When signal number 2 is raised in Kalinga, people usually prepare for dark clouds and downpour–but there are times that one looks outside expecting rain, only to find the sun shining instead.
People get confused, or even annoyed, and assume that the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) has gotten its forecast wrong.
The reaction is understandable, but the forecast is not wrong, according to a PAGASA weather specialist. It is just that people are confusing wind signal with heavy rainfall warning.
Contrary to popular notion, PAGASA’s tropical cyclone wind signals, which go up from signal number 1 to signal 5, are not based on rainfall but on wind, and are raised to warn places that they are on the path of an incoming tropical cyclone and must prepare for the hazards of strong winds.
“Nu agingatu ni PAGASA ti signal, these are the areas that are directly mako-cross noong bagyo, the higher the signal number, mas closer sa area ng pupuntahan noong sentro ng bagyo,” Romeo B. Ganal, weather specialist of PAGASA Northern Luzon explained during an orientation of local government units on November 11.
As for rain, PAGASA issues a separate color-coded heavy rainfall warning: yellow, orange, and red.
An important distinction between the two is wind signal is a forecast track issued even before the tropical cyclone’s actual landfall to give a lead time for places to prepare for its impacts.
On the other hand, heavy rainfall warning is issued based on the observed amount of rain in real time (“agdama nga tudu”), said Ganal.
A place may either have a wind signal or a heavy rainfall warning, or both, depending on the type of the tropical cyclone or the concentration of the rain in a cyclone’s eyewall, Ganal further explained.
“Yung asymmetric type na bagyo haan nga balanse, maaring mas makapal ang ulap dito, dito walang masyadong ulan, tapos dito wala silang nakataas na wind signal pero ang threat malakas na ulan so may separate issuance ng heavy rainfall warning,” he said.
“Magi-issue ng heavy rainfall warning kahit walang signal. Maaring mag-issue silang sabay pero maaring kahit walang signal number, may heavy rainfall warning,” he added.
Before, automatic suspension of classes in kindergarten to high school takes effect based on wind signals, but with the recent changes stipulated in Department of Education Order number 37 issued last September 1, automatic suspensions can now also be triggered by heavy rainfall and flood warnings.
“The problem is what about those in tertiary level and work in private and public sector? May power parin si local chief executive to cancel classes if he deems mayroong threat sa kanyang locality,” said Ganal.
The local chief executive has the prerogative to cancel classes and work based on wind signals, heavy rainfall warning, or flood warning issued over his or her locality, Ganal said.