Page 28 - ARUBA TODAY

A28 SCIENCE
Wednesday 6 september 2017

How forecasters deal with ‘spaghetti’ of hurricane scenarios

By SETH BORENSTEIN where mountains can eat “Good forecasters look at
AP Science Writer up storms, can weaken the whole suite” of models,
WASHINGTON (AP) — Hur- Irma considerably. Emanuel said.
ricane Irma, with its record WHAT GOES INTO A MODEL: And sometimes one model
strong winds, is lashing the Computer models are like is just nailing a certain storm
Caribbean but where will it massive apps that try to so you stay with the hot
go from there? solve complex equations model.
Forecasters turn to com- that simulate the behav- Forecasters also run so-
puter simulations to try to ior of the atmosphere and called ensembles with as
predict a storm’s path and oceans, said MIT meteorol- many as 51 tweaks to the
how strong it will be. ogy professor Kerry Eman- data and formulas. They
Different computer mod- uel. Usually they don’t go are lower resolution and
els — often run by different much farther out in time quality but provide more
governments and various than five days, and if they information and possibilities
agencies — use different do, it’s with decreasing ac- for forecasters.
recipes or formulas to mim- curacy. They use real-time WHAT SHOULD YOU LOOK
ic the atmosphere. They all This photo made available by NASA shows Hurricane Harvey over readings of wind, tempera- FOR
also approximate current Texas on Saturday, Aug. 26, 2017, seen from the International ture, air pressure, humidity “The best guide for risk is to
conditions differently. Space Station. and more. But those real- look at the cone” of pro-
So the resulting models look Associated Press time readings are sparse jected landfall, often called
like a plate of spaghetti computer models other the Gulf of Mexico, or chug and spread out over the the “cone of uncertainty,”
thrown on a map. But in people don’t, judges in- off Africa in classic Atlan- open Atlantic. Sometimes said Jeff Masters, meteorol-
that messy mass, meteorol- dividual models and uses tic storm mode like Irma. the models point to the ogy director at the private
ogists can get an increas- a consensus of the better The models usually agree same general conclusion, forecasting service Weath-
ingly strong idea of where performing models, he said. about where the storm will like Superstorm Sandy hit- er Underground. If you are
a storm like Irma is heading. The center also shows how go for the next 12 to 24 ting the New York-New Jer- in the cone, you should be
A look at how those predic- well they do over time — hours and the spread out sey area. The models did concerned and prepared,
tions are made: and they are doing better. with time. well about five days out in he said. Even if you aren’t
WHO TO TRUST: The trouble, say those ex- Today, the five-day forecast 2012, said Emanuel. Some- in the cone but nearby,
The place to start is the Na- perts, is that those same im- is as good as the three-day times they are all over the you need to pay attention.
tional Hurricane Center’s ages of models are spread- forecast was 15 years ago. place. This time they are in The trouble is with the spa-
official forecast, say several ing over social media and And the margin of error for between, not widespread ghetti of models, people fo-
meteorologists who are not they are getting misread. the five-day track forecast but not clustered, he said. cus too intently on one line,
part of the federal govern- There are even bogus hur- is nearly half of what it was THE BETTER MODELS Masters said. The hurricane
ment. “You can’t beat the ricane tracks spreading on when it was first introduced The top performing model is center cone only goes out
hurricane center forecast,” social media. in 2001. What’s key is that usually the European mod- five days — and people
said Miami television me- HOW GOOD ARE THE PRE- meteorologists don’t stick el, which is slightly ahead in want to know if they are
teorologist Max Mayfield, DICTIONS: to a single line or track be- long-term accuracy over in danger earlier, Masters
who was the director of the Forecasters track the be- cause a slight change can the American one, Eman- said. So that’s when they
hurricane center from 2000 ginnings of storms, whether mean a big difference, uel said. But that doesn’t turn to the longer range
to 2007. they come out of unstable Mayfield said. For exam- mean the European will be models even if it is beyond
The hurricane center sees weather that pops up in ple, a tiny turn over Cuba, better every time, he said. that cone.q

Experts: Bad design, building

caused dangers at tallest dam

By ELLEN KNICKMEYER February’s spillway failures ways at Oroville Dam col-
Associated Press at California’s Oroville Dam lapsed.
SAN FRANCISCO (AP) — say the state probably Authorities feared an un-
Bad design and construc- could have detected the controlled release of mas-
tion and inadequate state problems if dam managers sive amounts of water,
oversight led to a disastrous had reviewed the original which did not happen.
spillway collapse at the na- flaws in the half-century- Experts from the national
tion’s tallest dam, an inde- old dam, using modern en- Association of State Dam
pendent team of national gineering standards. Safety Officials and the U.S.
In this Feb. 28, 2017, file photo, water flows down the Oroville dam safety experts said Authorities ordered nearly Society on Dams are con-
Dam’s crippled spillway in Oroville, Calif. Tuesday. 200,000 people to evacu- ducting their own indepen-
Associated Press
The experts investigating ate Feb. 12 after both spill- dent review. q