March has already been a wet month and we might have another storm yet before we head into April but how much has this moisture impacted the overall drought from 2021? Let's take a look at how 2021 ended up for precipitation.
We received 25.96" of precipitation (liquid equivalent) in 2021, that was -5.66" below normal or roughly almost 1/5th less rainfall than normal. That's a large deficit that we went into 2022 with.
Up until this storm, we've wobbled back and forth from below and above normal for year to date (2022) precipitation. Most of this year has actually been below average: in other words ADDING to last year's deficit. In order to eat away at the deficit we carried over from last year, we need to have a net surplus this year.
Up through midnight Tuesday night (March 22nd) we received 0.88" of precipitation with a further 0.09" through midday Wednesday (March 23rd). We also had 0.80" of rainfall earlier this month making for a very wet March (over 2", when the whole month averages 1.68").
This wet month of March has helped to put us in the 'surplus' range for precipitation. WE're ahead for this year so far at +0.77", which is 17% of last year's deficit (-5.66"). So, this month has taken a nice bite out of last year's deficit, and most of that contribution has come from this storm's rainfall. We now have a deficit since January 1, 2021 of -4.89". Of course we need to end the year overall on a surplus for this to really matter. That means we need many wet months rather than just one or two here. It also means we can't have dry months that erase the wet ones. This is why extreme droughts like last year, often carry over for more than one year due to our volatile weather/climate.
Of course all these figures are for MSP airport, the Twin Cities' official observation. Here are some regional views:
The above image isn't exactly all of last year but rather a 365 day view, so since March 23, 2021 to March 22, 2022. In that time frame, northeast Minnesota and parts of west central Minnesota are running a net surplus, but many areas are far behind.
If we zoom in on a shorter time frame, the last 4 months, basically most of this winter and March so far, we see the pattern of precipitation: wet in the northeast (it's been a snowy winter northeast MN) and dry in the southern part of the state with the Twin Cities in between.
The other notable feature is the extreme dry swath from eastern Nebraska through Iowa. This has been noticeable as a major 'snow hole' that's been missed by nearly all storm systems this winter.
So, in conclusion, yes this storm has helped the drought- but for it to matter in the big picture, we need to keep up a wet spring, and have normal or wetter than normal precipitation through other seasons and a net surplus this year of almost 5" (of 20%) to erase last year. That's hard to do, but can be done over 2 years. It was just 2019 after all that we had our wettest year on record with nearly A FOOT of precipitation above the normal- so in Minnesota, you just never know!
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