Meanwhile; lets backtrack to an unusually cool summer, the Summer of 1992!
Temperatures during the late Spring of 1992 by all accounts were quite normal across Southeast Lower Michigan. May was generally a pleasant but dry month with temperatures averaging near normal. However, a subtle but definite change was beginning to evolve in the weather pattern late in the month.
After a warm spell occurred mid-May with high temperatures climbing into the mid 80s, a strong cold front raced southeast across the region on the 23rd,bringing with it thunderstorms and much colder weather. The high on the 23rd reached 80 degrees in Detroit and 74 at Flint,but on the 24th,the best the mercury could do was a cool 52 in Detroit and only 49 at Flint. Though the 52 at Detroit was not a record low maximum (that chilly honor belongs to a "high" reading of only 44 in 1925), the 49 degree reading at Flint was, and both were more than 20 degrees below the normal. Both cities did, however, establish record lows the following morning when the temperature skidded down to 35 at Detroit and 30 at Flint. The rest of May remained below normal which brought the monthly averages back to near normal. This turn to sharply colder weather late in the month reflected a temporary shift in the Jet Stream. A strong northwest wind blew from the Arctic southward into the Great Lakes region. When looking back,this temporary shift in the upper wind pattern was a foreboding of things to come during the Summer of '92.
Like its predecessor, the first half of the month of June was similar to the first half of May with a rather dry and benign weather pattern. Temperatures averaged slightly above normal with only minor deviations. Ironically, an abrupt change to much colder weather was heralded in around the official start of summer 11:14 PM on June 20th), between the 19th and 21st. In retrospect, this chilly annunciation of summer was uncannily accurate and most fitting for what would become the second coldest summer ever recorded in Detroit and the coldest at Flint since records began. Just before the arrival of the unseasonably cold air mass, temperatures climbed to what would be one of two 90s in Detroit and the only 90 in Flint that year.
An unusually strong and vigorous cold front was pushed across Southeast Lower Michigan by a massive, cool high pressure system in southern Canada. The temperature change between the 17th and 20th was quite impressive over the region. Detroit and Flint both rose into the lower 90s (Detroit-92, Flint-93 ) on the 17th but on the 20th,the day after frontal passage, readings barely climbed above the 50 degree mark Detroit-52, Flint-51), a forty degree drop! Both of these readings were record low maximums for the date. Low temperatures the next few mornings were in the upper 30s to mid 40s with Detroit establishing a record low of 42 on the 21st and Flint missing its record low by two degrees with a low of 39 on the 22nd. These are normal low temperatures in Southeast Lower Michigan for late April.
June averaged 2.2 degrees below normal at Detroit with a mean temperature of 65.5, while Flint was 1.7 below normal with a mean temperature of 64.2. Had it not been for the above normal temperatures the first half of the month, the monthly temperature departures would have been greater. Like May, June was again on the dry side across Southeast Lower Michigan with about two-thirds the normal rainfall.
The timing of the lousiest weather during the summer could have not been worse,coming right at the time when the summer is usually at its best, July into August.These months are usually heavy tourist and vacation months in the Great Lakes. The month of July was just about a total wash-out, figuratively and literally. Not only was the month abnormally cool, it was extremely wet, especially across the northern suburbs of Detroit into Flint (where it ended up with the honor of being the wettest July ever with 9.35 inches of rain, a hefty 6.54 above the normal). Across the northern suburbs of Detroit, over 7 inches (7.32) fell in Farmington and nearly 7 inches (6.92) was recorded in West Bloomfield. Officially at Detroit Metropolitan Airport, 5.91 was tallied up during the month which was 2.81 above normal. To add insult to injury, when it did rain, many times it was on or near the weekend. Every weekend showed rain falling either on one or both of the days and sometimes it wasn't just a passing shower. Flint measured nearly three inches of rain (2.72) on Saturday the 18th. Then, later in the month at the start of the weekend on Friday, the 31st, another 2.18 inches was dumped on the area. In Detroit, during the 4th of July weekend, a half an inch of rain fell on Saturday. Then on the following Saturday and Sunday (11th-12th), 1.24 inches accumulated, not to mention the 1.04 that fell on Monday, the 13th. In fact, if your vacation fell during that week of the 11th through the 19th, it rained every day but the last with the rain totaling 3.75 inches. It was even worse in Flint, where rainfall measured a whopping 4.70 inches for that vacation week!
The timing of the lousiest weather during the summer could have not been worse,coming right at the time when the summer is usually at its best, July into August.These months are usually heavy tourist and vacation months in the Great Lakes. The month of July was just about a total wash-out, figuratively and literally. Not only was the month abnormally cool, it was extremely wet, especially across the northern suburbs of Detroit into Flint (where it ended up with the honor of being the wettest July ever with 9.35 inches of rain, a hefty 6.54 above the normal). Across the northern suburbs of Detroit, over 7 inches (7.32) fell in Farmington and nearly 7 inches (6.92) was recorded in West Bloomfield. Officially at Detroit Metropolitan Airport, 5.91 was tallied up during the month which was 2.81 above normal. To add insult to injury, when it did rain, many times it was on or near the weekend. Every weekend showed rain falling either on one or both of the days and sometimes it wasn't just a passing shower. Flint measured nearly three inches of rain (2.72) on Saturday the 18th. Then, later in the month at the start of the weekend on Friday, the 31st, another 2.18 inches was dumped on the area. In Detroit, during the 4th of July weekend, a half an inch of rain fell on Saturday. Then on the following Saturday and Sunday (11th-12th), 1.24 inches accumulated, not to mention the 1.04 that fell on Monday, the 13th. In fact, if your vacation fell during that week of the 11th through the 19th, it rained every day but the last with the rain totaling 3.75 inches. It was even worse in Flint, where rainfall measured a whopping 4.70 inches for that vacation week!
