Thursday, October 13, 2016

Storm Update

UPDATE at 1 PM Friday


There are significant changes in the forecast.

Currently, we have an atmospheric river (a relatively narrow current of moisture and precipitation) aimed right for our regio).  This is evident in a recent infrared satellite image (see below)


Or in the forecast for the total moisture in the vertical valid at 11 AM.  Blue is large amounts

Over the past 24 hrs (ending 9 AM), some locations on the windward slopes of the Olympics have received 2-4 inches, with substantial amounts on the windward slopes of other terrain (like the N. Cascades.)  (the figure below only shows locations with more than 1 inch)


Plenty of rain today, with greatest amounts over Oregon (see 24h precip ending 5 AM Friday).


Most of you are probably more interested in windstorms...so lets consider that now.  Right now it appears that the late Thursday/Friday morning event will not be a severe one.  One problem for that storm is that we are really working with an initially amorphous, almost double system, rather than a consolidated single strong system.  Here is the surface pressure forecast for 11 PM...you can see the stretch out low, with lows of pressure gradient (and strong winds to the south).

 By Friday afternoon, a more consolidated low passes to our north and a large pressure gradient develops over western WA.
 As a result, it will get windy during Friday afternoon, with sustained winds reaching 15-25 mph with gusts of 30-40 mph over Puget Sound, stronger over the coast and NW WA.  Some power outages, but nothing catastrophic.


But now, lets talk about what you REALLY want to know about.  The Saturday storm, which potentially can be much stronger, representing the remnants of Typhoon Songda.   The confidence in earlier forecasts were lessened by the different solutions of the US model (GFS) and the vaunted European (ECMWF) model--a classic situation for forecasts.   The GFS was going for a historic storm with a central pressure in the 950s  mb that hit Vancouver Island, while the ECMWF solution was weaker (960s) and farther south (passing over Seattle!).

Well, the new US runs have now shifted to a compromise solution, halfway to the ECMWF track and weaker, but still a remarkably intense storm for our region.  And the storm is a bit later.  Let me show you.

The surface forecast (sea level pressure) for 5 AM Saturday show a strong low (980 hPa) off southern Oregon.

 By 5 PM Saturday, it has revved up to 968 hPa.  A very intense tight storm.  Such rapid intensification is know as "bombogenesis."  Not kidding

 By 11 PM on Saturday, the storm is just north of the border and a huge gradient is over western WA.  Big winds.

Two things.  This track is the perfect track of strong winds over Puget Sound.  Second, the worst windstorms are rapidly intensifying as the make landfall...like this storm.

The wind forecast map (for sustained winds) at 11 PM Saturday suggest sustained winds of 25-35 mph, with gusts of 35-65 mph over Puget Sound.

The 12 UTC European Center run is in and the forecast is very close to the US GFS.  Here is the 5 PM Saturday prediction... 967 hPa off of SW WA.
 The gust forecast from the European Center for the 6-h ending 11 PM Saturday shows 50-70 knot gusts over western WA.  That is serious.


Bottom line:  the Saturday storm is the big windstorm threat and has the potential to be one of the strongest windstorms we have seen in a few years.   There is still uncertainty in the forecast but it is far less than earlier.  

Keep in mind what we are trying to do...forecast the exact track and intensity of a storm that is now thousands of miles away and currently very weak.  If our track if off by 100 miles, the forecast is radically changed at nearly all locations.  It is amazing we can even attempt to do this.  So we still have to watch this system very carefully and update the forecast as we get close.
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31 comments:

Sita said...

Thank you for the updates! It's nice to have a place to go with some solid information instead of depending on places that over hype or dismiss the upcoming storm systems. With the changes, I feel like I have a few more hours of breathing room for prep of my home in case Saturday's storm is worst case scenario. I've done the shopping for supplies, now it's just organizing so I'm not doing the "I know the headlamp is around here somewhere" after the power has gone out.

AmyHP said...

Hi Cliff! Thanks for the update. I have a large fundraising event on Saturday night. Given your update what is the likely hood we are going to need to cancel?

derith said...

Hi,

Your bombogenesis image has a pretty intense gradient at the NW OR/SW WA border. What are projected conditions/winds so close to the center of the storm? I understand the storm is still 1000 miles out..

Thanks!

MBeebe said...

70 knots? That's 80.5 MPH! I hope Seattle is well-nailed down or it's going to blow all the way to Bellevue!

Theresa H said...

So our storms are called Pacific cyclones? I don't understand why our storms aren't called typhoons or hurricanes. I was recently in Japan and there was a typhoon while we were there. The winds topped out at around 30 mph in Tokyo. Why is this stronger storm the remnant of a typhoon and not just a typhoon?

Steve Allwine said...

So, worst case, if inland winds will be as high as 70 knots, what's the prediction for the coast?

As of now, my wife, son and I have reservations this weekend at a beachside cabin at Kalaloch Lodge to watch the storm. From the looks of the 5pm European model, we'll be at ground zero for the low pressure.

Joshua Wallace said...

Typhoons and Hurricanes are tropical systems, while ours are mid-latitude systems. Both are cyclonic storms however to be a tropical system there must be a closed circulation around the center of low pressure.

wff255 said...

Typhoons and hurricanes derive their energy from the warmth of the ocean, which makes them "tropical" storms. Our waters are far too cold to support a tropical storm, although the "extratropical" storms that we are subject to can be nearly as powerful as hurricanes or typhoons.

Bear said...

Yikes! This is much worst than I expected. Really timely info and analysis - I am so grateful! Time to re-batten down the hatches etc! Here in Bellingham people are bracing for a wild ride! Your the Best, Cliff Mass! Cheers! Barry Wenger

Sulla said...

