Thursday, July29, 2021
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Marine Weather and Tides
Joliet, 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 5:43AMSunset 8:14PM Thursday July 29, 2021 2:50 AM CDT (07:50 UTC) Moonrise 11:30PMMoonset 11:36AM Illumination 76% Phase: Waning Gibbous; Moon at 20 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:202107290930;;627078 Fzus53 Klot 290617 Nshlot Nearshore Marine Forecast National Weather Service Chicago/romeoville Il 117 Am Cdt Thu Jul 29 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>742-290930- Winthrop Harbor To Wilmette Harbor- Wilmette Harbor To Northerly Island- Northerly Island To Calumet Harbor- 117 Am Cdt Thu Jul 29 2021
.small craft advisory in effect through Friday afternoon...
.severe Thunderstorm watch 400 in effect until 8 am cdt this morning...
Rest of tonight..Southwest winds 15 to 20 kt becoming northwest 20 to 25 kt toward daybreak. Showers and Thunderstorms with gusty northwest Thunderstorm winds to 50 kt possible overnight. Waves 2 to 4 ft, though higher waves may occur around the line of Thunderstorms.
Thursday..Northwest winds 15 to 20 kt becoming northeast 20 to 25 kt in the afternoon. Chance of showers and Thunderstorms in the morning. Waves 2 to 4 ft building to 3 to 6 ft in the afternoon.
Thursday night..North winds 15 to 25 kt. Mostly clear. Waves 4 to 6 ft occasionally to 8 ft.
Friday..Northeast winds 10 to 20 kt. Mostly Sunny. Waves 4 to 6 ft occasionally to 8 ft subsiding to 3 to 5 ft in the afternoon.
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 290623 AFDLOT

Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 123 AM CDT Thu Jul 29 2021

UPDATE. 917 PM CDT

Current gridded forecast is in good shape, though storms are not moving quite as quickly at the moment. Earlier this evening rapid thunderstorm development occurred along and ahead of several boundaries in in northern Wisconsin, one being a warm front along the MN/WI border and a separate boundary just to the northwest of there. Lightning is now extensive across the entire line. Minneapolis was in the "true" warm sector earlier this evening extreme instability approaching 5000 J/Kg, 0-3 km shear of 37 kt and effective shear of 47 kt. There is a deep dry layer below the mid level moisture leading to substantial downdraft CAPE across the region. This instability/shear space is supportive of a hybrid bowing/supercell type environment. Therefore, damaging winds is going to be the main concern, but with the boundaries in place and some strong low level SRH (300-400 m2/s2 from Minneapolis to Lacrosse, WI) along with strong instability, large hail and even a few tornadoes are a concern in Wisconsin this evening. The Quad Cities sounding is equally juicy, high CAPE and lower level dry air to support storm maintenance southward in spite of some model capping and bit less shear.

We are starting to see the signs of these storms starting to congeal into a line of storms, and this would be the most likely storm mode as they move southward along the instability gradient and motion vectors southeastward. Still given the degree of shear, some individual storm segments may continue, and thus some leading edge QLCS tornadoes remain a concern. SPC mesoanalysis does depict this DCAPE axis will spread southward toward the Wisconsin border tonight and into northern Illinois. A bit lower shear and some stronger capping into the local area still adds uncertainty as to the southern extent of the impact, but if things get organized the capping is not that strong and shear still sufficient to allow this storm complex to continue into the area tonight. Of note, 55 kt was just reported in Wausau, WI with these storms (62 mph)

It appearing more likely that at least a portion of this complex will make it into our area, but weather it is as potent as it is now remains to be seen given the low level jet veering overnight tonight and some degree of mixed layer cap forecasted. The highest low level CAPE axis is still forecasted to increase with continued warm air advection along the core of the MDT/ENH risk areas from the SPC outlook, thus the mesovortex concern will continue into southern WI, getting close to our area.

KMD

MESOSCALE DISCUSSION. 1020 PM CDT

The instability gradient now suggests that Wisconsin will be one of the highest areas of concern, and that a slightly further westward track to these storms may place a slightly bigger portion of our area in the concern area later tonight. There are still some low level stability concerns, but with the airmass still recovering ahead of the line of storms and still getting its act together, it is likely this complex will intensify and keep moving for a while.

KMD

SHORT TERM. 328 PM CDT

Through Thursday night .

