Another Feast or Famine Summer Unfolds in an Atmosphere of Heat

While severe weather was at bay the majority of the summer; there is still plenty of other things to mention about the Summer of 2018. Again, it was warm with hot spells like so many other summers this new millennium. Feast or famine in the title not only refers to periodicity of the rain but also the resulting amounts. If this summer felt familiar it should, the Summer of 2016 was very similar with it's pattern of heat and erratic rainfall though it was warmer, still.

There is a stark contrast in the summer temperatures again between Detroit; and both Flint and Saginaw and especially White Lake in the northern suburbs (see Statistics Table, below). Detroit's average temperature of 74.4 made it the 6th warmest summer on record in the warmest summer lists. However; this was more as a result of the heat island frequently affecting overnight low temperatures and somewhat less due to the highs. Detroit Metro Airport /DTW/ average highs came in at 83.4 degrees while the normal or average high for the summer is 81.4 degrees therefore; the average high was two degrees above normal. Looking at the average low departure speaks more of the heat island. The normal average low for the summer is an even 62 degrees. The average low for the Summer of  '18 was 65.2 or 3.2 degrees above normal.

Heat Island Micro-Climate

What's even more significant about Detroit's normals is that the temperatures at the Detroit Metro Airport have been contaminated by the sprawling heat island affect since the 1980s. Case in point; the average summer temperature in Detroit in the 1980s (using 1951-80 norms) was just 70.0 degrees as compared to 71.7 now; or +1.7 warmer. The norms at Flint /FNT/ rose just 0.4 of a degree from 68.2 to 68.6 in the same time period. I don't have the exact change at Saginaw /MBS/ but I know when we did an in-house study at DTX years back, it showed little change. I worked at the NWS/DTW from the 1970s thru mid 1990s and witnessed the change in the airport's micro - climate and it's gradual temperature rise. My co-worker at the time, Dennis Dixon did an in-house study on the local heat island beginning in the 1980s at DTW.  Later, the new runways with the McNamara development in 2002, has  likely only added to the problem.  New normals for our present period (1991-2020) should be processed in the early 2020's. One guess as to what they'll show with temperature norms?

Summer's, What It's All About...
 
                                                                                Chart - 1

Perhaps no place is the heat island at Detroit Metro Airport become more apparent than in the temperature records - take for example the warmest summer records. Detroit's average temperature of 74.4 degrees and placed 6th for warmest summer on record. In comparison, Saginaw just managed to squeak out 16th warmest summer and Flint never even placed! In fact, Flint's average at 70.5 was a full degree /1.1/ below the 20th warmest spot for Flint.

                                                                            Chart - 2

Looking back at 21 summer temperature averages at the NWS at White Lake /DTX/ shows that this past summer was in at 6th place (a small sample, indeed with just 21 summers). What stands out the most is the fact that all the rest of warm summers beat out this summer's average by a degree or better.

DTX   Summer ave temp   Year
    1-             70.5               2005
    2-             70.3               2010
    3-             69.5               2011
    4-             69.2               2012
    5-             68.6               2016

 < 6-            66.9               2018

*Updated to add from the NWS Summer Temperature/Rainfall Averages

Feasts or Famine Summer Rains 
The isolated to scattered heavier rains that appeared over the southern areas of Southeast Lower Michigan (including DTW) early in the summer moved north over the northern half of the region in August.  Heavy rains at both Flint and Saginaw more than made up for what had been a dry summer at both locations June and July. In contrast; many southern areas including DTW saw deficits of rain in August. The driest parts of this summer came latter part of June and the first half of July. Rainfall at Detroit Metro while being around normal at that time; did not represent much of the region as evidenced by these rainfall in percent of the mean, maps. The worst of the dry spell came the first part of July; especially across the southern areas of South-central and Southeast Lower Michigan.


                          1                                                           2


The lack of rain during these periods can really be appreciated by looking at Map 2. Most areas saw less that less 1/4" of rain in July through mid month and that time period actually could be extended to June 23rd - July 13th. More general rains and thunderstorms appeared later in the summer. The areas in and around both Flint and Saginaw received 7-8"+ of rain in August. Flint measured 7.69" while Saginaw had 8.02". Both stations posted the 4th wettest August since records began. The surplus of rain; mainly due to convective training rains, shows up well over northern parts of Southeast Lower Michigan in this August departure rainfall map.

