Tuesday, August 26, 2008

Hurricane Gustav: August 26 Update A

As we expected since yesterday, he is now a hurricane. Also as expected,
they have shifted his forecast track near Cuba in a more westward
direction, changing his forecast track from a NW direction to WNW. The
forecast calls for this to happen tomorrow.

Intensity: He is a strong little fella with max. winds near 90 mph (cat 1
range: 74-95 mph). It is difficult to find an eye at the moment and an
exact center of circulation, but he is close to Haiti/DR at around 17.7N,
72W. It looks like the island of Hispaniola is hindering his development
because the north-east quadrant is not very well defined. Also, the
western side of the storm is not fully developed - looks like dry air is
being entrained (pulled in) on that side. So he may just hold steady as a
cat 1 as he checks out the island, although it won't take much to make him
into a cat 2 storm. Factors that will help in intensification include the
very warm sea surface temperatures (over 30 deg C), and warm 26 deg C
temperatures covering the upper 100m of the water column. Also, the wind
shear is fairly low.

As you know by now, the intensity depends on the track - more interaction
with land means weaker storm (unless your name is Fay)... so...

Track: He is currently moving NW at 9mph around the southern edge of a
large high pressure system over the Atlantic, and the track will depend on
how that moves over the next few days. At the moment he has a bit more
room to move NW-ish, but he will slow down and take a more westward
direction as he bumps up against that high. The westward turn is because
things move clockwise around high pressure systems in the northern

Too many of you asked me what I *really* thought about this storm
yesterday, so I will come clean ... I do have a little niggle in my brain
(how did you know?). But as the cover of The Hitchikers Guide to the
Galaxy says: "DON'T PANIC". :)

My little niggle is that the western edge of the high pressure is
currently oscillating between the Yucatan peninsula and Cuba... which
means that the storm will head NW for now, turn WNW, head towards the
Yucatan Channel and then curve into the Gulf and around to the eastern
side of the Gulf of Mexico. This is not my favorite path for this storm to
take, because it allows for intensification.

BUT it is TOO SOON to say this is definitely what is going to happen and
the caveats are:
1. this is a few days into the future (alas, my time machine needs a new
power supply so I can't just go and have a peep)
2. the high pressure system will change in that time - it is rare for it
to stay the same for that long
3. this is a broad outline of a track - small deviations can change the
intensity because he'll be close to Cuba

Regarding point #2:
a) If the high expands westward, then he will contuinue into the Yucatan
b) If the high retreats eastward, then he will cross Cuba, cross the
Straits of Florida, and come up towards the US from that direction.

So...everything depends on that high pressure. I will get the latest
pressure fields in the middle of the day so I'll send out another update.
But we are at least another day or two away from making a better
assessment - there's not much I can do about that. Something you can all
watch out for is how close he gets to Cuba. That will give an indication
of where the high is lurking.

Let me know if you need any clarification.

Later... oh! yes... later 'noles. See... I don't pay too much attention to
college football, being British and all that. These are how I look at this
football rivalry: 'Later gators' just rhymes better, but the 'noles have a
much better/flattering color scheme... ;)


Blogs archived at: http://www.jyotikastorms.blogspot.com/
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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