Tuesday, August 4, 2009

August 4: ORD

Today is August 4th. It's the 216th day of the year. 149 days remain. It's week 31 of the year.

Unless noted, the following data is based upon observations collected by the National Weather Service, Chicago, at O'Hare International Airport (ORD) between November 1978 and last year. ORD has been the official site of record for Chicago since Thursday, January 17, 1980.


According to the National Climatic Data Center (NCDC), the normal high is 83 and the normal low is 64. I've calculated the 30-year averages at 83 and 65.


On the hot side, in 1988 the high was 97 with the record warmest low of 78.
Other 90s highs were 93 in 1980 and 90 in 1984. Another warm low was 76 in 2005. The record high of 100 was set in 1947. 19 of the last 30 highs were 80s. Three highs were in the warmer 90s. Eight highs were in the cooler 70s. For the last 20 years, 1989 to 2008, there have been no highs in the 90s. It did hit 89 three times during this time (1989, 2002 and 2006).

In looking back through the years to the first August at O'Hare in 1959, the following instances were notable: In 19
78 the low was 49, a temperature cooler than the record low. In 1975 the high was 92. In 1971 the high was just 71. In 1970 the high was just 71. In 1966 the high was 81 with a low of 48, a 33 degree spread. That low of 48 was cooler than the record low.

More recently, there w
as a small spread of four degrees in 1998 (72/68).

Last year O'Hare recorded 2.43 inches of rain and Rockford had 1.22 inches. I noted that I hadn't seen lightning as severe as this in a long time. This was at the Crystal Lake train depot parking lot.

On the cool side, there were no days of a mean of at least 11.5 degrees below normal. The coolest low was the record low of 53 in 1992. The record low of 53 was originally set way back in 1894. The coolest highs were 72 degrees (1985, 1992 and 1998). The record coolest high of 62 was set back in 1915. The official thermometer was located near Lake Michigan at the time. 18 of the last 30 lows were 60s. Six lows were in the cooler 50s. Six were in the warmer 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 5:18 and sunrise was at 5:48. Sunset is at 20:09 and twilight ends at 20:40. Tomorrow twilight begins at 5:19 and sunrise is at 5:51. There's a total of 14 hours, 21 minutes of daylight today and 15 hours, 22 minutes between twilights. The moon is waxing gibbous, heading towards the full Sturgeon moon tomorrow. Illumination was 97% at midnight, will be 99% at noon and 99% at midnight tonight. Moonset was at 4:20 this morning. Moonrise is at 19:30 tonight. Moonset is at 5:22 tomorrow morning. Moonlight time is 8 hours, 50 minutes which is 30 minutes longer than yesterday.

My tennis coach, Bob Finder, will be 77 in 15 days. -Bernie-

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