*Updated to add from the NWS Summer Temperature/Rainfall Averages

Summer Analogue Performance 

I already surmised the analogues were too cool and is why I went a numerical value of up to 1.5 degrees above normal for the summer.  The average temperature departure across the Southeast Lower Michigan came in at +1.8    (see SE Mich temperature departure in Chart-1) As noted above, what can play havoc with these outlooks can be the heat island at Detroit Metro Arpt.

The best analogue years were 2006 and 2012. Analogue 2006 was a warm and somewhat wet summer like some parts of the region; whereas 2012 was even warmer than 2006 but drier - again like some other parts of the region. Looking further back into the spring; shows 2012 was a warmer spring than this past spring. In fact, Spring of 2012 was the warmest spring on record at all three stations. That year of 2012 recorded 30 annual 90 degree days at Detroit. Thus far this year; Detroit has recorded 25 through Sep 10 2018 and it's still possible to record a few more. So, as you can see both summers, 2006 and 2012 are good candidates for analogues.

Another recent summer, 2016 was not a strong hemispheric analogue as far as ENSO timing but is a good analogue for weather and patterns. That summer the SST's were changing from a El Nino pattern to Neutral; whereas this year's SST's pattern is the reverse; going from a Neutral pattern to El Nino. However; given the SST's were still similar during both summers; the Neutral Summer of 2016 was also another very warm summer and fairly wet across the Upper Midwest and Ohio Valley.

 

SUMMER 2018 ANALOGUES
DETROIT	JUN	JUL	AUG	SUM AVE	SUMMERS	90 DEG DAYS
	T	E	M	P	S
1894	70.7	73.9	69.4	71.0	1	N/A
1899	68.7	71.5	72.2	70.8	2	6
1911	69.5	73.6	70.7	71.3	3	14
1918	66.6	71.1	74.8	70.8	4	15
1951	67.8	72.7	69.5	70.0	1	7
1976	70.6	72.7	70.7	71.3	5	21
1985	62.8	71.3	69.2	67.8	2	3
2000	69.4	70.3	70.8	70.2	3	1*
2001	69.5	73.5	74.1	72.3	6	14
2006	69.3	76.1	72.9	72.8	1	10
2009	67.8	68.9	71.2	69.3	4	4
2012	72.3	79.0	73.0	74.8	2	30*
Ave	68.8	72.9	71.5	71.1	AVE	11
Norm	69.4	73.6	72.0	71.7	NORM	8-12
Dep	-0.6	-0.7	-0.5	-0.6
DETROIT	JUN	JUL	AUG	SUM TOT	SUMMERS	TSTM DAYS
	P	C	P	N
1894	2.63	2.62	0.16	5.41	1	NA/NA
1899	1.82	2.95	0.62	5.39	2	NA/NA
1911	1.48	0.79	1.31	3.58	3	NA/5_9/7_6
1918	3.30	0.74	1.29	5.33	4	NA/5_7/6_8
1951	3.13	4.10	2.99	10.22	1	29/7_8
1976	3.26	1.47	1.68	6.41	5	29/4_7/5
1985	1.62	3.96	4.88	10.46	2	37/7_9
2000	4.90	5.40	4.63	14.93	1	39/6_7/8
2001	3.40	1.16	2.87	7.43	6	33/4_5_8/6
2006	3.95	4.38	2.05	10.38	3	29/7_9
2009	5.27	2.56	2.76	10.59	4	21/5_5
2012	1.31	3.67	2.25	7.23	7	34/7_8
Ave	3.00	2.82	2.29	8.11
Norm	3.52	3.37	3.00	9.89	TSTM	LEGEND
p	-0.52	-0.55	-0.71	-1.78	First #	Annual Total
					Second/Third	Hiest
					#'s	Month_Total
Color	Temps	Degrees	Rain	Inches
Legend:	Below	1.0>	Below	1.00>	NA	Not Avail
	Normal	0.0-1.0	Normal	0.00-1.00
	Above	1.0>	Above	1.00>

_________________________________________________________________

Autumn Analogues  - More of the Same or not?

