Whither weather?

How about simplifying the rainfall / flood warning system to numerical alerts, like the storm signals?

Everyone has grown used to Signal Numbers 1, 2, 3 and 4 (Super Typhoon Yolanda was categorized as No. 4), and prepare accordingly – residents, government personnel, rescue and relief teams.

After Yolanda struck in 2013, the Philippine Atmospheric, Geophysical and Astronomical Services Administration added a higher warning signal level to accurately depict its extreme ferocity. So PAGASA now has Signal No. 5 for cyclones with the strength of Yolanda, which flattened much of Eastern Visayas.

In 2022, the warning signal was again refined, to specifically denote sustained top wind speeds of approaching cyclones. So tropical cyclone bulletins now provide “wind signal” No. 1, 2, up to 5.

We understand what those signal numbers imply, and prepare accordingly, canceling classes or work, rescheduling meetings and trips, picking what to wear for the day. Evacuations may be conducted in coastal communities and known high-risk areas, such as those prone to landslides and, in Metro Manila, in informal settlements along riverbanks.

But most of us still don’t make such responses to color-coded rainfall alerts.

Rain warnings are provided separately as part of weather advisories, to include thunderstorms and rainfall when there is no cyclone or strong wind warning. This is common especially during monsoon season.

PAGASA issues regular rainfall alerts on its websites, with warnings on approaching rain, whether monsoon-induced or spawned by a tropical cyclone. But how many people check the PAGASA website, especially on sunny days before the heavy rainfall arrives?

Many vulnerable communities don’t even have internet access, or lack gadgets to access the weather websites.

*      *      *

Also, the messaging can use fine-tuning.

Consider, for example, the PAGASA weather advisory as of 2 p.m. yesterday, on the “heavy rainfall outlook due to Tropical Cyclone Kristine,” which has caused record flooding in Naga City and other parts of Bicol.

The rainfall outlooks fell into three categories: “moderate to heavy” – with 50 to 100 mm of rain expected; “heavy to intense” (100 to 200 mm) and “intense to torrential” (200 mm).

“Under these conditions, flooding and rain-induced landslides are likely, especially in areas that are highly or very highly susceptible to these hazards as identified in hazard maps and in areas with significant antecedent rainfall,” the weather advisory declared.

It’s a pretty straightforward warning, although it presumes that people – or at least officials of local government units – actually read the hazard maps that are available for free online. I also wonder how many LGUs have personnel who regularly check the PAGASA website, for both cyclone and rainfall warnings as well as ocean tide alerts, for timely disaster preparedness and mitigation responses.

Local politicians in Bicol are now bickering over the apparent lack of LGU preparedness for Kristine.

I must admit that when a PAGASA forecaster ran those rainfall outlook numbers through us on One News’ “Storycon” last Wednesday while trying to explain the rain advisories, my math-challenged brain seized like melted chocolate mixed with water. I’m sure I’m not alone with this problem.

My unscientific self is asking the scientists if it’s possible to simplify the rainfall / flood warnings to numbers, or somehow combine them with the existing color alerts. There are wind signal Nos. 1, 2, 3, 4, 5. Why not rain warning signal Nos. 1 to 5?

What people currently rely on are the color-coded rainfall text alerts from the National Disaster Risk Reduction and Management Council, an agency under the Office of Civil Defense, which is under the Department of National Defense. But the NDRRMC bases its alerts on PAGASA data.

*      *      *

PAGASA, which is under the Department of Science and Technology, launched the color-coded rainfall and flood warning system way back in June 2012, initially using the colors of traffic lights: red, green and yellow.

Since green in traffic lights means go, this system that was pilot-tested in Metro Manila was confusing. Yellow, for “caution,” was supposed to mean flooding is possible. Red, for “stop,” warned of serious flooding in low-lying areas so people should stop what they are doing and evacuate. And green meant – uhm – go ahead and prepare for possible evacuation, because flooding is threatening. You can see why orange had to replace green.

The NDRRMC text alerts, however, are provided almost in real time – meaning you could already be stuck in heavy flooding on your way to work or school when you receive an orange or red flood warning alert.

Also, even after orange replaced green, perhaps many of us are unfamiliar with the color wheel, and the color-coded advisories fail to sufficiently convey the problems that can be expected from yellow, orange and red rainfall / flood alerts.

Some people are also confused by the wind signals for “typhoons” and “severe tropical storms.”

Kristine, which spawned cataclysmic flooding particularly in the Bicol region and is still moving slowly across the country, is merely a severe tropical storm, but it carries wind signals, with Bicol under Signal No. 3 yesterday and Metro Manila, Signal No. 2.

A PAGASA forecaster told Storycon yesterday that a tropical cyclone transitions from a severe tropical storm to a typhoon if the sustained peak winds hit 110 kilometers per hour. So Kristine wasn’t really that strong a cyclone, although it spawned torrential rainfall and destructive flooding. Yet it carried wind signals of up to No. 3.

Regardless of the type of weather disturbance, people have developed standard reactions to the numbered signal system. Perhaps it can be incorporated into the rainfall and flood alerts.

Disaster preparedness calls for a clear understanding of weather alerts.