What's The Most Underrated Lake Effect Snow Variable?

The snow event on December 1st makes a great case study on lake effect snowfall.  In many instances, its difficult to separate general synoptic/system snow from actual lake effect as they tend to overlap. I like to classify the events into three phases.  First is system snow. Second--the most tricky of the three--is system snow+lake enhanced snow. Third is only lake effect snow as the storm system moves out.

Lake Erie water temperature was 48 degrees F (9C). 850 mB temperature (5000 feet) was -9C so temperatures difference was around 18 C. You need a temperature difference of at least 13C to create lake effect snow so this was good enough. After checking my lake effect snowfall diary (yes I have one of these. It shows various lake effect snow events back to the 1960s/70s) a basic setup like this could easily create decent snowfall!  Yet Bufkit (NWS forecasting application) showed only conditional instability which meant the ability for the air to rise creating distinct bands of lake effect snow would be on the low end (see the radar loop above).   Hmmm.  

So why did the models, the NWS and other local meteorologists forecast significant snow?

Initial NWS Cleveland forecast

My initial forecast. Snowfall was conservative

I checked the system moisture to see if this was shallow or deep.  Sure enough, it was BOTH! Look at the coverage around the Great Lakes. The moisture depth was up to 10,000 feet. 

The final snow totals were extremely impressive. 20-25" in the snowbelt. 10-15 south and west of Cleveland.

This weekend, we have a few clipper cold fronts passing through.  Each one will produce periods of colder air. 850 mb temperatures (5000 feet) will drop to -9C late Sunday/Monday.  Lake Erie water temp is between 45 and 48 degrees F (7-9C).  Instability per Bufkit (NWS forecasting tool)  will be conditional.  So far it looks very similar to the big event earlier in the week!

So why is this weekend's snowfall forecast so much different than the December 1 event?

Answer is simple:  TOO LITTLE MOISTURE

The overall system moisture is not widespread nor is it deep as Tuesday's storm.  See how the dry air denoted by tan colors is pulled in from the west.

Here is my initial snowfall forecast for December 5-7 and the NWS snowfall forecast.  HUGE difference compared to the snow earlier in the week

In my opinion, one of the most underestimated components in forecasting lake effect snow is moisture.  You can have temperature conditions that are very similar yet the snowfall results can be hugely different. 

So don't forget to check the depth and spatial coverage of the moisture before each snow event. 

First BIG snowfall of the season!

My previous post written before Thanksgiving illustrated the strong possibility of a significant snow. The pattern has been ripe for this type of event. Sometimes the large scale pattern doesn't always translate to a big weather event locally so I'm glad the outlook and subsequent forecast worked out. 

I try to enjoy forecasting success. I'll remind everyone on social media when we get it right.  I also know full well that long range and short range forecast failure will eventually give me a reality check. When that happens I always own it. I find out what I missed or didn't utilize. It's filed away so I can use it as a forecasting tool in the future.)

Here is the entire radar loop showing the widespread snow December 1st and the lake enhancement/lake effect at the end.

The 9.5" at Hopkins Airport was the 12th most single-day snowfall since record keeping began at the airport around 1940 and 15th since 1900. The list below shows Hopkins Airport snow numbers AND the downtown snow numbers which is from ~1890s to roughly 1940.

Here is the entire snowfall total list for northern Ohio

History of Snow Between Thanksgiving and Christmas: Are Our Chances Higher This Year?

In late October, we issued our WINTER WEATHER OUTLOOK for 2020-2021.  The general idea is for a backloaded winter with shorter "teaser" periods of cold and snow in December.  So far (as of this writing before Thanksgiving, we've had under an inch of snow). 

Sledding with my kids when they were much younger!

How much snow do we typically get between Thanksgiving and New Years' Eve? We average around 10" over the last 10 years although the trend for early season snow has dropped over the last 15 years.

How about actual snowfalls?  We average around 4 one-inch snowfalls during the holidays.

Snowfall is one thing. But snow on the ground during the holidays is entirely different. More days with snow on the ground, the better chance we will remember it as a "snowy" holiday. We average around 8 days with snow on the ground over the last 10-15 years. 

As of this writing we are watching for changes in the pattern that strongly show more cold.

* Ridge developing across central Asia

* Jet stream across the North Pacific changing

* More frequent lows across Northern Pacific

All of this is resulting in the high pressure across the western US/North America with low pressure across eastern US. We call this a +PNA pattern (Pacific North American)

The super-long range model output into Christmas week is also strongly hinting at this eastern TROUGH/COLD lasting beyond December 20th. While I think this is probable, my confidence is high ONLY through the first two weeks of the month.

