995
FZUS81 KCLE 200101
ICEGL

GREAT LAKES FREEZE-UP OUTLOOK
NATIONAL WEATHER SERVICE CLEVELAND OH
759 PM EST Wed Nov 19 2025


...Great Lakes Ice Season for 2025-2026 expected to Be Near Average
Ice Cover...


For this 2nd outlook, there are two important aspects of the
forecast to look at. First, the colder period that infiltrated the
Great Lakes a little over a week ago, and the second being an
expected significant pattern change that could result in a colder
period for the end of November and into the first part of December,
resulting in another bout of heat loss from the lakes.

From our colleagues at the Climate Prediction Center, there is
increasing confidence in colder than normal temperatures set for the
north central section of the country that will spread eastward into
the Great Lakes over the next couple of weeks. Per the CPC, this is
a combination of the current weak La Nina phase, the current/future
phases of the Madden-Julian Oscillation, and an event in the upper
portions of the atmosphere called the stratosphere where there is
warming that will be occurring. This stratospheric warming weakens
the tropospheric (the portion of the atmosphere where our sensible
weather occurs and lies below the stratosphere) polar jet stream and
allows colder airmasses to more easily spill southward from the
Arctic. Operational long term models and the ensembles are now
showing signs of this colder pattern coming to fruition just ahead
of the long Thanksgiving weekend. The other aspect of this colder
pattern is that these models/ensembles are indicating that this
could be a prolonged period where these airmasses will be colder
than normal, especially for the northern Great Lakes, well into the
first part of December. Portions of the northern Great Lakes could
be below freezing for a period of time.

Taking a look at the Great Lakes surface water temperatures...as
mentioned earlier, the colder air that affected the Great Lakes a
week and a half ago was effective in removal of heat from the
waters. The lakes went from 2-4 degrees Fahrenheit above normal to
near normal for Lake Erie, and 1-2 degrees Fahrenheit above normal
for Lakes Michigan, Huron, and Superior. For Lake Erie, water
temperatures in the western basin are in the low to mid 40s, while
the central and eastern basins are in the upper 40s to lower 50s.
Lake Huron sits in the upper 40s to around 50F for the southern half
of the lake while the northern half is in the mid 40s. Lake Michigan
remains in the lower 50s for the southern half, and upper 40s for
the northern half. Lake Superior is largely in the mid 40s across
the majority of the lake, with Whitefish Bay in the upper 40s.

There are some significant signs of cooling however. There are
pockets of water temperatures in the 30s in the northern lakes in
some of the smaller bays and inlets across Lake Superior and
northern Lake Huron. Green Bay is also showing nearshore waters in
the 30s in places as well, and also in Little and Big Bay de Noc.
Saginaw Bay is significantly colder than the rest of Lake Huron with
temperatures in the upper 30s to 40F.

With this forecasted colder air arriving late next week, expecting
the water temperatures to drop further, likely erasing the original
thoughts that there could be a delay to overall significant ice
formation for the season, however the remainder of December will
have something to say about this. That said, no significant ice
formation is expected in the next two week period until the next
freeze up outlook comes out in early December, but definitely could
see some minor ice formation occurring in some of the aforementioned
smaller bays and inlets across the northern half of the Great Lakes.
Nearshore/shallow area skim ice cannot be ruled out either where
water temperatures mentioned above are already in the 30s. Open
waters should remain ice-free through the end of the month.


Ice formation is determined by two factors: The amount of heat
stored in the water from the summer and how fast that heat can be
removed by arctic outbreaks of Polar/Arctic air and high winds. Long
range outlooks do not consider the "storminess" factor which can
significantly alter the thermal structure of the lakes over short
periods of time.


FREEZING DEGREE DAY ACCUMULATIONS AT SELECTED STATIONS
COMPARED TO NORMAL CALCULATED ON Tue Nov 18:

LOCATION           DATE   NORMAL CURRENT
----------------------------------------

   DULUTH,   MN  NOV   17   10    5
MARQUETTE,   MI  NOV   17    6   14
SAU_S_MAR,   MI  NOV   17    0    0
 GREENBAY,   WI  NOV   17    0    0
MILWAUKEE,   WI  NOV   17    0    0
  CHICAGO,   IL  NOV   17    0    0
 MUSKEGON,   MI  NOV   17    0    0
   ALPENA,   MI  NOV   17    0    0
  DETROIT,   MI  NOV   17    0    0
   TOLEDO,   OH  NOV   17    0    0
CLEVELAND,   OH  NOV   17    0    0
  BUFFALO,   NY  NOV   17    0    0


NORMAL TEMPS FOR SELECTED LOCATIONS AROUND THE
GREAT LAKES FOR Tue Nov 18

LOCATION     HIGH LOW
----------------------------------------------

    DULUTH,MN  31  18
 MARQUETTE,MI  34  23
  GREENBAY,WI  39  23
 MILWAUKEE,WI  43  30
   CHICAGO,IL  44  29
  MUSKEGON,MI  43  29
    ALPENA,MI  40  25
   DETROIT,MI  45  31
    TOLEDO,OH  45  30
 CLEVELAND,OH  46  33
   BUFFALO,NY  44  32



THE NEXT FREEZE-UP OUTLOOK WILL BE ISSUED IN APPROXIMATELY TWO WEEKS.

$$

Marsalek