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Old September 11th 03, 03:06 PM posted to alt.talk.weather,ne.weather,sci.geo.meteorology
Dan Dan is offline
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Default Isabel and GFS

I agree with pretty much your general thought, and I didn't want to imply I
believed the value of long term models was zero.

Regarding the =/ 18-hour forecast failing on small scale features,
sometimes these small scale feature have a tremendous impact and can be a a
matter of life and death. An extreme instance for example was late summer
in 2002. NWS Sterling forecasted 10-15kts all morning and day on the
Chesapeake Bay. From mid-morning thru the evening the winds were steady
upper teens to 20kts. No SCA were posted on their 10am nor the 4pm updates,
and two men drowned when their johnboat took on too much water b/n 12 & 2pm
that day. By 6pm, the NWS updated their 4pm marine forecast with SCA,
however, by that time, the winds were abating as the sun set. Errors in the
small scale features in the short-term, are magnitude exponentially in the
long-term.

"Joseph Bartlo" wrote in message
...
Dan wrote:

Computer models fail at times when predicting whether as far out as 18
hours.


For specific and generally small scale features.

The reliability for their accuracy 8, 10, or 11 days in the future is

nothing
more than fun to look at and ponder.


I think they are quite a bit more helpful than that. People routinely

making
medium range forecasts will attest that there is indeed a value for days

8-10,
and the general large scale pattern often forecast rather consistently.

The
fluctuations make them appear less reliable though.

Some people need to pipe down their enthusiasm that wx models are

god-like
--- although you are not one of them.


I generally agree with this statement, though the trick with tropical
cyclones is knowing how the actually storm would behave differently than
modeled (primarily because it would be MUCH stronger than modeled - though
there are other reasons - some which for which it may be unclear how it
would differ).




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Old September 11th 03, 04:19 PM posted to alt.talk.weather,ne.weather,sci.geo.meteorology
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Default Isabel and GFS

Along these lines, the runs on Saturday should be interesting, since by then
the Noaa high-altitude jet will have sampled the upper-level enviroment on
Friday and the subsequent GFS runs will have that data.

Mike B.

"Joseph Bartlo" wrote in message
...

I generally agree with this statement, though the trick with tropical
cyclones is knowing how the actually storm would behave differently than
modeled (primarily because it would be MUCH stronger than modeled - though
there are other reasons - some which for which it may be unclear how it
would differ).



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Old September 11th 03, 06:46 PM posted to alt.talk.weather,ne.weather,sci.geo.meteorology
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Default Isabel and GFS

On Thu, 11 Sep 2003 11:06:33 -0400, "Dan"
wrote:

I agree with pretty much your general thought, and I didn't want to imply I
believed the value of long term models was zero.

Regarding the =/ 18-hour forecast failing on small scale features,
sometimes these small scale feature have a tremendous impact and can be a a
matter of life and death.


Even just the speed of the storm can make a major difference in track.
As an example take just two major elements that will effect the final
track of Isabel. First a short wave that is forecast to turn the
storm slightly northwest. The second, ridging over the eastern US
which might tend to swing the track back west again.

From what I can gather if the storm moves slower than expected the
trough will not pull the storm north as much and the ridge will have
more time to develop and provide steering to the west or even
southwest. Just a few hours of difference either way makes hundreds
of miles of difference in track over 5 days.
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Old September 11th 03, 06:57 PM posted to alt.talk.weather,ne.weather,sci.geo.meteorology
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Default Isabel and GFS

In article ,
"Michael Bryson" wrote:

Yeah, I just looked at the 0Z run. It kinda pulls a "Floyd" on south
Florida, coming very close to Palm Beach, then turning SHARPLY to the right.



Looking at the latest WV loops...

http://www.ssd.noaa.gov/PS/TROP/DATA...l-wv-loop.html

....I think it's going to recurve well east (not even close enough to be
a "cockteaser"). Look at the trough going through Florida, and the
complex, multibarrel "Henri" hybrid upper-low thingy setting up....

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Old September 11th 03, 08:00 PM posted to alt.talk.weather,ne.weather,sci.geo.meteorology
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Default Isabel and GFS

In article ,
Michael Bryson wrote:
Along these lines, the runs on Saturday should be interesting, since by then
the Noaa high-altitude jet will have sampled the upper-level enviroment on
Friday and the subsequent GFS runs will have that data.


The first such missioin is scheduled for Saturday.
http://www.nhc.noaa.gov/text/MIAREPRPD.shtml
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disappointment that accompanying their own orgasm wasn't a big BOOM
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