T.S. Debby moistening up Florida soils

Tropical Storm Debby in the Gulf of Mexico has generated very heavy rainfall across Florida, especially the western portion of the peninsula.  Rainfall amounts have exceeded 10 inches in spots, according to the 1-week rainfall estimate from the Stage IV analysis valid today (FIG. 1).  This rainfall has led to substantial increases in the available soil moisture across Florida.  The column-integrated relative soil moisture shown in FIG. 2 depicts the ratio of the volumetric soil moisture between the wilting and saturation points through the whole 2-meter soil column.  The plot is derived from the real-time SPoRT Land Information System (LIS) running the Noah land surface model over the southeastern U.S. at 3-km grid spacing.  The Stage IV analysis provides the precipitation input for the LIS-Noah integration.  The relatively moist regions are given by the shades of green across western Florida, parts of south Florida, far southern Mississippi and Alabama, and along the Appalachians into the northeastern U.S.  The 1-week change in the column relative soil moisture illustrates the more recent occurrence of soil moistening over Florida (FIG. 3).  The rainfall from T.S. Debby has increased the column relative soil moisture by 10-20% or more within the past week (much of it in the last day or two).   Since Florida has a predominantly sandy soil type that recharges quickly, soils can moisten rapidly from a significant rain event.  Conversely, a period of dry weather with intense surface heating can dry out sandy soils very quickly.

Figure 1. One-week precipitation estimate from the Stage IV analysis (in inches) for the week ending 25 June 2012.

Figure 2. Column-integrated relative soil moisture valid at 0900 UTC 25 June 2012, derived from the real-time SPoRT LIS running the Noah land surface model.

Figure 3. One-week change in the column-integrated relative soil moisture, valid for the week ending 0900 UTC 25 June 2012.

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