April 17: ORD

Today is April 17th. It's the 107th day of the year. 258 days remain. It's week 16 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 58 and the normal low is 38. I've calculated the 32-year averages at 60 and 39.

On the warm side, in 2002 the high was 85 with a low of 65. In 1981 the high was 84 with a low of 59. In 2004 the high was 77 with a low of 51. A year later, in 2005, the high was 76 with a low of 47. Other warm highs were 76 in 1985, 74 in 1988, 70 in 1987, 70 in 2007 and 70 two years ago in 2009. The record high of 88 and record warmest low of 68 were set on the same hot day at Midway in 1976. 29 of the last 32 highs (91%) were in the: 40s (8), 50s (8), 60s (6) and 70s (7). On the warmer side, two highs were in the 80s. On the cold side, one high was in the 30s.

In looking back through the years to the first April at O'Hare in 1959, the following instances were notable: In 1977 the high was 87 with a low of 51, a 36 degree spread and hot day. In 1976 the high was 85 with a low of 67, a hot day. 1976 was the year of the record high and record warmest low. In 1975 the high was a warm 73 with a low of 42, a 31 degree spread. In 1972 the high was a warm 71 with a low of 37, a 34 degree spread. In 1971 the high was a warm 70 degrees. In 1968 the low was a warm 50 degrees. In 1967 the high was a warm 71 degrees. In 1966 the high was 66 with a low of 32, a 34 degree spread. In 1964 the high was 81 with a low of 56, a warm day. In 1963 the high was 75 with a low of 56, a warm day. In 1961 the high was a cold 40 with a low of 33, a seven degree spread and cold day. In 1959 the high was 75 with a low of 57, a warm day.

More recently, we had a small spreads of three degrees in 2000 (42/39), five degrees in 1992 (44/39) and five degrees in 2003 (44/39). There were large spreads of 38 degrees in 1985 (76/38), 38 degrees in 1996 (65/27), 38 degrees in 2009 (70/32), 34 degrees in 2007 (70/36), 32 degrees in 1980 (60/28) and 30 degrees in 1988 (74/44).

On the cold side, in 1983 the high was 36 with a low of 26. In 2001 the high was 46 with a low of 29. Other cold highs were 42 in 2000, 44 in 1984, 44 in 1992, 44 in 2003 and 46 in 1990. The record low of 17 and record coldest high of 26 were set on the same cold day way back in 1875. 25 of the last 32 lows (78%) were in the: 30s (17) and 40s (8). Four lows were in the cold 20s. Three lows were in the warmer: 50s (2) and 60s (1).

Today is a major day in Chicago's snow history. 1961 was the year. Midway had 0.3 inches, the third of three days of 6.8 inches of snow.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:41 and sunrise is at 6:10. Sunset is at 19:37 and twilight ends at 20:06. There's a total of 13 hours, 27 minutes of daylight today and 14 hours, 25 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 5:39 and sunrise is at 6:08. The moon is full tonight as the full Pink (a.k.a. Sprouting Grass, Egg or Fish) moon at 21:44. "Pink" moon refers to the wild ground phlox. Illumination was 99% at midnight, will be 100% at noon and 100% at midnight tonight. Moonset is at 5:27 this morning. Moonrise is at 19:36 this afternoon. Moonset is at 6:03 tomorrow morning. Moonlight time is 9 hours, 51 minutes which is 47 minutes shorter than yesterday.

The warm part of Spring (Warm Spring) began four days ago. Warm Spring runs for 52 days, through June 3. High temperatures in this period are usually in the 50s, 60s and 70s. Warmer 80s and 90s occur infrequently. Palm Sunday is today. Good Friday and Earth Day are in five days. -Bernie-