Current US Threat Advisory Level
Forecast for Chicago, Illinois
| Tonight | Wednesday | Wednesday Night |
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| Breezy | Sunny | Mostly Clear |
Partly Cloudy |
Chance Of Showers |
Chance Of T-Storm |
Chance Of T-Storm |
Chance Of T-Storm |
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Mostly Clear |
| Lo: 51°F | Hi: 71°F |
Lo: 51°F | Hi: 70°F |
Lo: 55°F | Hi: 71°F |
Lo: 61°F | Hi: 80°F |
Lo: 59°F | Hi: 80°F Lo: 59°F |
- Wind Advisory
Issued: 1049 AM CDT MON SEP 06 2010
Expires: 1015 AM CDT WED SEP 08 2010
- KMDW is at: Cook County
- In the state of: Illinois (IL)
- In the country of United States (US)
- Station Latitude = 41.81N (decimal)
- Station Longitude = 87.89W (decimal)
- Station Elevation = (meters)
- Time Zone Offset from GMT = -6* (hours)
The International Civil Aviation Organization (ICAO), an agency of the United Nations, codifies the principles and techniques of international air navigation. The ICAO Code is a 4-letter airport code used to determin current conditions at that location at the time of request.
Wind Speed: W 21.9 MPH G 33.4 (19 MPH G 29 KT)
Barometer: 29.90 in.
Dewpoint: 46°F
Heat Index: 77°F
Wind Chill: 77°F
Clear...Breezy. Lows in the lower 50s...Except in the mid 50s downtown. West winds 15 to 25 mph with gusts up to 35 mph at Times early in the evening Decreasing to 10 to 15 mph in the late evening and overnight.
Moon Phase: New MoonSunset: 7:15 PM CDT
Dusk: 7:43 PM CDT
Sunny. Highs in the lower 70s. Northwest winds 10 to 15 mph.
Sunrise: 6:22 AM CDT
Mostly clear. Lows in the lower 50s...Except in the upper 50s downtown. Light and variable winds.
Moon Phase: Waxing Crescent MoonSunset: 7:13 PM CDT
Dusk: 7:41 PM CDT
Partly cloudy. Highs around 70. Light and variable winds in the morning becoming east around 10 mph in the afternoon.
Sunrise: 6:23 AM CDT
Partly cloudy with a 20 percent chance of showers. Lows in the mid 50s...Except in the upper 50s downtown. East winds around 10 mph.
Moon Phase: Waxing Crescent MoonSunset: 7:11 PM CDT
Dusk: 7:39 PM CDT
Partly sunny with a 20 percent chance of showers and thunderstorms. Highs in the lower 70s.
Sunrise: 6:24 AM CDT
Partly cloudy with a 30 percent chance of showers and thunderstorms. Lows in the lower 60s.
Moon Phase: Waxing Crescent MoonSunset: 7:10 PM CDT
Dusk: 7:38 PM CDT
Mostly cloudy with a 40 percent chance of showers and thunderstorms. Highs around 80.
Sunrise: 6:25 AM CDT
Partly cloudy with a 20 percent chance of showers and thunderstorms. Lows in the upper 50s.
Moon Phase: Waxing Crescent MoonSunset: 7:08 PM CDT
Dusk: 7:36 PM CDT
Mostly clear. Highs around 80. Lows in the upper 50s.
Sunrise: 6:26 AM CDT
Mostly clear. Highs around 80. Lows in the upper 50s.
Sunrise: 6:27 AM CDT
Partly cloudy with a 20 percent chance of showers and thunderstorms. Lows in the upper 50s. Highs in the mid 70s.
Moon Phase: Waxing Crescent MoonSunset: 7:04 PM CDT
Dusk: 7:32 PM CDT
Partly cloudy with a 20 percent chance of showers and thunderstorms. Lows in the upper 50s. Highs in the mid 70s.
Sunrise: 6:28 AM CDT
Moon Phase: The phases of the Moon are related to (actually, caused by) the relative positions of the Moon and Sun in the sky. For example, New Moon occurs when the Sun and Moon are quite close together in the sky. Full Moon occurs when the Sun and Moon are at nearly opposite positions in the sky - which is why a Full Moon rises about the time of sunset, and sets about the time of sunrise, for most places on Earth.
New Moon: The Moons unilluminated side is facing the Earth. The Moon is not visible (except during a solar eclipse). New Moon follows waning crescent, beginning a repetition of the complete phase cycle of 29.5 days average duration. The time in days counted from the time of New Moon is called the Moons "age". Each complete cycle of phases is called a "lunation".
Twilight: Also known as "Dawn" preceding Sunrise and "Dusk" following Sunset. There are three kinds of twilight defined: civil twilight, nautical twilight, and astronomical twilight. For computational purposes, civil twilight begins before sunrise and ends after sunset when the geometric zenith distance of the center of the Sun is 96 degrees - 6 degrees below a horizontal plane. The corresponding solar zenith distances for nautical and astronomical twilight are 102 and 108 degrees, respectively. That is, at the dark limit of nautical twilight, the center of the Sun is geometrically 12 degrees below a horizontal plane; and at the dark limit of astronomical twilight, the center of the Sun is geometrically 18 degrees below a horizontal plane.
Sunrise and sunset: For computational purposes, sunrise or sunset is defined to occur when the geometric zenith distance of center of the Sun is 90.8333 degrees. That is, the center of the Sun is geometrically 50 arcminutes below a horizontal plane. For an observer at sea level with a level, unobstructed horizon, under average atmospheric conditions, the upper limb of the Sun will then appear to be tangent to the horizon. The 50-arcminute geometric depression of the Sun's center used for the computations is obtained by adding the average apparent radius of the Sun (16 arcminutes) to the average amount of atmospheric refraction at the horizon (34 arcminutes).
Accuracy of rise/set computations: The times of rise and set phenomena cannot be precisely computed, because, in practice, the actual times depend on unpredictable atmospheric conditions that affect the amount of refraction at the horizon. Thus, even under ideal conditions (e.g., a clear sky at sea) the times computed for rise or set may be in error by a minute or more. Local topography (e.g., mountains on the horizon) and the height of the observer can affect the times of rise or set even more. It is not practical to attempt to include such effects in routine rise/set computations.