There are three areas, outside of the Western US Mountains, that continue to increase drought area through early Spring. First, the expansive Bermuda High has prevented meaningful rain from entering the Southeast since early spring. Second, the MidSouth along and east of the Mississippi River has been too close to the edge of the Bermuda High for storms to effectively pass through the area. As a result, there is a narrow corridor from Texas through Missouri into the Great Lakes that has served as the primary region over which the heaviest spring rains have moved. The third area encompasses the Western Plains and parts of the Western Cornbelt. Storm systems this spring have been too quick to move east resulting in drier air from the Great Basin and/or Canada to invade this region before meaningful rain/storms can traverse these very dry counties. All of these regions have the compounding factor of multi-season soil moisture loss due to a dry fall and winter.
The figure shows the March 23 to April 9 soil moisture percentiles f0r 0-16" (0-40cm) from NASA. The bottom figure is the 10-day forecast for the probability of receiving less that 0.5" of total precipitation from the ECMWF.