Animation from Thanksgiving to December 21st

Historically we average 15 days with temperatures in the 30s or COLDER over the last 10-15 years. Last winter we had 14 days in the 30s or COLDER before December 31st

Either way, cold and BELOW NORMAL temperatures are coming the first week of December with good chances of accumulating snow along with lake effect multiple times! Winter is coming everyone...

What Period Of Time Had The Most Lake Erie Ice Cover?

Lake Erie ice coverage - Photo Courtesy: Scott Sabol, January 2011

High Resolution Satellite - March 8,2019

It took a while but I finally finished plotting the daily Lake Erie ice coverage for each season since 1972. I separated this into month periods starting with November and ending with May.  This is all color coded. 

• Light blue blocks indicates ice coverage under 1%
• Bright blue is 2% to 10%
• Dark Blue is 11% to 25%
• Purple is 26% to 50%
• Pink is 51% to 74%
• White indicates at least 75% coverage

You'll notice several things here:

1. Significant ice typically doesn't develop until late December.
2. Mid/late 1970s AND the early 2000s stand out as the most significant ice coverage period in  January and early Februar
3. First half of February is typically the peak for ice coverage
4. November 23, 2014 was the earliest ice cover
5. May 17, 1982 was the latest ice cover 

NOVEMBER

DECEMBER

JANUARY

FEBRUARY

MARCH

APRIL

MAY

The entire graphic assembled through winter of 2018-19

Monstrously HUGE Winter Scorecard. It's All Here!

The entire winter scorecard for each winter since the snowiest winter on record (2004-05) in northern Ohio.

I included these parameters:

* AVERAGE TEMPS (DEC-FEB)

* DEC-FEB TEMPERATURE RANKS

* AVERAGE TEMPS VS NORMAL (15 YEAR AVERAGE)

* AVERAGE TEMPS (THANKSGIVING TO MARCH 20)

* LIQUID PRECIP

* DAYS WITH SNOW ON THE GROUND (ONE INCH)

* PERCENTAGE OF TOTAL DAYS (WINTER) WITH ONE INCH

* TOTAL DAYS BETWEEN FIRST AND LAST SNOWFALL

* TOTAL DAYS WITH 3" SNOWFALLS

* MAX 3 DAY SNOWFALL

* MAX ONE DAY SNOWFALL

* SEASONAL SNOW TOTAL

* NUMBER OF DAYS ABOVE NORMAL

* DAYS ABOVE 60

* DAYS ABOVE 40

* NIGHTS BELOW 20

* NIGHTS BELOW ZERO

The scorecard is uploaded in two parts. If you want something else added to this list, let me know.

Recent Seasonal Snowfall Totals - Northern Ohio/Midwest/US - Part II

We start the snowfall retrospective with last winter's (2019-2020) snow totals in northern Ohio.

Last year was the 5th straight year with below normal snowfall. The longest stretch of below normal seasonal snowfall was 9 winters between 1963 to 1972. 

Here are the average snowfall totals for northern Ohio. (Color contours are different than the image above)

How about the last 10 winters?  Here are the local snowfall amounts. Colors might be different year to year.

Last year's running snowfall accumulations really tell the story when compared to other years.  (Hat tip to Jared Rennie for supplying these snowfall graphics below)

CLEVELAND

AKRON-CANTON AIRPORT

MANSFIELD

CHARDON

NORWALK

OBERLIN

Snowfall history since 1900. Black line is the 10 years running average.

Snowfall history since 1940

Snowfall history since 1960

Snowfall history since 2000

Snowfall departures since 2000 (red are years below normal. Blue above normal)

Number of days with at least ONE INCH of snow on the ground each winter

Number of days with at least ONE INCH of snowfall

What are the winter with the MOST/LEAST one inch+ snows?

What are the winters with the MOST/LEAST DAYS with at least 1" snow on the ground?

What has been the snowiest decade in Cleveland?

Ohio, Indiana and portions of Michigan saw below normal snowfall last winter. Yet snow was above normal snowfall across Illinois and the upper midwest.

Notice the high snow numbers across the Upper Peninsula of Michigan.

Overall snowfall departures last winter across midwest/Great Lakes. 

The last 5 winters (2014-15 to 2018-19) snowfall vs normal below. Last time Ohio had above normal snowfall was 2014-15.

How about the rest of the country? US snowfall vs normal over the last 6 winters. Purple is above normal snowfall. Tan/brown colors are below normal. (Thanks goes out to Jared Rennie for the images)  Last image is the winter of 2014-15.

Part III of the 3 part series will highlight Lake Erie Ice History...