Major Hurricane Irma

[rolltide_130]

3 minutes ago, Ralph Wiggum said:

Ugh. This is not good, not that I am expressing anything we already didnt know.

So what is our best hope at this point? A track which makes LF west of Key Largo then stays inland? A track that clips Cuba barely and weakens slightly? A track that remains East of FL?

Im in the camp that there really is no good modeled solution at this point, just want to hear other thoughts. Even if it skirts FL to the East its like robbing Peter to pay Paul as it remains strong over warm water before slamming SC(?).

Sent from my LG-V410 using Tapatalk
 

Honestly, your best hope is a total recurve which still isn't completely impossible, but it's not looking too hopeful by now either. 

 

Beyond that, there's really not many good options. Brushing Cuba and then landfalling in the swamps of SW FL is probably the best one, but the Keys would still get demolished. 

[RichardJacks]

Here is a great illustration I found on twitter

 

[friedmators]

4 minutes ago, klw said:

Interesting outer ring now showing up on MIMIC.  Had not seen this before with this one but can only find a GIF and not a still of the end.

 

I was just going to make a post about this.  Have to assume ERC but its a good 75 km away which would imply a long process.

EDIT: ERC analysis shows brightness around 75km.

[adiabatic13]

GOES16...warming, shrinking and more symmetrical eye, no signs of weakening evident at the moment

[Casualbrain]

1 minute ago, RichardJacks said:

Here is a great illustration I found on twitter

 

And here's a good steering current animation that helps understand this pic http://tropic.ssec.wisc.edu/real-time/atlantic/movies/wg8dlm1/wg8dlm1_loop.html

 

[CoastalWx]

43 minutes ago, jpeters3 said:

 

I'll agree that an expanding wind field is likely once the system begins to interact with the baroclinic zone and starts undergoing ET.  Seems to me based on model guidance though that the forecast for decreasing intensity in models is (1) because they generally don't show maintained intensity Cat 5 for whatever dynamical or numerical reasons (they've been showing weakening for a day and a half), and (2) because they are fairly well anti-correlated with vertical shear (which should gradually increase over the next few days).  Human forecasts (NHC) have shown decreasing intensity in accordance with model guidance, and the low statistical likelihood that TCs maintain 150 kt + intensity for an extended period of time.
 

Great post. Thanks for the one stop shop graphic!

[jpeters3]

1 minute ago, CoastalWx said:

Great post. Thanks for the one stop shop graphic!

Here's the link to the model graphic (and others like it):

http://rammb.cira.colostate.edu/products/tc_realtime/storm_model_data.asp?storm_identifier=AL112017

[NJwx85]

Just to give you an idea of the windfield, this is the NAM, but I think it can be somewhat useful here. For those that don't know, you're looking at the lowest 3 layers of the atmosphere. 925mb is about 2500 feet up. 850mb is about 5000 feet up. For reference, the Freedom Tower in NYC is just under 1800 feet to the tip.

[cwc]

Per the 8:00 advisory, hurricane force windfield extends 50 miles from center.  MIA can handle a 75 mph wind - the building codes post-Andrew are pretty good.  The question is how far from center the Cat 3-4-5 winds extend.

 

So a wobble of 25 or 50 miles makes a world of difference here.

[LakeEffectKing]

8 minutes ago, friedmators said:

I was just going to make a post about this.  Have to assume ERC but its a good 75 km away which would imply a long process.

EDIT: ERC analysis shows brightness around 75km.

No...it shows concentric eye walls, not ERC.  Concentric EW's can, and have in past cases, been quite stable. (as long as they remain far enough apart)

[friedmators]

1 minute ago, LakeEffectKing said:

No...it shows concentric eye walls, not ERC.  Concentric EW's can, and have in past cases, been quite stable. (as long as they remain far enough apart)

Thanks for the correction.  Pretty neat on MW.  This is the cat5 inside a cat2 you were referencing I guess.

[jm1220]

2 minutes ago, cwc said:

Per the 8:00 advisory, hurricane force windfield extends 50 miles from center.  MIA can handle a 75 mph wind - the building codes post-Andrew are pretty good.  The question is how far from center the Cat 3-4-5 winds extend.

 

So a wobble of 25 or 50 miles makes a world of difference here.

The major hurricane winds would just be in the eyewall. So there would likely be a 50 mile radius or so that experiences that kind of wind. Hopefully the east solutions win and the center can stay offshore. 

[donsutherland1]

32 minutes ago, bluewave said:

Remarkable Euro performance so far with only about a 60 mile track error with the 72 hr forecast.

 

 

 

To date, the ECMWF has performed exceptionally well over the 5-day period. Even as past performance is no guarantee of future outcomes, both its overall level of skill and its performance in handling Irma so far merit giving its solutions greater weight than the guidance that has fared less well.

[winterymix]

1 minute ago, donsutherland1 said:

To date, the ECMWF has performed exceptionally well over the 5-day period. Even as past performance is no guarantee of future outcomes, both its overall level of skill and its performance in handling Irma so far merit giving its solutions greater weight than the guidance that has fared less well.

Don:

 

I'd find it interesting if you could share your thoughts about potential inundation in the Miami area.

It occurs to a number of folks watching this unfold that perhaps nearly every building in Miami could

have water damage at least on the ground floor.

[SnowGoose69]

15 minutes ago, NJwx85 said:

The best case scenario right now is that the eye stays far enough East that is misses most of Florida, and then hits the Carolinas as a much weaker but still formidable cane.

