Revamping the SS Scale

[brunota2003]

Seeing how there was a debate going on in another thread about what can be done, figured I would start a thread strictly for that idea...and see what others' ideas are.

I think, as far as record keeping goes, hurricanes should still be given the SS Wind Scale rating in the TCR. When the hurricanes are out in the ocean, away from land, they should be referred to by their wind rating as well. Once a hurricane gets to within about 48 hours of possibly making landfall, the scale should be broken down for every element...to provide a more enhanced look at the threats each individual storm is bringing.

I like the idea of "categories" or "levels", and they could keep that, just have different scales. Winds keep their current scale, surge, and rain/flooding can get their own. The header on the bulletin can have the maximum risk present.

Wind Category:
TD: < 39 mph
TS: 40 - 73 mph
Cat 1: 74 - 95 mph
Cat 2: 96 - 110 mph
Cat 3: 111 - 130 mph
Cat 4: 131 - 155 mph
Cat 5: > 155 mph

Surge Levels:
Level I: 0 - 5 feet
Level II: 5 - 10 feet
Level III: 10 - 15 feet
Level IV: 15 - 20 feet
Level V: 20+ feet
*Note: Large, battering waves will occur on top of estimated storm surge sizes.

Rain/Flooding:
Low: Nuisance flooding, small streams flooding, poor drainage areas and street flooding may occur.
Medium: Smaller rivers may flood, nuisance flooding likely. Some evacuations possible.
High: Major flooding possible, many evacuations likely due to flooding.
Extremely High: Flooding of epic proportions likely (record levels). (Very rare, used in dire emergencies mostly...like a tornado emergency, almost).
(Or something similar)

Tornado Risk (I like how the SPC outlines severe wx threats):
Slight (will always be some risk of tornadoes)
Moderate
High
*Note: Perhaps some day, we will know better which hurricanes will only produce a couple tornadoes, and which produce 100s of them.


So, the product could end up looking like this:

*EXAMPLE*

...HURRICANE ISABEL APPROACHING THE MID-ATLANTIC...

OVERVIEW OF FORECAST THREATS AT LANDFALL AND WATCHES/WARNINGS:

WINDS: CATEGORY 2
SURGE: LEVEL II LIKELY...LEVEL III POSSIBLE
FLOODING POTENTIAL: MEDIUM
TORNADO RISK: SLIGHT

WATCHES/WARNINGS:

A HURRICANE WARNING REMAINS IN EFFECT FROM CAPE FEAR NORTH CAROLINA TO CHINCOTEAGUE VIRGINA...INCLUDING PAMLICO AND ALBEMARLE SOUNDS...AND THE CHESAPEAKE BAY SOUTH OF SMITH POINT. A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED WITHIN THE WARNING AREA...GENERALLY WITHIN 24 HOURS.

ALL PREPARATIONS TO PROTECT LIFE AND PROPERTY SHOULD BE RUSHED TO COMPLETION IN THE HURRICANE WARNING AREA.

A TROPICAL STORM WARNING IS IN EFFECT SOUTH OF CAPE FEAR TO SOUTH SANTEE RIVER SOUTH CAROLINA...AND NORTH OF CHINCOTEAGUE TO SANDY HOOK NEW JERSEY...INCLUDING DELAWARE BAY. A TROPICAL STORM WARNING IS ALSO IN EFFECT FOR THE CHESAPEAKE BAY FROM SMITH POINT NORTHWARD...AND FOR THE TIDAL POTOMAC.

-----------------------------

CURRENT STORM INFORMATION:

AT 2 PM EDT...1800Z...THE CENTER OF HURRICANE ISABEL WAS LOCATED NEAR LATITUDE 30.6 NORTH... LONGITUDE 73.0 WEST OR ABOUT 350 MILES SOUTH-SOUTHEAST OF CAPE HATTERAS NORTH CAROLINA.

ISABEL IS MOVING TOWARD THE NORTH-NORTHWEST NEAR 11 MPH. SOME INCREASE IN FORWARD SPEED IS EXPECTED OVER THE NEXT 24 HOURS. ON THE FORECAST TRACK...THE CENTER OF ISABEL IS EXPECTED TO MAKE LANDFALL IN EASTERN NORTH CAROLINA DURING THE DAY THURSDAY. HOWEVER...THE PRECISE TIMING AND LOCATION OF LANDFALL IS UNCERTAIN...AND CONDITIONS WILL DETERIORATE OVER A LARGE AREA WELL BEFORE THE CENTER REACHES THE COAST. TROPICAL STORM CONDITIONS ARE EXPECTED TO REACH THE COASTLINE LATE TONIGHT.

MAXIMUM SUSTAINED WINDS ARE NEAR 105 MPH...WITH HIGHER GUSTS. ISABEL IS CURRENTLY A CATEGORY TWO HURRICANE ON THE SAFFIR-SIMPSON HURRICANE WIND SCALE.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 115 MILES FROM THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 315 MILES.