July 1992 ended up the second coldest July on record at Detroit since 1870 with a mean temperature of 68.8 (the coldest occurred in 1891 with 67.2). It was the coldest July ever in Flint back to 1942 with a mean temperature of 66.9 (see Chart-1). Also, while it was the 11th wettest July at Detroit, it made the top of the list at Flint with the 9.35 inches that fell. When combining the cool temperatures and heavy rainfall, all of Southeast Lower Michigan experienced the worst weather in July on record. The other 10 wetter Julys in Detroit were not as cool, nor was the coolest July in 1891 a wet one. Interestingly enough, there were no record lows set in either Detroit or Flint. One explanation would be with all the rainfall, cloud cover averaged above normal (over 7 out of 10 tenths coverage for the month) and thus, this would somewhat hold up the overnight low temperatures. While on the subject of cloud cover, sunshine at Detroit averaged at pitiful 49 percent, down significantly from the 68 percent normally enjoyed in July. As would be expected, there were record low maximum temperatures set, two in both Detroit and Flint (see Chart-1). There were no 90 degree temperature days in Southeast Lower Michigan during July, the month that usually has the most with an average of 5.
It remained unseasonably cool right through August across Southeast Lower Michigan,though it did begin to dry up somewhat with normal to below normal rainfall. An average temperature of 66.7, which was 3.8 below normal, made it the 3rd coldest August on record in Detroit. In Flint, the temperature averaged 65.2 degrees which was 3.3 degrees below normal, making it the second coldest August on record. The temperature did manage to top 90 (91) only for the second and last time in Detroit that summer on August 10th, while Flint flirted with, but just missed its second 90 (89) the same day. Both cities only had six days during the month that averaged above normal reflecting a series of cold fronts that routinely pushed through the area. Two more record low maximums were established in Detroit, while one was set at Flint (see Chart-1) but again, no record lows were managed. This may have been very well because of the increase in cloud cover during the summer and thus, limiting the amount of clear mornings.
The cooler than normal weather held into early fall with both Detroit and Flint averaging a degree or two below normal in September. Precipitation again rose to above normal levels with Detroit reporting the 7th wettest September on record with 5.55 inches or rain.
While there were a few theories floating around as to the cause of our unusually cool summer, the most accepted and credited was the eruption of Mt. Pinatubo which occurred exactly one year earlier (June 14-15th, 1991) in the Philippines. The volcanic ash that was spewed into the atmosphere, circumnavigated the globe and caused a slight decrease in solar warming into the following year.
The average temperature for the three month (June-August 1992) summer period in Detroit was 67.0 which was 3.1 below the normal of 70.1 degrees. This made the Summer of 1992 the second coldest on record back to 1870. The coldest was just a half degree colder at 66.5 and occurred way back in 1915. The difference between that summer and the Summer of 92 was June of 1915 was cooler (ave: 63.1) than June of 1992, while July was warmer (ave: 70.4) and August again cooler (ave: 66.0). In Flint, the temperature averaged 65.4 degrees which made it the coldest summer on record back to 1942. Normally the summer temperature averages 68.4 through the three month period (see Chart-1).
C H A R T - 1
Summer of 1992
_________________________________________________________________________________
T E M P E R A T U R E S --- PRECIPITATION
Monthly Average/Depart - Record Low Maximum/ - Record Low/ - Rainfall/
Dates Dates Depart
_________________________________________________________________________________
-MAY DETROIT 58.3 + .2 ----- 35/25th 1.33/ -1.44 FLINT 57.3 + .9 49/24th 30/25th 1.64/ -1.14 --------------------------------------------------------------------------------- -JUNE DETROIT 65.5 - 2.2 52/20th 42/21st 2.35/ -1.08 FLINT 64.2 - 1.7 51/20th 46/28th 2.26/ -.97 --------------------------------------------------------------------------------- -JULY DETROIT 68.8 - 3.1 65/23rd, 65/30th ----- 5.91/ +2.81 FLINT 66.9 - 3.2 64/23rd, 64/30th ----- 9.35/ +6.54 -------------------------------------------------------------------------------- DETROIT 66.7 - 3.8 65/14th, 62/28th ----- 2.50/ +.71 FLINT 65.2 - 3.3 59/28th ----- 3.50/ +.12 -------------------------------------------------------------------------------- -SEPTEMBER DETROIT 61.4 - 1.9 ----- 5.55/ +3.30 FLINT 60.2 - 1.0 ----- * 34/23rd 2.50/ + .15 --------------------------------------------------------------------------------- -SUMMER OF 92 (June - August using 1961-1990 norms) DETROIT 67.0 - 3.1 FLINT 65.4 - 3.0 _________________________________________________________________________________ * superseded in 1995 with 27 degrees
Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian
No comments:
Post a Comment