As long as we are all aware of the arbitrariness of categorization and concentrating on the NATL basin, I think we will be able to rationally discuss the issues.

I should have added, of course, and particularly so after another David Smith object lesson on the subject, a rational discussion must include an acute awareness of the changing capabilities of detection of tropical cyclones over time.

Note, the National Hurricane Center seems to be rejecting any changes at all based on the principle that we shouldn’t change at all.

Regarding cat 4 and 5 storms, there’s an arguable case that the two categories should be lumped together anyway.

As I recall the categorization of storms was to provide a measure of potential damage they could do to building structures (for the time the categories were initialized). In fact that is why a category 5 exists and not anything higher because the damage to structures at the time of the introduction to categories a 5 would do in any structure. Certainly what we want here is something that can be related to the storm itself like an ACE score with maybe a maximum intensity kicker. As long as we are all aware of the arbitrariness of categorization and concentrating on the NATL basin, I think we will be able to rationally discuss the issues.

Short-lived tropical storms have a duration of 24 hours or less and are quite weak.

They are hard/impossible to detect without modern technology (like modern satellites and Doppler radar) and were generally missed or ignored in earlier times. As the plot shows their numbers continue to increase, inflating the modern storm count.

A NON-TROPICAL AREA OF LOW PRESSURE LOCATED ABOUT 320 NM
WEST-SOUTHWEST OF BERMUDA NEAR 30N70W…ANALYZED 1008 MB…HAS
GENERALLY CHANGED LITTLE IN STRUCTURE. A SURFACE TROUGH EXTENDS
SW FROM THE LOW TO THE BAHAMAS NEAR 24N78W. SATELLITE IMAGES
SHOW AN EXPOSED LOW-LEVEL CENTER WITH MOST OF THE SHOWER AND
TSTMS ACTIVITY STRETCHED OUT TO THE NE OF THE LOW FROM 28N-31N
BETWEEN 66W-69W AND ALONG THE TRAILING TROUGH AXIS. LITTLE
MOVEMENT IS EXPECTED DURING THE NEXT DAY OR SO. HURRICANE
HUNTER AIRCRAFT INDICATE THAT THE LOW HAS NOT YET ACQUIRED THE
CHARACTERISTICS OF A SUBTROPICAL OR TROPICAL CYCLONE. MOST OF
THE ASSOCIATED SHOWER ACTIVITY REMAINS EAST OF THE CENTER WHERE
WINDS TO NEAR GALE FORCE ARE OCCURRING. THE SYSTEM IS
INTERACTING WITH AN UPPER-LEVEL TROUGH…AND UPPER-LEVEL WINDS
ARE CURRENTLY NOT FAVORABLE FOR DEVELOPMENT. HOWEVER…
CONDITIONS ARE FORECAST TO BECOME MORE FAVORABLE AS THE LOW
MOVES SLOWLY AND ERRATICALLY…AND A SUBTROPICAL OR TROPICAL
CYCLONE COULD FORM DURING THE NEXT COUPLE OF DAYS.

Regarding cat 4 and 5 storms, there’s an arguable case that the two categories should be lumped together anyway. A few years ago, someone (Klotzbach?) found that the transformation from the common weak hurricanes into severe (cat 4 and 5) storms tends to be sudden rather than gradual. The central pressure suddenly “bombs” (rapid deepening). See Dean and Felix of 2007 for examples.

Cat 4 and 5 storms may be somewhat structurally different versus their weaker cousins, maybe some upper-air feature. My conjecture.

Here’s some background:

1. Dropwindsondes (GPS-equipped dropsondes capable of excellent windspeed measurement) have been in use since 1998.
2. Satellite imagery useable for Dvorak-type hurricane intensity estimates began in the 1970s.
4. SFMR began operational deployment a couple of years ago (2006 I believe) and may not be fully deployed yet.
5. GPS dropsondes, capable of reporting whether they landed in the hurricane eye or not, have been around since the 1990s.

All of these were obviously not around in the 1930s thru 1960s. But, what about aircraft?

In the mid-1940s aircraft began to (intentionally) fly into hurricanes and to report maximum “flight-level wind”. There have been several changes in this -

a. The pilot has to find the location of the maximum wind, which is considerably easier today with modern aircraft radar, satellite support and storm knowledge. Otherwise he misses the peak.
b. “Flight-level” is typically 10,000 feet above the surface, a height which experiences different windspeeds than exist at the surface. So, a correction factor has to be applied. The NHC has used various correction factors over the years and tends to use higher factors (= higher windspeed estimates) in recent years.

Even though aircraft were used in 1945-1959, the routine use of 0.9 flight-level correction factors, an important part of wind estimates, didn’t begin until the 1980s to 1990s.

So, the answer to the question posed in #486 is, “None of the above”.

The way we measure storms today is much different from the way we measured storms during the last Atlantic peak. Today we measure more-frequently and more-thoroughly. The more frequently we sample and the more-thoroughly we sample the greater our chances of catching the peak intensity.