Marine Forecasts

    EDIT      (on/off)   Help

---

7 Day Forecast for Marine Location Near Evanston, IL

   Hourly   EDIT   Help

---

Area Discussion for - Chicago, IL

      (on/off)   Help   NOTE: mouseover dotted underlined text for definition
FXUS63 KLOT 140544 AFDLOT

Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 1244 AM CDT Tue Jul 14 2020

SHORT TERM. 235 PM CDT

Through Tuesday night .

Short term forecast concerns are limited although thunderstorm chances do inch up Tuesday night mainly late. A couple stronger storms are possible primarily in north central Illinois.

Surface high pressure of 1017 mb prevails over the area this afternoon and GOES visible satellite imagery captures the high's anticyclonic low-level motion in the cumulus streets. It's a nice sign of fair weather. Winds will drop off to near calm early this evening with mainly a clear sky tonight and lows around normal.

During the day Tuesday, mid-level height rises are forecast to slightly magnify over the area with the ridging being a downstream response to a trough moving into the Northern Plains/Upper Midwest. This trough is an extension of a closed low moving eastward across the Canadian prairies, and one with a stout 100+ kt upper jet rounding its base through Tuesday. Mid- and low-level warm advection across much of the Midwest into the Great Lakes will be a response to this. A resulting elevated mixed layer (EML) plume will bring steepened mid-level lapse rates of 7.5+ C/km into Wisconsin and far northern Illinois through the day already, but a dearth of moisture especially from the state line region southward will likely limit any convective development. There may still be spillover cirrus from further upstream convection over Minnesota and western Wisconsin but confidence on this is low. With the low-level thermal ridge pushing 850 mb temperatures up to 17C-19C by midday, envision that upper 80s should be realized if high clouds are not too thick.

The aforementioned jet streak should drive forward-propogating convective growth and evolution into Wisconsin Tuesday night. Further southwest more development is likely over southern Iowa into Missouri Tuesday evening with a second short wave. This convection should have some upscale growth in time, but that may not be until quite late. In-between the two areas of expected Tuesday night convection, guidance is in fairly decent agreement of somewhat of a gap in forcing and a break in ingredients for rapid forward propagation. Thus the thunderstorm chances for Tuesday night look to be mainly late and it is more possible than it had been that no convection arrives prior to daybreak Wednesday if the moisture transport focus remains over southern Iowa/northern Missouri. Even if not organized convection, isolated cells could fire in the broader warmer advection regime over northern Illinois Tuesday night. Most guidance does not show this but if so, they could tap the steeper lapse rates to become strong to possibly severe, but again a conditional risk.

MTF

LONG TERM. 312 PM CDT

Wednesday through Monday .

Two main items remain in focus during the period:

1) Thunderstorms, possibly some strong to severe, Wednesday afternoon and evening 2) Dangerous heat possible this weekend

Upper ridging crossing the CWA on Tuesday will have shifted to the over the Lower Great Lakes by Wednesday while rather broad troughing extends from the northern Rockies into the the northern Great Lakes. A cold front well-removed from its parent low/trough lifting north from the northern Great Plains into southern Canada will be a focus for convection as it drifts southeast into the Upper Mississippi Valley through Tuesday night. See the short term discussion for more details on this.

Guidance continues to back off on remnant convection along the front to the northwest shifting well into the CWA, if it even reaches the northwest portions of the CWA at all. However, with modest mid-level lapse rates present above a shallow EML, decaying convection will have a chance of spilling into northwest portions of the CWA toward daybreak.

Reasonable agreement exists among models that a convectively enhanced and compact mid-level wave/MCV will eject ENE from the central High Plains Tuesday night, crossing the CWA late Wednesday afternoon into the evening. A conditional severe thunderstorm risk for all hazards including flash flooding exists with this wave during the late afternoon and early evening. Subdued mid-level lapse rates, possible residual mid-level clouds from convection to the northwest, and limited moisture return except for just ahead of the approaching system will all act to suppress the severe threat via reduced instability. With that said, an impressive wind field for this time of year with a slightly negatively tilted trough cannot be ignored in an environment capable of quickly becoming unstable. Again, this is a conditional threat, but given the potential dynamics in play (including backed low-level winds), strong wind gusts, and to a lesser extent marginally severe hail and a brief tornado or two would be possible. Additionally, with PWATs around two inches combined with strong dynamics, high rainfall rates could produce localized flash flooding.

