Q. What does TRANTECH stand for?
A. TRANTECH is the TRopical ANalog TECHnique model.
Q. How does TRANTECH work?
A. The user inputs certain parameters about the current storm in question.
Using this information TRANTECH then accesses a database containing all
storm tracks back to 1871. It then determines which storms match the
current storm's parameters close enough to be considered analog storms.
Then TRANTECH generates a weighted average of all the analogs depending
on how well the individual parameters match up.
Q. Why does the TRANTECH forecast jump around sometimes?
A. These "jumps" can occur anywhere, but especially occur near landfall.
When one or more analog storms "drop out" in mid-forecast, it can yield
a discontinuity in the forecast parameters. This is a much smaller problem
than in the past, as steps have been taken to alleviate this. However, it
can still occur, especially in instances where there are a low number of
analogs to start with.
Q. How accurate is TRANTECH?
A. Considerable progress is finally being made on the statistical evaluation
of TRANTECH. As of this writing the statistics are not yet posted... however,
as of your reading this, they may be available! In short, though, TRANTECH
shows skill (beats the "baseline" models) in both track and intensity
throughout the forecast period. Its forte is the the intensity forecast.
Its weakness is the longer term track forecast, where it is currently
exhibiting only minimal skill.
Q. Why do you forecast out to 120 hours?
A. I have figured that the point in which your error does not increase as
you forecast further in time is the point at which you are essentially
guessing. That is, a 12hr forecast should be worse than a 6hr forecast,
but better than a 24hr forecast. If you have large errors which are not
increasing with time then that tells me the forecast is essentially a pure
guess. I found that at around 108-120hrs my forecast error stays the
same. Therefore, I determined that any time beyond this is the point where
the forecast turns into guesswork, so, that's where I stop the forecast.
Q. Why does TRANTECH frequently overforecast the intensity of weak systems?
A. The database TRANTECH is working from contains only systems which became
tropical storms or hurricanes. Therefore, there is an inherent
assumption that every depression will become a tropical storm. This
produces an intense bias in every system which is currently a depression
or even a weak tropical storm. Work is being done to resolve this issue.
Q. When do you issue the forecasts?
A. TRANTECH is a model I have developed over several years in my spare time.
I have a full-time job so unfortunately my time is extremely limited.
When a storm is active in the Atlantic forecasts are generally issued
every day between 7 & 10PM Eastern Time, generally a little earlier on the
weekends. When a storm becomes a significant threat to the U.S. mainland
I may also issue forecasts between 6 & 8AM Eastern Time.
I hope this answers many of your questions. If you have any further
questions or think there is some burning topic that must be added to this
page, please e-mail me and let me know!! Thanks for visiting this site!
-Gary