Hurricane Katia

[dtk]

I thought the GFDN was the GFDL with NoGaps initialization and BC, but its worse than just being intialized with an older, poorer performing model. It is an older version of the GFDL with one less nested grid, so it really isn't to be relied on. A couple of the 6Z ensemble perturbations try to stay South of the ridge, but it isn't looking super positive right now for ECUSA action.

Actually, the GFDN is run at the same resolution as the operational GFDL, but you're right that it uses NOGAPS for the IC and boundary conditions (they both use a bogus vortex to initialize the actual storm). Here is the NHC table:

Edit, formatting sucked: NHC Model Documentation (see table 3)

The only thing I'm unsure of is if the Navy versions takes the (yearly, typically physics) updates that get put into the NOAA-run (NCEP/GFDL) version.

[PSUBlizzicane2007]

Actually, the GFDN is run at the same resolution as the operational GFDL, but you're right that it uses NOGAPS for the IC and boundary conditions (they both use a bogus vortex to initialize the actual storm). Here is the NHC table:

The only thing I'm unsure of is if the Navy versions takes the (yearly, typically physics) updates that get put into the NOAA-run (NCEP/GFDL) version.

I always thought they made their own updates to the GFDN?

[Ed Lizard]

I must have read something old about how many grids the GFDN had. My bad.

[dtk]

I always thought they made their own updates to the GFDN?

You may very well be right. I'm sure they collaborate with the GFDL folks, but I'm not really sure what their arrangement is (I was under the impression that they adopted/inherited GFDL changes eventually, once tested....but they could very well be doing their own thing).

[MJO812]

12z GGEM

It looks more south and west than the GFS.

[snowNH]

12z GGEM

It looks more south and west than the GFS.

How does this compare with last nights euro?

[MJO812]

How does this compare with last nights euro?

The GGEM is south and slower than the Euro.

[Scuddz]

How does this compare with last nights euro?

It doesn't

[donsutherland1]

Some quick thoughts today...

1. I still believe recurvature is more likely than not (possibly somewhere in the vicinity of 65W-70W).

2. The prospect of at least a closer pass than some of the previous guidance had suggested seems to be growing. The ECMWF Ensemble mean has hinted at it for several cycles. The 8/31 12z GFS has moved into reasonable agreement with the 8/31 0z ECMWF Ensemble mean.

3. Historical climatology associated with storms with origins in the proximity where Katia formed suggested that Katia would become a hurricane somewhere between 39.5W and 44.5W. With Katia at 40.8W at 11 am, that should be sometime today. At 5 pm, I suspect that it will either be a hurricane with 75 mph winds or a tropical storm with 70 mph winds given continued satellite presentation improvement. At 11 pm, I would be surprised if it were not a hurricane.

It will be interesting to see if the 12z run of operational ECMWF moves into better agreement with its ensembles and also the 12z GFS.

[battlebrick]

The Euro seemed to recurve Katia but at 168 hrs it goes back to due west.

[blazess556]

12z Euro from 144 hrs to 168 hrs moves Katia almost due west. It is probably a 275-280 heading during those 24 hrs.

[Juliancolton]

12z Euro from 144 hrs to 168 hrs moves Katia almost due west. It is probably a 275-280 heading during those 24 hrs.

Where is it at 168 (rough coords)?

[blazess556]

Where is it at 168 (rough coords)?

It is roughly at 25 N, 66 W.

[thewxmann]

12z Euro from 144 hrs to 168 hrs moves Katia almost due west. It is probably a 275-280 heading during those 24 hrs.

Yeah, it misses the first trough and a temporary ridge builds behind it. I still give Katia a 95% chance of recurvature, but it might get closer to the U.S. than people think, depending on how 93L develops.

EDIT: Actually this thing is going to come very close to the U.S. if the 12Z Euro verifies (just from looking at the run thru hr 192).

[donsutherland1]

Yeah, it misses the first trough and a temporary ridge builds behind it. I still give Katia a 95% chance of recurvature, but it might get closer to the U.S. than people think, depending on how 93L develops.

That kind of solution where the trough misses Katia and then the weakness closes was hinted at on yesterday's 12z run of the ECMWF ensembles. It's an interesting solution, to be sure.

[djr5001]

Euro and GFS greatly differ in how to handle system in Gulf... GFS has it get pulled north with a trough and Euro sends it south and west to the southern tip of Texas... Euro has strong high pressure over northeast to turn it west and doesnt have the weakness in the ridge like the GFS to allow Katia to recurve... what is interesting is that on Euro it slows down as it approaches 70W then turns almost due north/northeast right at 70W (25-27Nish)

*(edit: this is talking out to hr 222)

[Ed Lizard]

Where is it at 168 (rough coords)?

Did you know you can find things liken that right here at American, look at the "models" tab upper right. Alan Huffman maintains a model site for almost every purpose.

http://raleighwx.americanwx.com/models/ecmwf.html

[Juliancolton]

Did you know you can find things liken that right here at American, look at the "models" tab upper right. Alan Huffman maintains a model site for almost every purpose.

