September 2017 PNW Discussion Thread

[Phil]

It's hard to ignore several days worth of GFS runs which at some point take things sub-900mb. I don't recall ever seeing that.

Yeah, while the GFS is a spectral model and runs uncoupled to the ocean (hence over-deepening the storm), the historical tendency is for storms to strengthen quickly those fiery waters, even under moderately hostile conditions.

 

So I'd expect some deepening, maybe to 900-905mb, but I'm not sure I buy 890mb or lower.

[Kayla]

It's hard to ignore several days worth of GFS runs which at some point take things sub-900mb. I don't recall ever seeing that.

 

00z GFS still peaks it at 897mb just prior to landfall in the previous 6 hour frame FWIW.

[Deweydog]

Looking at video of where Irma has already been... wind damage might be pretty catastrophic in Miami if Irma goes right over the city or just to the west.

Obviously if it landfalls at 180+ with an eyewall trip over the metro area wind damage will be bat crazy. Right now the conventional wisdom seems to be in the 140-150 range.

[BLI snowman]

There is some shear, at least more than the storm has faced so far. But probably not enough to overcome the warmer water and really weaken the storm.

 

It's pretty amazing considering how long this thing has been a major hurricane, but it looks fairly unlikely it will hit Florida as anything less than a Cat 4.

Also it is going to be pulling away from land for awhile after the north turn away from Cuba. I think there was a slight amount of dry air entraining into it today from Hispaniola and maybe a similar interaction tomorrow with Cuba, but smooth sailing after that.

 

The shear in the Florida Straits on Saturday looks pretty minimal, as you said those scalding SSTs should overcome it easily.

[Phil]

Obviously if it landfalls at 180+. Right now the conventional wisdom seems to be in the 140-150 range.

Thing is, none of the models had Irma at 185mph east of the lesser Antilles, and neither did the NHC forecast.

 

If there's one thing I'd fault NHC for, it's an over-reliance on models and an under-reliance on historical tendencies/analog storms.

[Front Ranger]

Record ACE day.

 

 

Some pretty good and some pretty terrible PNW winter analogs!

[Phil]

Also it is going to be pulling away from land for awhile after the north turn away from Cuba. I think there was a slight amount of dry air entraining into it today from Hispaniola and maybe a similar interaction tomorrow with Cuba, but smooth sailing after that.

 

The shear in the Florida Straits on Saturday looks pretty minimal, as you said those scalding SSTs should overcome it easily.

The environment off the FL coast looks even better than the environment it had over Barbuda.

 

The waters arounfd the lesser Antilles were around 84*F and shear was stronger. The waters off south Florida are 90*F and shear is about 5kts weaker.

[BLI snowman]

True, but it's completely out of sync with the official forecast at this point.

NHC is probably factoring in climo. Atlantic hurricanes just don't maintain Cat 5 intensity for very long, especially after ERC's. But this thing has already kinda blown that climo out the window and there just isn't much to inhibit some more deepening before FL, let alone substantially weaken it.

[Deweydog]

Thing is, none of the models had Irma at 185mph east of the lesser Antilles, and neither did the NHC forecast.

 

If there's one thing I'd fault NHC for, it's an over-reliance on models and an under-reliance on historical tendencies/analog storms.

Yeah, it seems like all the technical discussion I've seen on media outlets unanimously indicate slow weakening from here on out. I just can't find an entirely discernable reason to discount several models which show pretty rapid intensification less than 48 hours before possible landfall.

[Deweydog]

NHC is probably factoring in climo. Atlantic hurricanes just don't maintain Cat 5 intensity for very long, especially after ERC's. But this thing has already kinda blown that climo out the window and there just isn't much to inhibit some more deepening before FL, let alone substantially weaken it.

Would be pretty f*cked up if it does...

[Front Ranger]

Yeah, it seems like all the technical discussion I've seen on media outlets unanimously indicate slow weakening from here on out. I just can't find an entirely discernable reason to discount several models which show pretty rapid intensification less than 48 hours before possible landfall.

 

Even with the lowering pressure before landfall, the 0z GFS shows peak gusts for Miami in the 150 mph range. So it would actually be a little weaker wind-wise than it is now.

[luminen]

Ever lived in Victoria?

 

Nope, and I would never live there for multiple reasons.

 

How can it possibly be more frustrating than So Cal?  Portland gets way more different kinds of weather than LA does.

 

Because you never expect anything there. There's 0% chance of snow and any summer rain is a bonus.

[TT-SEA]

Looks like Jose will not be a factor at all.   The media is starting to hype it as being another big hurricane bearing down on the same places destroyed by Irma.   But Jose is going to be weakening and turning out to sea.  

[Geos]

Irma is over 85-degree water now... but there is 89-degree water in its path towards Florida.   Maybe that is why its shown to deepen?

 

00Z GFS is the worst case scenario for Miami.    Actually its shows the worst case scenario for the entire east coast of Florida.

 

 

Yeah that's a bad track.

[Deweydog]

Looks like Jose will not be a factor at all. The media is starting to hype it as being another big hurricane bearing down on the same places destroyed by Irma. But Jose is going to be weakening and turning out to sea.

