Mechanics of the hurricane
- From: "Dora Smith" <villandra@xxxxxxxxxxxxx>
- Date: Fri, 23 Sep 2005 02:43:07 GMT
I'll get ultimate revenge on everyone who did not answer my questions.
Nothing aggravates a list full of people who don't answer questions more
than answering the question. I expect you'll all get angry, and start
telling me I'm wrong - and accidentally spill information I didn't know in
the process. Then again - on this list, we have people who spend their
energy making up nonsensical hurrricanes!
The high pressure system that has been over the southeastern United States
is a subtropical ridge, like the Bermuda high, and almost as permanent. It
was caused by abnormalities in Pacific weather systems, and by the warm
waters in the southern Atlantic. I was not supposed to go away until mid
October. These strong high pressure systems move in for long periods of
time and are hard to budge. The Bermuda high is actually a permanent
meteorological feature that moves back adn forth across the Atlantic over
the course of the year.
The subtropical ridge that caused the heat wave has at times merged with the
Bermuda high, which spread into the Gulf in a way that is unusual.
The low pressure system that was supposed to budge the subtropical ridge
today or Friday is a high level low pressure trough. A high level low
pressure trough is the low pressure equivalent of a ridge. On radar that
shows cloud cover it clearly shows as a long broad band of clouds that has
slowly spread eastward across southern California, Nevada, northwestern
Texas, and Colorado. On surface analysis maps, it shows as a bunch of
letter L's that bounce around in a way that makes no apparent sense.
WEather maps at weather. unisys.com and intellicast.com show the high
pressure ridge weakening over Texas as the highest pressure part of it moved
eastward, over the course of the past week.
This must have weakened the back end of hte high pressure ridge even more
than they expected. Instead of waiting for the trough to move and circling
around back of it, the hurricane was sucked into it and began to follow its
track; but it split the high pressure ridge. The future models show the
eastern portion of this high pressure ridge moving off the Atlantic coast.
One model shows it heading for New Foundland closely followed by the
hurricane. At the moment the western edge of this ridge is still
fluctuating between Austin and the Louisiana border. This is why the
hurricane keeps changing direction.
Meanwhile, now that the subtropical ridge is no longer in the way, a cold
front is moving southward across the middle of the country toward Louisiana.
Some other low pressure system is moving eastward toward Texas. The cold
front (I believe, adn not the high pressure ridge) is expected by most TV
weathercasters today, to cause the hurricane to stall over Louisiana, and
gradually spread across eastern and central Texas, causing pouring rain from
Sunday through Wednesday in areas the hurricane originally missed. A
different version of that model ahs the hurricane reach northern Louisiana,
turn around, and come southward through central Texas.
As for the low pressure system moving eastward, I think they are hoping it
will push the hurricane back to the north. I think they are not talking
about the high level trough, but I'm not certain. I think they are talking
about something new.
--
Yours,
Dora Smith
Austin, Texas
villandra@xxxxxxxxxxxxx
.
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