A weak El Nino is expected to continue to evolve during the fall. Weak El Nino's tend to affect our Autumn weather negligibly, especially if at the forefront of a developing El Nino. A moderate to strong El Nino tends to bring wet, cool falls to the region and luckily it doesn't appear she's is or will advanced that much.

As just discussed above; 2006 and 2012 were our best analogues and while the Summer of 2016 is a good analogue for the Neutral summer; the pattern went off into a La Nina that fall, not El Nino.

Check out the following Autumns of 2006/2012

Temperatures

Precipitation

By the looks of the temperature patterns in 2006/2012; the El Nino's were already affecting the country by Autumn with cooler than average weather extending from the Great Lakes south into the Ohio Valley and Southeast. Precipitation was generally typical for the falls in the Lakes but above in the Ohio Valley.


Autumn 2018

As we progressed into fall a notable cooling engulfed the area - as though Mom Nature read the calendar season change. Extended model guidance basically brings back the more normal to above temperature pattern recently experienced.  The best performing analogues for the summer, especially in regard to temperatures; conflicts with the fall warmer models below.

Comparing the analogue data with the computer data results in both temperature and precipitation conflicts


Check out the Outlook for the Fall by model standards...

Temperatures

One doesn't have to be a climate guru or meteorologist to see the various models keep our normal to above normal temperature regime continuing with the American model the most aggressive for warmth.

Rainfall

There is a discrepancy between the models as far as precipitation for the fall also with the American CFSv2 and British model leaning toward a wetter, mild fall; while the European and France model leans more toward normal precipitation, possibly a bit below. Again, the American model is the most aggressive in chances for the wetter scenario. These wetter solutions would intimate that El Nino begins to exude its influence sooner.

Temperatures & Precipitation For the Autumn

Given the conflicting recent and analogue patterns along with model forecast; 

I look for an average fall with regard to temperatures with normal to above precipitation.

Look for that all important Winter Outlook in early November!

Upcoming Autumn/Early Winter Dates:

Autumn arrives on Saturday Eve, Sep 22nd at 954PM.
Halloween is on Wednesday, October 31st
Thanksgiving is the earliest possible this year: Thursday, Nov 22nd.

Winter arrives on: Friday, Dec 21st at 522PM EST
Christmas is Tuesday; Dec 25th 2018





Making weather fun while we ALL learn,
 Bill Deedler - SEMI_WeatherHistorian

Projected Dry Spell Materialized Across Southeast Lower Michigan

In my Summer Outlook there was a fairly strong signal that our wet year thus far through the spring would dry-out somewhat and sometime during the summer. In the Summer Outlook:


RAINFALL:

"All researched data suggests a normal to below normal rainfall summer. While there were a few moderately wet summers, they were at a minimum. The wettest summer by far was the cool and wet summer of 2000 (No repeat, please)! Most summers indicated at least one dry spell, typical for summers in these parts with the majority of analogue years showing one notable (an inch or more) rain deficit month. This would be a drop from current trends thus far this wet year".

Thus far this July, many areas have seen a 1/4" or less of rain in the last two weeks. The only minor exception has been in the Saginaw Valley to the tip of the Thumb that was brushed with more measurable rain Friday. Detroit Metro Airport has reported only a trace thus far for the month through the 13th.

Perhaps no where is the lack of rain more evident (except for your backyard) than the percentage of normal rain maps.

RAINFALL:

Map 1

Last 30 days

Map 2

Last Two Weeks

Map 1
In the past month, most of Southeast Lower Michigan has accumulated 50% - 75% of its normal rain. That isn't great with most of the rain falling back in mid June with little appreciative rain since then.

Map 2
The lack of rain can be really appreciated looking at Map 2. Most areas have seen less that less 1/4" of rain in July thus far. However; remember that map time-period could be extended and actually encompass the past three weeks from June 23rd - July 13th.

Adding insult to injury; it's been hot this past month with the majority of the time high temperatures averaged 2 - 4 degrees above normal.


TEMPS:

Map 3

While chances of rain are up the next few days (Sat-Mon night) I'm not too excited yet, as our below average rainfall trend may still hold sway.

Seriously though; I'm really hoping we break the dry spell during the second half of July and it makes up for the dry first part. Looking further out this week; if we don't get any appreciable rain the next few days, then rain chances will dwindle back down to zilch the remainder of the work week. The good news though is the cooler and drier air scheduled for Tuesday through most of the week.

