May and Spring 2015 Saint Cloud Weather Summary

Heavy Rain Reverse Dry Trend

May and Spring 2015 Saint Cloud Weather Summaries

Rain, rain, and more rain. That's what dominated May 2015. Going into May, St. Cloud had only 2.61 inches of measurable precipitation, more than 3 inches short for the year. However, May produced 6.03 inches of rain, a little more than 3 inches above the average. The total precipitation was more than twice as much as the Jan-Apr total. May 2015 also ranked as the 12th wettest May in St. Cloud precipitation records, which date back to 1894. Both 2012 (8.76 inches, 2nd wettest) and 2014 (6.74 inches, 8th wettest) ranked higher.

There were 7 days with at least half an inch of rain and two back-to-back days, May 16 and 17, with over 1.4 inches of rain. The 1.41 inch May 17 rainfall broke the daily record, previously 1.10 inch, set in 1910. However, May 16 had the highest rainfall total of the month, 1.48 inches. Those days also produced 15 tornadoes in Minnesota, including a touchdown near Darwin, in Wright County, that damaged some barns.

The big rainfall allowed St. Cloud to quickly catch up on annual precipitation. At the end of the month, St. Cloud's Jan-May precipitation had climbed to 8.64 inches, 0.36 above average.

Rainfall was even heavier in parts of central, west central, and northwestern Minnesota with 6-8 inches of rain during the month.

The rainy pattern was due to a major change in the steering wind pattern across North America. Instead of the persistent northwest-to-southeast flow pattern that kept conditions relatively dry, a shift to a lot more storms entering the US in Oregon and California at times and also some northern storms pushing southward across the Rockies led to a much wetter pattern in all of the Plains states, producing the flooding problems over Texas and Oklahoma the second half of the month.

By the end of the month, all of that rain had drastically improved statewide stream flow in most of Minnesota , except for a part of the Boundary Waters. The US Drought Monitor still retained a moderate drought designation in the northern third of Minnesota and from the eastern Twin Cities southeastward to Red Wing, still a large improvement over the previous 6 weeks. At this point, it's questionable whether there is a ground water shortage (not affected by low snow season since the melted snow leaves before the ground thaws) or a surface water shortage with the now recharged streamflow.

The big problem with all the rain is that very few days were suitable for getting farm work done. The week ending May 24 only had 2.8 suitable days and the current week summary will be out later today.

Persistent Clouds Keep May Temperatures Down

The overall rainy May (14 days with measurable rainfall in St. Cloud) did keep a lid on temperatures, thanks to the persistent cloud cover. The average high temperature in St. Cloud was 66.3°F, 2.5°F cooler than average. The May average temperature ended up being 55.1°F, 1.4°F cooler than average. There were 20 days with a high cooler than 70 degrees. The first 80-degree high of the season was delayed until May 27. That was the latest first 80 since 1997 (May 31) and only the 11th time on record that the first 80 degree high came on May 27 or later. That's in large contrast to the relatively early first 60-degree and first 70-degree highs in the first half of March, mainly due to the lack of snow cover.

The cold spurts were also notable, with highs below 50 on May 10 and 11 and after the May 16-17 storm. There were snowflakes in the Red River Valley on the 18th with wind chill in the teens and 20s and a pair of St. Cloud frosts on May 19 and 20.

Spring Ends Up A Bit Mild and Wet

May 31 also marks the end of meteorological spring, since the meteorological summer is defined as the three warmest months of the year (June 1-August 31). Overall, the spring was slightly warmer than average (44.6°F, 1.1°F above average) with the very wet May pushing the three-month rainfall to 8.05 inches, 0.98 inch above average. The only spring snowfall was 3.3 inches in March, and 1.0 inch in April. The 4.3 inches was 6.7 inches under the March-May average and a large contrast to the past two snow years.

There has never been a frost in St. Cloud later than June 1, so it should now be safe for all plants.