Seasonal rainfall deficits shrinking with a wet August

At the beginning of this month, many observers were reporting sizable seasonal rainfall deficits ranging from 5 to 9 inches below normal since April 1st, especially across central counties. However since August 1st many areas of the state have received large doses of rainfall. These amounts are producing significant monthly totals already, as many observers report monthly totals of 6, 7, and 8 inches. Chaska with nearly 9.5 inches for the month so far has already recorded their wettest August in history (surpassing the 9.10 inches in 1984). Willmar with nearly 8 inches is reporting their 6th wettest August of all time, and Hinckley with nearly 8 inches is reporting their 4th wettest August of all-time. For most Minnesota weather observers the first 3 weeks of August represents the wettest period of the year.

Fortunately much of this rainfall has occurred across drought-stricken areas of the state, notably west-central and east-central counties. In fact Pine County observers reported 5 to 6 inches of rainfall over the 19th and 20th alone, verified by radar derived estimates. In fact if you want to examine the spatial character of these heavy rainfalls you can do it for any date using the National Weather Service Hydroloic Prediction Service web site. For many Minnesota locations this is the 4th time in the past 5 years that August has provided surplus rainfall to catch up on earlier season deficits. These excessive values are helping to close the seasonal rainfall deficit this year in many places. For example at Milan in Chippewa County, the seasonal rainfall deficit since April 1st was approximately 8 inches behind normal to start August, and it has now shrunk to 5 inches behind normal.

  • phuttner

    Excellent perspective Mark.

    I was wondering about the recent trend in dry early summer periods and wet Augusts.

    I wonder if there’s a naturalist out there (Jim Gilbert where are you?) who could chime in on this. Does it matter when we get our rainfall for the various prairie, and hardwood, and coniferous forest biomes in Minnesota? Or do we just need the rain at some point during the year?

    It sure seems to help make for a nice summer to have fewer mosquitoes the past few summers as a result of early season dryness.

    Mark, we are so fortunate to have your perspective and analysis on the MPR weather team.



  • John Reinert Nash

    The MPX radar loop right now (3pm Friday) is interesting. Small pop-up showers are moving from north to south, giving a striking effect of raindrops falling from the sky (i.e. the top of the map).