gale watch to a gale warning. The gale threat appears most substantial in the Illinois nearshore waters, but will be upgrading Indiana as well even though gales appear very marginal there until Monday. Confidence is high in 40-45kt easterly gales Sunday night into Monday morning, with a couple of the more aggressive models even hinting at a threat of a couple brief low end storm force gusts. Winds should begin to slowly subside Monday as they back to more northerly direction.

- Izzi

LOT WATCHES/WARNINGS/ADVISORIES. IL . Flash Flood Watch . ILZ019-ILZ020-ILZ021-ILZ023-ILZ032-ILZ033- ILZ039-ILZ105-ILZ106-ILZ107-ILZ108 . 4 PM Sunday to 10 AM Monday.

Lakeshore Flood Advisory . ILZ006-ILZ103-ILZ104 . 7 PM Sunday to 7 PM Monday.

IN . Flash Flood Watch . INZ001-INZ002-INZ010-INZ011-INZ019 . 4 PM Sunday to 10 AM Monday.

LM . Gale Warning . LMZ740-LMZ741-LMZ742-LMZ743 . 5 PM Sunday to 9 PM Monday.

Gale Warning . LMZ744-LMZ745 . 8 PM Sunday to 9 PM Monday.



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Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WHRI2 - Waukegan Harbor, IL 9 mi82 min 0G0
45174 13 mi32 min NE 5.8G9.7 62°F2 ft1015.9 hPa
45187 18 mi32 min N 3.9G5.8 55°F 57°F1 ft
KNSW3 - Kenosha, WI 24 mi82 min ENE 5.1G8 51°F 1016.6 hPa (-1.3)
OKSI2 26 mi142 min NE 1.9G2.9 51°F
CHII2 - Chicago, IL 27 mi32 min NNE 6G8.9 51°F 34°F
CNII2 30 mi37 min NE 6G8.9 52°F 34°F
JAKI2 35 mi142 min ENE 4.1G9.9 51°F
CMTI2 - 9087044 - Calumet, IL 39 mi52 min NE 6G8 1015.3 hPa

Wind History for Calumet Harbor, IL
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Chicago / Wheeling, Pal-Waukee Airport, IL9 mi30 minNW 310.00 miFair56°F32°F40%1016.8 hPa
Chicago/Waukegan Regional Airport, IL12 mi27 minno data10.00 miFair55°F33°F44%1016.1 hPa
Chicago, Chicago-O'Hare International Airport, IL18 mi31 minN 010.00 miA Few Clouds54°F31°F42%1016.3 hPa

Link to 5 minute data for KPWK

Wind History from PWK (wind in knots)
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Last 24hrN4N3N3N4N6N5NW5N7N8NW5NW3NW5NW4NW3NW4NW4NW4NW40W5NW6N70NW3
1 day agoNW8NW7NW5N8N7N7N6NW40NW3W3NW5NW4NW30NW3N4NW6N6N6NW8NW7NW5NW5
2 days agoS8S7S6S11S8S9S9S7S5W6W10
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Tide / Current Tables for
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