September 2018 Weather in the Pacific Northwest

[TT-SEA]

Raining pretty good from Tacoma on westward.

 

 

 

 

And eastward! 

[Phil]

Not at all. Florence weakens considerably and the NE eyewall never really makes it ashore until it's a Cat 1 level storm. The 60-70mph winds it shows for the populated areas isn't catastrophic. Surge effects are also lessened in this scenario. The rains near Wilmington would be the worst impact on that Euro run, and even there it's relatively isolated with the I-95 corridor largely being spared significant flooding.

Are you looking at the right model? The Hi-res ECMWF has the NW eyewall scraping the coast at 106kts between hr66-72, with slow weakening to 84kts thereafter while riding the coast to the SW. If the COC is over water and well-ventilated, weakening can be minimal (see hurricane Harvey strengthening upon approach, with half of the COC over land at the time).

 

In this case, it both prolongs the storm surge and affects a much larger area..the duration of such can be just as important as strength once you’re well into hurricane conditions. I’d argue the 12z Euro is a worst case scenario all around. What you avoid in terms of absolute maximum winds you pay for in terms of coastal surge and flooding.

[Phil]

[Phil]

Godspeed to anyone attempting to ride this out.

 

[Dave]

My uncle lives on Oak Island, NC. He's under mandatory evac orders. Gotta be out by noon tomorrow. Unfortunately, his place is not on stilts at an elevation of 12 feet. Gonna be close.

[Deweydog]

Haha! 18z...

[Farmboy]

18z GFS continuing with idea of Florence scraping the S. Carolina coast, 939mb just offshore from Charleston at 120hrs.

[ShawniganLake]

Some juicy thunderstorm cells roaming around. Mill bay which is just east of Shawnigan Lake, picked up a months worth of rain (1.2”) in the past half hour or so.

 

[ShawniganLake]

Haha! 18z...

The goofiest of all the goofus runs.

[Jesse]

Haha! 18z...

When is the heatwave?

[Geos]

Can see the cell near Maltby from here. Skies are really dark in that direction.

 

[Geos]

Crazy...

 

 

Much less crazy over here.

 

[Deweydog]

When is the heatwave?

Stop being so obsessed with your own backyard.

 

It shows a major hurricane approaching the east coast, slowing down and sliding just offshore to the south. What a pathetic piece of model. If this model held forecast contests I bet it would never score them.

[TT-SEA]

Can see the cell near Maltby from here. Skies are really dark in that direction.

 

 

 

Dumping rain here now and very dark.   Like the sun is setting dark.  

[Frontal Snowsquall]

Yeah Tim or anyone else with access to all the EURO maps... does is keep the eye off the coast entirely?

 

Everything from Cape Hatteras to Savannah would be ravaged.

Here's the exact track Hurricane Florence takes on the 12z EURO.

 

http://i68.tinypic.com/14vjpys.jpg

[TT-SEA]

Here's the exact track Hurricane Florence takes on the 12z EURO.

 

http://i68.tinypic.com/14vjpys.jpg

 

 

Charleston residents are like WTF???    Makes a beeline for the coast then comes to a dead stop and makes a sharp left turn and heads straight for them! 

[MossMan]

Dumping rain here now and very dark. Like the sun is setting dark.

Bright and sunny here still...at the moment.

[SilverFallsAndrew]

Hard Reign!

[Jesse]

Looks like some pretty intense cells around Woodland at the moment.

[Jesse]

Crazy...

 

 

Much less crazy over here.

 

I hope the upcoming hurricane victims keep our gloom situation in mind and count their blessings.

[James Jones]

Nice day. Had some moderate rain for a couple hours here this morning that gave way to a cool afternoon with clouds and sunbreaks. Will be nice to see things green up for a bit. 

[TT-SEA]

Bright and sunny here still...at the moment.

 

 

Now sunny here as well.  

[Farmboy]

I hope the upcoming hurricane victims keep our upcoming gloom situation in mind and count their blessings.

They should be thankful for the 40 inches of rain about to fall.

[Geos]

Wow, it actually rained enough for this...

 

Flood Advisory
National Weather Service Seattle WA
342 PM PDT TUE SEP 11 2018

WAC061-120145-
/O.NEW.KSEW.FA.Y.0003.180911T2242Z-180912T0145Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Snohomish-
342 PM PDT TUE SEP 11 2018

The National Weather Service in Seattle has issued a

* Urban and Small Stream Flood Advisory for...
Southwestern Snohomish County in west central Washington...

* Until 645 PM PDT

* At 339 PM PDT, the public reported heavy rain in southwest and
south central Snohomish county due to thunderstorms. This will
cause urban and small stream flooding. Up to two inches of rain
have already fallen.

* Some locations that will experience flooding include...
Everett, Lynnwood, Bothell, Mountlake Terrace, Mill Creek,
Snohomish, Brier, Paine Field-Lake Stickney, North Creek,
Clearview, Martha Lake, Seattle Hill-Silver Firs, Cathcart, Maltby
and Echo Lake.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, urban areas, highways, streets and underpasses as
well as other drainage areas and low lying spots.

&&

[Frontal Snowsquall]

Charleston residents are like WTF??? Makes a beeline for the coast then comes to a dead stop and makes a sharp left turn and heads straight for them!

Pretty crazy track. The models though might be starting to hone in on a solution. Here is what the 18z GFS and FV3-GFS show. It's going to be a hectic next couple of days model riding this thing.

