Rainfall totals above normal for July but moderate drought conditions continue to persist

Weather News

SIOUX CITY, Iowa (KCAU) – Siouxland’s month-to-date rainfall totals are slightly above normal, but the area is still sitting in moderate drought conditions.

The month-to-date refers to the first of the month through the day prior to the current date. For example, today’s month-to-date rainfall totals would start on July 1 and go through July 23. This goes up to the day prior to the current date due to official weather parameters getting released the following day so they can be fully assessed and analyzed by the National Weather Service (NWS).

The Siouxland area is still sitting in moderate drought with far southeastern Siouxland sitting in a severe drought.

Sioux City received around 2.33 inches of rain between the night of July 8 through the start of July 9, which actually put Sioux City above the normal rainfall amount for the month of July.

The normal rainfall total for July is roughly 2.59 inches. The month-to-date total is sitting around 3.13 inches, which is around .54 inches above normal.

So, why is Siouxland, especially Sioux City still in a moderate drought if portions of the area have above normal totals for the month?

Sioux City is currently sitting above the normal total for the month of July but is still in a moderate drought due to how the rain fell and how short it lasted.

The rain on July 8 through 9 only lasted an hour or so as a thunderstorm passed through the area. This rain came through in such a short period of time that the ground didn’t have time to soak up the rain that fell. Some of it was soaked up, but for Siouxland to get out of the moderate drought conditions, it needs to rain a lot more.

According to the National Integrated Drought Information System (NIDIS) the U.S. Drought Monitor (DSM) currently shows 914,000 Iowa residents in drought conditions, which correlates to 30% of Iowa’s population.

According to the NIDIS a moderate drought covers roughly 15.6% of Iowa, which is leading to:

  • Some damage to crops, pastures.
  • Some water shortages developing.
  • Voluntary water-use restrictions requested.

South central Iowa is currently experiencing a severe drought, which is leading to:

  • Likely crop or pasture loss.
  • Water shortages.
  • Water restrictions imposed.
Courtesy of NIDIS

Drought conditions can lead to poor soil moisture conditions. According to NASA’s Earth Science Office:

  • Soil moisture is the water that is held in the spaces between soil particles.
  • Surface soil moisture refers to the water that is in the upper 10 centimeters (cm) of soil.
  • Root zone soil moisture is the water that is available to plants, which is generally considered to be within the upper 200 cm of soil.

According to the NWS, the monthly calculated soil moisture in millimeters (mm) for northwest Iowa is around 300 mm, which is equivalent to 30 cm. This correlates to the surface soil moisture and the root zone moisture, which shows that northwest Iowa is on the dry side for growing crops or plants.

Courtesy of NWS.
100 mm is equal to 10 cm

The normal rainfall totals for Siouxland for the year-to-date (January 1 through July 23) is 16.46 inches. Siouxland is currently sitting at 12.37 inches, which is about 4.06 inches below normal. This means in order to get out of the moderate drought conditions, it needs to rain at least another four to five inches of rain.

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