A week ago much of Minnesota and some portions of eastern North Dakota were listed as either abnormally dry or in minor (D1) drought conditions. That changed quickly last week in central and eastern Minnesota when 3-5 inches of rain fell prompting flood warnings to be issued. Yet, that system stayed to our east keeping the local area dry and still waiting for rain. Our turn came on Saturday Night into Sunday morning when much of west central Minnesota recorded 2-4 inches of rain with localized higher totals.
Fargo Moorhead ended up right on the edge of that system with much of Moorhead receiving over 2 inches of rain, where as parts of West Fargo up towards NDSU only recorded near 1 inch.
It was a reminder that our wet phase is likely not over and we continue to be just one heavy rain system away from being over saturated with flooding problems once again.
Last year, Fargo officially dropped down to 33 degrees on May 26. It appears we will once again see a late season frost as temperatures tonight may also drop in the to 30s. Below is my projection for low temperatures at numerous cities in the area.
One thing in our favor tonight will be soil moisture. Many spots received quite a bit of rain Sunday morning. That soil moisture will help hold temperatures up a bit near the surface for emerging crops, yet, it could be a close call in low spots in particular.
Evaporation is simply the process of liquid water being converted to water vapor. If this process involves plants, then it is referred to as transpiration. The amount of water evaporated into the atmosphere varies not only from season to season, but also on a daily basis. Last year, North Dakota State Climatologist Dr. Akyuz acquired an Evapotranspiration Simulator (ETGage) which measures the amount of evaporation taking place each day.
This past Monday and Tuesday when the temperatures were in the 80s with dew points in the 20s the ETGage measured an evaporation loss of 0.65 inches over those two days. The dry air in combination with nearly 100% sunshine and a good wind made for an ideal evaporation environment. On the opposite extreme was May 8 when only 0.02 inches of evaporation loss was measured because of the combination of a light rain, cloudy sky and high relative humidity.
Dr. Akyuz reports his data on cocorahs.org if you want a better sense of water loss during the growing season.
May in some ways could be considered the start of our rainy season. Climatologically, Fargo Moorhead is quite dry from November 1 through April 30. That six month stretch averages just 5.8 inches of rain and melted snow with nearly half of that falling during the months of March and April.
With recent years recording above average rain and snowfall, our perceptions may have changed, but what we have experienced in the last six months has been very average from a historical perspective. Both March and April average around 1.3 inches of rain, but this month, that average jumps to 2.81 and in June we average nearly 4 inches of rain.
In total the next six months the average rainfall is nearly 17 inches. Looked at another way, about 75% of our yearly precipitation comes from May 1 through October 31. So although our climate does not have a true rainy and dry season, an examination of the data hints that we almost could consider ourselves in the category.