Keep the hoses handy.





Making weather fun while we ALL learn,
 Bill Deedler - SEMI_WeatherHistorian

 

Hot - Hot: Give Us All You Got!

THE "GRAND DADDY" OF SOUTHEAST MICHIGAN HEAT WAVES 

                                             July 8th - July 14th, 1936

 (originally written in the late 1990s with update 2013)

Written by: William R. Deedler, Weather Historian 

 

Though heat waves or hot spells generally occur nearly every summer, no heat wave compares in intensity nor in duration than the heat wave that occurred across Southeast Lower Michigan in the summer of 1936. For many of us, it was when our grandparents were in their young or middle-age adult years. Little, if any, exaggeration would accompany their tales of the oppressive heat experienced sixty years ago, back in July 1936.

The last week of June into the first week of July 1936 was quite variable with afternoon highs ranging from around 70 to near 90. Evidently, weather patterns were quite progressive. After a day or two of heat build up, a cold front would push through the area and sweep the heat to the south and east on a regular basis. A change in the weather pattern was heralded by a strong but dry warm front that pushed across the area midday on July 6th. Very warm air rushed north into Southeast Lower Michigan, causing the mercury to rise up to near 90 on the 7th, but this was merely a hint of the heat to come.

On the afternoon of the 8th, the temperature soared to just shy of 105 (104.4) degrees and thus, the unprecedented heat was on. For the next seven consecutive days, the mercury would "bubble" above the 100 degree mark (see Table 1). The oppressive heat was compounded by humidity levels generally ranging in the 30s and 40s during the afternoon hours. While those levels are relatively low any other time, when combined with temperatures 100+, the heat index or, how hot it really felt, ranged roughly from 110 to 130 degrees. Little, if any relief was found during the evening hours into midnight with temperatures ranging from the mid and upper 90s at the start (6 to 7 pm) to hovering still in the mid 80s at midnight. For a few hours before dawn, overnight low temperatures "cooled" into the mid 70s. Desert-like conditions were exaggerated by the non-existence of rain. The thirst of the parched land was left un-quenched as not one drop of rain was officially recorded at the Detroit downtown office through the period.

Since this was 1936, the residents of Southeast Lower Michigan did not have the luxury of air conditioned homes, businesses or shopping malls to take refuge from the heat. Most people had to make do with the old standbys such as fans, blocks of ice from the Ice Man (the Ice Man cometh') or maybe by just taking a swim. While other heat waves in Southeast Lower Michigan have lasted longer, none had been longer accompanied by the fierce heat of this one. I was unable to find any documentation of heat related deaths (I'm not sure it was even done at this time), but with this intense of a heat wave, I'm sure there were cases.

The break in this torturous heat wave came without fanfare (storms). Not even a shower was noted in the log. Looking at the observations on the 14th...the wind shifted from the southwest to the northwest and then to the northeast. A lot of the characteristics of a "backdoor" cold front pushing south- southwest out of southern Canada. Occasionally these fronts will come through dry with an abrupt wind shift and falling temperatures. The temperatures fell from 104 at 200 pm...to 85 at 400 pm to a relatively chilly 69 by midnight. The heat wave started with a 104 degree reading on the 8th and ended with the same on the 14th. The first drop of rain was long in coming and not observed until a measly .08 fell on the 23rd.

Table-1 - Summary of the daily highs, lows and resultant means
-------   for July 8th - 14th, 1936 in Detroit, Michigan.
         
           Date          High      Low       Mean
                       
         July  8th       104 *      72        88
                  
         July  9th       102        75        89
                                    
         July 10th       102        77        90 **
                                    
         July 11th       101        77        89 
                                    
         July 12th       100        76        88 
                                    
         July 13th       102        73        88
                                    
         July 14th       104        69        87
                                                        
              *  Second highest all time temp 
              ** Second highest all time mean

Another, very notable heat wave that baked the area for a longer period of time but was not quite as hot, occurred in the late summer of 1953 from August 26th - September 3rd. An eleven day string 90 degrees or better, cooked the area. What's worse, nine of those days were 95 degrees or higher, with two of those hitting the century mark. Those two 100 degree days occurred near the end of the heat wave on September 2nd and 3rd, and with the exception of one other day, were the latest 100 degree days ever reported in Detroit (the latest 100 was also back in the "dust bowl" 1930s, on September 15th, 1939). Still another heat wave, in the Summer of '64, was one day longer (12) than the one in 1953 and has the "honor" of the longest heat wave on record when looking at just consecutive days of 90 degrees or greater. This heat wave extended from July 17th - 28th, 1964. There were no 100 degree days during this period, with the highest temperature being "only" 95.