Theresa H - Typhoons are tropical in nature (another name for hurricanes). They derive their energy from the heat of the ocean, which is why you need to get over 79 degrees water temperature to support a strong one. That limits typhoons to largely tropical waters, which is why we don't get them since the water off of our coast is far too cold. Some typhoons (like Songda) transition into extra tropical cyclones as they move into cooler waters. Unlike a hurricane, extra-tropical cyclones get their energy from temperature contrasts in the atmosphere. Those types of cyclones have produced our worst windstorms.

Matt said...

@ Theresa H - Cyclones (not a Nebraska cyclone aka tornado) are cyclonic storms, where the winds revolve around a "center", as opposed to straight line winds (from a thunderstorm for example). Some cyclones are tropical cyclones (hurricanes, typhoons), and these must conform to a certain set of standards, such as a warm core, deep convection and possession of a low-level circulation center. They generally can only exist where waters are warm (26°C or better). The cyclones that exist in the mid-latitudes like ours cannot possess a warm core since our waters are so cool, therefore they aren't tropical cyclones, but they are no less powerful

John said...

What's your take on the renewed La Nina Watch? It appears that conditions have rapidly changed the past three weeks to warrant it's reissuing.

Fleetwood said...

Why does the official forecast for Saturday still look so benign?
http://forecast.weather.gov/MapClick.php?site=sew&textField1=47.622&textField2=-122.349&zone=1#.VhcqXr9HbCQ

It calls for winds only 12 to 18 mph which doesn't sound at all like what Im reading here.

K said...

If you've never been to Kalaloch I would suggest you change your plans. They say 25-40 mph sustained winds with 70 mph gusts tonight and Saturday is supposed to be worse. Plus Kalaloch is literally ocean front. It gets pretty messy on the peninsula with high wind storms. It's beautiful but not worth the risk.

Unknown said...

Unfortunately, your forecast earlier in the week were dead on for our section of the Oregon Coast Range. We have many inches of rain at the ODFW facility where I vulunteer, and the rain is already causing major problems. The really big event hasn't even started. Yikes.

wff255 said...

Fleetwood, I read the link you posted, and Saturday night it calls for sustained winds of 31 to 41 mph with gusts to 60. Doesn't look benign at all to me.

evie said...

Cliff - You have been spot on so far. Looking forward to tomorrow's update. Hope to see changes in Saturdays storm that will make it less ferocious than it appears to look right now.

Bert Wyman said...

Cliff,

What about more recent model runs which have reduced the severity of the winds/precipitation ?

Cheers,
Bert

The Drennans said...

I'm expecting something more like 2006 than 1962. But 2006 was pretty bad-- so if it's that bad Saturday night, that's pretty scary. I'm expecting it'll be even less than 2006, but maybe the strongest since then. Just my hunch.

I just did an evening drive Seattle to Portland. Heavy rain much of the way, I got pushed around a little by the wind-- and then there was the branch on I-5, all broken in pieces. I'm glad it wasn't worse. It's a bit dangerous with debris on the road, at night in heavy rain, -- but it wasn't all that bad. I found it somewhat fun to slog through it in 3 hrs. 30 min. It kept my attention at the least.

cgt said...

I'd say go to Kalaloch, we only live once. Especially if reservations are already made.
Might be an awesome display of nature at its finest, why miss that?
Or sit at home, witness the power go out, freezer thaw, perishibles perish, sounds more risky to me.

John Murphy said...

I would *LOVE* to be at Kalaloch...
That will be the best place to watch the storm!
And if the cabins get washed away, at least you will go with style!

Surprised they are not closing the in and boarding it up. I could see windows getting blown out.

Theresa H said...

Thanks for the responses about storm vocabulary! I knew this would be a good place to ask!

bob jones said...

Try Surfside (above Ocean Park) 660 yards from the water. Had a tornado warning earlier this morning. Still hearing the rumbling. C'mon saturday storm, let's rock.

windlover said...

Cliff - Pretty much all the reports for Saturdays storm focus on the coast, northwest interior, Everett northward to bellingham, seattle, tacoma, olympia, the I-5 corridor, and greater Puget sound. I know you're bombarded with questions, even complaints, but is there any chance you could expand the forcast to include those of us south of Olympia....like the eatonville area?

Carrie S said...

What will the storm be like in the mountains? I'm suppose to head to Hyak/Snoqualmie pass Saturday. Thanks!

Jody said...

I'm in Aberdeen and it is as dark as a late evening, despite being 9:00 AM. We are trying to do business as usual, but are very nervous. My daughter works in Ocean Shores tomorrow, and we would all very much appreciate an update as soon as possible. Thanks!

Unknown said...

GFS seems to disagree with the European and Canadian models on intensity. At 00:00 UTC Friday, GFS has the pressure of the Saturday storm at 978mb, while ECMWF has it at 966mb and CMC has it at 967mb.

Magi Speelpenning said...

How do these storms compare to the storm of December 2006?

William said...

Why the tornado warnings? I just saw a blurb on the Weather Channel and they stated - more tornado warnings for the NW in the last 24 hours than we have had in the last several years combined. Not that we get many tornado warnings here.

Matt said...

I realize you're extremely seattle and WA centric, but in the last graphic: "The gust forecast from the European Center for the 6-h ending 11 PM Saturday shows 50-70 knot gusts over western WA. That is serious."

It looks like just south in Oregon is dwarfing all other areas in size and wind speed but it is cut off, a shame.

Would really love if you could occasionally speak to Oregon more than ancillary, we don't have anyone that does weather to your level on our state (that I'm aware of).

Carl Harris said...

What is the Name of your UW Weather App for Android?