Friday, November 2, 2012

November 1: ORD

Today is November 1st. It's the 306th day of the year. 60 days remain. It's week 44 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. Before that, the official site was at various locations in Chicago going back to Monday, October 16, 1871. 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 56 and the normal low is 38. I've calculated the 34-year averages at 57 and 39.


On the warm side, in 2000 (O'Hare's second warmest November 1st) the high was 73 with a low of 53. A year later, in 2001, the high was 66 with a low of 58 (with 1977, O'Hare's warmest low of the date). In 1990 the high was 73 with a low of 48. In 1982 the high was 67 with a low of 51. In 1999 the high was 73 with a low of 45. Note that all three 70s highs were 73 degrees and these are O'Hare's second warmest highs of the date. These occurred in an 11 year span from 1990 through 2000. The other warm high of 70 degrees occurred in 1971.
The other warm lows were 52 degrees in 1975, 51 degrees in 1985 and 51 degrees in 1998. The record high of 81 degrees was set in 1950 at Midway. The record warmest low of 60 degrees occurred in 1933 at the University of Chicago. 23 of the past 34 highs (68%) were in the: 50s (14) and 60s (9). O'Hare recorded seven consecutive 50s and 60s highs from 1981 through 1987. Eight highs (23%) were in the cool: 30s (1) and 40s (7). Three highs (9%) were in the warm 70s. O'Hare's warmest November 1st was in 1974 as the high was 74 (O'Hare's warmest high of the date) with a low of 54 (O'Hare' second warmest low of the date). The other warm days were in: 1977 (high of 61, low of 58 (with 2001, O'Hare's warmest low of the date)) and 1968 (high of 71, low of 47).  

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 61 with a warm low of 58, only a three degree spread and warm day. In 1976 the low was a cold 26 degrees. In 1975 the high was 59 with a warm low of 52, a seven degree spread. In 1974 the high was 74 with a low of 54, a warm day. In 1972 the high was 51 with a low of 45, a six degree spread. In 1971 the high was a warm 70 with a low of 35, a 35 degree spread. In 1969 the high was 50 with a low of 44, a six degree spread. In 1968 the high was a warm 71 with a low of 47, a warm day. In 1966 the high was a cold 41 degrees. In 1962 the low was a cold 24 degrees. In 1960 the high
was 45 with a low of 40, a five degree spread.

More recently, there were
large spreads of 41 degrees in 1984 (67/26) and 30 degrees last year, in 2011 (65/35). There were small spreads of three degrees in 2004 (51/48), four degrees in 2003 (49/45), five degrees in 1998 (56/51), six degrees in 1992 (48/42), six degrees three years ago, in 2008 (54/48) and seven degrees in 1985 (58/51). 

On the cool side, in 1996 (O'Hare's coolest November 1st) the high was 38 (O'Hare's coolest and only 30s high) with a low of 25. In 2002 (O'Hare's second coolest November 1st) the high was 40 (O'Hare's second coolest high of the date) with a low of 25. Four years later in 2006, the high was 42 with a low of 27 (our most recent 20s low). In 1993 the high was 46 with a low of 23 (O'Hare's coldest low of the date). The other cold lows were 24 degrees in 1962 (O'Hare's second coldest low of the date), 26 degrees in 1976 and 26 degrees in 1984. The record low of 21 degrees was set way back in 1879, at a time when the official readings were taken adjacent to Lake Michigan. The record coolest high of 35 degrees occurred in 1954 at Midway. 23 of the last 34 lows (68%) were in the: 30s (12) and 40s (11). For seven consecutive years, from 1986 through 1992, lows were in the 30s and 40s. Six lows (17%) were in the cold 20s. Five lows (15%) were in the warm 50s. Our most recent 50s low was 58 degrees in 2001. O'Hare recorded two 50s lows from 1982 through 1985 and three 50s lows from 1998 through 2001. O'Hare's other cool high of the date is 41 degrees in 1966.

There's an instance of back-to-back years in which temperatures were just about as opposite as they can be. In 2001 the high was 66 with a low of 58, overall 15 degrees ABOVE normal. Then in 2002 the high was 40 with a low of 25, overall 14.5 degrees BELOW normal.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:58 and sunrise is at 7:27. Sunset is at 17:46 and twilight ends at 18:15. There's a total of 10 hours, 19 minutes of daylight today and 11 hours, 17 minutes between twilights. We lost three minutes of daylight from yesterday. Tomorrow twilight begins at 6:59 and sunrise is at 7:28. The moon is waning gibbous, having passed the full Hunter's moon three days ago at 14:49. Illumination was 95% at midnight, will be 93% at noon and 90% at midnight tonight. Moonset was at 10:02 this morning. Moonrise is at 19:41 tonight. Moonset is at 10:51 tomorrow morning. Moonlight time is 14 hours, 21 minutes which is eight minutes longer than yesterday. Moonlight time is at its peak today and tomorrow.

Warm Fall began September 22nd and runs for 41 days through today, November 1st. High temperatures in this period are usually in the 50s, 60s and 70s. Highs in the 30s and 40s occur infrequently. Standard Time returns in three days. Election Day is in five days.   

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