Friday, August 17, 2007

[Jyo_hurricane] Hurricane Dean: August 17, Update C

Well, the good news is that there isn't anything following Hurricane
Dean in the Atlantic at the moment (as far as I can see).

The bad news is really er... not so good :). He is a mid-to-strong cat
3 with sustained winds of 125 mph (109 kt) (cat 3: 111-130mph;
96-113kt). He is slowly slowing, and is now moving forward at (still
rapid) 21 mph. The min pressure is 961 mb and although a plane has
already been in the system once today, they will be sending another in
later today. What would we do without these planes (and when can I go up
in one)? The eye is at about 15N, 64.5W. He's over water temperatures of
around 29 deg C, in a region of low wind shear, and not interacting much
with land. All conducive to an increase in intensity.

This means that there is still nothing to stop him intensifying further.
It looks like that low I mentioned yesterday (was it only yesterday?) is
pulling him a bit more northwards but I don't know how much longer that
will have an impact. There is no good scenario at this point. The best
scenario would be that his track is even more north than the current
one, taking him over or very close to DR/Haiti and Cuba (eye within 30
miles) - and the only reason that is a good track is because it would
keep the intensity down a bit. The wind shear that I also mentioned
yesterday is weakening so I don't know how much that will impact this
storm (alas).

The only consolation in this is that currently the hurricane force winds
are confined to a small area, extending 30 miles from the center -
really small relative to the area that tropical storm winds are being
felt (out to 185 miles). There is a lot of rain across this system
though. To see the extent of the wind field from the center of the
storm, go to the nhc web page ( and click on the top
set of graphs in the Hurricane Dean box (one shows hurricane wind speed
probability, the next is the 50 kt wind speed and the third is the
tropical storm force winds). Then you can see who might be in a
particular wind field.

It is still too early to say what will happen after the next 24 hours.
Until that point, I agree with the official forecast, but beyond that I
am not so sure of the track (and therefore the intensity). It seems that
the models are also thinking along different lines after the next ~24
hours regarding the track (I think they agree on the intensity). The
GFDL model (a really good model - and I'm not just saying that because
there is someone who reads this who works on that), is predicting
landfall in Louisiana, whereas the UKMET (for example; another good
model in my unbiased opinion) is predicting landfall over Mexico but
barely clipping the Yucatan Peninsula, and NOGAPS is predicting landfall
closer to Belize. This is a good test to see which model is doing well
this year. I can see all of these as still being good possibilities
(I'll try and be less wishy washy in 24-36 hours :) ). Even out to three
days the models have some tracks going north of Jamaica and others going
south - these two tracks will result in different intensities, so the
tracks are really quite important.

I have to reiterate what the NHC is saying at this point: everyone in
the Caribbean and Gulf states should keep an eye on this storm (you can
use your other eye to do other things).

Ciao for now...

These remarks are just what I think/see regarding tropical storms - not
the opinion of any organization I represent. If you are making an
evacuation decision, please heed your local emergency management and the
National Hurricane Center's official forecast and the National Weather
Service announcements. This is not an official forecast. If I "run away,
run away" (Monty Python), I'll let you know.

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