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FZUS81 KCLE 191839
ICEGL

GREAT LAKES FREEZE-UP OUTLOOK
NATIONAL WEATHER SERVICE CLEVELAND OH
139 PM EST Tue Nov 19 2024


...Great Lakes Ice Season for 2024-2025 Expected to Be Below
Average Ice Cover...

In a summary preface for this 2nd outlook, expect a cool down
overall more towards normal temperatures in the next two weeks, and
perhaps even a bit below normal heading into the end of
November/early December time frame with some freezing temperatures
north. Great Lakes water temperatures overall continue to run
significantly above normal.


As we head through the last half of November and into the first part
of December, forecast future weather patterns for the Great Lakes
region are exhibiting a colder trend compared to what we have seen,
but for this area, that essentially equates to more typical weather
for this time of year. Over the next two weeks, expecting an active
pattern with multiple low pressure systems moving through, the first
of which will occur the middle to the end of this week. An expansive
upper level low pressure system not only brings in colder air along
with some rain/snow potential, but significant wind for all of the
lakes that will allow for more efficient heat removal, which has
been decidedly slow so far this season. Other weather systems moving
through may only affect certain portions of the Great Lakes, so
variability in the weather for each particular lake should be
expected beyond this weekend. A brief warm up is expected early next
week in the southern Great Lakes. Long range model ensembles are
showing Arctic air settling southward into the northern Great Lakes
beyond the middle of next week where we could see our first period
where temperatures do not climb above freezing during the day for
our far northern locations. But the trend overall is for more normal
to slightly below normal temperatures for this time of year, which
will feel quite different given the above normal temperatures
experienced in October and the first half of November.

We remain in neutral El Nino conditions, although it is still
expected to creep into La Nina territory for the winter months, and
a weaker La Nina is expected. Meanwhile, the North American
Oscillation (NAO) is currently in a negative phase and should remain
slightly negative into early December. For the Great Lakes, this
more directly translates to a lack of sustained milder conditions
that we have seen recently, which meshes with the long range model
ensembles. While it is going too far to say that it will be cold,
more normal to slightly below normal temperatures for the region, on
the whole with some natural variability, should prevail.

Taking a broad look at the Great Lakes, average lake-wide surface
water temperatures are 3-6 degrees Fahrenheit above normal for mid
November with Lake Erie and Lake Michigan on the higher end of that
range. Comparing this with averages taken from a database that goes
back to 1995, Lake Erie and Lake Huron are currently the warmest
they have been on the whole since this period of record began. Lake
Superior and Lake Michigan are in the top 3 as it currently stands,
but again, this is a fairly limited database.

We will be watching the system this weekend closely in reference to
the expected windy conditions across the lakes and how much those
surface water temperatures come down heading through next week.

Current surface water temperatures across the Great Lakes have Lake
Superior running the 40s with the coolest waters in the western end.
For Lake Michigan, the northern half is in the lower to mid 50s,
while the southern half has pockets of upper 40s appearing, but
still dominant in the lower to mid 50s as well. Lake Huron currently
sees temperatures in the upper 40s north to the lower to mid 50s
south, and for Lake Erie, low to mid 50s lake-wide. Whitefish Bay is
around 50F, St Mary`s River is currently in the lower to mid
40s, and Lake St. Clair is also around 50F. No significantly colder
water is present in any of the areas that typically respond quicker,
including Duluth Harbor, Green Bay, Big/Little Bay de Noc, the
Straits of Mackinac, Saginaw Bay, or the western third of Lake Erie.
But that may change as we get into early December.

For this issuance, no significant ice formation is expected in the
next two weeks. Skim ice could be possible towards the end of this
two week period in nearshore, shallower areas of the far northern
Great Lakes region after a cold overnight if there is enough
sustained sub-freezing temperatures leading up to it to get the
surface water temperatures down to the mid 30s.


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 air and high winds. Long range
outlooks do not consider the "storminess" factor which can
significantly alter the thermal structure of the lake over short
periods of time.



FREEZING DEGREE DAY ACCUMULATIONS AT SELECTED STATIONS
COMPARED TO NORMAL CALCULATED ON Tue Nov 19:

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

   DULUTH,   MN  NOV   17   10    0
MARQUETTE,   MI  NOV   17    6    0
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



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


$$

Marsalek