cloudy

Author Topic: Convective indices related to station elevation  (Read 167 times)

0 Members and 1 Guest are viewing this topic.

Offline Tom Ehrensperger

  • Posts: 1,902
  • OS/Browser:
  • Win XP
  • MS IE 8.0
Convective indices related to station elevation
« on: July 11, 2012, 09:02:50 PM »
The problem I discuss in the thread "Question about display of thunderstorm symbols with no rain forecast" got me thinking about the use of the convective numbers in WXSIM.  It occurs to me that K index, Total Totals, and Showalter Index are all at risk of inaccuracy if the site is anywhere near the 850 mb level.  For instance, a site at 3300 feet (about 1000 meters) might have a surface pressure of, say, 900-920 mb.  Since the 850 mb level is not much above the surface, really big diurnal variations in these indices, as well as too-high values in general, are likely.

Most of you don't live that high up.  I would be interested to know, though, if you've had overly thunderstorm-happy forecasts if you live more than about 2500 feet (800 meters) above sea level.  I do intend to improve the situation, but would like to know if the problem had been noticed.

Thanks!

Tom