It seems you can't look at weather headlines across the US without seeing notable flooding this past year and especially this summer somewhere - with portions of the deep south hit hard. Think it can never happen here; think again! It's been 30 years since a major flood hit much of Central and East-Central Lower Michigan into the Thumb on September 10-12th, 1986. While the Detroit Metro area was not hit hard like the other regions mentioned above and below, September of '86 was very wet across the entire area with it still remaining the
wettest September on record.
Let's take a look back at that Great Flood of 86, one of the earliest articles I originally wrote while employed by the NWS - DTX...
September, being somewhat of a transition month between summer and
fall, generally brings a taming of the summer heat and thunderstorms.
Normal rainfall amounts drop off from the summer maximum and the
weather, more often than not, goes into more of a tranquil period before
the fall storms begin to rage. But this was not the case on September
10-12th, 1986 in Central Lower Michigan into the "Thumb Region" of
Southeast Lower Michigan.
The September 1986 Michigan Flooding was the worst flood disaster in
50 years and would not be exceeded until the August 2014 Metro Detroit
Flood. Total damage was estimated between $400 and $500 million, which
is between $850 million and $1 billion in 2014 dollars . The August 2014
Metro Detroit Flood would eventually exceed the dollar damage with up
to $1.8 billion in flood damage. Of that total, around $120 million
($260 million in 2014 dollars) was crop damage, since the flood came
near harvest time. The entire flood area covered generally a 60 mile
wide band across the central portion of Lower Michigan. The central axis
of the flood area extended from north of Muskegon, near Rothbury, east
across all of Central Lower Michigan to near Port Sanilac, in Southeast
Lower Michigan's "Thumb Region". Some major cities in Southeast Lower
Michigan affected by the flood included Saginaw, Bay City and Midland.
It is interesting to note that the city of Flint actually experienced
more severe flooding in September 1985 than it did in September 1986.
Several estimates about the likelihood of such a flood like the one
in 1986 were tossed about such as a "100 year flood" or a "500 year
flood". But to the people of the flood stricken area it is known as "The
Flood"! A number of rain events plagued this area through September but
the main one occurred September 10-12th, 1986. The flooding rains were
triggered by a nearly stationary front which, like the flood area
itself, stretched east-west across Central Lower Michigan. Warm,
moisture-laden air from the Gulf of Mexico (enhanced by a moisture plume
from remnants of a tropical system over the Eastern Pacific), streamed
north and east out of the Midwest, across the stationary front into
Central Lower Michigan. To the north, cooler, drier air remained
entrenched over Upper Michigan. The upper wind pattern across the Great
Lakes was conducive in holding the surface front nearly in place,
resulting only in a slow drift to the north through the entire period.
This in turn, caused any available moisture pushing north across the
front to be wrung out and dumped persistently over the same general
area.
An extensive area of heavy rain and severe thunderstorms with
torrential rains developed just north of the front and extended west
from Michigan into Wisconsin. As the moisture from the south overran the
front and fell as heavy rain over Central Lower Michigan, it also
traversed the same area from west to east during the two day period.
This process of precipitation developing and repeatedly moving over the
same area is known all too well by meteorologists and hydrologists as
"train-echoing". This was the primary mechanism for the persistent heavy
rainfall during this particular flood event.
The rain began late Tuesday night, September 9th, over West-Central
Lower Michigan and steadily moved east across Central Lower Michigan and
into the "Thumb Region" of Southeast Lower Michigan overnight. Rainfall
during the September 10-12th period over Central Lower Michigan
averaged an incredible 6 to 12 inches, with even isolated reports of up
to 14 inches. Much of this deluge fell in a 12 hour period on the 11th.
The table below has the rainfall amounts for selected observation points
across Southeast Lower Michigan. The September 1986 rainfall ranks as
the
wettest month on record for Saginaw, the 3rd wettest month for Flint and the 11th wettest month for Detroit
City
|
Rainfall from Sept. 10th to 12th 1986
|
Rainfall for September 1986
|
| Midland |
11.78 |
18.35 |
| MBS |
10.09 |
16.16 |
| Saginaw |
10.50 |
16.06 |
| Essexville |
10.67 |
15.86 |
| Caro |
11.51 |
18.16 |
| Millington |
10.15 |
16.24 |
| Cass City |
10.97 |
16.96 |
| Sebewaing |
9.71 |
15.15 |
| Bad Axe |
8.48 |
13.39 |
| Harbor Beach |
8.24 |
14.17 |
| Sandusky |
8.75 |
15.27 |
| Owosso |
3.25 |
10.26 |
| FNT |
3.42 |
10.86 |
| Lapeer |
4.24 |
9.78 |
| Yale |
5.81 |
12.60 |
| Port Huron |
2.84 |
10.26 |
| Pontiac |
1.49 |
6.43 |
| DTW |
1.16 |
7.52 |
The heaviest band of rain over Southeast Lower Michigan for the two
day period extended from the Alma area, east across Saginaw into Vassar.
