Monday, November 16, 2015

Strong Winds Tomorrow, But Not An Historic Windstorm

There is a lot of excitement in the media over the big blow we will have tomorrow.   The latest warnings for Puget Sound:

THE NATIONAL WEATHER SERVICE IN SEATTLE HAS ISSUED A HIGH WIND
WARNING...WHICH IS IN EFFECT FROM 5 AM TO 6 PM PST TUESDAY. THE
HIGH WIND WATCH IS NO LONGER IN EFFECT.

* WIND...SOUTH OR SOUTHWEST 25 TO 40 MPH WITH GUSTS NEAR 60 MPH
  ARE POSSIBLE BEGINNING TUESDAY MORNING AND CONTINUING INTO THE
  AFTERNOON HOURS.


The forecasts for Northwest Washington are even stronger.

* WIND...WINDS MAY REACH 30 TO 45 MPH WITH GUSTS AS HIGH AS 65
  MPH ON TUESDAY.

I suspect that this event will cause some power outages but will not cause major damage.  One reason for optimism is that we already have had lots of wind and the leaves are substantially off the trees now.   On the other hand, the ground is saturated and that will foster the failure of tree root systems.

My latest examination of the model forecasts suggest that at the height of the storm, somewhere between 10 AM and 2 PM Tuesday, the winds will reach sustained values of 22-30 mph over land and 25-37 mph over water, with gusts reaching 30-50 mph over land and 50-65 mph over water.

Looking at the latest infrared satellite picture you would hardly think a windstorm is brewing, with no low center obvious off our coast.

8 PM Monday infrared satellite image

A modest low center will move into southern B.C. tomorrow (Tuesday) AM, while much higher pressure exists to its south (see image).  The result is a large pressure differences north to south.  Air tends to accelerate from high to low pressure near terrain and in this case it will produce strong southerly winds.


The updated NOAA SREF ensemble (many forecasts) is going for sustained winds of roughly 20 knots  (23 mph) at Seattle Tacoma Airport.

Looking at the latest UW WRF sustained wind forecast near the height of the storm (noon) shows sustained 25 knots over Seattle, with stronger winds over the water. Increase by roughly 50% for max gusts.  Much stronger winds along the coastal and near shore waters.  And expect strong winds in the Strait and on volcanic peaks.

This is a major blow but NOT like the Chanukah Eve (2006) or Inauguration Day (1993) mega events.

And did I mentioned the rain?  LOTS of it.  Here is the rain prediction over the next 24h. 5-10 inches in the mountains, while locations to the east of the terrain will enjoy substantial rain shadowing.

There have been large snowfalls in the mountains above 4000 ft today and several ski areas are planning on opening this week (e.g., Baker, Whistler). With the passage of a warm front tonight, the freezing level will zoom upward and rain will fall on the some of that snow.  But don't worry--the rain will only be around for roughly 12-18h and lots of snow is in the forecast this week.  And believe it or not, it looks like a major break in the weather will occur this weekend and early next week.

I know what I will be doing...





9 comments:

Colin Parrish said...

What happened on Inauguration Day 1993? I was only 8 and remember lanterns at home... But what was the actual weather?

Unknown said...

Hi Cliff,

You say:
"My latest examination of the model forecasts suggest that at the height of the storm, somewhere between 10 AM and 2 PM Tuesday, the winds will reach sustained values of 22-28 mph over land and 25-35 mph over water, with gusts reaching 30-40 mph over land and 50-60 mph over water"

Wind criteria states
WIND ADVISORY Sustained winds 31-39 mph (27-34 kts) for at least 1 hour; OR any gusts to 46-57 mph (40-49 kts)
HIGH WIND WARNING Sustained winds 40-73 mph (≥35 kts) for at least 1 hour; OR any gusts ≥ 58 mph (≥50 kts

I'm a bit confused between your examination of the model forecasts and what NOAA has forecast. Should NOAA have only issue a High Wind Warning (Gale Warning) for over water? Lynnwood/Seattle/Tacoma and surrounding areas are currently under a High Wind Warning but you are saying that we are not going to even have enough wind for a Wind Advisory for us over land? Which is it?

Unknown said...

Colin, you can go here for info on the Inauguration Day Storm in 1993: http://www.climate.washington.edu/stormking/January1993.html

rybackaz said...

Hurricane-force 70 to over 100 mph winds Colin! I was only 5 but I remember it well! I lost my power for 4 and a half days!

Unknown said...

^Here: http://www.climate.washington.edu/stormking/January1993.html

Think of it as the 2006 event, but happening during the daytime. I was in college at the time.

David Holter said...

Cliff,

Take a look a the Lake Spada level of 1444.75 feet at 5:00AM. Is this reservoir at danger of going over the top of the Dam. Did water managers let the reservoir fill too high?

Joseph Ratliff said...

I'm glad the Storm King (Wolf Read) is active again. Great resource.

I lived in Ocean Shores during the 2007 "Great Coastal Gale." Unofficial gusts around Westport during that storm reached 133mph.

http://www.climate.washington.edu/stormking/December2007.html

The sustained winds kept blowing 50 - 70mph for quite some time. Sometimes reaching 80 - even (unofficially) 90mph sustained.

It was insane. Power was out for almost two weeks, with roads blocked etc...

The storm today will blow, for sure. But not anywhere like the "legendary" storms like we've had in the past, I'm afraid.

Be safe and keep warm folks.

Unknown said...

David,

Lake has a crest of 1450, so it's still got a ways to go. In addition dam has a spillway that is designed to handle 100 year flood flows.

Jim said...

That '06 storm was brutal. Ripped our 3rd story glass surround railing right off its mounts. Permanently tipped/bent 1/2 dozen pines south of us that Dad had to cut them down before the next storm hit and that was '07. Surely would've destroyed our roof.