Sunday, November 18, 2012

November 11: ORD

Today is November 11th. It's the 316th day of the year. 50 days remain. It's week 46 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. Before this, the official site was on the south side of Chicago at Midway International Airport (MDW), beginning on Wednesday, July 1, 1942. From Friday, January 1, 1926 through Tuesday, June 30, 1942, the official site was at the University of Chicago. Observations taken from October 15, 1870 to October 8, 1871 were lost in the Great Chicago Fire.

According to the National Climatic Data Center (NCDC), the normal high is 51 and the normal low is 35. I've calculated the 34-year averages at 47 and 32.


On the warm side, two years ago, in 2010, the high was 67 (O'Hare's second warmest high of the date) with a low of 46. In 1982 the high was 61 with a low of 49. Another warm high of 65 degrees occurred in 1961 (O'Hare's third warmest high of the date). The record high of 74 degrees was last set in 1964 (at Midway) after originally being set in 1911. The record warmest low of 62 degrees occurred way back in 1882, at a time when the official readings were taken adjacent to Lake Michigan.
23 of the past 34 highs (68%) were in the: 40s (11) and 50s (12). Seven consecutive highs, from 1998 through 2004 were in the 40s and 50s. Three highs (9%) were in the warm 60s. The other 60s high was 60 degrees in 2005. Eight highs (23%) were in the cold 30s. O'Hare's warmest November 11th was in 1964 as the high was 73 (O'Hare's warmest high of the date and only 70s high of the date) with a low of 57 (O'Hare's warmest low of the date). Another warm day was in 1967 (high of 59, low of 50 (O'Hare's second warmest low of the date)).  

In looking back through the years to the first November at O'Hare in 1958, the following instances were notable: in 1977 the high was a cold 39 degrees. In 1976 the high was 33 with a low of 19, a cold day. In 1972 the high was 45 with a low of 41, a four degree spread. In 1969 the high was 49 with a low of 43, a six degree spread. In 1967 the high was 59 with a warm low of 50, a warm day. In 1964 the high was 73 with a low of 57, a warm day and year of the record high of 74 at Midway. In 1961 the high was a warm 65 with a low of 33, a 32 degree spread.


More recently, there were no
large spreads. There were small spreads of four degrees in 1985 (40/36), five degrees in 2002 (41/36), six degrees in 1991 (38/32) and seven degrees in 2006 (41/34).

On the cool side, in 1986 (O'Hare's coolest November 11th) the high was 31 (O'Hare's coolest high of the date) with a low of 20. In 1995 the high was 36 with a low of 17 (O'Hare's coldest low of the date). A year later, in 1996, the high was 32 (O'Hare's second coolest high of the date) with a low of 22. A year after that, in 1997, the high was 33 with a low of 25. In 1979 the high was 40 with a low of 18 (O'Hare's second coldest low of the date). In 1984 the high was 35 with a low of 25. A year earlier, in 1983, the high was 36 with a low of 24. In 2008 the high was 38 with a low of 23. The other cool highs were 38 degrees in 1991 and 39 degrees in 1977. The record low of 15 degrees was set in 1950 at Midway. The record coolest high of 28 degrees occurred way back in 1894, at a time when the official readings were taken adjacent to Lake Michigan. 27 of the last 34 lows (79%) were in the: 20s (10) and 30s (17). There were seven consecutive lows in the 20s and 30s from 1996 through 2002. Two lows (6%) were in the cold 10s (a.k.a. teens). Five lows (15%) were in the warm 40s. O'Hare's second coolest November 11th was in 1976 as the high was 33 with a low of 19 (O'Hare's third coldest low of the date).
 
There was an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 1982 the high was 61 with a low of 49, overall 12 degrees ABOVE normal. Then in 1983 the high was 36 with a low of 24, overall 13 degrees BELOW normal. 

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:10 and sunrise is at 6:39. Sunset is at 16:35 and twilight ends at 17:05. There's a total of 9 hours, 56 minutes of daylight today and 10 hours, 55 minutes between twilights. We lost two minutes of daylight from yesterday. Tomorrow twilight begins at 6:11 and sunrise is at 6:41. The moon is waning crescent, heading towards new in two days at 16:08. Illumination was 10% at midnight, will be 7% at noon and 4% at midnight tonight. Moonrise was at 3:51 this morning. Moonset is at 15:00 this afternoon. Moonrise is at 5:05 tomorrow morning. Moonlight time is 11 hours, 9 minutes which is 37 minutes shorter than yesterday.

Cool Fall began on November 2nd and runs for 29 days through November 30th. High temperatures in this period are usually in the 30s, 40s and 50s. Highs in the 20s, 60s and 70s occur infrequently. Veteran's Day is today. Thanksgiving is in 11 days.

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