Dean_175 wrote:I remember several years ago- the NHC would give a formalized break down of the probability that a storm would be at any given intensity category at a given time- it looked something like this:
12 hours : dissipated : 0 percent, TS : 0 percent, Category 1: 15 percent, Category 2: 20 percent, Category 3: 40 percent, Category 4: 20 percent, Cat 5: 5 %
24 hours : ditto
They have removed this product from their page. It was very insightful, as it gave an estimated likelihood that the system would fall into each category-- almost like a forecast cone , but for intensities.
You are talking about the Maximum Wind Speed Probability Tables and Graphics, as seen in the image below.
It was discontinued in 2014 due to the problem of many users misinterpreting the data shown in the table.
I was a fan of that graphic as well, mainly because of the amount of probabilities and detailed information.
Official statement
Effective May 15,2014 the following changes will take place with
the text Tropical Cyclone Wind Speed Probability (PWS) product
issued by the National Hurricane Center and Central Pacific
Hurricane Center:
1. Removal of Maximum Wind Speed (Intensity) Probability Table
(Table I) This table gives the likelihood that a tropical
cyclone will be at any of several different intensity
categories (e.g., depression, storm, category 1 hurricane,
etc.) at fixed points in time (e.g., 12 hours, 24 hours, 36
hours, etc.). These probabilities are estimated by creating
a large number of potential track and intensity scenarios
based on the latest official forecast and a climatological
error distribution. NHC has learned that many users consult
this table to estimate the chances that a tropical cyclone
will make landfall at one or more of the various intensity
categories. Unfortunately, the current methodology provides
a highly misleading estimate of landfall intensity.
The problem can be seen by considering a storm that is
forecast to be just offshore at 72 hours. A sizable fraction
of the potential scenarios have already encountered land by
that time, and for these over-land scenarios the expected
intensity at 72 hours will be much lower than what would be
expected for a storm that was still over water and about to
make landfall. Even though the table accurately assesses
what the intensity is likely to be at 72 hours, it grossly
underestimates the likely intensity for when the storm comes
ashore.
The table was originally intended to help users assess the
risk of different categories of storms at particular times,
and for storms well away from land the product serves that
function well; however, because of the high likelihood of
misuse for land-threatening storms, and the consequences of
that misuse for the general public, NHC and CPHC are
discontinuing this table until a better procedure to
estimate intensity risk can be developed.
In addition, NWS will no longer provide the stand-alone Intensity
(Maximum Wind Speed) Probability graphic. This graphic contained
the identical information to Table I of the PWS product, which is
being discontinued.
Source:
http://www.nhc.noaa.gov/news/20140228_s ... hanges.php