Tuesday, January 12, 2021

Will Lake Erie Freeze Over This Winter?

If you live around the Great Lakes especially downwind in wintertime, you probably experience lake effect snow especially during the first half of winter when the lakes are warmer and free of ice. Here in northern Ohio we live on the southern edge of Lake Erie (warmest and shallowest lake) directly in the lake effect snow firing line.  More ice on Lake Erie reduces lake effect snow potential. So each winter by mid January, the same question pops up: Will the lake freeze?

Photo Courtesy:  Scott Sabol February 2013

Let's see how much ice is on the lake right now (as of January 12). Roughly 0.6% 

(Right after Christmas, we reached 1.2% ice coverage on the 27th of December before it melted off)

Ice coverage is well below normal so far (red line is this winter 2020-2021 through 1/11)

For initial clues on where this year's ice coverage might end up, Great Lakes historical ice coverage data (GLERL) might shed some light. This data goes back to 1973. (I wish it went back further). 

The graph below shows the historical ice coverage through January 8th since the early 1970s. 

How many years have had similar (20% and under) ice coverage at this stage of the winter--January 11th?  24 total since 1973.

Which one of those years ended up with more than 80% or more ice coverage? Only 6:  1985, 1997, 2000, 2004,, 2005 and 2019

In these years ice coverage jumped significantly in just a few weeks!

Why did those years develop ice so quickly?  Look at the temperatures vs normal across the Great Lakes and Ohio Valley between January 11th (low ice coverage) and the day when ice coverage reached at least 80% FOR EACH OF THESE 6 YEARS. 

I tabulated the number of days where the high temperatures in Cleveland stayed at/under 32° and the overnight lows stayed at/under 15°.

The below normal cold wasn't just relegated to Ohio. In each year, the cold was widespread over multiple weeks!

1985: Every day was under 32 degrees. Half of nights under 15 degrees

1997: Half of days under 32 degrees. 10 of 13 nights under 15 degrees

2000: 14 of 18 days under 32 degrees. 11 of 18 nights under 15 degrees

2004: 9 of 15 days under 32 degrees. 10 of 15 nights under 15 degrees

2005: 10 of 14 days under 32 degrees. 8 of 14 nights under 15 degrees

2019: Half of days under 32 degrees. Only 8 of 20 nights under 15 degrees

The Lake Erie water temperatures in these years started out well above freezing between January 11 and January 13. By day 10 (January 23) the water temp had dropped to between 32 and 34 degrees...

...It wasn't until the water temperature dropped under 34 degrees between January 21 and 24 that the ice coverage increased.  The ice coverage jump day to day (see below) was significant beyond day 10 once the water temperature dropped and the cold air temperatures were firmly established.  

*  What are the shortest jumps from 20% to nearly 80% ice coverage?

2/7/1973 to 2/13/1973:    17% to 81% in 6 days
2/6/1995 to 2/11/1995:    16% to 80% in 5 days
1/17/1997 to 1/22/1997:  24% to 77% in 5 days
1/19/2005 to 1/24/2005:  24% to 82% in 5 days
2/4/2013 to 2/10/2013:    20% to 82% in 6 days
2/10/2016 to 2/15/2016:  0.7% to 79% in 5 days

In each of these years (with the exception of 2016), the ice coverage remained at around 80% for 3+ weeks

*  The average ice coverage for specific dates between 2010 and 2020:

January 15:    38%
January 20:    40%
January 31:    46%
February 10:  56%
February 20:  50%
March 1:        49%
March 15:      34%
March 31:      17%

Average dates where ice coverage is highest:  February 13-18th

Historically here is the daily ice coverage for each year in January and February. 

Based on the temperature forecast for the remainder of January and into early February, what are the chances the lake freezes over--80% or more?   Pretty small.

We are entering a 2 week stretch through the end of January with periods of colder than normal temperatures.  Based on what I am seeing, on the higher end I think the ice coverage will be between 40-50% by month's end.  In reality I believe it will verify closer to 25%.

Bottom line, Lake Erie will stay open for lake effect snow business into early February!

The first 10-14 days of February will be key to the rest of the winter Lake Erie ice coverage.