Does A Cold Spring Mean a Warmer than Normal Summer?

I have gotten a lot of questions and comments about the connection between a colder-than-normal spring and conditions during the summer.

Several folks are convinced that a cold spring means a warm summer, mainly based on what happened last year.  

So let's look at the data and find out!

Let's start by plotting spring (March-May) temperatures over Washington State using the NOAA Climate Division dataset for the past century (through 2022).  Warmer earlier in the period, then cooling in the 1950s-1970s and then warming back to the earlier levels during the past decades.  

I then identified the top ten coolest springs.

Next, I determined the top ten coolest springs and plotted their anomaly (different) from normal (the averages for 1991-2020) temperature for the summer (July through September)-- below.   

The result?  Summer surface air temperatures were substantially cooler than normal after cool springs.

So based on climatology, there is no reason to expect a warmer than normal summer...in fact, just the opposite.

But what about seasonal forecasting models, such as the one run by the European Center?    Below is its forecast for the surface air temperature anomaly from normal for July through August.     Very close to normal conditions are being predicted.


The Canadian seasonal model, which is quite good in general, is similar to the European Center (see below).  Near normal for our region.


In contrast, the American Model (CFSv2), which generally is not as skillful, has this summer warmer than normal by .5 to 2C.

The Bottom Line:

    At this point, there is no strong reason to expect a warmer-than-normal summer here in the Northwest.  Climatologically, cold springs do NOT tend to be followed by warmer than normal summers, if anything it is just the opposite.   The best season models show near-normal temperatures from July through September.

And I can't help but note that our seasonal forecasting skill, particularly for summers, is generally quite poor.  Meteorologists have come a LONG way with short-term weather prediction, but our seasonal prowess is something we need to be very humble about.  😇


Comments

Post a Comment

Popular posts from this blog

The Time of Year You Can See the Air Move

Image
  Most of the time, you can not see the air move.   You can feel it, but the complex, turbulent motions are invisible to you, except when it interacts with leaves and branches on trees and plants. But for a few weeks of the year, the sky is full of small, cotton-like tuffs that like a natural MRI machine reveals the complex three-dimensional motions of the atmosphere.   Cottonwood season.  And we right in the middle of it.   Being cottonwood aware is of particular value this year.  It reveals the active dispersion and movement of air that makes the outdoors essentially COVID safe, and thus should be of some comfort for those nervous about transmission outside. Cottonwood seeds are embedded in small cotton-like fibers.   A million seeds weigh about 3 pounds.  Yes, each seed and tuff weights about .000003 pounds.   And that fact, plus the cottonwood tuff, means that these seeds fall VERY, VERY, VERY slowly.   So slowly that they are excellent markers for the three-dimensional flow of the
Read more

Why so little lightning in the Pacific Northwest? And a very nice weekend ahead.

Image
During the past 24-hours, there have been a few lightning strokes over the region (see below) but nothing to write home about (see below). It turns out that the Pacific Northwest and the remainder of the West Coast have some of the lowest frequencies of thunderstorms in the entire country (see below). But why?    My podcast provides the answer. And I also give the weekend forecast....and I think most will like what I have to say. To listen to my podcast, use the link below or access it through your favorite podcast service. Some major podcast servers:     Like the podcast? Support on Patreon 
Read more

Strong Atmosphere River Heads into British Columbia and Southeast Alaska

Image
While the Northwest has been drier than normal, it has been drenching wet a few hundred miles to the north. An unusually strong atmospheric river ....a long current of moisture stretching southward to the subtropics...has been in place for days, bringing large amounts of water vapor to Alaska.   And the atmospheric river will be in place for several more days, slowly moving southward. To illustrate, the scale and beauty of the atmospheric river, here is a water vapor satellite image for 11 AM today. The lighter areas have more water vapor.  You can see the current of moisture extending from near Hawaii into central BC.  This current is the result of low pressure over the Gulf of Alaska and high pressure offshore of California.   A forecast of total water vapor content in the atmosphere for 11 PM tonight shows a healthy atmospheric river (white and blue colors indicate the higher amounts of moisture). As this atmospheric river slams into the mountainous West Coast, the air is forced to
Read more