I think we can get it assuming this doesn't approach the FL peninsula from the S or SSE any west of 80W.  These things like to for whatever reason, be it friction or just natural tendency to somehow seek water environment try to avoid landfall.  So a system moving N or NNE along 80W may just continue skirting just offshore the entire way up the SE peninsula and keeping at least some areas out of the worst conditions 

[MillvilleWx]

43 minutes ago, LakeEffectKing said:

Your take on my take was correct (in your original post).  Also, every model has this expanding in size (wind field), that energy comes from the boundary (higher SST's), but also from an expanding core.  The pressure gradient through the entire storm, and most likely into the core, should decrease a bit, even with the system obtaining a stout low pressure.  Factor in the likelihood of increasing shear 6-10 hours from LF, and you get some additional slackening of the max winds, even without a robust pressure increase.

This makes sense. I've been skeptical on the intensity aspect of the storm for a while now with NWP lagging behind on the observed trends with Irma and the eventual numerical output. I agree with jpeter on that front for sure, but I feel the biggest reason for a incremental decrease in max winds is the what you mentioned with the expanding core and the increasing size of Irma in general. It's been unanimous on guidance the wind field will be expanding around the system as she heads through the Bahamas and towards the US and in a physics sense, I gotta feel the winds would eventually adjust down just due to sheer size and the decreasing pressure gradient. It's tough to argue the figure skater analogy. If this storm had a small eye, wind speeds would likely be at over 200mph given the lack of shear and dry air intrusion over the last several days with such a robust core. It's been a sight to behold out in the Atlantic. 

[jbenedet]

25 minutes ago, OUGrad05 said:

That is a large spread and there's a lot of people that do not realize that spread exists.  There is still a tremendous amount of uncertainty on track.

Follow the tracks that are closest to Irma's current position...you can filter out a number of solutions already...

[OUGrad05]

Just now, jbenedet said:

Follow the tracks that are closest to Irma's current position...you can filter out a number of solutions already...

Agreed but the forecast uncertainty remains quite high for a quickly approaching projected landfall.

[donsutherland1]

7 minutes ago, winterymix said:

Don:

 

I'd find it interesting if you could share your thoughts about potential inundation in the Miami area.

It occurs to a number of folks watching this unfold that perhaps nearly every building in Miami could

have water damage at least on the ground floor.

A large part of Miami would be inundated by a 10-foot storm surge.

Here's a useful tool for those who are interested. One can click anywhere on the map to check the elevation.

http://en-us.topographic-map.com/places/Miami-7034739/

[NJwx85]

Recon is headed back in to do another NW to SE pass of the RFQ.

[5speed6]

4 minutes ago, donsutherland1 said:

A large part of Miami would be inundated by a 10-foot storm surge.

Here's a useful tool for those who are interested. One can click anywhere on the map to check the elevation.

http://en-us.topographic-map.com/places/Miami-7034739/

The interaction with the Bay could also be a significant factor in how/where surge becomes a major problem, all dependent on the final approach track, of course. 

[Parterre]

What are the chances Irma breaks 190mph over the next few days?

[jbenedet]

Nam already noticeably south out to 9hr versus 6z

[OUGrad05]

Anyone noticing how large the windfield is on the N Side of the storm with current recon?  Pretty impressive winds well out from the center of circulation.

 

Re: 190mph, seems possible but perhaps a long shot. Going over the PR trench, stirring up some cooler water and other environmental influences we may see it slowly weaken a bit in the near term before intensifying again tomorrow.  But getting to 190 is tough, though with this storm?  Anything is possible.

[CTWeatherFreak]

2 minutes ago, jbenedet said:

Nam already noticeably south out to 9hr versus 6z

Does it matter that Nam init  value for strength is 40mb too weak?

[psv88]

3 minutes ago, CTWeatherFreak said:

Does it matter that Nam init  value for strength is 40mb too weak?

It's about trends. NAM trending South or West would be bad.

[Drz1111]

3 minutes ago, OUGrad05 said:

Anyone noticing how large the windfield is on the N Side of the storm with current recon?  Pretty impressive winds well out from the center of circulation.

 

Re: 190mph, seems possible but perhaps a long shot. Going over the PR trench, stirring up some cooler water and other environmental influences we may see it slowly weaken a bit in the near term before intensifying again tomorrow.  But getting to 190 is tough, though with this storm?  Anything is possible.

The PR trench has no bearing on water temps or upwelling.  There is a slight increase in near shore upwelling due to Ekman transport every time it passes north of an island.

[jbenedet]

2 minutes ago, CTWeatherFreak said:

Does it matter that Nam init  value for strength is 40mb too weak?

I agree with what psv88 said above. But what's most important is it is being modeled correctly as a vertically stacked TC.

[Chicago Storm]

Does it matter that Nam init  value for strength is 40mb too weak?

No.

The plotted initialization number you see will almost always be off on most guidance.

This is why Ryan Maue's tweet about the GFS being so far off with an initialization pressure yesterday was pointless.

[OUGrad05]

Just now, Drz1111 said:

The PR trench has no bearing on water temps or upwelling.  There is a slight increase in near shore upwelling due to Ekman transport every time it passes north of an island.

Explain, because everything I've read including a conversation I had with a friend at NWS indicate that these storms and Irma in particular with the low pressure will pull up cooler waters that are cooler.  This slightly cooler water may serve to limit intensification until the waters become shallower, which they do fairly quickly once out of the trench.