THE MOST RECENT MINIMUM CENTRAL PRESSURE REPORTED BY RECONNAISSANCE AIRCRAFT WAS 956 MB...28.23 INCHES.

-----------------------------

DETAILED FORECAST LANDFALL THREAT INFORMATION:

WINDS: CATEGORY 2

HURRICANE ISABEL IS CURRENTLY A CATEGORY 2 HURRICANE WITH MAXIMUM SUSTAINED WINDS OF 105 MPH...WITH HIGHER GUSTS. LITTLE CHANGE IN STRENGTH IS ANTICIPATED PRIOR TO LANDFALL. (Insert more specific info if warranted, for example, unusually strong gusts, high rise buildings/terrain, strengthening before landfall, etc).

SURGE: LEVEL II LIKELY...LEVEL III POSSIBLE IN SOME LOCATIONS

STORM SURGE FLOODING OF 7 TO 11 FEET ABOVE NORMAL TIDE LEVELS...ALONG WITH LARGE AND DANGEROUS BATTERING WAVES...IS EXPECTED NEAR AND TO THE NORTH OF WHERE THE CENTER CROSSES THE COAST. STORM SURGE FLOODING OF 4 TO 7 FT ABOVE NORMAL TIDE LEVELS IS EXPECTED IN SOUTHERN CHESAPEAKE BAY AND THE TIDAL PORTIONS OF ADJACENT RIVERS.(Insert more info as needed).

RAIN/FLOODING POTENTIAL: MEDIUM (for example, Hurricane Floyd or TS Allison would be either high or extremely high risks)

STORM TOTAL RAINFALLS OF 6 TO 10 INCHES...WITH LOCALLY HIGHER AMOUNTS...ARE LIKELY IN ASSOCIATION WITH ISABEL. NUISANCE FLOODING IS LIKELY...WITH THE POSSIBLY OF SOME RIVER FLOODING. (More info as needed).

TORNADO RISK: SLIGHT

THERE IS THE THREAT OF ISOLATED TORNADOES TONIGHT OVER EASTERN NORTH CAROLINA. (More info as needed).

-----------------------------

REPEATING THE 2 PM EDT POSITION...30.6 N... 73.0 W. MOVEMENT TOWARD...NORTH-NORTHWEST NEAR 11 MPH. MAXIMUM SUSTAINED WINDS...105 MPH. MINIMUM CENTRAL PRESSURE... 956 MB.

FOR STORM-RELATED INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR PRODUCTS ISSUED BY YOUR LOCAL WEATHER OFFICE...AND STATEMENTS FROM LOCAL EMERGENCY MANAGEMENT OFFICIALS.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT 5 PM EDT.

FORECASTER XXXXX

Actual intermediate public advisory most of the info is from:
http://www.nhc.noaa.gov/archive/2003/pu ... .046.shtml?

At the end of Isabel's life, she would still go down as a Category 2 hurricane at landfall in the TCR (for continuation)...but there is a better means to describing threat levels leading up to the landfall itself.

So as you can see, there would only be some modifications to the public advisories to adjust to a multiscale system...and the public could quickly learn about the generalized threats the hurricane provides...and it is not all based specifically on the SS Scale. For specific info, obviously as usual, you would go through your local NWS. This is only meant as a better "scale" type setting. (And yes, I know the format to the public advisories has changed since 2003, this is only a rough draft).

[somethingfunny]

I like this, alot.

[brunota2003]

I think the only way to really break people of the "SS Scale Surge" is to implement a different scale, but dealing with surge specifically. However, you can't color code it "red, yellow, etc" or say "medium, high, etc" because surge levels in different areas does different things. In coastal NC, 4 foot of surge will flood many houses along the river and sound front businesses...whereas elsewhere, 4 foot might just cause bad beach erosion. Using "Levels", however, allows for standardization across the board, and evacuation zones can be set using them.

If a Level III surge is expected (10 to 15 feet), mandatory evacuations out to Level IV (15 to 20) can be issued...which gives the local EOMs up to 5 feet of surge error to play with, when considering evacs. Also, the reason I overlapped the surge Levels is to give a little leeway on the Level posted. If you are expecting a surge of 7 to 10 feet (within Level II), you could say Level III possible, or upgrade to Level III...for example, if there is a strong possibility the surge could be higher (would be beneficial to note the reason why one upgraded, too).

I did think about the surge scale more, and I would like to amend it slightly:

Level I: 0 to 5 feet
Level II: 5 to 10 feet
Level III: 10 to 15 feet
Level IV: 15 to 20 feet
Level V: 20 to 25 feet
Level VI: 25+ feet

I wanted to add in another level, so that it can be shown when surge gets to be above 25 feet...like in Katrina.

