Overall US soil moisture is highest since the late 90s

- While parts of the US are still drought stricken, the overall moisture levels in the United States are at their highest levels in nearly 20 years.  According to the Palmer Drought Severity Index, the US continues its upswing in precipitation since a little valley, or lull in precipitation, centering on the year without a winter, AKA 2012.  Since that year, overall moisture has been climbing across the country.  Just look at the difference in the overall drought from last fall compared to this week…

The Palmer Drought Severity Index (PDSI) is an index that measures the relative dryness or wetness affecting water sensitive economies. It uses readily available temperature and precipitation data to formulate a standardized index that spans -10 (dry) to +10 (wet).

When you take all of these figures and plug them into a graph, you can get general trends from year to year and decade to decade as seen below…

The PDSI currently stands at just over +1, meaning that the country as a whole is actually wetter than average.  Now, even then you can find very dry areas and very wet areas.  But if you look back, the waxing and waning of precipitation is perfectly normal as the index has gone back and forth since its inception in the late 1800s. 

So why do many of us think we are in record breaking drought all the time? Well, perception and a much larger population can affect the way we see this.  First off, the country as a whole needs far more water than it did even 20 years ago as the population continues to grow.  Second, even though our very dry year of 2012 was still nowhere close to the drought experienced in the 30s and 50s, it was the first several year dry spell in more than a decade and by far the worst since the 50s.  This plays a role in the perception of what we are seeing.  Because the 70s, 80s, and most of the 90s were so wet, many of us thought it was normal to get that much precipitation, when in fact, that just wasn’t true.  We exceeded many precipitation records in those years and saw a drastic rise in water levels across the Continent.  But now that we have returned to a more normal baseline AND there are nearly double the number of people living in the US that now need clean drinking water, it has drastically affected the way we perceive our current moisture.


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