 

http://i66.tinypic.com/2wdshmt.png

http://i66.tinypic.com/28007yr.jpg

[MossMan]

Now sunny here as well.

And it’s now raining.

[TT-SEA]

And it’s now raining.

 

 

Most of King County is now in a dry slot and mostly sunny... with lots of rain to the north and south.  

[Farmboy]

[seattleweatherguy]

Most of King County is now in a dry slot and mostly sunny... with lots of rain to the north and south.

Got some sun, clouds, then sun , and now clouds again

[BLI snowman]

Are you looking at the right model? The Hi-res ECMWF has the NW eyewall scraping the coast at 106kts between hr66-72, with slow weakening to 84kts thereafter while riding the coast to the SW. If the COC is over water and well-ventilated, weakening can be minimal (see hurricane Harvey strengthening upon approach, with half of the COC over land at the time).

 

In this case, it both prolongs the storm surge and affects a much larger area..the duration of such can be just as important as strength once you’re well into hurricane conditions. I’d argue the 12z Euro is a worst case scenario all around. What you avoid in terms of absolute maximum winds you pay for in terms of coastal surge and flooding.

The NW eyewall is the weakest part of the storm, and dry air, friction, and shear are all likely to impact a larger storm's intensity once its core starts to come ashore. The Euro shows this and shows 10-15mb of weakening as it slowly sits near the coastline, which will significantly reduce the wind and surge impacts once it does make a full landfall. The surge may be prolonged but its severity would be lessened with slowing winds and a low forward speed.

 

The Euro also shows more localized rain impacts with this track, mostly relegated along the immediate coast. The freshwater flooding with a storm like this is far more destructive than the 50-80mph wind gusts that are realized at the surface on the weak side of a diminishing hurricane. Floyd is an example of how that can go.

[Jesse]

I think the north Portland/Vancouver area must have been in the eye all day. Rain to the north and south but not much here. Hopefully the next few days are better.

[Deweydog]

CNN says Aunt Flo is a BEAST LIKE NO OTHER. I'm going with that.

[Phil]

Stop being so obsessed with your own backyard.

 

It shows a major hurricane approaching the east coast, slowing down and sliding just offshore to the south. What a pathetic piece of s**t model. If this model held forecast contests I bet it would never score them.

[Phil]

The NW eyewall is the weakest part of the storm, and dry air, friction, and shear are all likely to impact a larger storm's intensity once its core starts to come ashore. The Euro shows this and shows 10-15mb of weakening as it slowly sits near the coastline, which will significantly reduce the wind and surge impacts once it does make a full landfall. The surge may be prolonged but its severity would be lessened with slowing winds and a low forward speed.

Except I believe surge precedes the maximum in winds and is mostly a function of storm size/strength before landfall..so I’m not sure what the benefits of a larger storm could possibly be here especially with the concave shape of the coast there. Damage/erosion can be a function of time as well as intensity..the longer the pounding goes on, the more damage it can do.

 

As for the eyewall/winds, I think the strongest quadrant, whether or not the storm weakens upon approach, etc, is not certain right now. Would probably be dependent on the timing of eyewall replacement cycles, any potential SWerly shear, exact location of the storm relative to the coast to promote ideal upwelling/SST cooling, etc.

 

Does it weaken to a 110-115mph Cat2/borderline Cat3? Or can it drop to 90mph or so? Hard to know. Under ideal conditions it might take 12-24hrs to start weakening after stalling.

 

The Euro also shows more localized rain impacts with this track, mostly relegated along the immediate coast. The freshwater flooding with a storm like this is far more destructive than the 50-80mph wind gusts that are realized at the surface on the weak side of a diminishing hurricane. Floyd is an example of how that can go.

I agree that flooding is the most prolific hazard, but wasn’t that always the case? Even in a clean landfall scenario, it was a major issue. A coastal hugger would stay stronger for much longer..cause much more damage across the region in the form of storm surge and wind, and dump more rainfall as well.

 

I think it’s a terrible outcome. Hopefully we rip the bandaid off and get Florence inland quickly to begin weakening instead of hugging 150 miles of coastline as a nasty Cat2-3 hurricane.

[Phil]

Well she’s back up to 140mph now. Hopefully that’s the ceiling, but diurnal maximum isn’t for another 10hrs or so.

[Phil]

Surf city camera. This might be ground zero, FWIW.

 

http://surfchex.com/cams/surf-city-pier-north/

[Phil]

Where *exactly* Flo stalls is crucial too. If it’s right on the coast as some models suggest, that’s a worst-case outcome. If the eyewall stays fully offshore, however, like with Matthew in 2016, it could spare the immediate coast from the worst winds even if it affects more people and stays stronger as a result. And some of the models really stall it, and instead just make a right turn before landfall. Tough call for sure.

 

[WeatherArchive]

CNN says Aunt Flo is a BEAST LIKE NO OTHER. I'm going with that.

Clinton News Network 100 percent credibility gotcha! A broken clock works right twice a day.

[WeatherArchive]

Probably no coincidence that the GFS also surrended to the Euro with regard to the deeper weekend trough out here.

 

As sad as it is, I have definitely noticed a correlation between intense landfalling hurricanes along the eastern seaboard and strong early season troughing out here. I’m guessing it has something to do with the strength of the Bermuda high and associated teleconnections.

weather is interconnected with a lot of complex relations we just don't always see it due to human biases.  Your getting there though Keep practicing!

[WeatherArchive]

Is this the great 2018 hurricane solar eclipse special?