The potential for a complex of severe thunderstorms capable of damaging wind gusts and maybe a tornado remains the forecast focus through tonight. Within this, substantial uncertainty remains, enough so to limit confidence on specific impacts within the CWA. The overall threat level remains highest within the level 3 (Enhanced) risk category per SPC Day 1 outlook given variance of solutions and conceptually how things may play out tonight. We are messaging a primary threat time of 12 AM to 5 AM CDT, possibly as early as 11 PM into the far northern CWA.

Even if the main corridor of wind damage ends up to the north and east of the CWA, the forecast southeastward trajectory of the organized MCS potentially packing higher end wind gusts necessitates close monitoring of southern Lake Michigan water level monitoring for meteotsunami or seiche potential early Thursday morning. Finally, should the MCS become more west (or WNW) to east (or ESE) oriented, moisture and steering flow parameters support a localized flash flooding risk, though confidence was far too low for any Flash Flood Watch issuance.

As of mid afternoon, the primary seasonably strong short-wave and mid-upper speed max resides on the far northeast periphery of the impressive mid-level ridge over the central Plains. This places it along/near the MN/Canada border. Pockets of elevated convection downstream of this wave have extended down to central Wisconsin, with current strongest convection north of DLH. In the immediate near-term, despite SPC (RAP) mesoanalysis indicating 3-4k J/kg of uncapped MLCAPE across the center of the CWA, it appears that the extensive cirrus blow from earlier and existing convection is limiting CI in the vicinity of remnant MCV near the MS River in northwest Illinois. Maintained slight chance PoPs through 00z given the very warm and oppressively humid (low-mid 70s Td) air mass, focused into northeast Illinois and northwest Indiana. To note, a few convective cells were developing as of this writing over interior northern Indiana. Should a stronger thunderstorm be able to form within the CWA, it would have a conditional downburst wind threat.

Turning to the main event, later tonight-early Thursday, the lack of widespread strong and maturing convection upstream near the main short-wave path greatly limits predictability even at this late hour. Two of the most utilized CAMs, the HRRR and 3km NAMnest, for their 18z runs, have significantly divergent solutions. Conceptually, with the very sharply northwest flow pattern in place, storm motion to the southeast introduces the risk for propagation into the CWA if maturation of expected MCS occurs far enough south over Wisconsin. The forecast 850-300 mb thickness fields and forward propagating Corfidi vectors both point toward more south of east motion than from mean steering flow aloft alone. This being said, the rather far north vort and mid-level speed max path would seem to continue favor north and east of the CWA for the highest threat for a corridor of significant damaging winds.

Given the conflicting signals in this regard and not much help from the available guidance, largely maintained forecast continuity. This includes a nod toward the western flank of the MCS orienting moreso from WNW to ESE and extending farther west than much of the available guidance would entail, along with a faster forward motion than much of the guidance would suggest. Very steep mid- level lapse rates and associated extreme MUCAPE reservoir, plus dynamical support and strong deep layer shear do support MCS maintenance and longevity deep into the night. At this point, think odds favor apex of a possible/likely bow echo to pass to the north (possibly just north of far NE IL). Segment extending back west into our CWA as per official forecast would then have a relatively lower end but still evident damaging wind gust threat (60-70 mph type gusts) and lesser chance for significant (75+ mph) gusts.

Of concern for the flash flooding risk, should the west to east orientation materialize as the complex presses southeast across the area, forecast backward propagating Corfidi vectors slow greatly after 06z. Thus backbuilding convection along the forward flank of the MCS would have a flash flood risk. Observational trends will need to be monitored closely tonight for this. Finally, regarding the embedded QLCS tornado threat, forecast 0-3 km bulk shear magnitudes are favorable at 30+ kt. However, shear vector orientation may tend to be more parallel to the line than ideal so that tornado threat would be brief/shorter lived from any transient stronger mesovortices that can develop.

There may be some lingering convection beyond 12z Thursday as the MCS exits to the east-southeast, and as mentioned earlier, we'll need to monitor closely for signs of meteotsunami or seiche development. The true cold front will not have passed yet Thursday morning, and with the MCS expected to be primarily out of the area, any renewed showers or storms toward mid day and into the afternoon will be on lingering confluence ahead of this front and on the primary MCS outflow which may be extending northwestward through the CWA. This will eventually all be shunting southward as one boundary into the early afternoon, and isolated to perhaps widely scattered thunderstorms remain a threat along this, mainly south of I-80, ending prior to sunset (possibly well before if front clears fast enough). The high moisture and residual CAPE would support an isolated severe threat, though confidence is low.

