Cool and Wet Pattern to Prevail

Cool and Wet Pattern to Prevail:

So far this year 62-65% of all the calendar days have brought temperatures that are below normal. The late spring has taxed everyone’s patience, but especially gardeners and farmers.

The temperature in the Twin Cities finally reached 82 degrees F on May 16 this week, the first such reading since last September 17th, a period of 240 days. If you think that seems like a long time, the climate history in the Twin Cities shows that from September 17, 1911 to June 22, 1912 there were no days with temperatures of 82 degrees F or higher, a period of 280 days, 77 percent of a year.

Nocturnal thunderstorms on Wednesday night this week brought a half inch to an inch of rain to portions of southeastern Minnesota. Many were awakened by the thunder and lightning, a precursor to what is expected this coming weekend.

The new seasonal outlook for the USA released on Thursday (May 16) suggests that for our region of the country we will see a cooler and wetter than normal climate pattern prevail across most of the state. This is further reinforced by history which shows that a strong prevalence of cooler than normal temperatures throughout the spring is most often a precursor to a cooler than normal growing season (something we refer to as a serial correlation). It is not a guarantee by any means, but the probability is certainly stacked in favor of cooler and wetter. Remember too, that a majority of the recent growing seasons in Minnesota have been warmer and wetter.

Weekly Weather Potpourri:

NOAA announced this week that the most recent 12-months (May 2018 to April 2019) have been the wettest in the history of our country (at least in the instrumental record which dates to the late 19th Century). Of course there was great variability across the country with areas that recorded normal precipitation, and even below normal precipitation in parts of the Northwest. There were also many geographic areas that saw the largest ever amount of precipitation over the 12-month period including, all of northern Iowa and most of southwestern Minnesota. This wet anomaly kept most Minnesota watersheds running at high volume throughout most of the period.

According to BBC News North Korea is suffering from one of the worst droughts in years, with severely diminished crop production expected. North Korea's state media outlet KCNA said 54.4mm (2 in) of rain fell throughout the country in the first five months of the year. It said this was the lowest level recorded since 1982.

University Corporation for Atmospheric Research helped produce a baseball video cartoon analogy to explain how greenhouse gases enhance the atmospheric ability to produce extremes of weather. It is a good video to use in educating children in the primary grades of school.

MPR listener question:

We were excited to see our first 80 degree F day in Roseville this week and wondered if May always brings at least one such day, or has there ever been a May with zero 80 F days?

Answer:

Actually it is somewhat rare not to see an 80 F temperature in May here in the Twin Cities. The last time this happened was 2005, and the time before that was 1983. But in the far past it happened with greater frequency. Other years include 1873, 1878, 1882, 1883, 1888, 1892, 1893, 1905, 1910, 1924, and 1935.

Twin Cities Almanac for May 17th:

The average MSP high temperature for this date is 70 degrees F (plus or minus 10 degrees F standard deviation), while the average low is 49 degrees F (plus or minus 8 degrees F standard deviation).

MSP Local Records for May 17th:

MSP weather records for this date include: highest daily maximum temperature of 93 degrees F in 1987: lowest daily maximum temperature of 46 degrees F in 1890; lowest daily minimum temperature is 31 degrees F in 1915; highest daily minimum temperature of 69 degrees F in 1911; record precipitation of 1.81 inches in 2017; and there was a trace snowfall in 1890.

Average dew point for May 17th is 45 degrees F, with a maximum of 69 degrees F in 1996 and a minimum of 17 degrees F in 2009.

All-time state records for May 17th:

The state record high temperature for this date is 100 degrees F New Ulm (Brown County) in 1934. The state record low temperature for this date is 14 degrees F at St Vincent (Kittson County) in 1888. State record precipitation for this date is 4.43 inches at Blue Earth (Faribault County) in 2000; and record snowfall is 12.0 inches at St Cloud (Stearns County) in 1890.

Word of the Week: Astraphobia

This term derives from the Greek words astrape meaning lightning and phobia meaning fear. It is the morbid fear of lightning and thunder. Certainly lightning should be feared, unfortunately some people who suffer from this disease are completely incapacitated by storms which bring lightning and thunder. Incidentally, climatology shows that the highest frequency of thunderstorms occurs in June across Minnesota.

Past Weather Features:

Far and away the warmest May 17th in state history occurred in 1934. Over 30 climate stations reported daytime highs of 90 degrees F or greater. It was just one hot day in a long hot month, the 2nd warmest month of May in state history.

An unusual storm brought 1 to 4 inches of snowfall across portions of northern Minnesota on May 17, 1968. Some fishermen on Lake of the Woods and Rainy Lake were seen in their boats reeling in fish while it was snowing. Only in Minnesota!

Outlook:

Cool and wet is the theme throughout the weekend. It should be drier on Monday, but then a chance for rain returns for Tuesday through Thursday of next week. Widespread showers and thunderstorms will bring significant amounts of rainfall to many areas over the next week. Drier weather should return by Friday with temperatures slowly climbing back closer to normal.