On a more recent note and better in the memory of Southeast Lower Michiganders, is the hot summer of 1988, when a record amount of 90 degree or better days, 39 to be exact, produced one hot, sultry summer. The previous record was 36 days which again, occurred in "dust bowl 30s" (1934) when also, the hottest temperature of all time, (105 July 24th, 1934), occurred in Detroit. In addition to the record amount of 90 degree days in 1988, we topped the 100 mark 5 times, with the highest at 104 on June 25th. We missed the all time high by just a degree, but for those who remember, a hot, desert-like wind blew across the area that day as dew points dropped into the lower 60s, and humidities fell into the 20s.

That memorable summer of '88 became the seventh hottest summer (Jun-Aug) ever recorded in Detroit with a average of 74.2 (see updated listings below). The fourth hottest summer goes to 1955, with an average of 74.4 degrees. During that hot summer, the month of July set the record for days of 90 degrees or greater in a month with 17. This was the primary reason why July 1955 became second hottest month ever in Detroit, with a average temperature of 79.1. Last July (2012) superseded that temperatures with 79.3 for Detroit's hottest July. We now come to our hottest summers, at least in the last 142 years (1870). The "gold" medals goes to 1995 and again,  just last year in 2012! That's right, just last year during the 3 month summer period (Jun-Aug), Detroit averaged 74.5 degrees helped tremendously by the hottest July. Strangely enough though, back in July 1995 that July didn't even place in the top 10 hottest months. The hot month in the Summer of '95 was August, with an average temperature of 77.1, making it the hottest August on record. June 1995 placed in at the eleventh hottest.

Here is the updated top 7 Hottest/Coldest Summers on record at Detroit, Flint and Saginaw. Several of our recent summers have entered the record books for heat and changed previous rankings, especially at Detroit.

Top 20 Coldest/Warmest Summers in Southeast Lower Michigan
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	66.5	1915	74.8	2012	65.4	1992	74.2	1933	64.8	1915	73.0	1933
2	67.0	1992	74.8	2005	66.1	2009	74.0	1934	65.1	1992	73.0	1931
3	67.3	1927	74.5	1995	66.2	1958	72.7	1936	65.5	1982	72.5	1955
4	67.5	1875	74.5	1955	66.3	1960	72.6	1939	65.8	1945	72.3	1995
5	67.6	1903	74.4	2011	66.5	1969	72.6	1931	65.9	1950	72.1	1930
6	67.8	1985	74.4	2010	66.6	2004	72.6	1921	65.9	1924	72.1	1921
7	67.9	1912	74.2	1988	66.7	1985	72.3	2010	66.1	1985	72.0	2012

---

The Deadly Summer Heat

Written by: Jeff Boyne - National Weather Service La Crosse Wi

 

In a normal summer, about a 175 Americans die as a result of the taxing effect that excessive heat and humidity can have on the body. In a disastrous heat wave of 1980 more than 1,250 people died in St. Louis, Missouri. Just last summer, Chicago experienced its worst weather-related disaster with 465 heat related deaths recorded during the period from July 11-27.

How Heat and Humidity Affects the Body:

The human body gets rid of excessive heat (above 98.6 F) by increasing the rate of the blood circulation. This causes the blood vessels to expand to accommodate the increased flow. The tiny blood capillaries in the upper layers of the skin are also put into operation. By doing this, the blood is able to circulate closer to the skin's surface and the excess heat in the body is able to be dispensed into the cooler atmosphere surrounding the body.

At the same time, water diffuses through the skin from the sweat glands in the form of perspiration. Sweating, by itself, does nothing to cool the body. Evaporation of the perspiration must take place in order for the process of sweating to be of any use. When perspiration evaporates, it takes some of the excess heat away from the body; thus, the body is cooled.

