Saturday, August 15, 2015

Deluge

Western Washington was hit very hard by thunderstorms on Friday, with some locations getting as much as 1.5-2.5 inches, while a few Cascade foothills locations were doused with 4-5 inches.  Much of Puget Sound enjoyed over an inch on Friday.  As we will see, even more amazing than the daily totals were the amounts falling in 15 minutes to a half hour.   Even though the ground was very dry, there still was some localized urban flooding, particularly near impenetrable surface like concrete and asphalt (see the picture below near Seattle's University Village).


On a more personal note, I almost met my maker yesterday.   I waited at the UW until the rain started to slow (around 6 PM) and began riding home along the tree-covered Burke Gilman trail.  All of a sudden there was deafening sound behind me (I was about 400 feet south of the location of the picture).   I stopped and could not believe what I saw---a large branch had fallen inches behind me.  If it had hit me, you would not be reading this blog right now.  A person, behind me by about 50 ft, rushed up and told me I missed being hit by the branch by less than a second.  Wow.  Why did it happen?   Loading of the leaves by rain?   The wind had picked up a bit.    Happy to be alive.

Back to precipitation.

On Friday AM a series of thunderstorms started moving in around 3 AM, first on the coast, forced by an approaching upper level trough.  As the trough moved over Puget Sound during the morning, steady and very heavy precipitation moved over most of western Washington.

Here is the NWS radar-based precipitation analysis (shading) with observed values shown as well, for yesterday.  The heaviest rainfall was in a swatch from Olympia to the north Cascades.


Yesterday's lightning strikes followed a similar path.

Yesterday's rainfall totals were stunning.   Here are a few samples:

..KING COUNTY...
1 W WHITE CENTER             2.10 IN   0757 AM 08/15   278 FT               
1 W WHITE CENTER             1.92 IN   0809 AM 08/15   131 FT               
LYNN LAKE                    1.80 IN   0600 AM 08/15   3901 FT              
2 SW ISSAQUAH                1.71 IN   0810 AM 08/15   1378 FT              
3 NE SEATTLE                 1.42 IN   0810 AM 08/15   275 FT               
WHITE CENTER                 1.41 IN   0808 AM 08/15   403 FT               
MEADOWS PASS                 1.40 IN   0600 AM 08/15   3500 FT              
REX RIVER                    1.40 IN   0600 AM 08/15   4000 FT              
6 SSE PALMER                 1.36 IN   0803 AM 08/15   4100 FT              
COUGAR MOUNTAIN              1.30 IN   0600 AM 08/15   3200 FT              
1 NE SEATTLE                 1.29 IN   0804 AM 08/15   26 FT                
3 NW WHITE CENTER            1.24 IN   0810 AM 08/15   305 FT               
2 NE FAIRWOOD                1.24 IN   0801 AM 08/15   584 FT               
1 SSW SHERIDAN BEACH         1.23 IN   0800 AM 08/15   213 FT               
SEATTLE TACOMA  ARPT         1.20 IN   0453 AM 08/15   370 FT               
4 SE VASHON ISLAND           1.18 IN   0700 AM 08/15   0 FT                 
SEATTLE 3.0 WNW              1.18 IN   0700 AM 08/15   0 FT            

..THURSTON COUNTY...
5 S LACEY                    3.37 IN   0809 AM 08/15   229 FT               
OLYMPIA 2.3 ESE              1.36 IN   0600 AM 08/15   0 FT                 
OLYMPIA 1.3 S                1.16 IN   0445 AM 08/15   0 FT                 
2 WSW TUMWATER               1.08 IN   0807 AM 08/15   177 FT 
 
..WHATCOM COUNTY...
21A07 - EASY PASS AM         4.70 IN   0600 AM 08/15   5269 FT              
WELLS CREEK                  4.60 IN   0600 AM 08/15   4200 FT              
ELBOW LAKE                   2.80 IN   0600 AM 08/15   3200 FT              
BROWN TOP                    2.20 IN   0600 AM 08/15   5830 FT              
MARTEN RIDGE                 2.00 IN   0600 AM 08/15   3560 FT              
BEAVER PASS                  1.90 IN   0600 AM 08/15   3620 FT  
At the UW we had some amazing short-term precipitation amounts:
 
Peak 5 min amount: 0.23 inches ending 13:58 PDT 
Peak 10 min amount: 0.38 inches ending 14:02 PDT 
Peak 15 min amount: 0.51 inches ending 14:07 PDT 

A half-inch in 15 minutes is very heavy rain around here. The most extreme report was at South Lake Union (Weather Underground KWASEATT4190

This station received 3.24 inches over the day and had 1.43 inches during the 15 minutes ending 14:16 PDT. Here is the picture of their site:



Could they have gotten water splashing off a nearby roof? Was there localized flooding around south Lake Union?