[SouthDadeFish]

I think the only way to really break people of the "SS Scale Surge" is to implement a different scale, but dealing with surge specifically. However, you can't color code it "red, yellow, etc" or say "medium, high, etc" because surge levels in different areas does different things. In coastal NC, 4 foot of surge will flood many houses along the river and sound front businesses...whereas elsewhere, 4 foot might just cause bad beach erosion. Using "Levels", however, allows for standardization across the board, and evacuation zones can be set using them.

If a Level III surge is expected (10 to 15 feet), mandatory evacuations out to Level IV (15 to 20) can be issued...which gives the local EOMs up to 5 feet of surge error to play with, when considering evacs. Also, the reason I overlapped the surge Levels is to give a little leeway on the Level posted. If you are expecting a surge of 7 to 10 feet (within Level II), you could say Level III possible, or upgrade to Level III...for example, if there is a strong possibility the surge could be higher (would be beneficial to note the reason why one upgraded, too).

I did think about the surge scale more, and I would like to amend it slightly:

Level I: 0 to 5 feet
Level II: 5 to 10 feet
Level III: 10 to 15 feet
Level IV: 15 to 20 feet
Level V: 20 to 25 feet
Level VI: 25+ feet

I wanted to add in another level, so that it can be shown when surge gets to be above 25 feet...like in Katrina.

I like this idea, but I don't understand how you say one color code warning doesn't fit all, but yet you are suggesting we implement "Levels" which from what I see, are the very same thing, just with a different name. Please explain to me if I'm reading this wrong. On the Storm Surge forum put out by the NHC, I suggested something very similar, but instead of levels, use a color code system. The goal would be to make something very distinguishable from the SS category system. You don't want numbers and numbers. Although you may write it with a roman numeral here, imagine how it would be spoken on the news. They would both be numbers.

A color system helps to minimize confusion. I do agree with you that a new system would have to be set in place. It is foolish that people died in Katrina because they had the mentality that they survived a cat 5 so nothing could be worse than that. Instead, it has been simulated that any storm of Camille's size in the same geographic location, even at Maximum Potential Intensity of 880mb, would not have produced a surge larger than Katrina. Clearly, we need a new system to separate the hazards of wind and surge. In my opinion, a color system would be the most effective method of doing so. For example Katrina would still been a category 3 on the Saffir-Simpson Hurricane Wind Scale, but there also could have been a "Code Black" storm warning. My color proposal would be Blue<Yellow<Orange<Red<Black. The heights could be determined by the NHC or emergency management, but similar to the intervals you suggested. Therefore Camille would have been a Code Red, but Katrina would have been a Code Black, so just because you survived Camille, doesn't mean you would have survived Katrina in the same location.

Also just wanted to clarify that these color code warnings would be issued based upon maximum expected storm surge levels. So even if the bathymetry at Location A is different than Location B, the color warning only reflects that resulted surge. This way the warning can incorporate the different factors that affect surge such as max wind speed, radius of maximum winds, and bathymetry.

What do y'all think?

[brunota2003]

I see where you are coming from...my main issue was that a code red at this location could be completely different from a code red at another location. I was trying to fit the levels in with specific heights, which is why I was saying the colors wouldn't work too well...though I guess they could be used in the same manner.

The Levels thing was to help aid in evacuations, like the flood zoning maps that are done (which, really, could be used in the exact same way).

[Hurricane Jed]

Given what Ike did and the whole size matters thing. I was a thinking of a size based scale and size being based on the size of the wind field
Very Small- TS Marco
Small- Hurricane Alicia
Medium- Hurricane Charley
Large- Hurricane Allen
Very Large- Hurricane Igor

And to get surge values examine a variety of past hurricanes at each size, their wind speeds and their landfall effects. It would be confusing yes. Comparison Ike vs. Alicia. Ike's storm surge was massive compared to Alicia.

So something like. VS Category 4 Debby is approaching South Texas etc, etc.


But its hard to come up with any scale. So many factors: topography, forward speed of the storm, size of the storm, wind field size, wind strength, direction of approach, location of the strongest winds (i.e. Celia's strongest winds weren't in the right front quadrant), how well are structures in the path of the storm constructed, how much rainfall does the storm contain (dry/wet), etc.

[CrazyC83]

Some notes:

* That works well for mainland landfalls, but can be misleading for islands when the core stays over water but the impacts overspread them, example being Omar in 2008. (Although there would be a margin of error!)

* When it comes to the islands, conditional situations should be mentioned, like for surge. An example is this (from the 11 pm advisory on October 15, 2008 - actual advisory containing most of the information is http://www.nhc.noaa.gov/archive/2008/al ... .011.shtml?), I also added conditional notes for winds (and a tornado blurb, there was none):

...OMAR BECOMES A MAJOR HURRICANE AS IT APPROACHES THE VIRGIN AND
NORTHERN LEEWARD ISLANDS...

