ATL: DANNY - Models

[ronjon]

Looking at last nights euro run I realized it actually moved the storm south of west for a few days. When was the last storm to move south southwest in this region?

http://moe.met.fsu.edu/cgi-bin/ecmwf-opertc2.cgi?time=2015081800&field=Sea+Level+Pressure&hour=Animation

unusual for that deep in the tropics but the setup this year is unusual....modeling is going to be marginal the rest of the season not that it has been stellar the last few years

NHC discusses in their 11 am advisory - mid-level ridge rebuilds forcing the storm on a more westward or even slight w-sw during days 4 and 5.

[Frank2]

Considering the ridge is pretty consistent through Day 10, it could also do what a number of fairly strong systems have done the past 5 years - stay on a westward course into Central America.

Right now that seems possible, but hopefully the strong shear will play a role...

[Blown Away]

12z

[SeminoleWind]

Considering the ridge is pretty consistent through Day 10, it could also do what a number of fairly strong systems have done the past 5 years - stay on a westward course into Central America.

Right now that seems possible, but hopefully the strong shear will play a role...

I had the same idea in mind as well. But all it takes is a little weakness down the road.

[gatorcane]

12Z GFS has shifted a bit more north sending it into the NE Leewards/Puerto Rico on a WNW heading but also shows it opening up into a sharp trough.

[Alyono]

BS Flag raised again on MU (not like that is anything new). Favorable environment, yet it weakens it to a wave moving through the islands

[gatorcane]

Yes could be B.S. on the MU.

But even weak it is not showing a Caribbean cruiser and sends it WNW. Wonder if it were stronger if it would end up just a little north of the Leewards/Puerto Rico (ala UKMET). That is where conditions could be quite favorable.

[NCSTORMMAN]

GFS has done poorly and the Euro have done poorly. I am sticking with a mix of UKMET for path and SHIP model for intensity.

[WeatherEmperor]

BS Flag raised again on MU (not like that is anything new). Favorable environment, yet it weakens it to a wave moving through the islands

I hate asking this but why why why does the Gfs have a tendancy to do this??

[gatorcane]

12Z GFS 192 hours, 700MB chart - GFS has weakened TD #4, but the vorticity is just a little NE of Hispaniola on the Atlantic side with that ridge to the north. Would think it would head WNW towards the SE Bahamas. Fortunately there is a TUTT that is sitting right over the SW Atlantic / Bahamas that would shear it apart. Of course all out in the long-range and just speculation at this point.

[PTrackerLA]

Looks like it is the GFS vs NHC on this one .

[tropicwatch]

Bet I know who wins

[SeminoleWind]

IMO (which don't mean much) The GFS has always been less trustworthy that far out.

[CrazyC83]

I still wonder what is making the models move it north, when the ridge is supposed to only strengthen in the days to come?

[Alyono]

I still wonder what is making the models move it north, when the ridge is supposed to only strengthen in the days to come?

MU is notorious for moving TCs through ridges

[gatorcane]

I still wonder what is making the models move it north, when the ridge is supposed to only strengthen in the days to come?

It's the orientation of the ridge. In the latest GFS run, you can see it has a ESE to WNW orientation which would move the system WNW.

As for the shorter to medium range, the UKMET gets the system deep enough so that it hits the weakness to the north, but then the weakness fills in so the UKMET bends it back WNW. It's an entirely plausible scenario. The UKMET has not budged from this solution so is very consistent with it.



00Z UKMET:

[Frank2]

Perhaps the ridge isn't forecast to be very deep, or because systems that strengthen that far east usually turn northward, though the NHC does seem to be favoring the UKMET outcome.

Too early to tell, as usual : )

[gatorcane]

Perhaps the ridge isn't forecast to be very deep, or because systems that strengthen that far east usually turn northward, though the NHC does seem to be favoring the UKMET outcome.

Too early to tell, as usual : )

Frank from what I can see there will be a strong ridge across the Western Atlantic next week. Even if the system were strong I don't think it could escape. Lots of time to watch but haven't seen a setup like this in years this time of year. We are so used to a big trough off the East Coast of the U.S. instead.

For example, here are the 00Z ECMWF ensembles (of course it is long-range and subject to change). Look how they expand the ridge westward between hours 144 and 240:

[gatorcane]

12Z GEM, near Puerto Rico:

[gatorcane]

I am going to have to give the UKMET model kudos on this. Judging by the way things are unfolding. This model has nailed this one. Just go back and look at the model runs. Clearly it is outperforming the GFS and ECMWF right now. Perhaps those upgrades are paying off for that model.