Hurricane Bertha: July 9 update A

Building Bertha - I know, I am scrapping the bottom of the barrel here are
for alliterations. If I get them all out now, you may be spared from such
silliness later in the season. Or perhaps not :) Right... down to
Bertha-Business:

Intensity:
The 5AM NHS advisory this morning says that Bertha looks like she is
getting better formed and the vertical shear may be decreasing - which is
what I said yesterday. Despite a better looking storm (much better than
the 'cat 2' they had her at yesterday), they have continued to lower her
wind speed to 75 mph, so barely at hurricane strength (cat 1: 74-95mph). I
do agree with her cat 1 status and I think that we'll see some
intensification to a strong cat 1, also in agreement with the NHS.
Although still surrounded by dry air, the water underneath is 27-28 deg
C., and she is in a region of low wind shear.

Track:
So far the track models have been pretty good as they have forecast her
move around the clearly defined Bermuda/Azores High. They still keep her
to the east of Bermuda - moving past in about 4 days - but I am not as
certain of this as I was yesterday. She's at 23.5N, 56.5W, her forward
speed has slowed down to 10mph, and the NHS say she is moving in a NW
direction. I did some quick calculations (because I'm a geeky scientist)
and it looks like she is moving more on a W-NW trajectory now and has been
since yesterday - this brings her track closer to Bermuda (~lat: 32.3,
long: 64.8W) so we may see the envelope shift westward.

The track forecast may be about to get a bit more complicated though, as
there is a second high pressure system moving off the US into the
Atlantic. The ideal situation is for Bertha to pass between the two high
pressure systems (in a lower pressure area known as a trough), but because
she is slowing down I am wondering if she is actually already interacting
with this second high, which will continue to keep her west of the current
forecast track - hence the possible westward movement of the track
envelope. I don't have a fine enough resolution pressure field to be able
to see this so we will have to watch what happens in the next 24 hours.

So, to sum up: if you are still planning on a research cruise on Saturday
out of Bermuda the most helpful advice I can provide is... don't forget
your sea-sickness aids :)

Another update later...
J.

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

_______________________________________________
Jyo_Hurricane mailing list
Jyo_Hurricane@marine.usf.edu
http://seas.marine.usf.edu/mailman/listinfo/jyo_hurricane