Ian,

A very valid point, and absolutely agree that the rating is not issued
in isolation. The plan for my region is to basically issue a rating
ALONG WITH the full forecast. Something like the following:

SCI for Wednesday, 17 August is a 3.
Synopsis: Cold front moved through overnight, with weak high pressure
building. Moderate NW flow throughout operating range and relatively
drier air building in.
Forecast: 2-4kts with some better over the ridge and Poconos.
Moderate Cu generally at 5,000 going to 6,000. Some chance of
vertical OD and an isolated shower. Winds NW at less than 15kts in all
areas. Weak ridge possible to sustain but may be treacherous. Expect
day to start and end early. Best conditions to the North and
Northwest.

I actually have a matrix in an excel sheet that gives the parameters
as set up for "my" local area. Elements and ratings guidelines are
reasonably granular. Just as a for instance (pipe delimited here in
free text):

Parameter|Measure|Weighting|Comments
Achieved Climb|FPM|3|200 fpm max rating is 2, 200-400fpm max rating is
3,400fpm-600fpm max rating is 4

Interpretation: Thermal strength measured in FPM. Weighting is 3
(highest weighting). 200-400fpm gives a max day rating of "3"

Another parameter (cloud interference) uses Spreadout % and a weighting
of 2 (medium weighting).

It looks a lot better in a single table - honest :-)) There's really
no way to plug all of this into a table and compute a mathematical
result, as the "rules engine" is actually pretty complex. That's why
we still need a human forecaster. The only thing this really does is
to give an indicative number that should get somebody to sit up and
take notice, for example, if they see a 5 ("Hi honey - wont' be home
tomorrow for our anniversary dinner after all - looks like the big day
for the 750Km triangle... CLICK [sound of phone slamming into cradle])

Cheers,
P3