Heat and humidity on Thursday will maximize south of I-80 and especially south of a PNT to RZL line, where heat indices could approach or reach 105 degrees prior to cold frontal passage. Opted to let the midnight shift take a look at whether a Heat Advisory may be needed for the southern tier counties of the CWA. Cooler and drier air will be flowing into the area driven by brisk north-northeasterly winds through Thursday night. This will present a rebuilding of high wave action and strong currents after morning choppiness and seiche/meteotsunami potential. The dangerous swimming conditions will then linger into Friday. Given the threat for rapidly fluctuating water levels and hazardous conditions Thursday morning and more prolonged hazardous conditions developing Thursday PM, opted to issue a Beach Hazards Statement from 1 AM tonight through 7 PM Friday.

Castro

LONG TERM.

Friday night through Wednesday .

123 AM . Only forecast concern remains a chance of thunderstorms ahead of a cold front Saturday into Saturday night. Another cold front will move south across the region Saturday night into Sunday and there is a low chance for showers and a few thunderstorms ahead of this cold front. There will likely be another area of convection across portions of southern IA/northern MO into west central IL Friday night into Saturday morning. This may remain southwest of the area but blended low chance pops across this area seem reasonable for now. High pressure will move across the area Sunday into Monday with a rather cool airmass in place with highs possibly only in the 70s both days. Temps rebound back into the 80s by midweek. cms

AVIATION. For the 06Z TAFs .

1229 AM . Primary forecast concerns include .

Thunderstorms early this morning. Wind shift to northeast late this morning. Possible mvfr cigs this morning.

A line of the thunderstorms over south central WI will continue moving south into northern IL during the early morning hours. Adjusted tempo timing a bit later based on current location and movement. Scattered showers will be possible ahead and behind the line of storms.

A northerly wind shift is expected with these storms. Depending on how strong the line of storms is as it moves through the area, there could be a wake low behind the thunderstorms which would allow the potential for a stronger winds after the storms move through. Thus, low confidence for winds for a few hours after the storms end. In the absence of a wake low, westerly winds shifting northwest by mid morning looks reasonable with some gusts into the 20kt range during this time period. A cold front will move south across the area by early afternoon shifting winds to the northeast and off the lake for the Chicago terminals. Gusts to 20kt look on track for this afternoon as well and should slowly diminish this evening. Ifr cigs/vis will be likely with the storms, but there may be a period of sct/bkn mvfr cigs during the mid/late morning. Confidence is low for prevailing mvfr cigs but maintained them for a few hours in the mid/late morning. cms

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

IN . Beach Hazards Statement . INZ001-INZ002 until 7 PM Friday.

LM . Small Craft Advisory . nearshore waters until 1 PM Friday.



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Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
CMTI2 - 9087044 - Calumet, IL 36 mi50 min SSW 6 G 9.9 1013.6 hPa (-0.0)
JAKI2 36 mi110 min W 6 G 8 82°F
CNII2 37 mi20 min WSW 7 G 8.9 81°F 74°F
OKSI2 39 mi110 min W 4.1 G 11 83°F
CHII2 - Chicago, IL 41 mi30 min W 16 G 20 82°F 77°F
BHRI3 - Burns Harbor, IN 54 mi70 min SW 6 G 8 80°F 1014.6 hPa

Wind History for Calumet Harbor, IL
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Joliet Regional Airport, IL1 mi75 minN 010.00 miFair80°F76°F89%1014.2 hPa
Lewis University Airport, IL7 mi75 minWSW 510.00 miPartly Cloudy79°F77°F94%1014.6 hPa
Morris Muni-James R Washburn Field Airport, IL15 mi55 minN 07.00 miFair77°F76°F98%1014.2 hPa
Aurora Municipal Airport, IL24 mi58 minWSW 59.00 miFair79°F77°F94%1014.1 hPa

Link to 5 minute data for KJOT

Wind History from JOT (wind in knots)
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1 day agoCalmCalmCalmCalmCalmCalmCalmSW3NW5N4SW3SW7SW8SW5SW4W4CalmCalmCalmCalmCalmCalmS3Calm
2 days agoCalmCalmCalmCalmN3----CalmNW3NW4CalmW5NW3W3W5W6W3CalmCalmCalmCalmCalmCalmCalm

Tide / Current Tables for
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