Re: Laws and Theories

["P. O. Johnson" <pojhome@FLASH.NET>]

One of the lab exercises I do in the meteorology part of my Physical Science
course is have my students clip and save the daily Weather Page in the
Dallas Morning News for 15 consecutive days. They then record the five-day
local forecast in a five-day sliding window through the 15 days, recording
the error each day between yesterday's actual high and low temps and the
1-day, 2-day, 3-day, 4-day, and 5-day forecasts for yesterday.

When I began this exercise, I naively assumed that the errors would converge
toward zero as the forecast interval decreased to zero. But no-o-o-o, every
year the errors show no convergence at all. Either the 1-day forecast is
just as erroneous as the 5-day forecast, or the 5-day forecast is no less
accurate as the 1-day. Take your pick.

DMN gets its weather page from Weather Data Corp in Kansas City. I wonder if
their forecasts for the KC area, or NOAA's forecasts for the D/FW area, are
any more accurate.

poj

----- Original Message -----
From: "Richard W. Tarara" <rtarara@SAINTMARYS.EDU>
To: <PHYS-L@lists.nau.edu>
Sent: Saturday, April 08, 2000 9:39 AM
Subject: Re: Laws and Theories

> You must have better meteorologists in your area than here.  I watch the 5
> day forecasts published in the paper with some amusement.  Say I look at
> Friday's forecast on Monday.  By Thursday that forecast will have changed
> significantly at least twice and usually the Thursday forecast for Friday
is
> still wrong.  It seems to be the case that long term forecasting has
gotten
> better, but as far as I can tell, the short range forecasting is just as
bad
> as it has been for the past 50 years.
>
> Richard W. Tarara
> Associate Professor of Physics
> Department of Chemistry & Physics
> Saint Mary's College
> Notre Dame, IN 46556