Power Outage Prediction Maps for the Friday/Saturday Storm

 As a new service of this blog, I will indicate the areas where powerlines might be damaged by the approaching storm.  You can't say you don't get cutting-edge products on this site. 😊 

Perhaps the forecasts might help local utilities pre-position necessary assets.

The latest European Center sea-level pressure forecast is for a very respectable 977 hPa low with a ring of strong winds wrapping around it (shown at 4 AM Saturday, winds in knots). 

 No, this is not some doomsday machine and, no,  it is not a BOMB CYCLONE.  I will not hype this storm like some amateur sites and certain local media.

Now the serious part....where will the power outages be, if any? 

 My general experience is that power outages during December and January generally get started when gusts surge above 40 mph (35 knots).   Definitely, some losses when gusts exceed 50 mph (43 knots), and expect lots of blackouts when winds surge above 60 mph (52 knots).

Of course, there are subtleties. Outages early in the fall require less wind to damage trees and, thus, the powerlines. Unusual directions (like the easterlies of Nov. 19) do more damage.

But with all that said, let's examine the prediction winds of the best local model around (the UW super-high resolution WRF model).   I will show you some new graphics that we have developed, showing the strongest wind prediction over a period.

For the period through 4 AM Saturday, there is potential trouble on the Washington coast and northwest Washington (see below).   I particularly worry about Sequim to Port Townsend to central Whidbey Island).  The San Juans and Bellingham could see some flickering lights.  Some modest potential for the western foothills of the Cascades but NOTHING LIKE Nov. 9.

Extending the period through early Sunday morning, we see an enhanced risk over NW Washington and along the coast.  Potentially strong downslope winds on the NE slopes of the Olympics....but few people live there.

Here in Seattle, it will get blustery, but I don't expect a lot of wind damage.   

A good source to check is the City of Seattle WindWatch website (a project of my group), which shows the strongest winds over the city from a variety of forecast sources (below).    A max gust in the low 30s mph looks like a good bet.   Those of you in Seattle who bought generators during black Friday/Monday will probably not get a chance to use them.

The strongest winds over the northwest interior of western Washington will probably be on Saturday morning around 10 AM.  Below are the forecast gusts at that time.

If you are in purple or blue, charge your batteries.  Red....you might have some issues.

Enjoy.

Announcement

_________________

I will hold a special online zoom session at 10 AM on Saturday for Patreon supporters.  I will discuss the storm and answer your questions....assuming my power does not go out!

A Major Cyclone Will Approach Our Coast But Not a Repeat of November 19

A very strong, rapidly developing, midlatitude cyclone will approach the Northwest coast on Friday and move through on Saturday.

Fortunately, the wind situation will be far less threatening in the interior compared to the November 9 event.  This blog will explain why.  But big waves may cause problems on the northwest coast.

Let's start with the predicted sea level pressure and surface wind gust map at 10 AM Friday morning.  

Pretty scary looking, with a 979 hPa low-pressure center.  Strong winds (up to 60 knots) will occur in a ring around the low center.  An associated occluded front will be hitting the Oregon coast with even stronger winds at this time.

By 7 PM on Friday the low will move northwestward and strengthen slightly to 977 hPa. 

Overnight the system will weaken and move across northern Vancouver Island.

Importantly, this will change the orientation of the isobars, producing a large north-south pressure difference and strong winds over NW Washington,

Over western Washington, the winds will evolve in three acts.

In the first, shown at 1 PM on Friday, strong winds (blue colors) will occur along the coast and over the waters of NW Washington.  Strong downslope winds will occur on the lee (NE) side of the Olympics. Moderate (20-35 kt) easterly winds will descend the western slopes of the Cascades, but their strength will be NOTHING like November 19th.

In stage two,  shown at 1 AM Saturday, the coastal winds will weaken, although still strong on the northern WA coast.  The downslope easterly winds will have ended and winds will pick up over Puget Sound.

In stage three, northern Puget Sound winds (from roughly Seattle to Bellingham) will strengthen with gusts reaching 30-40 knots from the Sound.   A few branches may fall and I expect a few minor power outages.  Nothing significant.  Winds will fade later in the day

This event will represent a typical mid-winter blow.

The most serious impacts may be the waves and high water levels on the Washington Coast.

The strong winds acting on the Pacific should produce substantial wave action on our coast and Vancouver Island.  The latest NOAA WaveWatch3 prediction is for significant wave heights of 20-30 ft.

That will be on top of some higher-than-normal astronomical tides (see below for La Push/Quilayute):

Clearly, some potential for coastal flooding on the northern Washington coast late Friday and Saturday.