Monday, August 04, 2008

TS Edouard: August 4 Update B

Things I've learned (or learnt if you prefer UK English) since my last

1. Some names are tricky to spell (why didn't anyone tell me this
before?!?). Apparently I had the 'o' in the wrong place. I was so close,
but it's not at the end of the name (Eduardo) it's in the middle:
Edouard! Really, don't you think names should be intuitive to spell...
just like mine? (that's why you'll never come across a Hurricane Jyotika).

2. "Weather forecasting is the only job where you can be wrong 50% of
the time and not get fired." ;)

Edouard is now at 28.3N, 91W, so he's moving along at 8mph in a WNW-ish
direction. Coastal LA is getting the outer rainbands now. The latest NHC
forecast track has shifted a tad bit south, but at the moment he looks
to me as though he'll be heading a little north with landfall closer to
the TX/LA border - it's still within the cone though. The tricky part in
assessing this earlier today was that there was a high pressure in the
way, that he is moving around (remember clockwise around a high pressure
system) and it extended over the TX coast, but it looks like it's
shifted northwards to me. We'll know with 100% certainty within 24 hours
- because er... by then he'll have made landfall.

Winds are still listed as being at 45 mph, but again, I'm not sure about
this because he looks like he's improved in features and his circulation
has definitely picked up. I think there's a plane in the system now and
the 5pm (EST) update will have more up-to-date information. Central
pressure is about 1001 mb. I expect him to have stronger winds than that
in the next advisory.

Forecast water levels are 2-4 feet above normal. The observations so far
show that along the MS and LA coastlines the water levels have already
reached a peak of about 1 foot above normal and are beginning to drop
now. Texas observing stations are still increasing but have not yet
reached 1 foot above normal.

Now for my "Satellite Imagery Primer - Part One". If I lose you, send me
an email and I'll try and muddy the waters further (oh, and all puns are
always intended ;) ).

You can see close-up images of a storm, or sometimes even a system with
potential (the NHC and everyone else calls them 'Invests', I prefer to
call them 'Blobs' and 'Blobettes' because it's just, well, more fun :) ) :

1. Go to the National Hurricane Center website satellite link page:

2. Scroll down to the 2nd major heading: "GOES Floater Imagery - 30
minute updates". GOES are the satellites that the images come from: the
Geostationary Operational Environmental Satellites.

3. Under this heading you will see sub-headings: "Atlantic Floater 1",
"Atlantic Floater 2" etc. And under those will be a sub-sub-heading with
the name of the storm, or the number of the 'Invest', or it will say
'Not Active'.

4. Under each one is a list of 5 different types of images. If you want
the latest still snapshot of any of the images, click on 'Image'. For a
movie (which is what I usually look at), click on 'Loop' (this may take
a bit more time to load onto your machine though). At the bottom of each
image or movie is a date and time stamp. The time is in UTC (Universal
Time Coordinate/ Coordinate Universal Time) and is about 4 hours ahead
of EST in the summer. So for example, 17:45 UTC is actually 13:45
Eastern Standard Time.

For example, look under Edouard - Atlantic Floater 2. The three most
useful images:
- "Visible": This is a visible image in black and white. If you want to
see the center of circulation, this is the image to look at. The other
images will just cloud the issue :).
- "Infrared": This is an infrared image and give you the temperature of
the cloud tops and hence an indication of how much convection (rain,
thunder etc) is actually going on. White means warm cloud tops, which
means they are not very high in the atmosphere and therefore there is
not a lot of rain (no rain actually). Blue are cooler, but indicate
thick cloud cover, with possible drizzly type of rain. Yellow indicates
even cooler clouds tops, so these are higher in the atmosphere, usually
associated with a lovely downpour (I like the rain). Reds indicate
really cold tops, which are associated with "Thunderbolt and lightening,
very, very frightening" (Bohemian Rhapsody, Queen). A quick re-cap about
why cold cloud tops indicate more stormy weather is in the July 9 Update
C entry:

- "Water vapor": This shows you if the surrounding atmosphere has dry
air (brown) or whether there is already some water vapor (not brown).
This one is often used on tv reports (from what I've seen).

5. Click on any of the loops (if you can). Once it has loaded, across
the top you will see a number of little buttons. Click the one that says
'LatLon' and it will draw a lat/long grid over the image. Click on
'TropFcstPts' and it will add the latest Forecast Track. I won't go
through them all, but have a play - click the buttons. It's quite a lot
of fun really. Let me know if you have any questions on any of them. On
the bottom you will see controls to slow the movie down, move through it
frame-by-frame, play it backwards (Fun Fun - yes, it doesn't take much
to amuse me), stop it etc.

That's part one.
If something of interest happens later today I'll send out another note.
Otherwise, tomorrow amigos...

Blogs archived at:
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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