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Drought Conditions Largely Unchanged Over US In Last Week

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According to the US Drought Monitor, 52.65% of the US was under moderate or worse drought conditions as of July 31st.  This is a very slight improvement from the week before when 53.44% of the US experienced similar conditions.  Areas with moderate or worse drought shifted spatially: some areas got better while others got worse.  In the previous week, a large amount of new area started to experience extreme or worse drought.  There was not a similar expansion of such area this week, but conditions did not improve appreciably either.

These drought conditions are expected to continue through the month of October, with relief in some areas (intermountain West) due to monsoon precipitation.

If Tropical Depression 5 eventually makes its way to the US Gulf Coast (at least one week from now, if at all), it could help relieve some drought conditions.  The specific track of the tropical system and its rainfall patterns will ultimately determine whether any help is available.  But it won’t help most of the country due to its limited size.  The reason is clear is the following graph:


Figure 1. This map shows the amount of precipitation that would be required to end current drought conditions in one month’s time (NOAA).

As you can see in the Figure, many places across the US Midwest would need 9 to 12″ of rain in only one month to end current drought conditions.  The map is divided in to Climate Divisions.  Those in white are currently experiencing wetter conditions than the `-2` Palmer Hydrologic Drought Index value.  While they are likely experiencing some level of hydrologic drought, it was not of sufficient intensity for this analysis.


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