Ironically, that turns out to be the same average attained last summer...74.4! But again, a bit of that heat record is accounted for by the warm overnight lows related to the metro heat island around Detroit. This is much more obvious when one looks at Flint and Saginaw who... surprise, surprise...actually had a cooler summer than last summer! That's right, while Detroit tied it's average mean for last summer and placed in fourth place for hottest summer two years in a roll, both Flint and Saginaw actually fell shy of last summer's average temperature! Flint averaged 71.83 / or 71.8/+3.4 rounded/ degrees for this summer, a full half degree /0.5/ cooler than last summer when the temperature averaged 72.3. Saginaw with an average temperature of 71.33 / or 71.3/+2.4 rounded/ this summer, averaged a full 0.7 tenths of a degree cooler than last summer with an average temperature of 72 even. The cooler temperatures at both Flint and Saginaw are especially notable when looking at the hottest summer rankings. Flint's temperature last summer placed in 7th place for hottest while this summer placed in 12th place. Saginaw's data has even more of a notable difference with last summer placing 7th /like Flint/, however this summer placed way down near the bottom of the list at 16th! Averaging all three locations together gives a mean temperature this summer of 72.5 degrees across Southeast Lower Michigan. This is nearly a half degree /0.4/ cooler than last summer when the average came to 72.9!
The question I proposed at the beginning of the blog is thus answered. Basically, over the entire SE Michigan area, it was NOT a hotter summer that last year when the averages and hottest summer placement are looked at (and in the future that is what will be considered first, where the cities placed on the hot summer's list). When all three cities are averaged together, then NO. However, when considering the hot July and 90 degree days across the area it was a hotter summer than last summer!
|Top 20 Coldest/Warmest Summers in Southeast Lower Michigan|
|Rank||Detroit Area*||Flint Bishop**||Saginaw Area***|
*Note: all data is preliminary as official data from NWS is not available as of 9/7/11
There are a number of reasons why this summer seemed as hot or hotter than last summer. The first reason "boils down" (pun intended) to our miserable July this summer. The second reason is the number of 90 degree or better days this summer . The third, which is more debatable, is the cool and wet spring that proceeded this summer.
1-While last summer's July was also hot, averaging 75.0 degrees in Southeast Lower Michigan or close to 3.3 degrees above normal, our most recent July was even worse with an average temperature across the land of 77.4 degrees or about 5.7 degrees above normal! Detroit recorded it's hottest July and month on record this summer while Flint recorded it's third hottest July and third hottest month with 76.8 /+6.2/ degrees. Saginaw recorded its fourth hottest July and fourth hottest month with 76.1 /+4.9/ degrees. Remember too, this is normally our hottest month anyway across Southeast Lower Michigan. When you consider that, it's exceptional that we could muster an average temperature for July of nearly six degrees above normal at Detroit. Standard deviation ranges during the summer months are much narrower (or smaller) than the winter months.
2-The number of 90 degree days this year thus far totals 23 ... as opposed to last years tally of 17 (and our last 90 last year was Sep 21st, 2010). In that bunch of 90 degree days or plus this summer, it would be remiss of me if I did highlight the ungodly heat and humidity on the 2nd when we just about nicked the century mark with a 99 and then, succumbing to it on the 21st with a 100 degree high (and hottest for the summer) at Detroit! July by fall had the largest amount (it usually does) of 90s. A total of fourteen 90 degree or plus days occurred during the month.
As it turned out, the spring temperatures for Southeast Michigan /ave 46.1 just -0.3 below the 46.4 norm/ and well less than a degree below normal being well within the normal range. The number of cool days this past spring were many and many people have commented to me about the “lousy spring”. However, looking at just the average temperature and departures would counter that claim, truly another case where statistics lie as the dominant pattern was cool! None of the three cities even placed in the top 20 coolest springs (tell that to your friends).
Of course the other big problem about the spring weather was it was very wet. Also from the Spring Review:
Spring Rains Were Aplenty
No disagreement here it was wet and the stat’s clearly reflect that! Detroit came in second place for wettest spring on record with 14.60” /1947 was the wettest at 16.31”/ Flint handily smashed its record wet spring with 17.00” even, /the previous wettest spring was in 13.80” in 1945/. And, while it was wet further north in Saginaw, the magnitude wasn’t nearly as great as in Flint nor Detroit. Saginaw received 11.88” which placed further down the list in tenth position.
