Thursday, February 23, 2012

The Spada Lake Anomaly

There is a precipitation anomaly around here that is rarely discussed.
In many ways, it is the anti-Sequim, anti-rainshadow.
A place of extraordinary precipitation near Puget Sound.

I am talking about the Spada Lake anomaly.

Spada Lake
 Let us begin by talking about the mountain foothills, east and northeast of Everett, much of it in the Sultan River watershed.  On the map below,  Spada Lake is labeled and the red A is at Verlot.

Spada Lake is circled
During the 48 hrs ending Wednesday at 8 AM, Spada Lake got over TEN inches of rain (10.47 inches)--no other regional station was close.  On average, the surrounding Sultan River basin gets about 165 inches a year--almost identical to the Olympic Peninsula Hoh rain forest!  And consider the typical annual precipitation of nearby locations on the Mountain Loop Highway:

Verlot Ranger Station (elevation 980 ft):  135.5 inches
Big Four Ice Caves (elevation 1750 ft):  142.5 inches

Here are some gee-whiz numbers for Spada Lake precipitation:
Peak annual - 224 inches (1990-91)
Highest Month – 51 inches (November, 1990)
Wettest Day – 13 inches  (November 11, 1990)

Folks, this is a REALLY wet place.  In contrast, nearby Everett, gets only about 37 inches a year.  The city of Everett has a reservoir there and let me assure you, they don't have a problem of lack of water.  And will not have one under any imaginable circumstance.  Official precipitation maps (see below) suggest the effect (although this map has its issue).
A wet region extends from Spada Lake up through Verlot and beyond to Mt. Baker.  Why?  Take a look at the larger terrain map of the region (below)    You notice the Cascades takes a cant to the left from Everett northward.   Strong southerly to southwesterly flow, which is very prevalent around here in winter, moves up Puget Sound and then slams into this blocking terrain.   This forces the air to rise, which leads to clouds and precipitation.  Mount Baker enjoys some of this effect, and that explains why it holds the record for more annual snowfall of any location in the world.  As in real estate, location is everything.


 Although the winds were westerly and northwesterly at higher levels, southwesterly winds WERE observed during that period.   To illustrate this, here are the winds from the Seattle profiler during 24-h of the events:

 PS:  For the lowland snow lovers in the crowd, there appears to be an enhanced chance of some light snow in some lowland locations on Sunday.....more on that tomorrow.  No big storm though. And the long-term pattern is excellent for mountain snows... classic La Nina year late season snowfall!  Don't put your skis away!

16 comments:

Lance said...

Would the Chuckanut Mtn terrain south of Bellingham create a mini rain shadow effect for Bellingham when the onshore flow is southwesterly? Interesting to ponder!

blackcap said...

I have learned from experience to not go hiking in that part of the Cascades if the weather is even the least bit showery in the lowlands, unless for some reason I am desiring to hike in a continual downpour.

Matt_Jeglum said...

I don't know if you trust this precip gauge, but Olallie Meadows SNOTEL reported 10.1 inches over the same time frame.

Matt_Jeglum said...

Oops, forgot to include that that is SWE increase, not actual precip in the rain gauge!

chrisale said...

We have a similar place up here on Vancouver Island called Henderson Lake near Kildonan on the Alberni Inlet.


It holds, last I checked, the record in Canada for rainiest place.



Greatest precipitation in one year. 9,479 mm (373inches or 31ft) (1997)

Greatest average annual precipitation. 6,655 (262in or 21ft)

It has a similar geographical situation as Spada Lake being the first hit as systems come off the Pacific and slam into the prickly spine of Vancouver Island.
(map on first link above)

Dan McShane said...

The Mount Baker weather station is on the north side of a ridge. If some one want to break the record a new station on the soutwest slope of baker would have a great shot.

Ellen Henderson said...

Your blog is bookmarked on my computer. Love your skill and commentary.

From my west-facing deck in Lake City at sunset last night (gorgeous!) I saw three layers of clouds moving in three directions, the highest heading south, the middle going due east and the lowest north west. Is this common? No major weather event last night or today. What gives?

blarsen said...

Cliff, wasn't the heavy rain event over the last few days due to strong NW flow, and not SW flow? How would this explain why Spada Lake got more rain than almost anywhere else?

Drew said...

Cliff - do you know that the RSS and ATOM feeds for your blog are broken? Both stopped updating with the January 30th post.

blarsen said...

If surface flow was SW why was Seattle rain-shadowed so much during this event? Thanks, I love reading your blog!

Ferdi said...

It should also be noted that Spada Lake is in the region of the Puget Sound convergence zone, so probably gets some significant enhanced precipitation from these events too.

olie said...

rss is working with google reader.

Buzz's Marine Life Puget Sound said...

Bathtub Lakes above Spada Lake hold snow longer than any place I know at an altitude of 4,700 ft. In early Sept. 2011 the lakes remained frozen with 6' of last winter's snow still remaining......and this is a south facing slope.

Unknown said...

I have been tracking rainfall and lake levels at Spada for the past several years. For the last couple years I have noticed something interesting. Although the annual rainfall amounts have remained fairly consistent with the ten year averages (2011 was down 5 inches from avarage, 163.8 versus 168.9), when the rain occurs has changed. The traditionally wet months have been getting less rain than the average and the dry month more. Not enough data to make any conclusions at this point, but it has our attention.

Mary Deaton said...

I live in Silverton, on the Mt. Loop Highway. None of the Spada Lake Anomaly surprises me. It distresses me, however, when we get the La Nina later snows just about the time I want to start my garden for the year.

David said...

We live just west of Verlot, on the plateau at the foot of Green Mountain (it's most western slope, essentially the intersectioon of Green Mtn Rd/Mtn Loop Hwy) I've noticed that our micro-climate here is very different from Verlot, which is 2.5 miles from us. We tend to get sun breaks more often and our rain gauge usually records lower amounts than Verlot. I wonder if Mt. Pilchuck is given us a rain shadow effect during the winter. But I also wonder if our elevation (1036') which positions us away from the river (we're essentially at the mouth of the Robe valley and Robe Canyon) affects us in a good way too. Living on the river out here is much colder than living on the southern flank of Green Mtn... Here's us: www.pacapride.com