Mid-August Weather Update

Mid-August Weather Update:

Daylength is getting noticeably shorter. We started August with 14 hrs and 40 minutes of daylight and we will end up with just 13 hrs and 17 minutes. Each day we are losing close to 3 minutes of daylight. This is probably a challenge on those golfers who want to be able to get in 9 holes after work.

Overnight storms brought from half an inch to an inch of rainfall to many areas of the state over August 14-15 this week. Some climate observers even reported new record daily amounts, including:

Lake Bronson (Kittson County) with 1.41 inches
Lancaster (Kittson County) with 1.19 inches
Warren (Marshall County) with 2.18 inches
Spring Valley (Fillmore County) with 1.29 inches
Wells (Faribault County) with 0.93 inches

Wells has now reported 43.29 inches of precipitation for the year so far, while their normal annual precipitation there is 34.51 inches. Elgin (in Wabasha County) now reports over 47 inches of precipitation for the year so far. USDA reports that soil moisture levels are adequate to surplus in nearly 95 percent of all cases across the state, a condition that is not seen in most years when soil moisture levels usually decline in August.

So far this month rainfall is accumulating well ahead of normal in most of the state, while temperatures are averaging 2-3°F cooler than normal.

State Fair Starts:

The Minnesota State Fair starts its 12-day run on August 22 concluding on Labor Day, September 2nd this year. The DNR-Minnesota State Climatology Office web site features a wealth of historical information about the State Fair, along with details about weather history during the Fair.
A few details from State Fair Weather History:

Highest maximum temperature was 104°F on September 10, 1931
Lowest maximum temperature was 52°F on September 7, 1911
Lowest morning temperature was 33°F on September 13, 1890
Second coldest morning was 36°F on September 1, 1974
Most number of 90°F days, six, was in 2013
On average it rains 3 or 4 days during the 12-day run of the Fair
The driest State Fair was in 2003 when only 0.02 inches of rain fell
The wettest State Fair was in 1977 when 9.48 inches of rain fell
Wettest evening at the State Fair, August 30, 1977 when 4.06 inches of rain fell
On August 31, 1989 golf ball size hail fell on the Fairgrounds during the afternoon

I will be at the State Fair on two dates this year, both times at the MPR stage located at the corner of Judson and Nelson. On August 23 (Friday) from 11am to noon I will be a guest on TPT Almanac program. Then on August 28 (Wednesday) Cathy Wurzer and I will be on from noon to 1pm for the Minnesota Now Program and share the 28th Annual State Fair Weather Quiz. If you plan to attend the State Fair please drop by if you can.

Weekly Weather Potpourri:

Jonathan Erdman writing for the Weather Underground this week highlighted how July was the record warmest month globally perhaps going back 175 years. In addition, it was the 14th straight month that Earth climate data has documented a record warm month. Although the warm anomaly in temperature was mixed in North America, it was more emphatic in Africa, Asia, and Greenland.

This week’s AGU-EOS Bulletin features an article about soil carbon storage and how it may be enhanced by the presence of soil panels in agricultural settings. The shading of the soil by solar panels affects both the soil moisture as well as the respiration rates of microbes in the soil environment (reduced because of lower temperatures). This may have some significant long-term effects for the storage of carbon in the soil.

MPR listener question:

You and Cathy have spoken a good deal about climate change in Minnesota over the years and mentioned how temperatures have warmed but not uniformly throughout the year. Which months have warmed the most over the past 100 years or so?

Answer:

The official data from NOAA for Minnesota show the following changes since 1895 (period of 129 years in average monthly temperature:

January +4°F
February +5°
March +4°F
April +0.8°F
May +2°F
June +2°F
July +1°F
August +1.1°F
September +2°F
October +0.6°F
November +3°F
December +4°F

The larger changes have occurred during the snow season (Nov-Mar) at least partly as a result of more variability in persistent snow cover across the state. Many winters with low or no snow cover have produced remarkably warm daytime temperatures. The transition months of April and October have both shown a higher degree of variability in recent years due to presence or absence of snow cover in the northern parts of the state. The background rise in Greenhouse Gases has also caused an upward change in temperature across all 12 months of the year, regardless of the inherent variability in our climate.

Twin Cities Almanac for August 16th:

The average MSP high temperature for this date is 81 degrees F (plus or minus 7 degrees F standard deviation), while the average low is 63 degrees F (plus or minus 6 degrees F standard deviation).

MSP Local Records for August 16th:

MSP records for this date: highest daily maximum temperature of 99 degrees F in 1988; lowest daily maximum temperature of 64 degrees F in 1943; lowest daily minimum temperature of 47 degrees F in 1962; highest daily minimum temperature of 77 degrees F in 1988, and record precipitation of 1.97 inches in 2002. No snowfall has occurred on this date.

Average dew point for August 16th is 59°F; the maximum dew point on this date is 76°F in 1908 and the minimum dew point on this date is 40 degrees F in 1924.

All-time state records for August 16th:

The state record high temperature for this date is 107 degrees F at Madison (Lac Qui Parle County) in 1988. The state record low temperature for this date is 27 degrees F at Tower (St Louis County) in 1976. The state record precipitation for this date is 4.21 inches at Willmar (Kandiyohi County) in 1926. There has been no snowfall on this date.

Past Weather:

Strong thunderstorms brought heavy rains to northeastern Minnesota on August 16 of 1972. Many climate observers reported from 4 to 6 inches of rain. Duluth saw almost 6 inches, while Kettle Falls in Voyageurs National Park reported a record 4.83 inches.

A very cold morning greeted campers in northeastern Minnesota on August 16 of 1976. Morning low temperatures were commonly in the 30s F, while Meadowlands and Tower reported just 29°F and 27°F, respectively.

August 16 of 1988 was the hottest in state history, with most areas of the state reporting afternoon high temperatures in the 90s F. Climate stations in 43 counties reported temperatures of 100°F or greater. Even the overnight low temperature remained in the 80s F at a number of locations (83°F at Winona).

Outlook:

Some lingering shower activity in southern counties for early Saturday, but otherwise mostly sunny with near normal temperatures over the weekend. Increasing cloudiness by late Tuesday and Wednesday with a chance for showers. Warming trend towards the end of next week, with daytime high temperatures in the 80s F in many places.