|The Influence of Lake Michigan|
On West Michigan Weather
In many instances the weather model data does not pick up on or include the
influence of Lake Michigan on the weather in West Michigan. Sometimes there are
differences in the model data. This can create a problem with the accuracy of the
forecast if the influence of the lake is not taken into account. One of the ways it can
make a particular event difficult to forecast for is in snowfall amounts from a lake effect
snow event. The consequences of that is not forecasting enough snow letting the public
know so that they can be prepared for what’s coming i.e. city services, snow plows,
businesses, schools etc.
For the purpose of this paper I will look at West Michigan’s location, aspects of
Lake Michigan and the influence the lake has on the area in different seasons and
different weather situations with different air masses.
West Michigan is located in the Lower Peninsula of Michigan and includes the
major cities of Grand Rapids, Kalamazoo, Battle Creek and Muskegon. The land mass
is made up of farm land, forests and lakeshore sand dunes. Lake Michigan is the
second largest Great Lake by volume with just under 1,180 cubic miles of water. It is the
only Great Lake entirely within the United States. It averages 279 feet in depth and
reaches 925 feet at its deepest point. The Lake is 118 miles wide and 307 miles long
with more than 1,600 miles of shoreline spanning 4 states. Most of the shoreline is
along Michigan and Wisconsin with a very small part along Indiana and Illinois.
The average temperature in West Michigan is influence by Lake Michigan; for
example in the winter with lake effect cloud cover over the region it won’t be as cold as
it would be with a clear sky. The average temperatures are not as cold as other regions
unless there is an arctic air mass effecting the area or daytime heat loss due to clear
skies. In the winter the area can and does experience several days in a row that are
cloudy that helps to keep the temperature from falling as low as it could.
Air masses from other regions are influence by the lake, warm and humid air
from the Gulf of Mexico, cold dry air from the Arctic. Lake Michigan with these different
air masses flowing into and across West Michigan affect the region at different times of
the year during the four seasons, winter, spring, summer and fall.
In the fall and winter when the lake temperature is warmer than the land
temperature and there’s more moisture in the air, the temperature at night will not have
a significant cool down. Because of this you have warmer than normal average low
temperatures during those times of the year when this occurs. In the spring and summer
you have the opposite effect with a colder lake temperature and a warmer land
temperature. A cool wind coming across the colder lake will keep the average high
temperatures below normal.
The weather in each season in West Michigan is influence by Lake Michigan. For
instance, in the summer a tropical air mass from the Gulf of Mexico can cause a
temperature inversion. It occurs when the warm air crosses over the colder Lake
Michigan waters warming the top layers of the water while the bottom layers remain
cool which occasionally traps the cool layer below trapping moisture and airborne
pollutants from rising and being distributed in the air. The result of this is a temperature
inversion which affects the weather with humid conditions in the summer. Increased
summer sunshine warms the water on the lakes surface making it lighter than the colder
water below. The release of the heat stored in the lakes moderates the climate near the
shore in the fall and winter months.
In the spring and fall with alternating air masses moving through rapidly,
variable weather conditions prevail with frequent cloud cover and some thunderstorms.
Also the warmer air and the increase in sunshine in the early spring melt the snow
and lake ice creating a thermal layering of the lakes. Cool conditions are sometimes
prolonged well into April because Lake Michigan is slower to warm than the land keeping
the land area cool. If you’re wondering if Lake Michigan completely ices over it rarely
In an interesting note from the influences of Lake Michigan on West Michigan
weather it will remain cool sometimes well into April. In those years, this delays the
leafing and blossoming of plants which protects plants such as fruit trees from late
frosts. This allows plants from warmer climates to survive in West Michigan and is the
reason for the presence of wine and grape vineyards in the area.
A special wind system may form along the coastline of Lake Michigan on late
spring and summer days when the temperature soars, called a lake breeze.
