Comparison of Typhoon Signals and Hurricane Categories
October 2nd, 2009 / View Comments » / by 謝施洗 (Shixi Xie)
Early this evening, a family member was panicking because s/he received a text message from someone who wrote what CNN said during their weather report. The message that CNN upgraded Typhoon Parma (locally known as Pepeng) as a Category 5 Hurricane.
But the way the message was understood was like this: “Typhoon Parma has been upgraded to Signal #5″ (even though what was written was Category 5). You can understand the cause of panic because we do not have Public Storm Warning Signal No. 5 here in the Philippines.
So what happened? Two different storm scaling systems from two different worlds (the West and the East). First, a news report from a US-based news network, and secondly we do not use the Saffir-Simpson Hurricane Category Scale in Asia, and not even taught in schools in the Philippines (unless it is course-related).
For this post, we will clear the difference between the two to avoid another misunderstanding.
Follow up:
But before that, I want to request to news networks like CNN to at least take extra effort in giving storm scales based on a particular region or country’s system. In this case, Typhoon Parma is obviously within the Philippine Area of Responsibility and as such, they can call the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (or PAGASA) and ask for the local storm scaling system.
For my fellow Filipinos, here is a table of the difference between PAGASA’s Public Storm Warning Signal (PSWS) system and the Saffir-Simpson Hurricane Category Scale.
* NOAA NHC - National Oceanic and Atmospheric Administration’s National Hurricane Center
As you can see above, the Saffir-Simpson scale Categories 1 through 5 is equivalent to PAGASA’s Signal #3 and #4 only. Interestingly, Signal #4 is simply “any wind speed greater than 185 km/h” which is a strong Category 3 storm. This means that a strong Category 4, and Category 5 itself is that STRONG, it can even be Signal #6!
Another thing to remember here is that, a super typhoon is a typhoon that reached a wind speed of 150 mph or 240 km/h. This is a strong Category 4 storm according to the Saffir-Simpson scale. Not because a Typhoon has been classified as Signal #4 or Category 4 does it mean it is a super typhoon.
So when you hear a typhoon upgraded to super typhoon level, then it is no weaker than 150 mph or 240 km/h. This is a strong Category 4 or already a Category 5 typhoon, which locally in the Philippines is simply Signal #4.
Always remember, we do not have Signal #5. Also remember that Signal #4 and super typhoon are two different terminologies. If you want to panic, wait until you hear that a typhoon is a super typhoon, or specifically Category 5. Regardless, there are NO reasons why we should even panic, when people starts to panic this is when we start to make serious and grave mistakes. Our top-most priority is safety, safety, and safety.
All clear? Good!
We’re done! But if you want to continue reading and know additional information (more like a trivia) then proceed to the next page of this post.
US National Hurricane Center
PAGASA - DOST
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