MM5FSU Model has Major Hurricane Dennis up FL West Coast

[gatorcane]

that MM5 is still scary...

[Steve H.]

Eric, you bring up a good point. With a high pressure ridge, you can't have it both ways. Currently I don't see any strong ridging to warrant a continued westward path, particularly if this intensifies quickly and slows down. As Stacy Stewart pointed out, a trough is forecast to pull into the east coast. How could this puppy not go poleward, particularly in the wake of Cindy? Not that I want to see anything here. I'm still repairing my ceilings from last year.

[ericinmia]

Also the little discussed coriolis effect can/will cause this storm to move more poleward, ESPECIALLY the stronger and farther north it gets.

So wherever this weakness opens?? The storm should be able to move failry well north. I haven't looked at the lastest model data but this evening's didn't have a strong enough ridge axis to send Dennis west of LO.
-Eric

[Hurricaneman]

The MM5 might just be right for once on intensity

[Wthrman13]

for the 100th time

the FSU MM5 is run at too low of a resolution. MM5 needs to be run much higher, more like under 20km (tomorrow, with Dennis being farther to the west, I can start using 15km instead of 18

I keep meaning a low resolution, not high

Derek, I wonder if it's not so much the low resolution as something involving the surface flux parameterization in the FSU MM5. Simulations of hurricanes are VERY sensitive to the surface fluxes, which is not surprising because they are ultimately driven by them. I don't know that much about how the MM5 is set up there, so I'm not sure. That said, I agree with you, models need to be run at a much higher resolution to have any hope of reasonably handling hurricane intensity, but if the details of the physics of the model are off, particularly the surface physics, then increased resolution is not going to help you.

[Derek Ortt]

I would think it is the resolution.

we have ran past runs on Ivan using different resolutions. The lower the resolution the worse it did. Even a change from 15 to 12km made a significant improvement

[Wthrman13]

I would think it is the resolution.

we have ran past runs on Ivan using different resolutions. The lower the resolution the worse it did. Even a change from 15 to 12km made a significant improvement

Interesting. In some ARPS simulations I did last year of Charley, increasing the resolution from 27 km to 9 km to 3 km did not have much of an effect on the intensity (although I did not run the 9 and 3 km grids for as long as the 27 km, and they were smaller). The lowest central pressure I saw in the model was 979 mb. It appears that the surface flux parameterization in the ARPS over the oceans is likely resulting in too low of a drag coefficient, which is causing the surface fluxes of heat and moisture to be too low, which ultimately is not allowing the hurricane to deepen significantly past a certain point in the model, no matter the resolution. The situation may be different for MM5, and resolution may have more of an impact. A colleague and I are tweaking with the surface physics over water in ARPS to see if we can get a more realistic forecast in the case of Charley, but we are just now starting this.

[clfenwi]

Referring to original post...

It is not quite the bomb-out that it looks like.

See

http://moe.met.fsu.edu/mm5/archive/2005 ... R.pres.png

and http://moe.met.fsu.edu/mm5/archive/2005 ... R.wind.png

Note that it is over pressure for Dennis as he was at 1001 mb at 00z.

[clfenwi]

and the 12Z run is even more over pressure at the moment:

http://moe.met.fsu.edu/mm5/archive/2005 ... S.pres.png