Chicago Weather Forecast (O'Hare Official) 6:17 pm CDT Aug 6, 2017 with Forecast Discussion

Tonight: Mostly cloudy, with a low around 61. South southeast wind around 5 mph becoming calm in the evening.

Monday: Isolated showers before 4pm. Mostly cloudy, then gradually becoming sunny, with a high near 74. North northeast wind 5 to 10 mph, with gusts as high as 15 mph. Chance of precipitation is 20%.

Monday Night: Mostly clear, with a low around 58. North northeast wind 5 to 10 mph.

Tuesday: Sunny, with a high near 81. West northwest wind around 5 mph.

Tuesday Night: Mostly clear, with a low around 62. North northwest wind around 5 mph becoming calm in the evening.

Wednesday: Mostly sunny, with a high near 83.

Wednesday Night: Partly cloudy, with a low around 63.

Thursday: Partly sunny, with a high near 83.

Thursday Night: A slight chance of showers and thunderstorms after 1am. Partly cloudy, with a low around 64.

Friday: A slight chance of showers and thunderstorms after 1pm. Partly sunny, with a high near 82.

Friday Night: A chance of showers and thunderstorms. Mostly cloudy, with a low around 65.

Saturday: A chance of showers and thunderstorms. Partly sunny, with a high near 80.

Saturday Night: A chance of showers and thunderstorms. Mostly cloudy, with a low around 63.

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

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


641 PM CDT Sun Aug 6 2017


Through Monday...

Main concern for the short term forecast period will focus on chances for showers this afternoon through this evening.

Two upper level features will impact the pcpn trends for the area. A northern stream shortwave tracking over srn MN/cntrl WI with bring shra/tsra to srn WI.  However, the greatest forcing from this shortwave will remain well north of the Wisconsin border and, in the absence of any significant sfc forcing or low level instability, any thunder chances should remain to the north.  A southern stream shortwave tracking through the lower Ohio Valley will keep the main focus of pcpn and and thunder chances well to the south of the CWA. The short range model guidance is in good agreement on keeping the track of the system well to the south, so any associated thunder will also remain to the south of the CWA.  However, the nrn edge of the pcpn shield could still graze the far southern or southeaster counties where the best chance for widespread measurable pcpn will be most likely. Pcpn accumulations should be less than a quarter inch total rainfall.  Temperatures will remain below seasonal normal levels through the period.  Temperatures this afternoon are being temperated by widespread layered cloud cover, but where the sun has been able to peak through, temperatures should be able to reach the middle 70s.  The far southern portions of the CWA, where cloud cover and pcpn will be most expense, may top out in the upper 60s, which is about 15 degrees below the normal high of 83 F for early August.

As the upper level shortwaves and the sfc low tracking through the Ohio Valley push off to the east tomorrow, pcpn should taper off to some isold lingering showers tomorrow morning.  Prevailing enely winds, with a fetch off of lake Michigan should help keep temps tomorrow from rebounding much.  Highs tomorrow should only be in the lower 70s along the lakefront and the middle 70s inland.


Monday night through Sunday...
A rather quiet weather pattern is expected to persist across the area Tuesday through Thursday as a surface ridge of high pressure dominates across the region. This will set the stage for seasonal temperatures, in the low 80s, and dry conditions through this period. Otherwise, a light and variable wind pattern under the influence of this surface high is likely to set the stage for afternoon lake breezes each afternoon along the Lake Michigan shores. This could keep temperatures slightly cooler along the lake shore.

The chances for showers and thunderstorms don`t look to return to the forecast until late Thursday. Forecast guidance suggests that a more active weather pattern will set up over the region later in the week into the weekend. During this period it appears that a rather stout mid-level short wave disturbance may shift across the area sometime during the Thursday night into Friday morning period. This feature could spark of showers and storms over the region, depending on it actual timing. Following this wave, it appears possible that another disturbance/closed low could set up over the Northern Plains, before gradually shifting towards the Great Lakes Region sometime later next weekend. As a result, there will continue to be chances for additional periods of showers and storms at times through the weekend. The actual timing of these systems is a bit uncertain at this time, but there is definitely a signal in the forecast guidance to suggest that a period of more active weather may set up during this later period.

Temperatures during the later half of the period look to remain near or just below seasonal normals.



.AVIATION... For the 00Z TAFs...

Large hole in the cloudiness has opened up over northern IL, which could result in some fog development overnight as winds becoming calm/light & variable. Best chances for fog development are away from the city, so only included a period of some patchy fog for ORD and nothing at MDW, but DPA will likely see IFR vsby in fog overnight. Any fog will quickly dissipate at sunrise Tuesday with light northeast winds gradually freshening up, especially near the lake Tuesday afternoon. Best chances for isold SHRA look to remain west of the Chicago terminals and low enough of a probability to keep the TAFs dry, but can`t completely rule out a shower late tonight or early Tues morning. Morning cloudiness should give way VFR conditions as lake stabilized air spreads inland Tues PM.

 - Izzi



A cold front will shift southward down the lake tonight into early Monday morning. In its wake expect the winds to increase out of the north. Winds will increase to 15 to 25 KT over the southern half of the lake Monday afternoon as the surface gradient strengthens in response to a surface ridge of high pressure building eastward from the Northern Plains. Overall, this is expected to set up another period of hazardous waves (4 to 6 FT) across the southern end of the lake late Monday into Monday night. As a result, a small craft advisory may be needed for this period.

Following this period of northerly winds, expect the Northern Plains high to gradually shift over the Lower Great Lakes and Ohio Valley regions through midweek. This pattern will set up light and variable winds over far southern sections of the lake, with afternoon lake breezes resulting in the development of onshore winds each afternoon. However, farther north of the high center, expect southwest winds to prevail on the northern 2/3rds of the lake.



.LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...Beach Hazards Statement...INZ001-INZ002...2 PM Monday to 3 AM      Tuesday.


+ + + + + +

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).