Thursday, March 9, 2017

Good Blow Friday Morning

A modest low pressure system will move across Vancouver Island, which will bring a good blow to the coast and the western Washington interior.  Around Puget Sound we are talking about sustained winds of 20-30 mph, with gust to 30-40 mph.  Higher winds over the near the water.

This is not going to be a great windstorm.

The visible satellite imagery this morning shows the low pressure system as a swirl of clouds due west of the WA/OR border, but the structure is not well defined and not indicative of a strong system.


The UW WRF model forecast for 10 PM tonight (below, sea level pressure and sustained wind speed), shows an elongated low (central pressure is an unimpressive 1002 hPa), with the strongest sustained winds over the ocean of 35 kts.  Again, nothing to write home about.


The low makes landfall on central Vancouver Island around 4 AM Friday (see below), with wind revving up along the coast and the interior by that time.


Here is a more detailed view of western Washington at 4 AM, sustained winds from Seattle to Tacoma of 25-30 knots.


Switch to gust forecasts.  At 5 AM, winds could be getting to around 40 knots around Seattle.

 And wind keep on blowing into the midmorning (see 10 AM prediction below).
As the low moves northeastward, a surge of westerly flow pushes into the Strait, with gusts of around 50 knots north of Sequim.   I wouldn't walk out to the Sequim lighthouse tomorrow morning.  It could be the last walk you take.


So what about uncertainty of the forecasts?  The latest NWS/NCEP SREF (Short Range Ensemble Forecast System) sustained wind forecast for Sea-Tac Airport suggests a peak of around 15 knots, with only one ensemble member showing nothing, and a few going as high as 25 knots.


The NOAA GFS ensemble (GEFS) forecasts a bit less and there is little uncertainty.  Interestingly, the high-resolution member (blue line), which drives the regional forecasts shown above, is an outlier, being considerably stronger than the rest.

So getting back to the bottom line.  We are close enough in time to the event and the ensembles are sufficiently close together (low spread) that it appears one can have some confidence in making the following forecast:

Winds will pick up in the western WA interior between 10 PM and 2 AM tonight/tomorrow AM.   The strongest winds will probably be between 4 AM and 1 PM Friday.  Over central Puget Sound over land, sustained winds of 20-30 mph, with gusts of 30-40 mph are quite probable.  Stronger near the water, with gusts to 40-45 mph.

There could be a few scattered power outages, but a late season storm of this magnitude should not be a real problem.    Bring your garbage cans in and don't park your car under a decaying tree and you should be fine.  And yes...don't hike along the shores of the Strait of Juan de Fuca Friday morning and early afternoon.

21 comments:

Miles Raymond said...

Dang! Friday morning is our garbage day...

Asher said...

This whole winter has been merde.

Iam TwoOtaku said...

So how reliable is the NOAA site? It shows like not much of anything for my area. That would be nice! I don't do big winds... I leave because of huge trees quite close to the house which I hope I can get cut down this summer.

HerringMan said...

Thanks, Cliff. Here in Dungeness we are preparing for the big blow.

One small correction. You say "I wouldn't walk out to the Sequim lighthouse tomorrow morning." Sorry to nitpick, but there is no lighthouse in Sequim. Don't you mean the New Dungeness Lighthouse on Dungeness Spit?

Chris Woods said...

Grande merde

Willysmb44 said...

This is the major problem with the general forecasts in the media because they want to have something flashy to talk about and covering a huge range of weather in cases like this. Thanks, this puts it into better perspective.

Westside guy said...

@Miles Raymond Mine too - garbage and recycle day. But if the wind is out of the south, at least it'll be blowing the bins into my yard rather than into the street. :-D

TheWildLine said...

Is it true we will see more winds like this in the future?

http://news.ucsc.edu/2008/12/2644.html

Kelly's Entrepreneurship Blog said...

Ugh, I woke up about 3 am with intense joint pain. And knew something was brewing. 31 is the new 60.

I wish there was a secure way for people to open source their (possibly atmospheric related) joint pain via map to see if there really us correlation. In my experience my extreme rises amd falls have been when living very close to Lake WA and in the Bellevue Highlands - but I did live in these areas consecetivly, do my condition may have gotten worse in time.

Unknown said...

6AM Friday. No wind. Zero. Nada.

Alan Hansen said...

Friday morning here on the Strait...barely a puff of wind. Guess you guys "blew " this one again.

John Marshall said...

We didn't get any wind out on the notoriously windy Strait, and now the warnings have fallen. Maybe 5 to 7 knots over the open water at Dungeness Buoy and Smith Island.

Looks like all the wind was encountered from Edmonds and southward down the Sound. Wind from the south. I saw 44 knots on the beam for the Edmonds/Kingston ferry.

I'm presuming the low pressure tracked differently than forecasted to keep the Strait out of the pressure zone. Mariners on the Strait will be happy today.

Tony said...

Cliff, we have another example where we hear on radio, incl. KNKX
FREQUENT warnings about wind warnings yet branches are barely moving anymore.
Looks like the storm is over and still warning is BAD and erodes
confidence in the weather service and its warnings.

Like last fall storm of century, once it was obvious to calm down
it should be communicated AS QUICKLY AS POSSIBLE.

Stephen Day said...

We had a gust of 40 at about 6:30 this morning in View Ridge (west of the ridge), northeast Seattle. This was measured on a weather station. It is very rare to have gusts this high here. It is still quite windy.

Rebecca Timson said...

It's still windy here in Leschi-Madrona area of Seattle. Does anybody really expect a forecast to nail it down to the neighborhood level? Seems like the wind shifted a little but the forecast was otherwise good.

Unknown said...

As many of us have said for some time, the media do us no service by repeatedly overstating weather risks.

And again, the NWS badly missed the forecast here in Bellingham. This was big miss with virtually no wind since the wind warning was posted. NWS misses have become the norm here when it comes to significant events.

Cyle Messling said...

This was not supposed to be a serious windstorm. I disagree with people who say they blew the forecast. Winds gusted around 30-35mph here in seatac which is slightly below the forecast a few days ago. The past two days the forecast discussion has continually stated it looked weaker than forecast. The public needs to stop holding meteorologists accountable for them giving a heads up a few days in advance. They are predicting the future for Christ sake and it's not like they were calling for 60mph winds at any point

Kirsten Owens said...

We had gusts just below 50 mph on Bainbridge Island. Woke me out of a dead sleep hearing it roar.

MelissaF said...

We experienced the same as Kirsten Owens here near Indianola. Really roaring winds high up in the trees starting about 4 AM. Really warm here too by 9 AM.

John Marshall said...

When the forecast is right for at least a portion of the warning area, then it's a good forecast. This one was accurate for the south Sound, just not northward of Port Townsend or west.

40+ knots on the beam of the Kingston-Edmonds ferry was interesting when parked on the lower deck on the upwind (south) side. Good forecast.

suetunn said...

For Richland, the variance changes quite a bit over the years. Why? It gets both Columbia Gorge and NE fronts converging.