Saffir Simpson Scale

[Alacane2]

Has there been a change to the Saffir-Simpson Scale. Below is the current advisory from NWS Tiyan Guam for Tropical Storm Ewiniar. In the wind section of the advisory, it says that the storm is "...a severe tropical storm...Category B...on the Saffir-Simpson Scale."

Code: Select all

BULLETIN
TROPICAL STORM EWINIAR (04W) ADVISORY NUMBER 12
NATIONAL WEATHER SERVICE TIYAN GU
200 AM GUAM LST MON JUL 3 2006

...TROPICAL STORM EWINIAR STILL SLOW TO INTENSIFY...

NO WATCHES OR WARNINGS ARE CURRENTLY IN EFFECT.

AT 1 AM GUAM LST...1500Z...THE CENTER OF TROPICAL STORM EWINIAR WAS
LOCATED NEAR LATITUDE 11.9 DEGREES NORTH AND LONGITUDE 134.7 DEGREES
EAST. THIS IS ABOUT 280 MILES NORTHWEST OF YAP.

TROPICAL STORM EWINIAR IS MOVING NORTHWEST AT 7 MPH. THIS MOTION IS
EXPECTED TO CONTINUE OVER THE NEXT 24 HOURS...WITH A SLOW INCREASE
IN FORWARD SPEED.

MAXIMUM SUSTAINED WINDS ARE 65 MPH. [b]THIS IS A SEVERE TROPICAL STORM
...CATEGORY B...ON THE SAFFIR-SIMPSON TROPICAL CYCLONE SCALE. [/b]
EWINIAR IS EXPECTED TO INTENSIFY...AND SHOULD BECOME A TYPHOON THIS
MORNING.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 100 MILES FROM THE
CENTER OF EWINIAR.

REPEATING THE 1 AM POSITION...11.9 DEGREES NORTH AND 134.7 DEGREES
EAST...MOVING NORTHWEST AT 7 MPH WITH MAXIMUM SUSTAINED WINDS OF
65 MPH.

THE NEXT SCHEDULED ADVISORY WILL BE ISSUED BY THE NATIONAL WEATHER
SERVICE AT 8 AM GUAM LST.

$$
PRIOR



[P.K.]

In the NW Pacific when a storm reaches 50kts it is a Severe Tropical Storm. However currently it is only 45kts, and the SS scale is not used for this region anyway.

[Alacane2]

Right, the RSMC Tokyo office does not use the Saffir-Simpson scale. However, this is an advisory from the National Weather Service office in Guam. They are apparently using the Saffir-Simpson scale, since they reference it in their advisory.

[P.K.]

By the way the same is true of the SW Indian Ocean where this term is also used (For between 48 and 63kts).

Ah so that is where that is from, I didn't know, still I'd keep using the RSMC Tokyo advisories.

[Aslkahuna]

The Forecast responsibility for the NWS Office on Guam also includes the islands that Ewiniar is near by agreement with the US. When the various islands formerly under US Mandate out there became Independent, they requested that NWS continue to provide forecast service to them. Also, the Northern Marianas (Saipan, Rota, Tinian, Pagan, etc.) is a US Commonwealth and also comes under Tiyan's AOR. So these locales will use the SS scale. As for Category B, I have no idea about that one. On the last JT advisory (which NWS will use) the storm was at 55kt.

Steve

[Regit]

Guam uses a variation of the Saffir Simpson Scale. You can read more about it at the link below:

http://www.typhoon2000.ph/tropical_SS.htm

[P.K.]

That is a little odd as that doesn't follow what either M-F or the JMA use as I would expect, but uses 44-63kts instead. Then again they appear to start the TS category at 26kts rather than 34kts.

[WindRunner]

Then again they appear to start the TS category at 26kts rather than 34kts.

Because those numbers are in 10min average form. I assume it converts to roughly 34kts in 1-min winds.

[P.K.]

It says 26-43kts, which they convert to 23-37kts for a ten minute average.

[WindRunner]

Oh, yeah, your right, and what I said is a little bit too much of a difference at that low of a number anyway. You know, I guess I've been having a real problem with things that deal with 10min winds recently, the way you have to keep correcting me on these things . . .