Category 6 Hurricanes

Is there such a thing as a Category 6 Hurricane? Not according to the National Oceanic and Atmospheric Administration (NOAA), which uses the Saffir-Simpson scale to measure hurricane intensity. According to them, hurricane categories are from 1 to 5. However, I have seen a couple of storms last year reach 175 mph. Does that warrant a Category 6? Camille hit 200 mph, but that was a gust. Isabel hit 236 mph in the clouds, but I have never heard of more than 155 mph on the ground. Still that should have rated Isabel a 7 or and 8 or something. So if we were to define a Category 6, what would its wind speeds be?

To find out what a Category 6 hurricane's wind speed should be, I did an exponential least squares fit on the Saffir Simpson scale and found this formula:

Level = 69.958 * 10^1.1969,

Or if you round off, it is quite close to

Level = 70 * 10^1.2

The idea is that a storm is, say a Category 3 hurricane if its level is between 2.5 and 3.5. I get from this hurricane levels beyond 5, but also four Tropical Storm levels, plus three other classifications of weak systems. From this formula, I get these limits for the categories of storms. I chose an exponential least squares fit, because that seems to fit the data better, and it seems to me that damage is proportional to the logarithm of the wind speed.

Level From To(mph) Description
-inf- -6 0 25 Pile of rain showers
-5 26 30 Weak System
-4 31 36 Moderate System
-3 37 43 Category 1 Tropical Storm
-2 44 52 Category 2 Tropical Storm
-1 53 62 Category 3 Tropical Storm
0 63 75 Category 4 Tropical Storm
1 76 90 Category 1 Hurricane
2 91 108 Category 2 Hurricane
3 109 130 Category 3 Hurricane
4 131 156 Category 4 Hurricane
5 157 187 Category 5 Hurricane
6 188 224 Category 6 Hurricane
7 225 268 Category 7 Hurricane
8 269 321 Category 8 Hurricane
9 322 NoLimit Inconceivable Hurricane

Since no tornado has ever been found with winds exceeding 321 mph, I just simply sum up Category 9, or Category 9+, as "Inconceivable Hurricane"; if you want to, you could use the formula to describe Category 10, 11, and so forth, maybe for measuring wind speeds in Jupiter's Great Spot.

If these storms are in the Eastern North Pacific, substitute "Typhoon" for "Hurricane". If they are elsewhere other than the Atlantic or North Pacific, substitute "Cyclone" for "Hurricane".

So therefore a Category 6 Hurricane has wind speeds from 188-224 mph. Hope we never get one of these hitting a city - might as well put the city in a blender and turn it to "high".

120 Degrees Below Zero

Today at 2006 April 26 16:38 EDT, I got the weirdest weather forecast from Weather Underground, which gets its forecasts directly from the National Oceanic and Atmospheric Administration (NOAA). This is the forecast, and I actually saw this on the site: "Tuesday Night and Wednesday - Mostly cloudy with a 30 percent chance of showers. Lows in the upper 40s. Highs around 70. Wind chill values as low as 120 below." Wind chills of 120 below zero??? Won't spring ever come? Will I have to pull out my parka again or worse? Besides, what kind of a wind speed with a temperature in the upper 40s would create a wind chill that cold?

That's the problem with automated forecasts. Flip a bit, and perhaps "light winds" becomes "over 24 inches of snow accumulation possible". I sought to inform others about it, so I posted a message on Storm2k, sent a message out to the listserver of the Richmond Astronomical Society (RAS) (because weather affects viewing of the sky), and two local meteorologists, Jim Duncan of WWBT-TV and John Bernier of WRIC-TV.

So far I haven't heard from RAS or Storm2k, but the two meteorologists responded promptly. Jim Duncan said, "Aren't computer-produced products great. Winds chill that low....no." This is another way of saying that humans err but to really make a colossal mistake takes a computer. John Bernier expressed the same sentiment: "Didn't you know that next Tuesday is 'The Day after Tomorrow'?! (after the movie) Gotta love how these automated sites mess up." Boy do they ever. Last year some of these NOAA messages were saying that the wind in the Bahamas was 567 mph. What category hurricane would that be?

The Day after Tomorrow? I saw that movie. It's based on a book entitled "The Great Global Superstorm". I commented on Amazon on that book on the questionable science in that book, including 63 degrees below zero in New York City (150 below in the movie). Air that is that cold above is so sparse that if it got on the ground it would affect ground temperatures like a pea-sized hailstone would affect a huge vat of boiling water. That comment by Mr. Bernier was a good one. Let's see - if Tuesday night is the Day after Tomorrow, then this must be Sunday. What's the Sunday night movie? The Day after Tomorrow? Oh come on.

This whole thing shows that NOAA people need to be careful in entering data, especially the place in the field. If the place gets shifted, data intended to show one thing may be treated as another, sometimes with peculiar results, such as a wind chill of 120 below zero.

And what am I going to do next Tuesday? If I go out at night, I will put on a jacket, for it will be in the 40s.