Saffir-Simpson Scale Update - May 15, 2012 Options

[beninbaltimore]

This was posted Thursday.

NOUS41 KWBC 011848
PNSWSH

Public Information Statement
National Weather Service Headquarters Washington DC
148 PM EST Thu Mar 1 2012

To: Subscribers:
-Family of Services
-NOAA Weather Wire Service
-Emergency Managers Weather Information Network
-NOAAPORT
Other NWS partners and NWS employees

From: Mark Tew
Chief, Marine and Coastal Services Branch

Subject: Minor Modification of Saffir-Simpson Hurricane Wind
Scale Thresholds Effective May 15, 2012

Effective May 15, 2012, the Saffir-Simpson Hurricane Wind Scale
(SSHWS) will be adjusted slightly to resolve issues associated
with the conversion of units used for wind speed. This change
follows a public comment period conducted in 2011.

The National Hurricane Center (NHC) and Central Pacific Hurricane
(CPHC) assign intensities of hurricanes in 5-knot (kt)
increments. For advisory products, these intensities are
converted to miles per hour (mph) and kilometers per hour (km/h),
and then rounded to the nearest 5-mph or 5-km/h increments.
Challenges occur when the current Category 4 intensity is 115 kt
(132.3 mph). Although 115 kt is within the Category 4 range, the
equivalent rounded wind speed in mph is 130 mph, which is in the
Category 3 range. To classify the hurricane as a Category 4 in
both sets of units (kt and mph), NHC and CPHC must incorrectly
convert 115 kt to 135 mph in the advisory products. A similar
issue occurs when the current Category 4 intensity of 135 kt is
converted to km/h.

Effective May 15, 2012, to resolve these rounding issues,
Category 4 on the SSHWS will be broadened by one mph at each end
of the range, yielding a new range of 130-156 mph. This will
also result in a minor modification of the Category 3 and 5 wind
speed thresholds. The SSHWS will change as follows:

From:

Category 3: 111-130 mph (96-113 kt, 178-209 km/h)
Category 4: 131-155 mph (114-135 kt, 210-249 km/h)
Category 5: 156 mph or higher (136 kt or higher, 250 km/h or
higher)

To:

Category 3: 111-129 mph (96-112 kt, 178-208 km/h)
Category 4: 130-156 mph (113-136 kt, 209-251 km/h)
Category 5: 157 mph or higher (137 kt or higher, 252 km/h or
higher)

There will be no change to the wind speeds currently assigned to
Categories 1 and 2.

With this change, a 115-kt Category 4 hurricane will have its
intensity properly converted to mph and rounded to the nearest 5
mph (130 mph) and remain within the Category 4 mph range.

Important note: Since intensities are assigned using 5-kt
increments, neither storms in the historical record nor any
future storms will have their SSHWS category changed as a result
of this modification to the scale.

The NWS wishes to remind media, partners, and the public the
Saffir-Simpson Hurricane Wind Scale provides information on wind
impacts only. The scale does not provide commentary or
information on other impacts or characteristics of tropical
cyclones.

Additional information on this change can be found at:

http://www.nhc.noaa.gov/aboutsshws.php

If you have any questions, please contact

John Kuhn
National Weather Service
Silver Spring, Maryland 20910
301 713 1677 ext. 121
john.f.kuhn@noaa.gov

National Public Information Notices are online at:

http://www.weather.gov/om/notif.htm

$$

source

[weather-major94]

This was posted Thursday.
source

This might be slightly off topic, but are they ever going to fix the issue of the scale not accounting for size? I am referring to the inaccurate measurements when they predicted Hurricane Ike, September 2008, and the storm surge was off by upwards of 5 feet in many places, due to the sheer size of the storm.

[NYCSuburbs]

This might be slightly off topic, but are they ever going to fix the issue of the scale not accounting for size? I am referring to the inaccurate measurements when they predicted Hurricane Ike, September 2008, and the storm surge was off by upwards of 5 feet in many places, due to the sheer size of the storm.

That's why its name has been changed not long ago to the "Saffir-Simpson Hurricane Wind Scale". Ike was one of the reasons that resulted in the changing of the scale to wind, not including other factors. Still, I would think that an additional scale including size/wave impact may be needed.

[weather-major94]

That's why its name has been changed not long ago to the "Saffir-Simpson Hurricane Wind Scale". Ike was one of the reasons that resulted in the changing of the scale to wind, not including other factors. Still, I would think that an additional scale including size/wave impact may be needed.

I agree, i lost some property because of the inaccurate measurements, and i think a scale is needed, at least in that area.

This post has been edited by weather-major94: Mar 25 2012, 05:59 PM

[Superstorm93]

There actually is a scale that accounts surge and size of a hurricane.

It's called the "IKE" scale and believe it or not, Hurricane Ike had the highest numbers on it.

EDIT: Link to the IKE scale that was patented in 2007

This post has been edited by Superstorm93: Mar 25 2012, 06:40 PM

[Niyologist]

There actually is a scale that accounts surge and size of a hurricane.

It's called the "IKE" scale and believe it or not, Hurricane Ike had the highest numbers on it.

Irony at its' greatest and historic moments.

This post has been edited by Niyologist: Mar 25 2012, 06:07 PM

[weather-major94]

There actually is a scale that accounts surge and size of a hurricane.

It's called the "IKE" scale and believe it or not, Hurricane Ike had the highest numbers on it.

EDIT: Link to the IKE scale that was patented in 2007

they need to use this scale more than the saffir simpson. this scale has a bit less margin for error, and the calculation is pretty much foolproof.