|
|
|
|
Tropical Forecasting
Mon Jul 19, 2004
Listen in RealAudio 
Hi, I’m Bryan Yeaton for The Weather Notebook.
If you’ve ever spent much time in the tropics, you may have noticed how unreliable the
short-term forecasts are compared to those in the mid-latitudes. "Showers likely
tomorrow afternoon" just doesn’t mean as much in Jakarta as it does in Chicago.
Interestingly enough, the exact opposite holds true when it comes to long-term
forecasts. You’re better off in Bogota than in Boston if you want to gamble on next
season’s forecast – or next year’s, for that matter. Even for the non-gambler, this
discrepancy is worth pondering, because it reveals something fundamental about the
world’s weather – and about our ability to predict it.
With the notable exception of hurricanes, tropical weather tends to come in the form of
brief, violent convective events that affect a relatively small area and dissipate quickly. It
stands to reason that these storms would be tougher to forecast than typical
mid-latitude cyclones, that evolve over a period of days, and stretch over half a
continent. On the other hand, the influence of the ocean, which covers the vast majority
of the earth’s surface in the tropics, makes tropical weather less likely to change very
quickly or very much from season to season or year to year. Once they factor in El
Nino, meteorologists should have a pretty good handle on the big picture from Brazil to
Indonesia.
So, next time you’re tanning in Tahiti, think twice before you bank on the weekend
outlook. However, if you’re planning Tahiti’s energy consumption for the next year,
you’ve got that extra edge of accuracy in the long-range forecast, and that could make
a very big difference.
Seattle writer David Laskin sent in today’s story. Our show is produced by the Mount
Washington Observatory with funding from the National Science Foundation, and
Subaru: Driven By What’s Inside.
|
|
