Saturday, October23, 2021
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Marine Weather and Tides
Sleepy Hollow, 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 7:14AMSunset 6:00PM Saturday October 23, 2021 2:59 PM CDT (19:59 UTC) Moonrise 7:42PMMoonset 10:10AM Illumination 92% 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 Sleepy Hollow, IL
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location: 42.1, -88.29     debug


Area Discussion for - Chicago, IL
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FXUS63 KLOT 231935 AFDLOT

Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 235 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. 329 AM CDT

Sunday through Monday Night .

The main forecast concerns remain around a period of steady, soaking rain and blustery winds from Sunday afternoon through Monday morning across much if not most of our area.

As an elongated 180-200kt jet streak currently stretching from the Kamchatka Peninsula of Russia to the northern California coast propagates eastward over the Rocky Mountains this afternoon, a low pressure system will develop in southern Colorado and rapidly deepen overnight thanks to favorably "coupled" diffluent upper-level flow. Ensemble model guidance is in fair agreement the low will track from near Wichita, Kansas to Kansas City, Missouri by midday Sunday, and pass through central Illinois overnight Sunday into Monday.

Increasing warm-air advection early Sunday morning will lead to the burgeoning of showers and thunderstorms along an axis from northern Missouri to southern Illinois along a developing 850mb warm front. As the surface low approaches Sunday afternoon, the 850mb front will tighten and frontogenetical forcing will increase leading to the development of waves of steady rain across our area (e.g. the morning hours may end up mostly dry). Sunday evening, the surface low will track through central Illinois potentially lifting the surface warm front as far north as Livingston, Ford, and Iroquois counties. Should the front indeed make it so far north, at least some threat for surface-based severe storms cannot be ruled out with an associated threat for all severe hazards. However, it currently appears more likely that the surface front will remain south, and the approach of the surface low will "merely" allow the zone of active thunderstorms (with effective inflow above the boundary layer) to lift northward into our area but south of I-80. Behind the center of the low, steady rain will continue overnight into Monday thanks to a healthy TROWAL and impressive low-level moisture convergence aided by an easterly 40-50kt 950mb low-level jet. Rain should taper from west to east through morning on Monday, with all areas expected to be dry by afternoon.

Pinpointing where and how much rain will fall can sometimes be tricky whenever warm-season moisture (PWATs of 1.25 to 1.5") overlaps with cool-season synoptic-scale forcing, especially when convection is involved. However, it appears most of our area has a good shot at seeing at least 1" of rain by Monday morning (EPS probabilities are 80-100% chance areawide), with the heaviest totals exceeding 2" increasingly likely as one heads downstate (especially south of I-80). Depending on whether the zone of active convection works as far north as our area (again, looking at Livingston, Ford, and Iroquois counties) rainfall totals may easily get out of hand leading to a narrow, localized west to east zone where flooding of roads, farm fields, and low-lying areas would become likely. Our feeling at this point is that the zone of most active convection should remain just to our south, but trends will need to be monitored closely. Regardless of how much rain falls, confidence is high that Sunday afternoon through Monday morning will be wet and that river and stream levels will increase toward bankfull.

Increasing easterly low-level flow north of the center of the low will lead to blustery winds particularly Sunday night through at least daybreak Monday but possibly as late as Monday afternoon. EPS mean ensemble wind gusts peak between 35-40 mph north of I-88 during the overnight hours, which is right on the cusp of strong enough to blow around twigs, lawn furniture, and even down a few small tree branches. The strongest wind gusts are likely along the immediate Illinois shoreline of Lake Michigan, where EPS mean ensemble peak wind gusts approach 50 mph. With such strong winds over the lake, waves heights are likely to build greater than 8 feet (highest toward daybreak Monday) which will splash up on lakeshore trails, parks, and low-lying spots. Meanwhile, winds south of I-80 may end up rather light as the low tracks overhead.

In all, Sunday afternoon through Monday morning will be raw, blustery, and wet, especially considering temperatures will be somewhat stagnant near 50 degrees. The Monday morning commute in particular may be gnarly with steady rain and blustery winds. The best way to get through these fall storms is with a comfy sweater and a good book (or sturdy rain gear if heading outdoors is inevitable).

Borchardt

Tuesday through Saturday .

Tranquil weather conditions make a very brief return to the region on Tuesday in the wake of the Sunday/Monday soaker. As high pressure noses into the region, lingering north winds will trend northeasterly off the lake through the afternoon yielding fairly seasonable temperatures with highs in the upper 50s. With relatively light winds expected to prevail through most of the overnight hours, temperatures look set to drop back into the mid and upper 30s across most of the forecast area away from the immediate lakeshore, and pockets of near-freezing temperatures seem to be in play based on the latest statistical guidance.

As has been the case the past few nights, noting quite a bit of model disparity and run-to-run continuity issues as we head towards the end of the week as our next potent PV-anomaly translates across the Great Basin and out across the Continental Divide. Latest EPS shows tremendous spread in surface low centers with this next system from as far north as about Wisconsin to the northern Gulf, and this amount of spread is seen across the rest of the ensemble model suite. The main change for this forecast package was to trend PoPs downwards and a bit slower heading into Wednesday, but no significant alterations to the blended offering were made Wednesday night and beyond given the aforementioned guidance spread.

Carlaw

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 subiside 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.

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

LM . Gale Watch . LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745 . 6 PM Sunday to 4 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 31 mi120 min W 4.1G8
45174 34 mi40 min N 5.8G9.7 62°F2 ft1016.2 hPa
45187 38 mi40 min NNW 1.9G5.8 55°F 57°F1 ft
OKSI2 38 mi120 min ENE 5.1G8 52°F
CHII2 - Chicago, IL 40 mi40 min NNE 8G9.9 50°F 33°F
CNII2 40 mi45 min NNE 8.9G9.9 53°F 32°F
KNSW3 - Kenosha, WI 42 mi60 min NW 4.1G12 51°F 1016.9 hPa (-1.0)
JAKI2 44 mi120 min NE 5.1G11 51°F
CMTI2 - 9087044 - Calumet, IL 47 mi78 min N 7G12 1015.6 hPa

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 mi68 minVar 410.00 miFair54°F32°F43%1016.8 hPa
Chicago / Wheeling, Pal-Waukee Airport, IL21 mi68 minNNW 710.00 miFair55°F32°F42%1017.5 hPa
Chicago, Chicago-O'Hare International Airport, IL22 mi69 minN 010.00 miA Few Clouds53°F31°F43%1016.8 hPa

Link to 5 minute data for KDPA

Wind History from DPA (wind in knots)
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Last 24hr4W8W6NW5N4N4N3N3N5NW4NW5NW4NW3NW40N30N4NW3N30034
1 day agoW9NW10N9NW8NW6N5N8N10N7N7NE5N3NW4NW3NW50000N5N5NW6W8NW7
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