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.

HUGE Winter 2014-15 Recap: Reasons for Arctic Cold, Snow, Records

I hesitated to post the final details on this past winter until I was pretty darn certain we were finished with snow. Historically, we have always used April 15th (Tax Day) as this magical, non-scientific date that signifies the demarcation between snow and spring.  If you can make it to the 15th, 99 times out of 100 you're good to go.  This winter worked out great in this regard.


Here are the final winter numbers. See my early March post on the metrics we typically use and why we used them.  Many of these graphics compare this winter to last winter and the COLDEST winter ever (1976-77) in northern Ohio.


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Our winter outlook was created by analyzing the global sea surface temperatures in these regions.

Pacific warm and cool pools have shifted since last winter (2013-14). Yet the result was the same:  COLD EAST, MILDER WEST.

The pressure pattern over the Pacific Ocean and North American continent reflected the sea surface temperature pattern:  This pressure configuration was a strong -EPO, -WPO, +PNA set up. It stood firm all winter which locked in the ridge west and trough east for the most part.

Image courtesy: Larry Cosgrove

Negative EPO favors eastern cold. Eastern US Cold periods circled in red

Positive PNA favors eastern cold. Cold periods circled in blue

-WPO favors eastern cold. Cold periods circled in red

Last summer (2014), talk of a strong El Nino faded as a central based El Nino developed called a "Modoki". These central based weak El Nino come in many different flavors. The current El Nino is circled at the top of the graphic below.

These favor below normal temperatures across the eastern US and above normal temperatures across the west.  Ridge west, trough east. 

Our winter forecast was created with weighting certain years in our analog set. Our forecast matched up very close to the overall average temperatures across the US from December through February.

We started off very cold in November partially driven by the Typhoon in the Pacific. It boosted the Gulf of Alaska low which boosted the ridge of warmth in the west which in turn drove cold south across the eastern US.  I wrote about the Typhoon Rule back in November and how we uses that to forecast the November cold.

Overall temperatures across the continental US on November 18th were the coldest since 1976!

The high of 18 degrees on the 18th was the coldest November day since 1958; 4th coldest high temperature in November since the 1870s.  
 
US temperatures rebounded in December after the cold November. We had one SNOWFALL in December which was under an inch. The 3rd lowest total since 1893; lowest since 1931.

By New Year Day, people were wondering where this cold winter was we had outlined in our outlook back in late October. I kept telling people on Facebook and Twitter to be patient. The cold is coming and when it does, it will harsh and similar to the year before.  Guess what happened in January?  The slow turnaround toward ARCTIC COLD began across the eastern US.

By February, the arctic floodgates had opened across the eastern 1/2 of North America. It was ALL-TIME COLDEST February in Cleveland since weather records began in 1871.

Rome, Ohio in the heart of Ashtabula County, due to cold air drainage down the surrounding terrain had a low of -39 degrees!

As the winds dropped, so did the temperatures. The next day, temperatures jumped 65 degrees in 30 hours!

February 14th through the 20th was 5th coldest 7 day stretch in 145 years in Cleveland coming close to matching the arctic cold of 1994.

Remember back a few winter ago when the ski resorts were having a tough time staying open because of the lack of snow and cold? Look at the winter 2012-13 temperature ranks vs the last two winters.

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Coldest winter since 1977-78

Less days above 40...

More days below freezing

 

Arctic cold and clear/calm skies produced huge ranges of temperature.

 Very cold late season morning lows we haven't seen since the early 1960s!

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 We had much more snow in 2013-14 vs this past winter...hard to believe.  If December snowfall would have been closer to average, the last two winter snow totals would have very close.

Days with snow cover of at least ONE INCH. Last winter we had more.

 Peak Lake Erie Ice Cover and Dates.

End of Winter Right? Not So Fast

Northern Ohio has not had a string of days above 40 degrees similar to what we will enjoy this week since the week of Christmas. That stretch went from December 22nd to December 28th (44, 52, 59, 41, 49, 54 and 47).  While it feels great as it melts off the majority of the snow cover (big piles will stay around a while), the pattern is still ripe for more cool air relative to the averages for this time of year.

To be clear, mid March sun is much stronger than mid January sun.  The average temperature for March 8th is 44 degrees. The average temperature on March 23rd is 50.  So temperatures in the 30s or lower 40s would be considered below average. It's all relative to the season in question. It's not arctic but its not considered spring.

One of the components that we use in formulating longer range outlooks of 8-14 days is the EPO.  Its a measure of the pressure patterns in the eastern Pacific Ocean (EPO region in red boxes---excuse my crude drawing). I also included the WPO which is another favor in evaluating the pressure pattern (further west) over the Pacific Ocean.

This winter (since January), high pressure has settled over Alaska and western Canada/western US while low pressure developed south northern of Hawaii. Notice the trough and cold across the eastern US.  When the EPO is negative, this favors cold and snow east; milder temps and dry west.

The EPO has bounced back positive recently.  The trough in the east and the cold have retreated north as the ridge slid east.

By the 3rd week of March, it will more than likely drop negative again which will strongly favor colder than normal temps in the east again.

I CAUTION EVERYONE. THIS DOES NOT MEAN HIGHS IN THE 10s AND 20s WITH BELOW ZERO TEMPERATURES SIMILAR TO WHAT WE SAW IN FEBRUARY!



Notice how the temperatures spike later this week (dates are on the bottom) then drop below normal starting mid week next week on the graph below. See how temperatures fall but only into the 30s.

The bottom line:  Below normal temperatures around the 20th of March means temperatures below 50 degrees.  So highs in the 30s up through the mid 40s would classify. Not arctic cold but NOT SPRING...yet.

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

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1) AVERAGE 3 MONTH TEMPERATURE RANK SINCE 1871

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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!