National Weather Service Weather Forecast Office

Rank	Detroit Area*				Flint Bishop**				Saginaw Area***
	Coldest		Warmest		Coldest		Warmest		Coldest		Warmest
	Temp	Year	Temp	Year	Temp	Year	Temp	Year	Temp	Year	Temp	Year
1	67.1	1891	79.0	1955	64.0	2009	78.0	1921	64.5	2009	77.5	1921
2	67.9	2009	79.0	1921	66.9	1992	77.7	1935	66.2	1992	76.8	1916
3	68.8	1992	77.9	1916	67.3	1967	76.7	1934	67.1	1924	76.2	1935
4	68.9	1967	77.7	1931	67.3	1962	76.5	1955	67.2	1920	76.0	1931
5	69.6	1971	77.1	1988	67.4	1971	76.1	1931	67.3	1945	75.9	1955

 

 

Checking out our coolest summers on record (see: top 10 coldest/warmest Summers on record below, note where we stand as of mid July, temperature- wise at Detroit, Flint and Saginaw). 

 

 “Our selected analogue years do tend to imply a building ridge axis over the center part of the country, shifting from west to east and flattening with some of the more potent cold shots from Canada. Therefore, something’s got to give. While some seasonal weakening of the Canadian trough can be expected, it still should be a competent competitor much of the summer.”

This pattern, in varying degrees, has been the case much of the first half of the summer. The Canadian blocking pattern has dominated, to a large extent, and has resulted in a parade of strong and fairly cold upper low pressure systems dropping southeast into southeast Canada.  Periodically, when the ridge (also mentioned above) has built into the lakes, it has routinely been flatten by the Canadian trough. This has been the main reason why our summer thus far has been so cool. As of mid July, all stations are averaging 2 ½ to nearly 3 degrees below normal.  While it was forecast that our coolest part of summer would come the first half (from the Outlook), what can be expected the remainder of the summer?

“there are still a few trends to watch for this summer; one being the warmest weather (relative to normal) will come mid to late summer (July and/or August). The stubbornness of the trough in Canada along with some of the cold June’s found gives a little more credence to the warmer temperatures mid‐late season. “

Note in the Detroit table below, the June months at all three stations were fairly mixed, However, in not one July did the temperatures average warm enough (>+1.0 degrees) to be placed in the above normal category (all were normal or below). In fact, the average temperature departure overall the analogue July temperatures came in 1.4 degrees below normal. As one can also see in the table below, five summers averaged below normal (better than a degree), eight averaged within a degree of normal and only two averaged above. Moving into August shows more mixed results (like June) but there were still a good number of normal to below. 

 

 

Keeping one eye on our upper air pattern and the other on our analogue Augusts, even if we do warm some, the overall summer should average lower than the normal category (-1.0 to 1.0) used for the analogues.  Simply put, it was expected the warmer second half of the summer would offset some or most of the below normal departure established the first half.  While the forecast of below normal has materialized the first half of the summer, due to the magnitude of the cool weather, the aforementioned tenacity of the upper low (and associated pattern) in Canada and the mixed data of the analogue Augusts, I’m looking for below normal departures to prevail in the neighborhood of one to three degrees for the entire summer in the end.

I feel it’s reasonable to still stick with a warmer second half of the summer over the first as discussed (and, asked at the beginning of the article) so don’t give up and put away the bathing suits just yet. 

On the rainfall front, normal to locally above normal rainfall was forecast and that has played out thus far. It was discussed early-midsummer was expected to be the wettest with dry spells more prevalent mid-late summer. Under wet summer scenarios discussed (especially early-mid summers), the following was written and tagged in the Outlook for this summer.

The upper air pattern seen late spring could easily evolve into one of these patterns as the summer heats up and the trough in Canada holds somewhat tough, somewhere a confluent zone will likely set up. At the same time, a dry or drier spell this summer looks just as likely and there‐in‐lies the problem (between dominant dry summers and less dominant wet). Therefore, and going with the trend seen, rainfall looks to be heaviest early to mid summer with drier weather later.