Saturday, February 28, 2015

Lions, Lambs and March Weather

There is the old saying that March comes in like a lion and goes out as a lamb.

In other words, March starts out cold and stormy, but by the end of the month the weather has warmed and moderated considerably.

But is that true here in the Northwest?   Is it true anywhere in the U.S.?    This critical question will be answered in this blog.


Since this blog is dedicated to a scientific approach in all matters, we will quantify this issue by devising a LionToLamb (LTL) index at locations around the U.S.  The LTL is the difference between the April and February temperatures at a weather observing site:

LTL= Average April Temperature - Average February Temperature

If April is much warmer than February, the weather is undergoing a substantial lion to lamb transition in March.

So let's examine the evidence.  Here are the LionToLamb numbers for major cities in the U.S. in degrees F.   You will note that very large LionToLamb transitions (greater than 20F) are limited to the Upper Plains and northern Midwest.   For these folks,  the approach of spring is a big deal.

Moderate LionToLamb numbers are evidence over the Northeast the northern portions of the SE U.S. and into the high Plains from Montana into northern Texas.

Where is the LionToLamb transition very weak, so that spring is only evinced by weak, gradual warming?  The answer: the Pacific coastal zone where the index ranges from 6.9F in Seattle to a measly 2.8F in Los Angeles.   Spring is much more noticeable east of the Cascade crest.

Spring is really not a dramatic season west of the Cascade crest as illustrated by a plot of climatological temperatures at Seattle Tacoma Airport (average highs and low shown by red and blue lines).

You can see the problem by looking at the climatological temperatures at about 3000 ft (925 hPa pressure)  for the nearest radiosonde sounding location  to Seattle (Quillayute on the Washington coast).  The black line shows the a average temperatures at this lower-atmospheric level.  No increase until roughly mid-April!  The red and blue lines are the record high and low temperatures at that site for those days.


Contrast this with the temperatures at the same level at Minneapolis (MPX).  Major warming in March.   Lions transform to lambs!


Why don't we have a major Lion to Lamb transition in March along the West Coast?    One major reason is the Pacific Ocean, which greatly moderates our temperatures year round.  Since we never get that cold, we don't get a major warm up when the sun revs up.   In essence, the Pacific acts as a big temperature flywheel.

But there is more.  In Spring, our flow generally transitions from southerly (originating over warmer water to our south) to westerly and northwesterly flow (from colder climes).   This slows down the warming considerably.  

Let me illustrate this.   Here are the average winds near the surface (1000 hPa) in February. Southerly flow over the coastal Northwest, but northwesterly low over the upper plains.
In April the winds over the eastern Pacific are more westerly (and thus passing over colder water), while southerly winds are pushing up into the Midwest.   

The bottom line:   the old saying about March weather goes from a lion to lamb is really not true in western Oregon and Washington, as well as coastal BC and California.   Perhaps we should say that in the Northwest "March comes in as a goat and goes out as a sheep."    Or perhaps  "in July, sun glasses must buy."   Or "in June, beware the gloom."  

I better stick to numerical weather prediction and let others deal with witty aphorisms.

12 comments:

Rod said...

"March comes in as a goat and goes out as a sheep."

Good one, Cliff!

Kevin Pogue said...

Growing up in Kentucky, I was always told that the saying was "IF March comes in like a lion it goes out like a lamb" and "IF March comes in like a lamb it goes out like a lion". I have always attributed the saying to jet stream pattern shifts. If there's a pattern of consistent high pressure over the eastern US in early March, it's possible (probable?) within a few weeks that the pattern will shift and be replaced by an upper level low and consequent incursions of Canadian air (and vice versa).

Westside guy said...

And, looking ahead to next month, in the Pacific Northwest I think it's appropriate to modify the old saw:

"April showers bring May... showers".

Don Atkinson said...

I also remember this proverb the way Kevin states

Christopher Wagner said...

Dear Cliff Mass,
I thank you very much for this blog post, as I have never believed in the lion-to-lamb transition for western Washington, of which I am a native. I like to say, "In like a lion and out like a lioness," because I believe the weather becomes more dramatic at the end of March. This blog uses temperature data to support that March weather is no less dramatic at its end than at its beginning, but I wonder if we also consider amount of precipitation and wind speed whether we can prove an actual lamb-to-lion transition (or lion-to-lioness, if you will).

Respectfully,
Christopher

Rod said...

"In like a lion and out like a lioness,"

Good one, Chistopher.

You must live on the top of Mount Rainier, though, to compare western Washington weather in early March to a lion....woah, Nellie....

freewaydiva said...

This was very silly, yet informative. My favorite! ::grin::

Traveller said...

Temperature is important but what about precipitation, cloud cover vs sun, and wind?

Malderi said...

Cliff,

The midwest also has much larger temperature variations in general, as you stated. So perhaps the thing to look at isn't temperature swing in March, but *percentage* of temperature swing from e.g. January to July that occurs in March?

So, something like:

Apr 1 Temp - March 1 Temp
--------------------------
July 1 Temp - Jan 1 Temp

That'll give you an indication of how much of the spring occurs in March.

Scott said...

In Minnesota we say that March comes in like a crack addict and goes out like an alcoholic. Still really bad, just not as bad.

Bob said...

Sorry for the unrelated comment, but somebody kicked your west-facing webcam over the weekend. That, or the squirrels escaped...

Thanks for the great blog, Dr. Mass!

Karl Bonner said...

March came in like a somewhat "chilly lamb" the first few days due to the cool polar high pressure to our east. Does that mean it will go out like a "warm lion" (i.e. atmospheric river)?