How does this summer compare to other hot summers in Detroit?
Looking at the charts, one can see that this summer's average temp of 74.4 is a duplicate of last summer and is nearly a duplicate of 1995 and 2005 (2nd/3rd hottest summers at just a tenth higher). So where does the more notable difference show up? This past summer's high temperature /84.1/ averaged over a 1/2 degree warmer than last year (and no one will debate that one). Still, it was far "cooler" that our summer of 1988 when the average high temperature of was 86.2! (editor note: to me and I'm sure many others, the Summer of '88 will long be remembered as the hottest summer in recent memory even though it placed 5th (now 6th) in the hottest summer rankings. That summer saw high temperatures push to 90 or better 39 days with five of those, 100's). No summer since 1988 has even come close! It was only because the overnight low temperatures averaged lower with its "desert-like" atmosphere at times).
The summer of 1995 was the closest to this summer in regards to average highs/lows and number of 90s (there was also a 100 that summer too). The summer of 1955 was a little hotter in average highs (containing 9 more 90s+). It also had one hot July, I made note of this in my July write-up.
Detroit July Ave: 79.3 - Hottest July/month on record
Flint July Ave: 76.8 - Third hottest July/month on record
Saginaw July Ave: 76.1 - Fourth hottest July/month on record
|Rank||Detroit Area*||Flint Bishop**||Saginaw Area***|
By the end of the summer, the three climate stations saw normal to above normal with the entire region seeing around normal, though time-dispensed very unevenly, to locally above normal in the heaviest storm areas.
Summer 2011 /Rainfall/ /Norm/ /Depart/ /Summer 2010/
Detroit 10.76 9.89 +0.87 11.97
Flint 10.84 9.57 +1.27 5.93
Saginaw 10.32 8.94 +1.38 9.21Note the big difference in Flint's rainfall this summer as opposed to last summers.
Severe weather episodes across the region were sporadic in nature with two to four events each month about an average to slightly above average season depending on location. Tornado events were below average with three confirmed in the CWA (see below). Damage from the summer storms was overwhelmingly from straight line winds. August contained four notable events of straight line winds (9th,13th,20th,24th) with numerous power outages most notable occurring across Detroit north suburbs where power remained out locally for up to 5 days. Another stormy area during the entire summer, like last summer, occurred over the southern suburbs of Detroit and the Downriver Communities where heavier rains fell (mentioned above). A confirmed tornado /EF0/ occurred on August 20th near Chesaning in Saginaw County. Another confirmed tornado /EF0/ on July 25th at Sanford in Midland County. A third tornado /EF1/ occurred in Bay County near Willard
back on May 31st. Individual storm events in the DTX CWA can be found here.
June-Aug rainfall maps (courtesy of the Midwest Climate Center)
However in my own defense, I upped the temperatures in my mid-summer update issued 7/13.
I have decided to up my temperature departure for the summer to 1 1/2 to 3 degrees above normal. As far as 90 degree days, I originally went 8-12 days for the entire region. I will also boost that to 11-15 for the Detroit and Flint areas but remain with the original projection for the Saginaw Valley region
While the average temperature departures were in the ballpark in the update, the number of 90 degree days, especially at Detroit and Flint which still too conservative. However, I failed to see any summer outlooks that called for a top ten warmest summer in Southeast Michigan with some even calling for a cool summer ;-). I did, however, zero in and discussed the problematic pattern that I felt would develop for the summer. Years of experience did tell me the ridge, already rearing it ugly head in the south late spring, was going to expand and be a major force to reckon with (but exactly where that would be was yet to be told). This is why I decided against the cool analogues. In addition, the Neutral pattern over the Pacific had little or no influence on the jet stream (there were even some La Nina traits still in the global pattern).
"projections for the upper wind pattern suggest ridging over the south-central part of the country will periodically expand into the Great Lakes bringing more heat into the region. The temperature outlook is a tough call and will mainly depend on the how strong the ridge becomes and its placement. At this time, it looks like the ridge will oscillate from just to our west (Midwest) to the eastern third of the country. This will bring periods of heat and cool downs"