WINDS: CATEGORY 3
SURGE: LEVEL I EXPECTED...LEVEL II LIKELY JUST EAST OF EYE
FLOODING POTENTIAL: MEDIUM-HIGH
TORNADO RISK: SLIGHT

WATCHES/WARNINGS:

A HURRICANE WARNING IS IN EFFECT FOR THE U.S. VIRGIN ISLANDS AND THE
ISLANDS OF VIEQUES AND CULEBRA. A HURRICANE WARNING IS ALSO IN
EFFECT FOR ST. MARTIN/MAARTEN...SABA...ST. EUSTATIUS...ST.
BARTHELEMY...THE BRITISH VIRGIN ISLANDS...AND ANGUILLA. A
HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED
WITHIN THE WARNING AREA WITHIN THE NEXT 24 HOURS. PREPARATIONS TO
PROTECT LIFE AND PROPERTY SHOULD BE RUSHED TO COMPLETION.

A HURRICANE WATCH AND A TROPICAL STORM WARNING REMAIN IN EFFECT FOR
PUERTO RICO...AND ALSO FOR THE ISLANDS OF ST. KITTS AND NEVIS.

A HURRICANE WATCH MEANS THAT HURRICANE CONDITIONS ARE POSSIBLE
WITHIN THE WATCH AREA...IN THIS CASE..WITHIN THE NEXT 24 HOURS.

A TROPICAL STORM WARNING IS IN EFFECT FOR ANTIGUA...BARBUDA...AND
MONTSERRAT.

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED WITHIN THE WARNING AREA WITHIN THE NEXT 24 HOURS.

A TROPICAL STORM WATCH IS IN EFFECT FOR GUADELOUPE.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...INCLUDING POSSIBLE
INLAND WATCHES AND WARNINGS...PLEASE MONITOR PRODUCTS ISSUED
BY YOUR LOCAL WEATHER OFFICE.

---------------------------------------

CURRENT STORM INFORMATION:

AT 1100 PM AST...0300Z...THE CENTER OF HURRICANE OMAR WAS LOCATED
NEAR LATITUDE 17.4 NORTH...LONGITUDE 64.5 WEST OR ABOUT 30 MILES...
45 KM...SOUTHEAST OF ST. CROIX AND ABOUT 105 MILES...165 KM...
WEST-SOUTHWEST OF ST. MARTIN.

OMAR IS MOVING TOWARD THE NORTHEAST NEAR 20 MPH...32 KM/HR...AND
THIS GENERAL MOTION IS EXPECTED TO CONTINUE FOR THE NEXT COUPLE OF
DAYS. ON THE FORECAST TRACK...THE CENTER OF OMAR WILL PASS JUST
EAST OF THE VIRGIN ISLANDS IN THE NEXT FEW HOURS...AND NEAR THE
NORTHERN LEEWARD ISLANDS EARLY THURSDAY MORNING.

MAXIMUM SUSTAINED WINDS ARE NEAR 115 MPH...185 KM/HR...WITH HIGHER
GUSTS. OMAR IS CURRENTLY A CATEGORY THREE HURRICANE ON THE SAFFIR-
SIMPSON HURRICANE WIND SCALE.

OMAR IS A SMALL HURRICANE. HURRICANE FORCE WINDS EXTEND OUTWARD UP
TO 35 MILES...55 KM...FROM THE CENTER...AND TROPICAL STORM FORCE WINDS
EXTEND OUTWARD UP TO 115 MILES...185 KM.

THE MINIMUM CENTRAL PRESSURE JUST REPORTED BY THE HURRICANE HUNTER
IS 967 MB...28.56 INCHES.

------------------------------------------

DETAILED FORECAST THREAT INFORMATION:

WINDS: CATEGORY 3

OMAR IS NOW A CATEGORY 3 HURRICANE WITH MAXIMUM SUSTAINED WINDS
NEAR 115 MPH...185 KM/HR...WITH HIGHER GUSTS. SOME ADDITIONAL
STRENGTHENING IS POSSIBLE TONIGHT AS OMAR MOVES THROUGH THE
NORTHERN LEEWARD ISLANDS. STRONGER WINDS MAY BE EXPERIENCED ON
HIGHER TERRAIN.

SINCE THE CORE OF OMAR IS SMALL, THERE IS STILL UNCERTAINTY WHICH
ISLANDS MAY EXPERIENCE THE STRONGEST WINDS AND NOT ALL ISLANDS WILL.
EXPERIENCE STRONG HURRICANE FORCE WINDS. HOWEVER, ALL INTERESTS IN
THE WARNING AREA SHOULD HAVE PREPARED FOR AN INTENSE HURRICANE.
CATEGORY 3 WINDS WILL LIKELY PRODUCE DEVASTATING DAMAGE, WITH VERY
DANGEROUS AND DESTRUCTIVE WINDS IN CATEGORY 1 AND 2 CONDITIONS AS
WELL.