Now couple that with a fortuitous offshore turn by Irma and you have yourself a media worst-case scenario.

[Geos]

Isn't this trajectory worse?   Everyone gets their turn in the NE quadrant.

 

Yep, right up the most populated corridor of FL.

[TT-SEA]

Now couple that with a fortuitous offshore turn by Irma and you have yourself a media worst-case scenario.

 

Very true.

[Phil]

Even with the lowering pressure before landfall, the 0z GFS shows peak gusts for Miami in the 150 mph range. So it would actually be a little weaker wind-wise than it is now.

The GFS doesn't have the resolution to accurately depict wind gusts in hurricane eyewalls. It peaked wind gusts at 115mph for Barbuda just 3hrs before landfall.

[Phil]

Looks like Jose will not be a factor at all. The media is starting to hype it as being another big hurricane bearing down on the same places destroyed by Irma. But Jose is going to be weakening and turning out to sea.

Huh? It's ready a major hurricane (120mph) and will cross near or right over the northern lesser Antilles.

[TT-SEA]

Huh? It's ready a major hurricane (120mph) and will cross near or right over the northern lesser Antilles.

 

Going to be weakening and should pass north of those eastern islands before turning north into the middle of the Atlantic.

 

Poor Barbuda might feel the strongest effects.

[Jbolin]

Biggest pairing of solar flares to directly impact earth in nearly 15 years and all this D**n smoke and scattered cloud cover screws us again. Where is the onshore flow when you need/want it? 

[Geos]

Huh? It's ready a major hurricane (120mph) and will cross near or right over the northern lesser Antilles.

 

Probably the worst place hit; Barbuda, seems likely to feel the wrath of Jose.

[Deweydog]

Canadian has her down to 980mb in an hour.

[VancouverIslandSouth]

Nope, and I would never live there for multiple reasons.

 

 

Because you never expect anything there. There's 0% chance of snow and any summer rain is a bonus.

 

I reckon Victoria is more frustrating than Portland weatherwise. But aside from constantly being screwed out of snow/convection it's a pretty nice city to live in.

[Front Ranger]

I reckon Victoria is more frustrating than Portland weatherwise. But aside from constantly being screwed out of snow/convection it's a pretty nice city to live in.

 

The distinct lack of hurricanes is also a plus.

[Front Ranger]

The GFS doesn't have the resolution to accurately depict wind gusts in hurricane eyewalls. It peaked wind gusts at 115mph for Barbuda just 3hrs before landfall.

 

Perhaps, but there's also some mets saying that with a storm this large, lower pressure doesn't necessarily mean higher wind speeds. The energy is just spread over a larger area.

[VancouverIslandSouth]

The distinct lack of hurricanes is also a plus.

 

The only significant natural disaster we'd see is a major earthquake. They happen far less frequently but I'd rate them as scarier because you can't see them coming and get out of the way. Looks like Mexico just got hit by a mag 8 quake on the Pacific coast with a hurricane approaching from the opposite Atlantic coast.

[TT-SEA]

The only significant natural disaster we'd see is a major earthquake. They happen far less frequently but I'd rate them as scarier because you can't see them coming and get out of the way. Looks like Mexico just got hit by a mag 8 quake on the Pacific coast with a hurricane approaching from the opposite Atlantic coast.

 

I was just thinking that maybe we will have an earthquake just to add to the natural disaster fun and then the report came in that there was an 8.0 in Mexico.    

[stuffradio]

Huge magnitude 8 earthquake in Southern Mexico.

[TT-SEA]

The smoke is finally cleared out on Saturday!    Montana has been stuck no matter which way the smoke mass ebbs and flows.   

 

[Front Ranger]

Looks like Irma has weakened to Cat 4 for now.

[Deweydog]

Looks like Irma has weakened to Cat 4 for now.

Pretty sure 160 is still a 5.

[TT-SEA]

After a gloomy week of smoke... we have a solid marine layer day tomorrow and then a front with rain on Saturday.   Looking forward to the sun on Sunday... it will have been almost a week since we have seen blue sky.  

[TT-SEA]

Get ready to see 'Miami Strong' everywhere.

[Phil]

Going to be weakening and should pass north of those eastern islands before turning north into the middle of the Atlantic.

 

Poor Barbuda might feel the strongest effects.

Euro takes Jose right over Barbuda as a category 3. After that it's very complicated.

 

From there it weakens due to Irma's exhaust and cold wake but then steering collapses as Irma phases with the ULL and the NE trough evacuates. So it could very well loop around and return much like Jeanne did back in 2005.

[TT-SEA]

00Z ECMWF has Irma at 942mb and a little farther southwest at 48 hours.

 

[SilverFallsAndrew]

After a gloomy week of smoke... we have a solid marine layer day tomorrow and then a front with rain on Saturday.   Looking forward to the sun on Sunday... it will have been almost a week since we have seen blue sky.  

 

So it begins...

[SilverFallsAndrew]

Was hoping we would have seen a bit more rain today. I counted about 6 drops...

[TT-SEA]

Naples is ground zero on Sunday morning per the 00Z ECMWF.   

 

[TT-SEA]

So it begins...

 

It never ends.   I always appreciate blue sky and sunshine here.