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. 

Monday, January 04, 2021

How Will January's Weather Play Out?

We've already have a few decent snow events this winter.  The first was on December 1st.  The second was Christmas Eve and Christmas Day, the snowiest Christmas Eve/Day since 1995. The National Weather Service here in Cleveland has a great summary HERE .

Now that we are a few days into January 2021, what does the current pattern tell us?

If you remember back on December 8th on my post, I mentioned the possibility of a GREENLAND BLOCK (red color) which would increase the possibility of cold and snow to finish out December.

MODEL animation from December 8 showing potential Greenland Block

It was too early at that point to say for certain that the mid-late December pattern would be a harbinger of what was to come in January. Now look at the animation below. See how the block (red color) near Greenland is staying in place.  Also see how the western North America ridge (red colors) is starting to develop. This is a bigtime one-two punch: Ridge west (potential block) and a ridge (Greenland block) east.

The jet stream is trending MUCH stronger. Look at the warmer colors across the eastern US. East coast snow lovers will love this!

Top years with similar pattern shows below normal temperatures the 3rd week of January

So after watching the pattern over the last month becoming more persistent, as of this writing (January 4) all this seems to be foreshadowing more cold and deeper southern storm systems!

Some projections are starting to show this idea.

First 2 weeks of January snowfall

3rd week of January snowfall projection

What about the Polar Vortex? Are there indications this become more unstable in the weeks ahead?  Absolutely. 

Look at the surface map over Asia and the large surface high pressure. 

Meteorologist Mike Adcock noted this on Twitter on December 28th:  "Looking at 2100 UTC obs in Mongolia, Tosontsengel is reporting 1089.5 hPa. This station is the record-holder from 2001 (1084.8 hPa). Further, Tsetsen Uul (labelled w/ H) is reporting 1093.5 hPa (32.29"). These, along with other reports, if verified, would break the world record."

This Siberian high pressure ridge is very large. Its been locked in since last month.

Climate specialist Rick Thoman also noticed the abnormally low pressure near the dateline on December 30th: "The GFS is all in for the deepest cyclone in a long time in or near Alaska waters. I've listed the four storms since 1975 that I know of with an analyzed minimum pressure below 930hPa".

The jet stream has been extremely strong off of Asia east into the northern Pacific which probably enhanced the storm above around New Years Eve. Notice the up and down jet across North America.

What does this have to do with the Polar Vortex and the potential for cold for the eastern US?

The super-high pressure center over Mongolia if located just right creates friction along the Mongolian Mountains. This process creates atmospheric waves that propagate into the stratosphere! The mountains change the pathway so that these waves can significantly weaken the stratospheric jet stream. This can cause warming events at the top of the atmosphere called Sudden Stratospheric Warming events. When these occur, its just a matter of time before the "top-of-atmosphere warming" creates a weakening of the jet stream closer to the surface in the northern latitudes along with expansion of cold around the north pole. A weaker polar jet stream means the Polar Vortex can move south easier. 

See how the temperatures have jumped recently in the stratosphere

Also notice how the wind direction made a big directional change

Here is great tutorial on how this all fits together.

It doesn't happen overnight.  Its usually weeks down the road.  

See how the cold reloads across western Canada and then drains into the central US by the 20th?

Expect our chances for MORE wetter snows second half of January!