Friday, January 6, 2012
To strengthen my (and hopefully your) intuition for the Palmer Drought Severity Index I'm going to try and post the current US map on a monthly basis. For more background on the Palmer Index see this post.
The map for the week through Dec 31 is shown above. You can see that most of Texas is still in the grips of an extreme drought and a lot of the southeast is also pretty badly off. This continues a pattern that lasted through most of last year in which a lot of the southern half of the country was very dry while the northern half was unusually soggy. However, the southern droughts are not as extensive now as they were at their height in August.
You can see a nice animation of the monthly PDSI for the whole of 2011 at NOAA's site.
You can also construct longer movies of any portion of the twentieth century you'd like to watch - for example here's one of the dust bowl years. We still haven't managed to create anything that bad (in general most of the US has been trending wetter not drier under global warming) .