ST. CROIX RECENTLY REPORTED SUSTAINED WINDS OF 39 MPH...63 KM/HR...
WITH A WIND GUST OF 59 MPH...94 KM/HR.

SURGE: LEVEL I...LOCALLY LEVEL II JUST RIGHT OF THE CORE

COASTAL STORM SURGE FLOODING OF 4 TO 6 FEET ABOVE NORMAL TIDE
LEVELS...ALONG WITH LARGE AND DANGEROUS BATTERING WAVES...CAN BE
EXPECTED NEAR AND TO THE RIGHT OF THE PATH OF OMAR. COASTAL STORM
SURGE FLOODING OF 2 TO 4 FEET ABOVE NORMAL TIDE LEVELS...ALONG WITH
LARGE AND DANGEROUS BATTERING WAVES...CAN BE EXPECTED ALONG THE
COASTS OF THE VIRGIN ISLANDS AND PUERTO RICO. IN ADDITION...OMAR
IS EXPECTED TO PRODUCE LARGE SWELLS THAT WILL AFFECT THE WEST- AND
SOUTH-FACING COASTS OF PUERTO RICO AND THE ISLANDS OF THE LESSER
ANTILLES. THESE SWELLS COULD CAUSE BEACH EROSION AND DAMAGE TO
COASTAL STRUCTURES.

RAIN/FLOODING POTENTIAL: MEDIUM...LOCALLY HIGH IN HIGHER TERRAIN

OMAR IS EXPECTED TO PRODUCE TOTAL RAINFALL AMOUNTS OF 5 TO 10
INCHES...WITH MAXIMUM AMOUNTS UP TO 20 INCHES POSSIBLE...ACROSS THE
NORTHERN LEEWARD ISLANDS...THE VIRGIN ISLANDS...VIEQUES...AND
CULEBRA. ADDITIONAL RAINFALL AMOUNTS OF 2 TO 4 INCHES WITH ISOLATED
MAXIMUM AMOUNTS OF UP TO 8 INCHES ARE POSSIBLE FOR PUERTO RICO.
THESE RAINS COULD PRODUCE LIFE-THREATENING FLASH FLOODS AND MUD
SLIDES.

TORNADO RISK...SLIGHT

ISOLATED TORNADOES ARE POSSIBLE TO THE RIGHT OF THE CORE OF OMAR. (not in the original forecast but the lowest potential that could be added, in reality there were no tornadoes)

---------------------------------------------

REPEATING THE 1100 PM AST POSITION...17.4 N...64.5 W. MOVEMENT
TOWARD...NORTHEAST NEAR 20 MPH. MAXIMUM SUSTAINED WINDS...115 MPH.
MINIMUM CENTRAL PRESSURE...967 MB.

INTERMEDIATE ADVISORIES WILL BE ISSUED BY THE NATIONAL HURRICANE
CENTER AT 100 AM AND 300 AM AST...FOLLOWED BY THE NEXT COMPLETE
ADVISORY AT 500 AM AST.

$$
FORECASTER XXXXX

[boca]

Given what Ike did and the whole size matters thing. I was a thinking of a size based scale and size being based on the size of the wind field
Very Small- TS Marco
Small- Hurricane Alicia
Medium- Hurricane Charley
Large- Hurricane Allen
Very Large- Hurricane Igor

And to get surge values examine a variety of past hurricanes at each size, their wind speeds and their landfall effects. It would be confusing yes. Comparison Ike vs. Alicia. Ike's storm surge was massive compared to Alicia.

So something like. VS Category 4 Debby is approaching South Texas etc, etc.


But its hard to come up with any scale. So many factors: topography, forward speed of the storm, size of the storm, wind field size, wind strength, direction of approach, location of the strongest winds (i.e. Celia's strongest winds weren't in the right front quadrant), how well are structures in the path of the storm constructed, how much rainfall does the storm contain (dry/wet), etc.

Actually Charley was small to very small.We had no effects here in SE Florida 130 miles away.

[CrazyC83]

A good size comparison could be:

Very Small - TS field diameter less than 80 + 2x latitude nautical miles (since storms become larger normally as they go north)

Small - 80 + 2xL to 150 + 2xL

Medium - 150 + 2xL to 250 + 2xL

Large - 250 + 2xL to 500 + 2xL

Very Large - Larger than 500 + 2xL

(For a storm at 15N, add 30 to the calculations. At 25N, add 50. At 40N, add 80)

[wxman57]

Given what Ike did and the whole size matters thing. I was a thinking of a size based scale and size being based on the size of the wind field
Very Small- TS Marco
Small- Hurricane Alicia
Medium- Hurricane Charley
Large- Hurricane Allen
Very Large- Hurricane Igor

And to get surge values examine a variety of past hurricanes at each size, their wind speeds and their landfall effects. It would be confusing yes. Comparison Ike vs. Alicia. Ike's storm surge was massive compared to Alicia.

