Chicago Weather Forecast (O'Hare Official) 5:18 pm CDT Aug 22, 2017 with Forecast Discussion

Tonight: Mostly clear, with a low around 58. Northwest wind 10 to 15 mph, with gusts as high as 25 mph.

Wednesday: Sunny, with a high near 76. Northwest wind 10 to 15 mph, with gusts as high as 20 mph.

Wednesday Night: Partly cloudy, with a low around 57. North northwest wind 5 to 10 mph becoming light north in the evening.

Thursday: Mostly sunny, with a high near 72. North northeast wind 5 to 10 mph.

Thursday Night: Mostly clear, with a low around 55. Northeast wind 5 to 10 mph.

Friday: Mostly sunny, with a high near 74.

Friday Night: Partly cloudy, with a low around 56.

Saturday: Mostly sunny, with a high near 76.

Saturday Night: Partly cloudy, with a low around 58.

Sunday: Partly sunny, with a high near 77.

Sunday Night: Mostly cloudy, with a low around 61.

Monday: Partly sunny, with a high near 78.

Monday Night: Mostly cloudy, with a low around 62.

Tuesday: A slight chance of showers and thunderstorms. Mostly sunny, with a high near 79.

Amf Ohare IL
 41.98°N 87.9°W

Area Forecast Discussion below ad ...

National Weather Service Chicago/Romeoville, IL
GO Current Forecast Discussion


218 PM CDT Tue Aug 22 2017


Through Tonight...

Drier air continues to spread southeastward into the forecast area on breezy northwest winds as a cold front continues southeast. There is enough convergence near the boundary to trigger a few isolated showers across north-central Indiana and cannot rule out an isolated shower developing further west across Newton, Jasper, Benton or Iroquois Counties over the next few hours. Otherwise clouds will scatter into the late afternoon and dissipate this evening. Clear skies are expected overnight and temps will cool into the 50s away from the heart of the Chicago metro.




Wednesday through Tuesday...

A seasonably strong upper trough currently setting up over Ontario and much of the Great Lakes will allow a strong northwest flow pattern aloft to persist across much of the area through the end of the week. Within this flow pattern, a shortwave disturbance over northern portions of Alberta and Saskatchewan is expected to dig southeastward across southern WI and northern IL Wednesday night into Thursday morning. While precipitation potential with this feature will be low, it will help drive another surface cold front with a reinforcing shot of a cool autumn-like airmass southward across the area by early Thursday.

Prior to the arrival of the cold front, it looks like Wednesday will be great day across the area as temperatures warm into the mid to upper 70s under partly cloudy skies. However, by Thursday, the lower-level airmass looks to cool by around 3 degrees C as cooler air filters southward over the area. This in combination with the prospects of some lake effect cloudiness will likely yield high temperatures only in the lower to mid 70s for most areas (a good 5 to 8 degrees below average). Also I cannot rule out a few isolated light showers or sprinkles Thursday morning, especially near the lake.

A surface ridge of high pressure then looks to set up over WI and into northern IL Thursday night into Friday. Light winds and clearing skies look to set up a rather chilly night across the area. Many of the outlying areas of northern IL could drop into the mid 40s into early Friday morning. Also, we could see some spotty fog develop as the temperatures radiate into the 40s.

Temperatures are only expected to slowly moderate back through the 70s over the weekend as the region remains under the influence of high pressure over the Great Lakes region. Otherwise, the next potential for precipitation will not be until early next week. Model guidance suggests that another upper disturbance will set up over the mid section of the country during this period. However, at the same time a strong tropical system could impact portions of the TX or LA Gulf Coastal areas, and this could play havoc with any local chances of precipitation early next week. For this reason, I will only continue to mention low end chances at the end of the period.



.AVIATION... For the 18Z TAFs...

West-northwest winds gusting in the 20-25 kt range will trend northwesterly early this afternoon with gusts gradually diminishing later this afternoon. MVFR ceilings are lifting to lower end VFR and decreasing in coverage, though variable scattered to broken coverage will persist through early afternoon. Winds will ease this evening then increase modestly Wednesday morning. Wind direction at ORD/MDW will be tricky Wednesday afternoon as it may turn north-northwest or possibly north- northeast, while winds further inland across Illinois remain west-northwest to northwest. GYY should see more of a north component by afternoon.




North-northwesterly winds of 15 to 20 KT will continue down Lake Michigan into Wednesday as a stout area of low pressure continues to shift over northern Quebec and a surface ridge of high pressure builds over the Upper Midwest. With these winds, expect waves of 4 to 7 feet over southern Lake Michigan with hazardous conditions for small craft into Wednesday for the Indiana near shore waters. Expect the winds over the lake to gradually abate for a short period on Wednesday before another cold front shifts southward down the lake Wednesday night night into Thursday morning. As this front passes, expect a bit of resurgence in some of the northerly winds over the lake for a period. A few showers, and possibly an isolated water spout may also be possible over Lake Michigan early Thursday morning with the frontal passage. However, with time expect the surface ridge of high pressure to build eastward over the lake late in the week and into the weekend. This will result in a period of lighter winds, which should gradually become southeasterly late in the period as another area of low pressure takes shape over the Upper Midwest.



.LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...Beach Hazards Statement...INZ001-INZ002 until 4 PM Wednesday.

LM...Small Craft Advisory...IN nearshore waters until 4 PM Wednesday.

+ + + + + +

Important links below ad ...
NWS Forecast Chicago (O'Hare)
(NEXRAD Radar Chicago)
(Chicagoland Weather Radar)
(Satellite Cloud Cover East United States)
(US Weather Forecast Chart)
Ultraviolet Index/UV Index
Chicagoland Sunrise, Sunset and Solar Information for Chicago area
Chicagoland Moonrise, Moonset and Lunar Phase information for Chicago area

Full climate/weather details
(Desktop Mac/PC links)

Chicago record high temperatures

Chicago record low temperatures

Chicago extreme records

Chicago normal temperatures

Chicago Weather Radar

Chicago Weather Forecast

See also ...
Arlington Heights Weather Forecast
Chicago allergy weather
Chicago arthritis weather
Chicago respiratory weather

Much of the information in, Chicago Weather Stations and Chicago Weather Station consists of material from the National Weather Service, which is in the public domain (See ABOUT section).


Hazardous Weather Outlook National Weather Service Chicago/Romeoville IL 310 PM CDT Tue Aug 22 2017

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019- 232015- Winnebago-Boone-McHenry-Lake Illinois-Ogle-Lee-De Kalb-Kane- DuPage-Cook-La Salle-Kendall-Grundy-Will-Kankakee-Livingston- Iroquois-Ford-Lake Indiana-Porter-Newton-Jasper-Benton- 310 PM CDT Tue Aug 22 2017 /410 PM EDT Tue Aug 22 2017/


.DAY ONE...Tonight.


  High Swim Risk.


Northerly winds will build waves along the northwest Indiana shore creating a high risk of rip currents tonight across the Lake and Porter County beaches.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Wednesday...   High Swim Risk.

Thursday...   Limited Fog Risk.


The risk of rip currents will continue along the northwest Indiana beaches in Lake and Porter Counties through at least midday Wednesday


Spotter activation will not be necessary through tonight.