Post by Wyatt Erminger on Sept 12, 2008 11:47:08 GMT -6
I'd think of it more as predicting rather than dictating the movement.
Thats what I think also. Its one of the first signs it may be heading that way.
There are several factors to consider here as far SFC pressure...
1. Diurnal changes, which naturally, during the daytime (in summer mainly) are going to fall due to surface heating.
2. Pressure field of the storm is so expansive, pressure falls are going to occur all over the NW GOM.
3. The steering features, 700-300MB flow, lag behind SFC features into colder air as you go up in the atmosphere, especially in this case since we're dealing with a pretty potent trof that is of a baroclinic nature. That's why we've paid so much attention to the CIMSS analysis, the global models, etc. because they paint a far greater picture than just SFC features.
SFC pressures were a good indicator that something was coming, but it wasn't a specific enough method to indicate where. Great examples are the standalone desktop weather stations that are so common today. They look at pressure trends and if they see a pressure fall, they say 'Oh, it's gonna rain tomorrow!' Or pressure rises, 'Oh, it's gonna be sunny!' It's just a very general tool if no other tools were available to say that something is out there. Back in the day when there was no GOES-12, no massive upper air soundings, no models, and a lack of understanding of what steered tropical systems - all we had were pressure trends at the surface. Another comparison, did anyone ever have one of those little porcelain frog statues in the toadstool that used to say if was going to rain or be sunny, where it would turn around with its back to you when it was going to rain or face you if it was sunny? Basically, it was a simple hygrometer, but it was in no way accurate enough to say if it was really going to rain. Same kind of deal.
Now we're beyond the point of what the models forecasted, we're just going to have to stare this one all the way in, which seems to be trending a little further to the east. The brief slowdown we saw earlier was so critical in the track, b/c the trof coming in is still digging in while the storm paused briefly. This was the only way I felt last night that SW LA could have taken the eye.