It forms during the daylight because the lake waters do not warm as quickly as the
surrounding land surfaces. Air cooled by contact with the cold lake waters is denser
than that surrounding the lake and it forms a high pressure cell over the lake. When
the sun heats the land, the air above it warms becoming less dense. Solar heating over
the land produces lower pressure. The pressure gradient between the two pushes
winds inland off the lake, know as lake breeze flow. When the lake breeze forms and
brings the colder lake air onto the land a boundary zone forms between the two air
masses forms called a lake breeze front. A lake breeze front could cause enough
instability to cause convective storms over land, yet another influence of the Lake
Michigan on West Michigan weather.
In the winter arctic air from the northwest is very cold and dry but as it crosses
Lake Michigan is warmed and picks up moisture from the warmer lake and when it
reaches land, the moisture condenses as snow creating heavy snowfalls inland. The
vastness of Lake Michigan is a big influence on the cold air traveling across the
relatively warmer lake waters which evaporates a lot of moisture in the air and with
other processes help to produce lake effect snow. How far the snow goes inland is
determined by the strength of the wind.
Clouds influence the weather greatly and especially in West Michigan with the
influence of Lake Michigan. If you don’t forecast the cloud cover right it can throw off
your high and low temperature forecast.
There is a decrease in cloudiness in the summer because of the cooling and
stabilizing effect of the relatively cool water. This decrease can extend 20 or so miles
inland along the western shore of Lake Michigan.
In the winter however there are significantly more lake effect clouds thus
producing a higher average of cloudy days. These cloudy days impact the temperature
greatly by producing warmer temperatures at night while being cooler during the day.
There have been some studies done on different events and different aspects of
Weather on the Great Lakes such as: Mesoscale Vortices Embedded within a Lake
Effect Shoreline Band, A Climatology of Cold-Season Nonconvective Wind Events in
The Great Lakes Region, Convective structures in a Cold air Outbreak over Lake
Michigan during Lake-ICE and Cold front acceleration over Lake Michigan just to name
The last study about cold front acceleration looked at the impact of Lake Michigan
on a cold Front, which accelerated over the southern part of the Lake. Part of the study
concluded that two primary reasons existed for the increase in speed of the front. One
was “the change in the frontal temperature gradient directly caused by changes in
thermal fluxes compared with those over land.” Secondly, “changes in surface
roughness and near surface thermal stratification that alter the effect of friction.”
In order to accurately forecast the influence of Lake Michigan on West Michigan
weather you must use all the weather tools at your disposal the models ETA, GFS etc.,
soundings, skew-t, upper air data, take into account the lake temperature and BUFKIT
(a forecast profile visualization and analysis tool kit) which is extremely helpful in certain
weather situations. Most important is your experience and weather history of the region
to spot those intangibles you may not pick up from the forecast models.
Lake Michigan has a great influence on West Michigan weather and more studies
need to be done on the lakes influence in certain situations. As far as technology is
concern, more automated weather observation instruments need to placed in the area
and more buoys could be placed in Lake Michigan to pick up these rapid weather
changes to help the accuracy of forecasts.
The challenge for any forecaster is to put his or her experience, the history of
weather in the area, along with the many weather variables and lake influences in
perspective to produce an accurate forecast.
Great Lakes Atlas, Environment Canada and U.S. Environmental Protection Agency 1995
Cold front acceleration over Lake Michigan
William A. Gallus Jr. Moti Segal. Weather and Forecasting: Boston: Oct. 199. Vol. 14, Iss,
5; pg 771, 11 pgs.
Convective Structures in a Cold Air Outbreak over Lake Michigan during Lake-ICE
Suzanne M Aurn-Birkhimer, Ernest M Agee, Zbianiew Sorbian. Journal of the
Atmospherice Sciences. Boston: Jul 2005. Vol. 62, Iss. 7; Part 2 pg. 2414, 19pgs
A Climatology of Cold-Season Nonconvective Wind Events in the Great Lake Region
Matthew C. Lacke, John A. Knox, John D Frye, Alan E. Stewart, et al. Journal of Climate.
Boston: Dec 15, 2007 Vol. 20 Iss. 24; pg. 6012, 9 pgs.
Mescoscale Vortices Embedded within a Lake-Effect Shoreline Band
Joseph A. Grim, Neil F. Laird, David A R. Kristovich, Monthly, Weather Review,
Washington: Sep2004. Vol. 132, Iss. 9; pg. 269, 6 pgs