MANILA, Philippines (UPDATED) – “Very heavy damage” – that, in a nutshell, is how the state weather bureau PAGASA describe the potential destruction Typhoon Lando (Koppu) can bring to areas under public storm warning signal number 4.

This was the storm signal raised by Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) over the province of Aurora on Saturday, October 17, as Typhoon Lando (Koppu) packs winds of up to 175 km/h.

The last time PAGASA hoisted Signal No. 4 was when Super Typhoon Yolanda (Haiyan) ravaged the Visayas in November 2013, but the public storm warning system in place was different. (There is now Signal No. 5.)

‘Very heavy damage’ expected

If an area is placed under Signal No. 4, it means the area will experience winds of 171 to 220 km/h.

In general, the effects of Signal No. 4 include “very heavy damage to high-risk structures” and “almost total damage to banana plantations,” according to PAGASA.

PAGASA lists the following effects of wind under Signal No. 4:

• Very heavy damage to high-risk structures
• Heavy damage to medium-risk structures
• Moderate damage to low-risk structures
• Considerable damage to structures of light materials (up to 75% will likely be totally and partially destroyed); complete roof structure failures.
• Unroofing of many houses of medium-built materials, some of these having collapsed walls; extensive damage to doors and windows
• Partial damage to a few houses of first-class materials
• Blowing down of all signs/billboards
• Almost total damage to banana plantations
• Damage to most mango trees, ipil-ipil trees, and similar types of large trees
• Extensive damage to coconut plantations
• Severe losses in rice and corn plantations

PAGASA began raising Signal No. 4 only in 1991.

Before Yolanda in November 2013, only 14 other storms had prompted PAGASA to raise Signal No. 4. 

Six of these Signal No. 4 events affected Aurora, where Lando is expected to unleash its wrath on Sunday, October 18. – Rappler.com

(In an earlier version of this article, we compared the wind speeds to traveling along EDSA, which has confused some readers. The article has been revised to reflect a clearer explanation of the storm signals.)