So something like. VS Category 4 Debby is approaching South Texas etc, etc.


But its hard to come up with any scale. So many factors: topography, forward speed of the storm, size of the storm, wind field size, wind strength, direction of approach, location of the strongest winds (i.e. Celia's strongest winds weren't in the right front quadrant), how well are structures in the path of the storm constructed, how much rainfall does the storm contain (dry/wet), etc.

Alicia (1983) was WAY bigger than Charley (2004) when comparing wind field sizes. There's no comparison at all. But Alicia was considerably smaller than Ike.

There are two primary factors that govern a storm's surge:

1. Coastal bathymetry. That is, where the storm strikes. Some parts of the U.S. coastline with very shallow water extending far offshore (central LA, MS, Tampa) would see 2-3 times the surge of the same storm hitting central Texas, for example. Or Ivan hitting Pensacola - 10ft surge, Ivan hitting MS - 25-30 ft surge. Same storm, different coastal bathymetry. There is quite deep water near shore at Pensacola.

2. Wind field size. A larger hurricane (radius of max winds) produces a larger storm surge. Peak winds (SS Cat) are nearly irrelevant.

One major problem we keep running into when assisting clients with hurricane response plans is that they still associate storm surge with Saffir-Simpson. The plan says stay put for Cat 1-2, evacuate for Cat 3-4-5. It's going to take generations for people to quit using SS for estimating storm surge.

By the way, the NHC was forecasting Ike to produce a 20 ft storm surge days before landfall. Even then, some communities (like Texas City) based their evacuation decision on the 9-12 ft storm surge from a Cat 3 hurricane, as Ike was forecast to be at landfall. If Ike had moved inland just 10 miles farther south, then Texas City would have been under 6-9 feet of water.

From the 10am CDT Thursday, Sept. 11th Ike advisory:
COASTAL STORM SURGE FLOODING OF UP TO 20 FT ABOVE NORMAL TIDE
LEVELS...ALONG WITH LARGE AND DANGEROUS BATTERING WAVES...CAN BE
EXPECTED NEAR AND TO THE EAST OF WHERE THE CENTER OF IKE MAKES
LANDFALL.

The problem isn't that we need to specify levels of surge, the problem is that people still associate Saffir-Simpson with surge threat.

[psyclone]

I'm scaled out. and wxman's post above illustrates the futility of one-size-fits-all scales. there's only one scale we need for storm surge: feet (or meters for those with metric inclinations). people need to know if they're going to be swimming. storm surge scales related to tropical cyclones create an impression with the public that storm surges are unique to tropical cyclones. they are not. witness the coastal inundation in the FL big bend from the no name storm in march of '93.

[wxman57]

The SLOSH (Sea, Lake and Overland Surge from Hurricanes) model is quite primitive compared to the new ADCIRC (ADvanced CIRCulation) model. ADCIRC, combined with LIDAR mapping of coastal topography, should allow for forecasts of actual water depth at any location. So instead of a forecast of a 20ft storm surge, the forecast could say the water could be 12 ft deep at a specified location along the coast.

Of course, the problem with that will be that an accurate forecast of storm surge requires a perfect track forecast (within a few miles). I've monitored landfall forecasts from 24, 48 and 72 hours out over the past 10 years. Typical 24 hour error is 41 miles. At 48 hours before landfall, the average error was 59 miles. And 3 days before landfall, the average error was 115 miles.

This means that it's impossible to accurately predict storm surge for any given location along the coast. At best, we can provide a range of possible surge heights based on the projected storm size/intensity and the range of locations that the storm could hit along the coast (given typical forecast error).

[Ptarmigan]

Given what Ike did and the whole size matters thing. I was a thinking of a size based scale and size being based on the size of the wind field
Very Small- TS Marco
Small- Hurricane Alicia
Medium- Hurricane Charley
Large- Hurricane Allen
Very Large- Hurricane Igor

And to get surge values examine a variety of past hurricanes at each size, their wind speeds and their landfall effects. It would be confusing yes. Comparison Ike vs. Alicia. Ike's storm surge was massive compared to Alicia.

So something like. VS Category 4 Debby is approaching South Texas etc, etc.


But its hard to come up with any scale. So many factors: topography, forward speed of the storm, size of the storm, wind field size, wind strength, direction of approach, location of the strongest winds (i.e. Celia's strongest winds weren't in the right front quadrant), how well are structures in the path of the storm constructed, how much rainfall does the storm contain (dry/wet), etc.

Alicia was a medium sized storm with hurricane force winds extending up to 60 miles and tropical storm force winds extending up to 125 miles. Charley was small with hurricane force winds extending up to 30 miles and tropical storm force winds extending up to 80 miles.