If high humidity accompanies the hot temperatures, the body will have a very hard time cooling itself down, because the perspiration on the skin will not evaporate off of the skin. As a result, the body will continue to try to cool itself down by sweating. This will not only cause the body to lose water, but it will also lose salt. If the body cannot cool itself down or if it loses too much salt, one of the following three heat disorders will result in the table-2 below.

Table-2 3 Types of Heat Disorders
HEAT DISORDER	SYMPTOMS	FIRST AID
Heat Cramps	Painful spasms usually in the muscles of the legs and abdomen. Heavy sweating.	Get the person to a cooler place. If the victim has no other injuries and can tolerate water, give one- glassful every 15 minutes for an hour.
Heat Exhaustion	Heavy sweating, weakness, skin cold, pale and clammy. Pulse thready. Normal temperature possible. Fainting and vomiting.	Get the person out of the heat and and into a cooler place. Have them lie down on their back and elevate their feet with something. Either remove or loosen the victims clothing Cool them by fanning and applying cold packs (putting a cloth between the pack and the victim's skin) or wet towels or sheets. Care for shock. Give the victim one-half glassful of water to drink every 15 minutes, if they can tolerate it. These first aid steps should bring improvement within a half hour.
Heat Stroke	High body temperature (106 F or higher). Hot, dry skin. Rapid and strong pulse. Possible unconsciousness	Heat stroke is a life-threatening situation. Call 911. Get the person out of the heat and into a cooler place. Cool the victim fast. Immerse them in a cool bath, or wrap the wet sheets around their body and fan it. Care for shock by laying the victim on their back and elevate the feet with something Wait for medical help to arrive. Also do not give anything by the mouth.

The most susceptible people to the above heat disorders are the very young, very old, chronically ill, overweight, those who work in hot places, and athletes. Studies indicate that, other things being equal, the severity of heat disorders tends to increase with age. Heat cramps in a 17-year old may be heat exhaustion in someone 40, and heat stroke in a person over 60.

The Heat Index:

This index is used to alert the public how hot it really feels when the Relative Humidity is added to the actual air temperature. These values were devised for shady, light wind conditions.

Table-3 Heat Index (or Apparent Temperature) Chart

Heat Index

		Relative Humidity (%)
		40	45	50	55	60	65	70	75	80	85	90	95	100
A	110	136
i	108	130	137
r	106	124	130	137
	104	119	124	131	137
T	102	114	119	124	130	137
e	100	109	114	118	124	129	136
m	98	105	109	113	117	123	128	134
p	96	101	104	108	112	116	121	126	132
e	94	97	100	103	106	110	114	119	124	129	136
r	92	94	96	99	101	105	108	112	116	121	126	131
a	90	91	93	95	97	100	103	103	109	113	117	122	127	132
t	88	88	89	91	93	95	98	100	103	106	110	113	117	121
u	86	85	87	88	89	91	93	95	97	100	102	105	108	112
r	84	83	84	85	86	88	89	90	92	94	96	98	100	103
e	82	81	82	83	84	84	85	86	88	89	90	91	93	95
(°F)	80	80	80	81	81	82	82	83	84	84	85	86	86	87

With Prolonged Exposure and/or Physical Activity
Extreme Danger	Danger	Extreme Caution	Caution
Heat stroke or sunstroke highly likely	Sunstroke, muscle cramps, and/or heat exhaustion likely	Sunstroke, muscle cramps, and/or heat exhaustion possible	Fatigue possible

*Editor's note: 7/11/13
I wrote the above article in the late 1990s. At the time, 1964 looked to be the longest streak BUT an 89 degree high occurred at DET City Arpt during the hot stretch (checked DET to DTW), In 1964, DET WAS the official site...so it can't be used...DTW Metro Arpt became the official site in April 1966. Funny what a problem a digit can cause (and it WAS 90 at DTW so it was hot anyway)!

The 1953 hot and miserable streak IS the longest heatwave with the Grand Daddy of all Heatwaves in Detroit in 1936 with the hottest and most miserable streak of days above 100 degrees. The all time hottest day at Detroit though was 105 back on July 24th, 1934. Back in the hot summer of 1988 we almost tied that with a 104 on June 25th 1988!

Before I retired, I went over all of Detroit's records and caught a few other mistakes... some back to the 1800s. Detroit's observation site moved several times in its history.

Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian