Are BAMM & BAMD More Viable Models Right Now?

[tropicstorm]

With weaker tropical systems (albeit, Irene has now moved westerly enough to enter an environment that should enhance development) and particularly, systems that are more subject to low level flow, don't the BAM models have a pretty good historical performance rating on eventual storm path? The BAM models have been the only ones bullish on the more westerly (or, southwesterly) track all along - now, it appears that the NHC is possibly jumping on this bandwagon.

[WeatherEmperor]

I wouldnt know for sure but the BAM models have been the ones suggesting a more westwards track while most of the globals wanted to take her out to sea. but there seems to be a slight better agreement now.

<RICKY>

[stormchazer]

From reading and watching on Storm2K and other boards I have heard that the BAMM Models are better with low level flow systems which means they are probably the models to watch with shallow systems, like Irene has been the past week. It is a much older and less effective Model overall though.

From Hurricane Alley website:

BAM (Beta and Advection Model)...
This model follows a trajectory from the Aviation run of the MRF model to provide a track forecast. This model incorporates a correction known as the "Beta Effect". This is used to account for the fact that the Coriolis force resulting from the rotation of the earth is greater toward the poles, so the winds on the northern side of the storm in the Northern Hemisphere tropical cyclone are turned more than those on its southern side. If no other winds were steering a tropical cyclone the "Beta Effect" would cause a westward-headed storm to drift toward the north in the Northern Hemisphere, and toward the south in the Southern Hemisphere. There are three (3) versions of the BAM...

1.. BAMS - the BAM Shallow, this version averages winds from 5,000 to 10,000 feet (850 - 700 mb)
2.. BAMM - the BAM Medium, this version averages winds from 10,000 to 24,500 feet (850 - 400 mb)
3.. BAMD - the BAM Deep, this version averages winds from 24,500 to up to 47,000 feet (850 - 200 mb)

For a weak hurricane without a well-developed eye wall extending deep into the atmosphere, or for a tropical storm, the shallow version of the model may work well, because storms of this nature tend to be steered by low-level winds. As the storm grows stronger and the eye wall gets deeper the deeper versions become more accurate, for these types of storms are steered more by the winds in the upper-level. If the forecast from the three versions is similar the forecaster can then assume that the storm may go as predicted, but, if the version vary by a great deal, then the forecaster has less confidence in the track predicted. The large differences can also point to wind shear in the atmosphere, which could affect the intensity forecast as well.

[mahicks]

er...
aren't BAMM BAMD pretty much the same model?

BAMM=medium...for weaker systems
BAMD=Deep.......... for stronger..read higher cloud top systems?

And I thought the general consensus is that both models are more for the DEEP tropics and historically not good above 20N?

Plz correct me if I'm wrong or misguided