Weather TALK [forecasts, etc]

[Monseratto]

the calm before the storm?

Nahh, typhoon just moving further away. Typhoon2000 is more reliable.



US vs PAGASA forecast

PAGASA's imperfect storm of typhoon forecasts - Technology - GMA News Online - Latest Philippine News

PAGASA's imperfect storm of typhoon forecastsJM TUAZON, GMA News
05/25/2011 | 09:45 PM


Just how well does the Philippines' weather bureau see into the stormy future?

In its Tuesday severe weather bulletin, PAGASA predicted that Typhoon Chedeng (international name: Songda) will make landfall between the regions of Isabela and Aurora by Friday afternoon.

Different weather monitoring agencies worldwide, however, report that the storm will merely graze Luzon's eastern coast—and thus will not make landfall at all—before heading to Taiwan and back out to the northern Pacific Ocean.

Then on Wednesday morning, PAGASA presented an alternate scenario,with the storm passing through Metro Manila. Then it revised its forecast in its evening bulletin, saying the storm is proceeding along its west-northwestern track, away from the nation's capital.

Conflicting and changing predictions confused anxious Luzon residents and raised doubts about the credibility of PAGASA, whose predictions can shut down local economies and send schoolchildren home.

"PAGASA is such an unreliable weather agency. Storm tracks by more competent weather agencies clearly predict it will NOT make landfall," *kevinyapjoco pointed out on Twitter.

Contradictory forecasts

At least three different international weather bureaus issued reports that contradicted that of PAGASA.

The Japan Meteorological Agency (JMC), the Joint Typhoon Warning Center (JTWC) and the Central Weather Bureau of Taiwan all predicted that Typhoon Chedeng will not make landfall in the Philippines, based on a 70 percent probability track area they released separately.

In an interview with 24 Oras, however, PAGASA officer-in-charge Graciano Yumul Jr. said these weather agencies use mathematical models to predict the storm's track, while PAGASA uses a combination of mathematical models and instrumentation to identify where the typhoon will go.

"Inaasahan pa rin namin na tatama ito (Typhoon Chedeng). Judgment call ng forecaster iyon, kasi mahirap naman, kailangan isa-alang-alang mo rin 'yung kapakanan ng mga tao. Habang malayo pa 'yung bagyo tapos pinalihis mo, eh paano kung tumama? Mas maganda patamain mo na, so kung tumama man, nakahanda na sila," he revealed.

"Kami po sa PAGASA ay matutuwa kapag hindi tumama sa kalupaan ang bagyo, subalit ang amin pong track lines at ang aming mga synoptic stations ay talaga pong nagpapakita na tatama ito sa Isabela at Aurora," Yumul said.

In adopting a cautious stance on forecasting weather disturbances, PAGASA is perhaps trying to learn from the dire lessons of Tropical Storm Ondoy in 2009, and the other missed predictions over the years.

Last year, President Benigno Aquino made an example out of former PAGASA head Prisco Nilo, who incorrectly predicted that Typhoon Basyang would not hit Metro Manila, before Aquino relieved him of his post.

Given its meager budget and the skyrocketing costs of acquiring equipment, it may take time before the country's weather bureau can issue forecasts with more hits than misses. - HS, GMA News