re: #239 publicityStunted

Good, then I’ll change the subject ;)

Are you familiar with what goes into the Palmer Drought Index? I’ve been doing a bit of reading on it, but I can’t figure out how to translate the numbers on its scale to an actual event - i.e. a reading below -4 is considered “extreme drought”, and some AGW models are predicting readings as low as -20(!) in many regions by 2070-onwards.

What does this mean in actual terms, like rainfall? -4 means no rain for months, while -20 means no rain for years? I want to turn the numbers into something the average person could relate to…

A whole bunch of things go into it. There is a rather complicated formula that is designed to give a dimensionless number. The issue with dimensionless numbers is that you really need to have the formula in front of you and play with it in your head to see what the number means.

So an image like this is really a bunch of meaningless colors without the math.

Image: palmer.gif

Therefore… you need to look at this:

npwrc.usgs.gov