High pressure will build in behind Wednesday's system as the heat dome currently over the southwest CONUS and southern Great Plains begins to expand northeast into the region. Warmer conditions with each passing day will begin on Thursday and continue through at least Sunday and possibly into Monday. 925 hPa temps of 25-28C Saturday and Sunday produce max temps solidly in the mid 90s both days based on local temp climatology. With dew points potentially in the low 70s, afternoon heat index values may near or possibly surpass local Heat Advisory criteria of 105F. Little relief in the heat would be expected at night, with lows generally in the mid to upper 70s with dew points in the 70s across the Chicago metro. As is often the case this far north, the one caveat will be the potential for convection or convective outflows to disrupt the heat each day, with a better chance on Monday. However, if the area remains undisturbed from convection, several days of dangerous heat are expected.

Kluber

AVIATION. For the 06Z TAFs .

VFR Conditions are expected through the TAF period.

Winds will remain light early this morning and continue gradually turning southerly as surface high pressure shifts to the east. Expect winds to pick up to 10 to 12 kts by Tuesday afternoon with occasional stronger gusts, especially across our northwest.

A system will be approaching from the west toward the end of the period at RFD. Current thinking is that this should stay east through 6Z, so have held off on a formal precip mention with this issuance.

Petr

LOT WATCHES/WARNINGS/ADVISORIES. IL . None. IN . None. LM . None.

Visit us at weather.gov/chicago

Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/NWSChicago www.twitter.com/NWSChicago www.youtube.com/NWSChicago

---

Weather Reporting Stations

   EDIT       (on/off)   Help   NOTE: Click on distance to see the station location on a map

Stations	Dist	Age	Wind	Air Temp	Water Temp	Waves	Pressure	DewPt
45174	7 mi	18 min	SSW 5.8 G 9.7	74°F	75°F	1 ft	1015.4 hPa	65°F
CHII2 - Chicago, IL	10 mi	38 min	SSW 8 G 8.9	74°F				65°F
CNII2	13 mi	23 min	SW 4.1 G 6	71°F				57°F
CMTI2 - 9087044 - Calumet, IL	22 mi	50 min					1015.2 hPa
45187	32 mi	58 min	SW 5.8 G 9.7	72°F	73°F	1 ft
KNSW3 - Kenosha, WI	39 mi	98 min	SSW 5.1 G 6	70°F			1015.2 hPa (-0.4)
45170	43 mi	28 min	3.9 G 5.8	70°F	76°F	1 ft		62°F

Wind History for Calumet Harbor, IL

(wind in knots)    EDIT      (on/off)   Help

2 AM

3 AM

4 AM

5 AM

6 AM

7 AM

8 AM

9 AM

10 AM

11 AM

12 PM

1 PM

2 PM

3 PM

4 PM

5 PM

6 PM

7 PM

8 PM

9 PM

10 PM

11 PM

12 AM

1 AM

Last 24hr

N8

N6 G10

N4

NW3

NW3

N4

N6

N6 G10

N6 G9

N7

NE7

NE7

NE7

NE7 G10

NE8

E9 G12

E7

E7

E6 G11

E5

E4

E3

S2

S4

1 day ago

SW1

SW3

SW2

SE1

--

SW1

S5

NE3

N6 G10

N13 G17

N13

N11 G15

N12 G16

N9 G14

N9 G14

N10 G14

N9 G14

N7 G11

N9

N7 G10

N6 G10

N6 G11

N6 G9

N5

2 days ago

W2 G5

W2 G5

W2

W2

SW4

SW2 G7

W4 G9

W5 G14

W8 G14

W4 G7

SW4 G10

W4 G9

W3 G6

W4 G7

NE3

NE4

SE3

S1

SW2

SW5 G9

SW4

---

Airport Reports

    EDIT      (on/off)   Help   Click EDIT to display multiple airports. Follow links for more data.