Very Small-Tropical Storm Marco
Small-Hurricane Charley
Medium-Hurricane Alicia
Large-Hurricane Allen
Very Large-Hurricane Igor (Largest storm in HURDAT from 1988-2010 with average tropical storm force winds extending to 400 miles)

[Hurricane Jed]

My bad my bad. I just don't have access to all that info or know where to find it. I was just throwing something out there without really thinking. My point is its difficult to come up with any scale. And you are right, people still have a tendency to associate storm surge with the Saffir-Simspon Scale. I think what you are trying to say is that the scale is pointless for people trying to determine whether or not people need to evacuate. Example if a Category 1 approaches New Orleans and has such a ridiculously huge wind field its predicted to produce lets say a 20ft surge. People need to ignore what the Saffir Simpson Scale tells them to do and listen to what the meteorologists tell them to do, in which case evacuate. If the experts say go, then go.

[tolakram]

I've always thought that a storm should be judged by forecast damage. The idea of a scale is to try and make the intensity estimate objective but forecasters are charged with warning people of impending peril so relying on a simple single measurement objective scale does not make sense to me.

The magic number that consumers of hurricane forecasts see should be the estimated danger through forecasting. Ike would have been at least a 3, maybe a 4, for example. One can still make an objective measurement, much like Dvorak intensity, to come up with this number. In Ike's case many more would have evacuated if they saw cat 3 instead of 2, based on numerous interviews I read after the storm hit.

[brunota2003]

Which is why I think when a storm threatens land, the whole "Category 3" thing shouldn't be in the headlines, except to categorize the wind threat level. Something has to be done, and I think the only way to break people of the SS Scale habit is to modify it. Call it something else, and have ones for each threat. My family lived inland, we would use the wind portion when considering evacuations, and all agreed Cat 3 or higher and we were gone. Families along the coastlines, though, could use the surge threat scale...along with local authorities when considering mandatory evacuations. If a Level II surge is forecast (based on worst case), evacuate out to Level III at least. You can hide from the wind, but have to run from the water. Just like the saying you should always plan for one category higher than forecast (and sometimes more).

An idea I saw on the surge opinions site set up by the NHC was water markers in towns. Then people could really get a feel of where 20 feet of surge can end up at.

[SouthDadeFish]

I'm scaled out. and wxman's post above illustrates the futility of one-size-fits-all scales. there's only one scale we need for storm surge: feet (or meters for those with metric inclinations). people need to know if they're going to be swimming. storm surge scales related to tropical cyclones create an impression with the public that storm surges are unique to tropical cyclones. they are not. witness the coastal inundation in the FL big bend from the no name storm in march of '93.

Yes, having too many scales and numbers will do more harm than good to the general public. The good thing about scales though is that it gives the public something to relate a measurement to. For example, the average person doesn't know what kind of damage a storm that has maximum sustained winds of 125mph will do. Instead, we tell them it is a category 3 hurricane on the SSHWS and they now know oh, this is a major hurricane. If they live in a hurricane prone area they will most likely know what a major hurricane is capable of doing. Same goes with this hurricane has max sustained winds of 85 mph = category 1. Oh ok this is still a hurricane, but not a major hurricane.

The same style of thinking can be applied to storm surge. Yes the NHC does a GREAT job of forecasting the high water level for storm surges, however, to the average person, what does 11 feet of storm surge mean? Instead, use a color scale or something similar to first of all, disassociate that Saffir-Simpson category from surge heights, and to also give the public something to relate this amount of surge to. If those along the Upper-Texas Coast knew Ike was not solely a category two hurricane, but they were also under a Code Red Surge Warning, they would have probably felt less inclined to stay.

Also, once the color code ranges are established, I propose putting the corresponding color sticker/logo/icon on every street sign, so residents or tourists know what zone they are in as a threatening tropical cyclone approaches. If they are unsure what zone they are in, all they have to do is walk over to the closest street sign to find out. Very easy. Plus, evacuations can be based off of these zones.

It may not be the best solution, but in my opinion, this does a lot more good than people still thinking a category two hurricane will produce a "category two sized surge" such as Ike. No such thing exists as each event is unique.

