298
FZUS81 KBUF 151830
ICESL

Saint Lawrence Freeze Up Date Outlook
National Weather Service Buffalo NY
130 PM EST Fri Nov 15 2024

...FREEZE-UP DATE OUTLOOK FOR THE SAINT LAWRENCE RIVER...

The date of the first freeze-up on the Saint Lawrence River near
Massena, NY is forecast to be January 5, 2025.

WATER TEMPERATURES...

Water temperatures have been running well above average across the
eastern basin of Lake Ontario and the Saint Lawrence River through
most of the fall. The water temperature across the Thousand Islands
region is 3 to 5 degrees above average for mid November.

Water Temperatures November 15th:

Alexandria Bay, NY   53F (normal 49F)

LAKE ONTARIO OUTFLOW...

The outflow from Lake Ontario has averaged just under 243,000 CFS
through the second week of November, which near the long term
average for this time of year. Near to slightly above average
outflow from Lake Ontario is expected to continue through the rest
of November.

Above average outflow from Lake Ontario results in faster current in
the Saint Lawrence River, which can delay the onset of shore to
shore ice.

AIR TEMPERATURES...

Temperatures have been mild and above average on the whole through
the fall so far. September through the first few days of October
were consistently above average most of the time, resulting in much
warmer than normal water temperatures heading into mid fall.

October was more of a mixed bag, with an extended period of
temperatures near to below average during the second and third week
of the month. This trend turned around for the last 10 days of the
month, with several stretches of well above average temperatures,
including record warmth on the last two days of the month.

The first half of November has continued the trend of above normal
temperatures, with a half dozen very warm days intermixed with
several slightly below normal days.

November Average Air Temperatures through November 14th:

Watertown, NY   44.5F (3.5F above normal)
Massena, NY     42.3F (3.3F above normal)

FORECAST FOR THE REST OF NOVEMBER...

There is moderate confidence that above normal temperatures will
continue for the rest of November, although positive departures from
normal may be smaller than the past few months as somewhat more
wintry air attempts to become established over the region late this
month. The persistent above normal air temperatures this fall will
continue to support above normal water temperatures leading into
early winter.

A weak La Nina pattern is expected this winter. This pattern may
allow for other, more difficult to predict circulations to have more
influence on the winter pattern across central and eastern North
America. Overall, trends favor a continuation of above normal
temperatures into December, then colder and more typical
temperatures for January and February in the eastern Great Lakes and
Saint Lawrence Valley.

Given the above factors, and the overall trend in later onset of
ice cover over the past 15 years, the first freeze-up on the Saint
Lawrence River near Massena, NY is forecast to be January 5, 2025.
This date is around two weeks later than the long term average.

NOTE: Once the water temperature drops to the mid 30s, ice cover can
develop in just one very cold, calm night.

NOTE: This forecast is for the first shore to shore freeze-up of the
Saint Lawrence River near Massena, NY. The first permanent shore to
shore ice often occurs several weeks later.

$$

Hitchcock