Airport	Dist	Age	Wind kt	Visibility	Sky/Weather	Temp	DewPt	Humidity	Pressure
Chicago / Wheeling, Pal-Waukee Airport, IL	12 mi	46 min	N 0	10.00 mi	Fair	68°F	63°F	84%	1015.9 hPa
Chicago, Chicago-O'Hare International Airport, IL	12 mi	47 min	N 0	10.00 mi	Fair	71°F	60°F	68%	1015.3 hPa
Chicago, Chicago Midway Airport, IL	17 mi	45 min	S 5	10.00 mi	Fair	71°F	57°F	63%	1014.7 hPa

Link to 5 minute data for KPWK

Wind History from PWK (wind in knots)

3 AM

4 AM

5 AM

6 AM

7 AM

8 AM

9 AM

10 AM

11 AM

12 PM

1 PM

2 PM

3 PM

4 PM

5 PM

6 PM

7 PM

8 PM

9 PM

10 PM

11 PM

12 AM

1 AM

2 AM

Last 24hr

Calm

Calm

Calm

Calm

Calm

NW3

NE3

4

3

Calm

Calm

5

E7

E8

E7

E7

SE9

SE5

SE5

SE4

Calm

Calm

Calm

Calm

1 day ago

NW6

NW5

N5

NW5

NE11 G20

NE14 G20

NE15 G23

N13

NE12

NE12 G21

NE10 G18

NE11

NE10 G15

NE11 G18

NE10 G18

E9

N8

NE5

N3

N4

N3

Calm

Calm

Calm

2 days ago

NW4

NW5

NW3

NW5

NW5

NW5

W7

W8

NW11

NW15 G21

W8 G18

W6

W8

NW9

W5

NW6

NW7

NW6

W3

NE3

Calm

Calm

W7

W4

---

Tide / Current Tables for

   EDIT   Weekend mode (on/off)   (on/off)   Help

---

Tide / Current Tables for

   EDIT      (on/off)   Help

---

Weather Map

       (on/off)   Help Weather Map

---

GEOS Local Image of Midwest    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.
Link to Loop

Other links: Northern Pacific     Contential US     Full GOES-East

---

Wind Forecast for Chicago, IL (3,6,7,8)

      (on/off)   Help

---

Ground Weather Radar Station Chicago, IL

   (on/off)   Help

---

Cookie Policy: This website uses cookies to save your settings. No personal information is saved. I do not collect statistics on your visit. You can disable cookies in your browser if you like but it is not recommended for this site. I do not sell cookies. Go to a bakery for that. In fact I do not sell anything. To disable cookies from L-36.com, please refer to the Help button in your browser. Privacy Policy: I do not sell or share any user data or anything else for that matter. The only personal information I save is in the site log which has a line for each page view which includes the IP address your browser sends in the header as well as which page you requested. I use this to block hackers and other bad actors. I do not use this raw data to create profiles on users. I periodically delete the log files. If you are subject to CCPA, Google ads on this site will not be based on your past behavior so you will likely not see an ad for a lawn mower just because you looked for one at a big box website. I do not believe this site is subject to CCPA but I am doing what I can to follow the guidelines anyway. Disclaimer: The information on this web site has not been checked for accuracy. It is for entertainment purposes only and should be independently verified before using for any other reason. There are five sources. 1) Documents and manuals from a variety of sources. These have not been checked for accuracy and in many cases have not even been read by anyone associated with L-36.com. I have no idea of they are useful or accurate, I leave that to the reader. 2) Articles others have written and submitted. If you have questions on these, please contact the author. 3) Articles that represent my personal opinions. These are intended to promote thought and for entertainment. These are not intended to be fact, they are my opinions. 4) Small programs that generate result presented on a web page. Like any computer program, these may and in some cases do have errors. Almost all of these also make simplifying assumptions so they are not totally accurate even if there are no errors. Please verify all results. 5) Weather information is from numerous of sources and is presented automatically. It is not checked for accuracy either by anyone at L-36.com or by the source which is typically the US Government. See the NOAA web site for their disclaimer. Finally, tide and current data on this site is from 2007 and 2008 data bases, which may contain even older data. Changes in harbors due to building or dredging change tides and currents and for that reason many of the locations presented are no longer supported by newer data bases. For example, there is very little tidal current data in newer data bases so current data is likely wrong to some extent. This data is NOT FOR NAVIGATION. See the XTide disclaimer for details. In addition, tide and current are influenced by storms, river flow, and other factors beyond the ability of any predictive program.