As a result of these monsoon-like rains, several rivers surged over
their banks and established record heights (see table below).
| River |
Flood Stage
|
Crest (date)
|
(old) Record (date)
|
Tittabawassee
(Midland) |
24
|
33.89 (9/13/1986)
|
29.70 (3/28/1916)
|
Saginaw
(Saginaw) |
17
|
*24.16 (9/15/1986)
|
*24.90 (3/30/1904)
|
Pine
(Alma) |
8
|
12.82 (9/12/1986)
|
10.81 (3/13/1948)
|
Cass
(Vassar) |
14
|
24.82 (9/12/1986)
|
20.80 (3/30/1948)
|
Cass
(Frankenmuth) |
17
|
27.52 (9/12/1986)
|
22.83 (3/6/1976)
|
| * Saginaw River at Saginaw did not establish a new record height |
The Cass River at Vassar with a flood stage of 14 feet rose to an
unprecedented (and almost unbelievable) 24.82 feet, or better than 10
feet above flood stage! This level of nearly 25 feet is even more
astonishing, when you consider the normal height of the river is about
4.5 feet. Likewise, the Cass River at Frankenmuth rose to around 10 feet
above its flood stage with a 27.52 feet reading (flood stage is 17
feet).
Like many locations in and near rivers and drainage areas, the
flooding in the town of Vassar was a nightmare! It was definitely one of
the hardest hit areas with all the downtown businesses and about 50
homes being flooded. The flood waters reached to the intersection of
Main and Huron St. on the northwest side of the Cass River and extended
to the intersection of Huron and East St. on the southeast side. The
river rose so quickly and forcefully, that some people barely had enough
time to get out. Several people awoke in Vassar to find their streets
and cars covered in rushing water as the raging river surrounded their
homes and businesses. But further downriver on the Cass, at Frankenmuth,
vigorous sand bagging on top of permanent levees protected the downtown
area from any serious flooding.
Several people lost their lives either directly or indirectly due to
the flood. Looking through newspaper articles and related storm reports,
at least 10 people died. The body of a hunter was found on the bank of
the Muskegon River, a woman who drove her car off a flooded road into
the Cass river, two children playing near flooded streams were swept
away, two more people drowned while in boats, falling overboard; and
another two men were electrocuted while using sump pumps in flooded
rooms. Sadly, the flood also took its toll on human life in another,
devastating way. Two farmers, after seeing all their crops under water,
committed suicide. Close to 100 people were injured in the flood.
Across Central Lower Michigan, 22 counties were declared disaster
areas. This encompassed nearly 14,000 square miles and where 1.8 million
people lived. Even though damage was estimated between $400 to $500
million (1986 dollars), it hard to put a dollar figure on the huge
amount of personal items these people lost and also, the emotional scars
some still carry with them. To give an idea the volume of water that
fell over Saginaw River basin, it was estimated by the state hydrologist
(at that time) that if that water could be drained into Lake St. Clair,
it would raise its level 10 feet! The Bay City Times, in retrospect,
summed up "The Flood" well by telling their readers to just scan the "D"
listings in the dictionary, "It’s all there, Downpours, Drenching,
Devastation and Disaster"!
Two key elements that contribute to flash flooding are rainfall
intensity and duration. Other factors that play important roles include
soil conditions, topography and ground cover. Flash floods cause more
deaths each year in the United States than lightning, tornadoes or
hurricanes! In the 30 year period ending 2015, averages of 82 people are
killed from flooding. Lightning claims 48 lives per year, tornadoes 70,
and hurricanes 46.
From the NWS DTX:
The National Weather service issues Flash Flood and Flood Warnings when
flash flooding or flooding is occurring or imminent. Remember the
following when you are in a flood situation...
Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian
