Seattle and Western Washington have the Longest Spring Season in the Nation!

Announcements

Public Talk: Weather Forecasting: From Superstition to Supercomputers

I will be giving a talk on March 16th at 7:30 PM in Kane Hall on the UW campus on the history, science, and technology of weather forecasting as a fundraiser for KPLU. This will be a fun, educational exploration of the amazing story of of weather forecasting's evolution from folk wisdom to a quantitative science using supercomputers. General admission tickets are $25.00, with reserved seating and VIP tickets (including dinner) available at $100 and $ 1000, respectively. If you are interested in purchasing tickets, you can sign up here.
_________________________________

There are many superlatives regarding Northwest weather:  wettest region in the lower-48 states, world record annual snowfall (Baker), foggiest location in the U.S. (Cape Disappointment), and greatest non-tropical windstorm (Columbus Day 1962).   But there is another one that few talk about:  the longest spring in the nation.

Astronomical spring is, of course, the three month period from March 20/21 to June 20/21.  But meteorological/biological spring can greatly differ from astronomical spring.  Here in Seattle,  spring arrives early and leaves late.

I like to tell folks that typically spring begins in western Washington the third week in February (let's say Feb. 25th) and ends in mid-July (local meteorologists like to use July 13th).  Look outside now:  flowers are blooming everywhere, weeds are growing, and the grass is getting longer.   After Feb 25th, the chances of major flooding, low-level snow, and strong windstorms plummet.  And we all know that June is often cloudy and cool and we don't make the real transition to reliable summer weather until mid-July. A spring of 4.5 months.

But let me go further.   Not only are our springs the longest, but we probably have the longest springs in the nation.  Prove it, you say?   OK, let me try to do so.

First, we need an objective measure of spring.  I will propose that spring is the period bracketed by two transitions:

1. the rise in maximum average daily temperatures from below 50F to above 70F
2. the rise in maximum average daily temperatures from below 70F to above 70F

Below 50F you feel cold without a good jacket or sweater, above 70F a tee shirt will do.   Objective measures.

Locations where the daily high temperature never falls below 50F never have real winter and thus never truly have a spring.  As illustrated by the map of maximum January daily temperatures (January is normally the coldest month), there is no real spring in much of California, southern Arizona and Nevada, Texas, and much of the SE U.S.  Average high temperatures, typically rise about 50F each day.  Region's without spring.  Depressing.

Here in Seattle, the average high crosses 50F in late February and rises above 70F on June 23rd. About 4 months. A very gentle rise of temperature from New Years until summer.

In contrast, for Chicago the story is very different.  The rise about 50F occurs on roughly March 17 and the climb above 70F around May 15th.  Two months of spring, half of that enjoyed by Seattle.

New York?    A rise above 50F on March 18th and a climb above 70F around May 20th.   Two months.

Mile-high Denver?  The transition across 50F on March 2 and the rise above 70F on May 15th.  2.5 months.

Portland, Oregon, which is warmer than Seattle?  The rise above 50F on Feb 13th and the climb above 70F on June 1.  3.5 months

I have done this exercise for another two-dozen locations and the answer is the same: 

NO MAJOR CITY IN THE U.S. HAS A LONGER SPRING THAN SEATTLE.

Imagine what the Seattle Chamber of Commerce could do with this information. Ads reveling in Seattle, the Springtime City, or Seattle City of Endless Spring, or Seattle's Eternal Spring.   Almost enough to make you forget about the traffic.

The inquisitive among you might be asking:  why does Seattle have such a long spring?  I believe the answer goes like this:

Seattle's marine climate is dominated by the Pacific Ocean, whose surface temperature even in midwinter only drops to around 50F.   We are isolated from the cold air of the continental interior and our air passed over the warm ocean rather the cool snow-covered interior.  Our average wintertime maxima are relatively high (low to mid 40s) and so when the solar heating starts revving up in February, we quickly climb above the 50F mark.   Thus, our early start to spring.

But the ocean cuts both ways, with the nearly constant 50F coastal waters working against any rapid increase in temperatures, even with the sun strengthening rapidly in March and April.  More continental climates (and that is really most of the U.S.) don't have such an oceanic restraint and warm rapidly.   Furthermore, the extensive low clouds of the eastern Pacific in spring and early summer (think June gloom) slow our warming further.   Only in July, when the building East Pacific ridge causes less onshore flow (as northerly flow increases), does the clouds relent and we surge into summer territory.
.....................

There are other related records that are worth noting, such as the longest spring roll (1428 feet) created in Indonesia.  But in many ways, our spring record is far more impressive and important.

And there has been lots of coverage of places with endless summer, but spring, the season of life and rebirth, is certainly superior.

_____________________________

Announcements

Northwest Weather Workshop

The big local weather gathering is less than a month away (March 4-5, Seattle).  If you are interested in attending, the agenda and registration information can be found here.  This gathering is the place to be if you want to learn more about local weather research and operations.  You MUST register to go.