How Often Do Conditions Develop To Produce Lake Effect Snow?

One of the many variables to produce lake effect snow is a significant enough difference between the water temperature and the temperature 5000 feet off the ground. Typically you need a difference of at least 13 degrees Celsius. So if the water temperatures is say 50 degrees F (10 Celsius) and the air temperature at 5000 feet is 27 degrees (-3 Celsius) that would be the lowest difference to allow evaporation and eventually the condensation of water vapor to occur as the colder air moves over the warmer lake.  The greater the difference, the faster the air rises and the more unstable the lake effect snow becomes.

This satellite image shows the uniform bands of lake effect cloud cover off every Great Lakes with a strong northwest wind. Notice the lack of cloud cover on the windward (western) side of each lake. The condensation of the water vapor occurs more than 20 miles offshore as the warm water vapor rises into the colder air aloft. 

How often does a difference of 13 degrees Celsius occur in northern Ohio in the prime lake effect snow time of the year?

I cross referenced the Lake Erie water temperature and the temperature at 5000 feet for five straight winters (Nov 2014 through January 2019). Each instance where the difference meets of exceeds 13 degrees Celsius I shaded that day in blue.

We average about four instances where the Lake Erie/5000 foot temperature difference exceeded 13 degrees (high enough for lake effect snow) each winter between 2014 and 2019.  How many of these produced significant snow?  More on that later.

Angry Lake Erie and Unseasonably Cold Temperatures

 

Strong NE winds developed Thursday and Friday which piled up water in the western basin of Lake Erie. Video above is from Kelley's Island Friday courtesy Todd Neu.

Wave heights reached 10-15 feet before they settled down Saturday and Sunday

The low resembled a late fall, cut-off system. You can see how it developed over the upper midwest and then stalled in the southern Great Lakes.

Temperature started out 20+ degrees below normal Saturday morning across the Great Lakes.

High temperatures Saturday stayed in the lower 50s north and upper 50s south. Temperatures this cool (under 55) don't happen very often this late in the year.

Lake Erie Water Temp vs 1998

The water temperature is still at dangerously cold levels. The lake water temperature lags behind the land temperatures a good 60-80 days in spring. Daytime temperatures in the suburbs can reach mid 60s or 70s yet the lake will stay very cold.  Water temperatures usually don't rise into the 60s until early June. Please, be very careful around the lake over the next two months.

We just came off of a big El Nino winter.  Milder temperatures with below normal snowfall. (we can very close to getting dumped on several times with large snowfalls. Those storms headed into New England). Will the lake water temperatures mirror the spring/summer of 1998, the end of the last big El Nino winter?

This graph show the water temperature in mid April as of this writing on the left.  The right box shows all of the Great Lakes during 1998 (after the last major El Nino).

The water temperature is already slightly above the 25 year average and in line with the April 1998 levels. Assuming we don't have significant runoff from heavy rainfall this spring through mid June along with average to slightly above normal temperatures, water temperatures should stay slightly above normal this summer if your heading to Edgewater or Cedar Point!

Here are the Lake Erie water temperatures in spring of 1998 with 30 year average in parentheses:

May 1:    52  (47)
May 15:  54  (52)
June 1:    64  (57)
June 15:  67  (62)
July 1:     71  (68)
July 15:   77  (72)(
July 21-23:  79 (Highest)  (73 on the 22nd)
August 1:    77  (74)
August 15:   77  (74)
September 1:   77  (73)
September 15:   73 (71)
September 30:   71  (67)

How Historic Is This April Cold? April Snow?

There is little sign that this cold April will end anytime soon.  The cold air this weekend will be similar to last weekend. In fact, the 850mB (5000 ft) temps over Lake Erie, the key component for determining lake effect snow amounts, might crack the top 5 coldest ever for the month of April since 1950!   Here is the list per the NWS

 Both the GFS and the European show pretty much the same amount of cold as of this writing.

The pattern shows some signs of moderation across the eastern US but not until at least the midway point of the month. Another wave of colder air will follow this weekend's cold by the middle of next week.

The lack of snowfall this winter is almost historic. So far, our season snow total is the lowest since the winter of 1931-32.

April snowfall of at least one inch happens roughly 50% of the time. Here is a look at the percentage of seasonal snowfall in April.  This past weekend's snowfall brings this year's percentage up to 5%. Expect snow chances to climb with each burst of colder air through the middle of the month.

Where Does This Winter Cold/Snow Rank All-time in Cleveland?

Frozen Tundra covering Lake Erie

The meteorological months of winter are December, January and February. The snow cover across northern Ohio is very deep after the recent snowfall. This endless blanket of the white stuff makes this definition seem, at the very least, misleading and pretty pointless to many of us who still have snow piled up high. When we do meteorological comparisons to past seasons, the three month periods nearest to the season in question is used by climatologists. For example, December through February are the winter months. March through May are spring months and so on.


So how does this winter compare to last winter (colder than average), two winters ago (milder than average) and the coldest winter ever (1976-77) in northern Ohio?  I'll use the same metrics for comparison I've used in the past:   

Average 3 month temperature rank all-time (December through February) since 1871
Seasonal Snowfall
Below zero nights
Days at or above 40
Days at or below 32
Consecutive days with at least one inch of snow cover
Total days with snow cover of at least one inch
Total days with snow cover of at least six inches

Monthly temperature ranks

==============================================================

1) AVERAGE 3 MONTH TEMPERATURE RANK SINCE 1871

Add caption

SIDE NOTES: 

* The only winters that were colder in the last 50 years were:  1976-77, 1977-78 and 1969-70

*  The average temperature from January 1 to February 28th was the 6th coldest EVER, coldest since 1977-78, 4th coldest in the last 100 years, 3rd coldest in the last 50 years

2) Seasonal Snowfall

SIDE NOTE:   

*  This winter's snowfall rank is 14th. Last winter was 9th, Two winters ago was 59th

3) Below Zero Instances

SIDE NOTE:  Only 4 other winters had more temperatures below zero since record keeping began in Cleveland:  1978-79 (14), 1962-63 (16), 1884-85 (19) and 1976-77 (24)

4) Daytime high temperatures at or above 40 degrees

5) Daytime high temperatures at or below 32 degrees

6) Consecutive days with at least one inch of snow cover

 SIDE NOTE: Current stretch now at 40 days as of March 2nd

7)  Total days with snow cover of at least one inch

 SIDE NOTE:  This winter's number of snow cover days is ranked 10th all-time. Last winter was ranked 8th all-time. 

8) Total days with snow cover of at least six inches

9) Monthly temperature ranks since November

Feel free to comment below; any questions always welcome!

Are The Number of Toledo Extreme Rain Events Increasing?

Over the last week, I've read several articles on the increase in extreme rain events as a contributor to the increase in Lake Erie algae bloom frequency.  Here is some rainfall data I compiled for Toledo Metcalf Field. The data goes back to the late 1890s. Instead of using the entire year, I focused on the growing season period from April 1st through September 30th.

A steady increase in one inch rain events since the 1970s. The 1970s and 80s are comparable to earlier decades

The period from 2000 to 2009 wasn't off-the-charts when compared to the 1900s, 1910s or the 1940s. Yet an increase since the 1980s is evident. In the first 4 years (through August 20, 2014) already 17 one inch rainfall events; 3 in 2014 alone.

Several questions come to mind:

1)  Are these rainfall numbers correct?

2)  Is there any record of significant algae blooms in the early 20th century?
If anyone can shed light on any of this, please let me know.