PAGASA denies it gave wrong ‘Usman’ forecasts

MANILA, Philippines — State weather bureau PAGASA denied allegations that it gave incorrect forecasts during the onslaught of Tropical Depression Usman, which devastated the Philippines—particularly the Bicol region—shortly after Christmas.

‘Usman’ hit central and eastern Philippines on December 29 and caused massive floodings and landslides, killing more than 155 individuals.

Disaster scientist Mahar Lagmay earlier cited inaccurate rain forecast as a contributing factor to the aftermath of the tropical depression. The executive director of the UP Nationwide Operational Assessment of Hazards claimed that intense to torrential rain actually hit Bicol, not moderate to heavy rainfall as forecast by PAGASA.

PAGASA administrator Vicente Malano acknowledged that Lagmay’s analysis was correct in terms of PAGASA’s hourly rainfall intensity classification but stressed that the weather agency defines moderate and heavy rainfall as 24-hour accumulated rainfall of 60 to 180 mm and more than 180 mm, respectively.

“The forecasts for 28 to 29 December 2018 indicated the ‘forecast 24-hour accumulated rainfall’ of moderate to heavy, which would trigger flooding and landslides. Verification of the observed 24-hour accumulated rainfall values for Bicol area showed that the amount falls within the moderate to heavy categories, as forecasted,” Malano said.

He added that the Southern Luzon PAGASA Regional Services Division at Legazpi City in Albay also issued separate color-coded heavy rainfall warnings.

From tropical depression to LPA

Malano also responded to the criticism that the downgrade of Usman from tropical depression to low pressure area confused the public.

He explained that meteorological data at the time indicated that Usman had indeed weakened into LPA at landfall, but stressed that this does not imply that weather will rapidly improve.

“[The]Tropical Cyclone Warning Signal System, which has been in effect since 1930s, is based solely on expected winds and its impact over a locality and has no relation with the accompanying rainfall of such tropical cyclone,” Malano said.

The agency’s administrator added: “However, PAGASA has always emphasized the threat of heavy rains and other hydrometeorological hazards and its impacts associated with each tropical cyclone in its heavy rainfall warnings and severe weather bulletin.” — Gaea Katreena Cabico