Most areas around Puget Sound, based on one day's rainfall, have exceeded their normal August rainfall.  For a number of sites, this one event has erased HALF of the precipitation deficit of the entire summer.   There was roughly an inch in the western Cascade foothills, not enough to have a major impact on the level of our reservoirs---so we all still need to conserve.  But water demands for irrigation should be very small during the next week, which helps a great deal.

Predictability

An extraordinary aspect of this event was its long-term predictability.  Numerical forecast models (like the UW WRF) were skillfully predicting this event nearly a week ahead of time (a fact noted in my earlier blogs).   Want proof?  Here is the observed 500 hPa height at 5 AM Friday and the forecast for 12 hr later. Strong trough moving through...that is what caused the thunderstorms.



Here is the forecast 156 hr earlier (from Saturday afternoon) for Friday 5 AM..  A nearly perfect forecast, except for being 12h too fast.  Amazing.


And the the 156h precipitation forecast showed lots of rain on Friday!  A really stunning example of how far we have come.

A reminder that for folks on the San Juan's I will be giving a talk on Lopez on August 19th and on Orcas on August 20th.

First, Lopez Island at 7 PM, August 19th on "The Future of Weather Prediction"  Details here.

And on Orcas Island at 5:30 PM August 20th at the Orcas Community Church in Eastsound on "Why is the Northwest so Warm?"

27 comments:

Morgan Palmer said...

Wow Cliff! That's scary. I'm glad you're okay.

Rob said...

Glad you're still with us! Falling branches are no laughing matter.

lizch said...

Glad you're OK. I have wondered if we're likely to see high losses of trees (with associated injuries, property damage, and power outages) this fall/winter. So many trees look battered by the drought, so a storm might be more damaging than usual.

don schilling said...

Your blog may be exposing too many truths about Mother Nature. That was just a warning. She doesn't want to give away all her secrets.

Barbara Oakrock said...

I sat through 60-70 green lights gridlocked on W Mercer heading toward SLU at 3:30 Friday; big Mercer Mess

C.P.O. said...

Glad you made it! Thank the maker.

Dean E Kurath said...

Cliff, Hi from Winthrop. I'm glad to hear you are ok. I would greatly miss this blog

Sadly, little rain made it over the crest to the parched east side. Just enough storm for a bunch of new fires. It was however a very interesting day; billowing storm clouds mixed with smoke, lots of thunder and wind. I thought we were going to lose some big pines. It seemed like armageddon for a time. The Chewuch river flow increased from 50 to 60 cfs. Whoo hoo, the normal average is 150 cfs.

Cailean said...

I'm also so glad you're ok. I've read stories of people who have indeed been killed by a big branch falling off a tree. It's highly possible it could have incapacitated you. We used to live right off the Burke Gilman and know how many trees there are on that beautiful trail. So glad your timing was good!

faronium said...

Was sad that Vancouver for island missed the action. The snow drought plus the drought drought has been hard on our watersheds.

As an aside, I've seen a lot of fresh downed trees while trail running lately. I wonder if dry conditions weaken the wood? A question for the arborists and silvaculturists out there. Glad you squeaked through.

rainycity1 said...

So glad that you're O.K.

Unknown said...

Your guardian angel was watching.

Do you know when we might get some rain in Victoria? It has been dry as a bone and we've missed all the precipitation that others seem to be enjoying.

thom said...

Here in the pine woods south of Spokane, I noticed yesterday something different with my pine trees. The limbs are drooping much faster than normal, and the many now within reach snap off like icicles, "green" ones...something new in my 35 years with this property. A 3 or 4 cm green pine branch, which normally bends around 180 degrees without breaking, snaps off easily. Wow,I have never seen it this dry.

snapdragon said...