[Hurricaneman]

I would do a bunch of different scales like the flood scale or surge scale above and ammend the SS to this

cat1 25-39mph
cat2 40-49mph
cat3 50-59mph
cat4 60-69mph
cat5 70-79mph
cat6 80-89mph
cat7 90-99mph
cat8 100-109mph
cat9 110-119mph
cat10 120-129mph
cat11 130-139mph
cat12 140-149mph
cat13 150-159mph
cat14 160-169mph
cat15 170-179mph
cat16 180-189mph
cat17 190-199mph
cat18 200+mph

Flood scale

cat1 creek swelling
cat2 creek flooding and stream swelling
cat3 major creek flooding and stream flooding and river swelling
cat4 major creek flooding and major stream flooding and river flooding
cat5 major flooding of everything

Surge scale

cat1 0-3ft
cat2 3-6ft
cat3 6-9ft
cat4 9-12ft
cat5 12-15ft
cat6 15-18ft
cat7 18-21ft
cat8 21-25ft
cat9 25-30ft
cat10 30+ft

[psyclone]

I would do a bunch of different scales like the flood scale or surge scale above and ammend the SS to this

cat1 25-39mph
cat2 40-49mph
cat3 50-59mph
cat4 60-69mph
cat5 70-79mph
cat6 80-89mph
cat7 90-99mph
cat8 100-109mph
cat9 110-119mph
cat10 120-129mph
cat11 130-139mph
cat12 140-149mph
cat13 150-159mph
cat14 160-169mph
cat15 170-179mph
cat16 180-189mph
cat17 190-199mph
cat18 200+mph

Flood scale

cat1 creek swelling
cat2 creek flooding and stream swelling
cat3 major creek flooding and stream flooding and river swelling
cat4 major creek flooding and major stream flooding and river flooding
cat5 major flooding of everything

Surge scale

cat1 0-3ft
cat2 3-6ft
cat3 6-9ft
cat4 9-12ft
cat5 12-15ft
cat6 15-18ft
cat7 18-21ft
cat8 21-25ft
cat9 25-30ft
cat10 30+ft

you can't be serious here. could you imagine what a mess this would be? this sounds like an infomercial....call right now and we'll throw in an extra 3 scales totally free! (just pay separate processing). we need to de-emphasize categories and emphasize sensible wx impacts at a given location to the best of our abilities. the cure to the problems inherent in the ss scale is not another scale...i have a feeling the ss scale will continue to haunt us for years to come...but it will still be utilized due to legacy and a desire for a point of reference.

[CrazyC83]

Given what Ike did and the whole size matters thing. I was a thinking of a size based scale and size being based on the size of the wind field
Very Small- TS Marco
Small- Hurricane Alicia
Medium- Hurricane Charley
Large- Hurricane Allen
Very Large- Hurricane Igor

And to get surge values examine a variety of past hurricanes at each size, their wind speeds and their landfall effects. It would be confusing yes. Comparison Ike vs. Alicia. Ike's storm surge was massive compared to Alicia.

So something like. VS Category 4 Debby is approaching South Texas etc, etc.


But its hard to come up with any scale. So many factors: topography, forward speed of the storm, size of the storm, wind field size, wind strength, direction of approach, location of the strongest winds (i.e. Celia's strongest winds weren't in the right front quadrant), how well are structures in the path of the storm constructed, how much rainfall does the storm contain (dry/wet), etc.

Alicia (1983) was WAY bigger than Charley (2004) when comparing wind field sizes. There's no comparison at all. But Alicia was considerably smaller than Ike.

There are two primary factors that govern a storm's surge:

1. Coastal bathymetry. That is, where the storm strikes. Some parts of the U.S. coastline with very shallow water extending far offshore (central LA, MS, Tampa) would see 2-3 times the surge of the same storm hitting central Texas, for example. Or Ivan hitting Pensacola - 10ft surge, Ivan hitting MS - 25-30 ft surge. Same storm, different coastal bathymetry. There is quite deep water near shore at Pensacola.

2. Wind field size. A larger hurricane (radius of max winds) produces a larger storm surge. Peak winds (SS Cat) are nearly irrelevant.

One major problem we keep running into when assisting clients with hurricane response plans is that they still associate storm surge with Saffir-Simpson. The plan says stay put for Cat 1-2, evacuate for Cat 3-4-5. It's going to take generations for people to quit using SS for estimating storm surge.

By the way, the NHC was forecasting Ike to produce a 20 ft storm surge days before landfall. Even then, some communities (like Texas City) based their evacuation decision on the 9-12 ft storm surge from a Cat 3 hurricane, as Ike was forecast to be at landfall. If Ike had moved inland just 10 miles farther south, then Texas City would have been under 6-9 feet of water.

From the 10am CDT Thursday, Sept. 11th Ike advisory:
COASTAL STORM SURGE FLOODING OF UP TO 20 FT ABOVE NORMAL TIDE
LEVELS...ALONG WITH LARGE AND DANGEROUS BATTERING WAVES...CAN BE
EXPECTED NEAR AND TO THE EAST OF WHERE THE CENTER OF IKE MAKES
LANDFALL.

The problem isn't that we need to specify levels of surge, the problem is that people still associate Saffir-Simpson with surge threat.

Does the central pressure help at all in determining storm surge? For example, a storm making landfall with a pressure of 950mb would have the same storm surge maximum whether it is a small Category 4 hurricane or a massive Category 1 hurricane with that pressure?