Yeah, it wasn't out on that site yet though

[Dunkman]

Well it bounces off of 70W like it's a wall, but still a really significant run that raises a lot of questions about the environment Katia will be in later in the period. Interested to see what the pros have to say, should make for some really good discussion today.

[LakeEffectKing]

So now the Euro slows this down so much, that it is back to a 9+ day threat....as I've said before....models at these leads can change quite drastically. IOW, any forecaster skill above climo is gererally not generally detectable outside 7 days...

[phil882]

That kind of solution where the trough misses Katia and then the weakness closes was hinted at on yesterday's 12z run of the ECMWF ensembles. It's an interesting solution, to be sure.

I think another key point is that the 12z ECWMF is also hinting at weakening between the 48-96 hour period. This might make it more susceptible to lower level steering at its weakest point, making it less likely to be picked up by the first trough. Its already at a significant latitude north though beyond 72 hours, so its still going to be rather difficult to get this system all the way to the East Coast, and even despite this more westward motion between 120-168 hours, the ECWMF does eventually steer Katia out to sea.

[atownwxwatcher]

The latest Euro does not steer Katia out to sea.

Actually it does ..

[djr5001]

I really think the way it looks now what happens with this system headed for the Gulf will be key in Katia's future. I noticed earlier that the hurricane models that had a turn west and excited some people does not have this Gulf system come in to play for the southeast US much like the Euro is currently showing. Both the hurricane models and Euro build a stronger ridge far enough west in the Atlantic to turn Katia west (before turning north and east near 70W) while the GFS has a trough move through eastern US and interact with that Gulf system. Therefore there is not as strong of ridge far enough west in Atlantic and Katia heads for the weakness and recurves away from east coast. Again, like everyone else has pointed out we are still over a week away from this even remotely being any form of threat so plenty of time for models to change quite a bit. It is just interesting to see what different scenarios 12z GFS and Euro have shown today.

[tmagan]

The latest Euro does not steer Katia out to sea.

Eventually it does. But, then again, tropical cyclone path forecasts beyond three days are fraught with error possibility.

[MarkSC]

Very weird run from the Euro. It seems that the trough should either be strong enough to take the storm fishing, or the storm should miss the trough and the ridge should be strong enough to bring it to FL or the SE. Euro can't seem to decide which and so has the storm go WSW from a strong ridge, then weaken, then head NNE even though there is no strong trough. A long way to go yet with K. Nogaps, CMC, and now Euro seem to be in agreement that K will miss the trough. That does NOT mean a U.S. strike is then inevitable, as the Euro shows that out to sea is still possible, but it would make it interesting and add another 5 days or more of tracking for us.

[stormspotterlive]

With what the 12z Euro puts out the 12z Euro ensembles should be rather interesting. With it being this far out any thing can happen given how fast things can change. But over all a Recurve is still likely. maybe just a bit closer then we earlier thought.

[Hugo]

Very weird run from the Euro. It seems that the trough should either be strong enough to take the storm fishing, or the storm should miss the trough and the ridge should be strong enough to bring it to FL or the SE. Euro can't seem to decide which and so has the storm go WSW from a strong ridge, then weaken, then head NNE even though there is no strong trough. A long way to go yet with K. Nogaps, CMC, and now Euro seem to be in agreement that K will miss the trough. That does NOT mean a U.S. strike is then inevitable, as the Euro shows that out to sea is still possible, but it would make it interesting and add another 5 days or more of tracking for us.

The models are saying to worry about Katia...

If you're in Bermuda.

[PSUBlizzicane2007]

Very weird run from the Euro. It seems that the trough should either be strong enough to take the storm fishing, or the storm should miss the trough and the ridge should be strong enough to bring it to FL or the SE. Euro can't seem to decide which and so has the storm go WSW from a strong ridge, then weaken, then head NNE even though there is no strong trough. A long way to go yet with K. Nogaps, CMC, and now Euro seem to be in agreement that K will miss the trough. That does NOT mean a U.S. strike is then inevitable, as the Euro shows that out to sea is still possible, but it would make it interesting and add another 5 days or more of tracking for us.

All of you weenies need to look at hour 216 of the Euro. Yes, it's far out, but it also shows consistency in terms of a recurve. This is not a significantly further west recurve... this is pretty much the same except just before hour 216, she gets bumped a little to the west before being recurved by that gigantic trough of no escape coming off the east coast.

[MarkSC]

All of you weenies need to look at hour 216 of the Euro. Yes, it's far out, but it also shows consistency in terms of a recurve. This is not a significantly further west recurve... this is pretty much the same except just before hour 216, she gets bumped a little to the west before being recurved by that gigantic trough of no escape coming off the east coast.

The point is that it misses the early week trough (unlike what it showed the last 2 days), which is a significant difference and now matches what the Nogaps and CMC have been showing with their west turns. If I'm a weenie for pointing that out, so be it.

[donsutherland1]

Its already at a significant latitude north though beyond 72 hours, so its still going to be rather difficult to get this system all the way to the East Coast, and even despite this more westward motion between 120-168 hours, the ECWMF does eventually steer Katia out to sea.

I agree. I still think recurvature is the more likely scenario (my guess is that Katia could get as far west as 65W-70W, but a lot can still change).