I'm so jealous- the Portland/Vancouver area got rain but not nearly enough. Sigh.

And glad that you are ok- I guess your Maker just wasn't ready for you yet!

jeb Thurow said...

Glad your OK! I found it interesting how much difference a couple of miles makes.I am in the SE corner of Thurston county and we had very little rain while to the north and west they were soaked. The radar images were depressing to watch as rain fell all around us!!!

Yo Cooley said...

Very grateful to your guardian angels and lucky stars Cliff. Our world would be much less brilliant, well informed and funny without you in it. Here is a toast to our favorite atmospheric scientist's long and healthy life. Thank you for being!

Gary said...

Just tonight we were toasting to Things We Take For Granted . . . then I read Cliff's blog about his near-miss of a falling tree limb. Whew! Another reason for bicyclists to wear helmuts!

Curious about the stresses on trees caused by drought, I ran across this KIRO news clip from July 10: http://www.kirotv.com/news/news/tree-falls-occupied-car-lake-city-neighborhood/nmwp2/. (This happened not far from the Burke-Gilman Trail, where Cliff was riding.)

From the article: " . . . Dry weather causes what arborists call sudden limb drop, or SLP, which sends otherwise healthy limbs to the ground. . . . "

I have several dozen trees and shrubs in my yard, and certain ones do droop noticeably from the weight of the rain, especially after a long dry period. And, in the end, all limbs do eventually fall for some reason, be it drought, internal disease, wind, snow, ice, or intentional pruning. Comforting thought, huh?!

Dan Gebler said...

Ride safe, Cliff! Glad you're okay.

Krishnan Gopalan said...

Cliff, I am glad you are safe. I can't take not reading your columns.

Ansel said...

Hi Cliff,

Glad you missed the branch.

I got 1.17 inches of rain at my house in May's Pond.

Saw some lightning around midday on the way to work.

M'sFan said...

Meanwhile, the coast was ho-hum... That doesn't seem to be the first time this has happened this year, with storms training up the I-5 Corridor and just brushing the coast. Between relative dryness, no fog this year, warmer water, you've heard it here first- If this is the new normal, buy property now! Aberdeen is the new Santa Barbara ;)

Raphael Hsieh said...

Glad to hear that you're ok!
Even more reason for the arguments in your earlier posts on the importance of better trail maintenance on the Burke-Gilman!

Merrill said...

Glad you're still here!

Tony said...

You are much more important than a missing blog.
We are all so glad you were not hurt.
I also saw thick branches that snapped near our building.

Two campers in Yosemite Park died.
http://www.cbsnews.com/news/2-young-campers-killed-by-falling-tree-branch-in-yosemite-national-park/

JordanP said...

Good to hear that it was a near miss and not a direct hit.

Fun to see my weather station make your list (second one listed as W White Center). It is on my roof with nothing higher than it within about a 50' radius, so I know nothing can splash into it. It was just coming down for an hour here, with the highest rain rate of .50" per hour. I've seen it rain harder here, but never that hard for that long.

In one day, I recorded more rain (1.92") than I had between April 14th and August 13th (1.62"). It really is being an interesting year.

Lance said...

I'm glad you're alive Cliff! Stay safe out there.

tracksdc89 said...

Clearly it wasn't your time to go. Thank heaven, something influenced you to be, quite literally, at the exact minimum safe distance. As the saying about lightening goes, you may be safe from falling trees for awhile.

Seeing how you're still with us :), I'm wondering why this is your last blog entry, as today is the 18th. I'm looking forward to your next post

stevemcn said...

I wanted to comment on the extreme wind and dust storms that battered central WA on Friday. We were on our way to Spokane when, about 3:30, just before Vantage, we started getting alerts on our phones about dust storms in Adams County, and the closure of Hwy 395, so of I90. We pushed on as the wind got stronger and finally I90 came to a complete stop about 5 miles E of Vantage. DOT had closed to road due to multiple accidents ahead of us. The backup streched about halfway back to the bridge, where the WSP has diverted traffic off I90. The car was rocking and rolling in the wind. Vantage reported 60mph gusts. After 2 hours, we finally decided to turn around on the eastbound lanes, head west for a few hundred yards, and crossed the median to the westbound lanes and headed back to Maple Valley, where the rain was finally letting up.