2015 Global model runs discussion

[lordkev]

Why am I seeing only 1003mb in the same timeframe? Using Tropical Tidbits.

12Z GFS 126 hours, down to 983MB:

[RL3AO]

Likely a resolution thing with one map being 13km grids and the other being 27km or something.

[tailgater]

Can someone tell me if there's something going on in the Western gulf o I'm on my phone thanks in advance

[chaser1]

Why am I seeing only 1003mb in the same timeframe? Using Tropical Tidbits.

12Z GFS 126 hours, down to 983MB:

Good question, and fortunately easy answer. When one goes to Tropical Tidbits Model website and then clicks on the GFS model, it first is defaulting to a particular map under the "Precip/Moisture" (Grey Button at bottom of that page). This map is not necessarily viewing the surface pressures in a detailed display but only showing a more broad outlay of the pressure field. Solution? While on the same Model page (still while having chosen the GFS model), notice the other grey buttons at the bottom of the page and click on the one labeled "Lower Dynamics". Now, click on the link labeled "Surface Pressure and 10M Winds". Then, you should be good to go!

[chaser1]

Can someone tell me if there's something going on in the Western gulf o I'm on my phone thanks in advance

Western tail end of of old frontal trough that extends west across the Northern Gulf, and out of some persistent Mesoscale feature just off Florida's West coast. There is evidence of some weak cyclonic motion at some level, just off of Corpus Christi but this looks weak and likely to be transitory. I did not take the time to look at local radar or at what levels the present analysis shows this weak feature at, but could enhance local precip

[tropicwatch]

Buoy readings indicate weak surface circulation from checking wind directions just south of western Louisiana.

[lordkev]

Thanks! Figured I might be on the wrong one.

Good question, and fortunately easy answer. When one goes to Tropical Tidbits Model website and then clicks on the GFS model, it first is defaulting to a particular map under the "Precip/Moisture" (Grey Button at bottom of that page). This map is not necessarily viewing the surface pressures in a detailed display but only showing a more broad outlay of the pressure field. Solution? While on the same Model page (still while having chosen the GFS model), notice the other grey buttons at the bottom of the page and click on the one labeled "Lower Dynamics". Now, click on the link labeled "Surface Pressure and 10M Winds". Then, you should be good to go!

[tailgater]

Thanks guys the little weak low in the NW GOM looked like something on the cheap radar loop I had.

[gatorcane]

The Euro is rolling now and does not show the Cape Verde system the GFS is developing. The only other model that shows some possible development is the GEM but it is quite a bit weaker and slower than the GFS.

Could the GFS be so wrong when calling for development to commence in 48-54 hours from now? Guess we will find out.

The wave the GFS is developing is starting to really build some convection the last several hours so there is an incipient area and it is not like the GFS is just forming it out of thin air.

[TheStormExpert]

Either it's the GFS's time to shine, or time to bomb hard as usual.

[gatorcane]

12Z GFS Ensembles tightly clustered just south of the Cape Verde Islands by day 3:

[blp]

I don't know if the GFS is going to bust here on this wave but from what I can see the wave has a few things going for it right now. It will be interesting to see what happens. The Euro still has the vorticity but does not develop after it leaves the coast.



SAL quite good:

[blp]

More from the GFS, it is really likes the E. Atlantic in Mid August. This coincides with the next strong wave that both the Euro and GFS are forecasting to emerge from the coast. Could get interesting soon.

[Hammy]

Latest run is now showing development in ~48 hours with a 1005mb low, but doesn't seem to be too strong with the winds.

[TheStormExpert]

Latest run is now showing development in ~48 hours with a 1005mb low, but doesn't seem to be too strong with the winds.

As of hr.138 it has a 992mb low, takes a few days to get going.

[Siker]

Trending weaker (but not to "next run will drop it" levels yet) and a little further south so far this run.

[Siker]

GFS also has the Euro's high latitude day 10 storm.

[Hammy]

The next few days will be interesting as far as the models go. GFS was the only one to show the two southeast storms not developing, while the Euro showed strong systems (and both being upgraded recently.) GFS has been very consistent and moved the point of genesis closer with each run, with Euro still showing nothing. If this doesn't form then we still have the same issues and the EC model storms were likely due to bad upper air data. If this does form though, we could have the GFS/Euro swapping, with the GFS being the more trustworthy model (though we'd need more than one instance to confirm this). Either way the next 48-60 hours will be very telling concerning the quality of the model upgrades.

[tolakram]

Historically (well, for a short time) the GFS has been more accurate with genesis. This was not the result of the GFS simple creating more storms and scoring a few hits, it predicted genesis correctly and had fewer false positives than other models. Last year we know what happened but some years are just really bad for a model, in my opinion, and it seemed like conditions last year exploited the GFS weaknesses.

If the GFS scores this time we might think of it as getting back to normal. I have to think with the horrible conditions, similar to last year, we're going to see a repeat bad performance but who knows.

This was the graph from the 2013 article. If it extended out from 2011 I suspect the GFS and Euro would be neck and neck.



It also seems to be basin specific. Here's a more recent article discussing model performance.

http://www.ofcm.gov/ihc14/presentations/Session4/s04-09-IHC68-tcgen2.mike.fiorino.20140305.pdf

Which contains the heading ..
…maybe those d!*#%ng models are pretty good after all…

[tolakram]

Oh,

and the GFS has completely dropped this storm. It breaks apart the vorticity almost as soon as it leaves Africa. Looks like the same thing as last year.