A monthly electronic newsletter summarizing Minnesota's climate conditions and the resulting impact on water resources.
State Climatology Office - DNR Division of Ecological and Water Resources, St. Paul
distributed: August 7, 2019
What happened in July 2019:
- Precipitation for July 2019 followed a familiar pattern for the year so far. In general it was wet in the south and normal to slightly below normal in the north. The wettest locations were in a swath from Mankato to Wabasha County. The highest total from a National Weather Service Cooperative Observer was 10.17 inches near Theilman in Wabasha County. This was 5.79 inches above normal. One of the drier locations was at Leech Lake with 1.77 inches or 2.47 inches below normal. The July statewide average was 5.53 inches or 1.50 inches above normal. For 2019 through July 31 the Twin Cities International Airport recorded 24.81 inches which is 6.94 inches above normal and the 5th wettest January-July on record for the Twin Cities back to 1871.
[see: July 2019 Precipitation Total Map | July 2019 Precipitation Departure Map | July 2019 Climate Summary Table | July 2019 Percent of Normal Precipitation Map]
There were a number of storm events in July 2019. The period of July 14th to the 20th was particularly stormy and muggy with perhaps the second highest heat index value recorded in the Twin Cities with 115 degrees on July 19th. Both July 19th and 20th had a thunderstorm high wind event called a derecho because they produced a continuous swath of damage reports exceeding 250 miles in length.
[see: A Muggy and Stormy Period, July 14th to 20th, 2019]
- The final week of July saw more storms. On July 26, two clusters of storms produced large hail. The storms produced half dollar-sized hail near Cook and Eveleth, and widespread ping pong ball to tennis ball-sized hail from St. Cloud into the northern suburbs of the Twin Cities. The largest hailstone reported was grapefruit-sized, or 4 inches in diameter, near Clear Lake in Sherburne County.
[see: Large Hail, July 26, 2019]
- Four tornadoes struck Minnesota on Sunday, July 28th, producing damage in McLeod, Washington, and Chisago Counties. Two of the tornadoes were rated EF-1, and two were rated EF-0.
[see: Tornadoes, July 28, 2019]
- The preliminary statewide average temperature for July 2019 was 71.4 degrees or 1.2 degrees above normal. This was the first month of 2019 where the average statewide temperature finished above normal. The warmest temperature reported in Minnesota for July 2019 was 98 degrees reported at Marshall in Lyon County on July 20 and the coldest temperature of the month was 36 degrees at Celina in northeast Minnesota and Goodridge in northwest Minnesota on July 30. International Falls set a record low for July 30 with a minimum of 37 degrees, breaking the old record of 38 set in 1898.
[see: July 2019 Climate Summary Table | 2019 July Departure from Normal Temperature Map ]
Where we stand now:
- Seasonal precipitation so far (April 1 through August 6) shows a continuing pattern of the state split by the very damp central and south, to near normal to below normal precipitation in the north. Some locations in southwest, south central and southeast Minnesota are ranked in the 98th percentile, or nearly the wettest on record.
[see: Seasonal Precipitation Maps]
- The U. S. Drought Monitor map released on August 1 depicts 4.5% of the state in the Abnormally Dry category, confined to northeastern Minnesota. The U.S. Drought Monitor index is a blend of science and subjectivity where drought categories (Moderate, Severe, etc.) are based on several indicators.
[see: Drought Conditions Overview]
- The U.S. Geological Survey reports that stream discharge levels are much above normal across southern Minnesota, with normal to above normal streamflow across central Minnesota and normal to below normal streamflow across the north..
[see: USGS Stream Flow Conditions]
- Water levels on Minnesota lakes vary depending on lake and location in the state. During June and July, Mille Lacs rose about a half a foot from the level in late April and leveled off though early August. On August 5, Minnetonka was at 929.29 feet with 75 cfs flowing through Gray's Bay Dam. On August 5, White Bear Lake was at 924.92 feet, a decrease of .49 feet since the recent high level of 925.41 feet on July 5. Rainy Lake and Lake of the Woods were both in the median range for early July. Lake Superior was forecasted to be at 603.28 feet on August 2, nine inches above the August average and one inch above the record August level set in 1952. Superior is forecast to fall an inch over the next month.
[see: Mille Lacs Lake Water Level | Lake Minnetonka Water Level | White Bear Lake Water Level | Lake of the Woods Control Board Basin Data | Corps of Engineers Great Lakes Water Levels]
- The Agricultural Statistics Service on August 6 reports that topsoil moisture across Minnesota is 1 percent Very Short, 9 percent Short, 76 percent Adequate, and 17 percent Surplus. Available soil water at Lamberton on August 1 was 1.14 above the historical average. The progress of the corn and soybean crop are about five days behind the five year average.
[see: Agricultural Statistics Service Crop Progress and Condition | U. of M. Southwest Research & Outreach Center (Lamberton)]
- The potential for wildfires is currently rated by DNR Forestry as Low across central and southern Minnesota. Moderate potential exists over north central and parts of northeast Minnesota, with High potential over the northwest and Very High south of Lake of the Woods. Historically, 80 percent of all wildfires in Minnesota occur during April and May.
[see: Fire Danger Rating Map]
- The August precipitation outlook has equal chances for above, normal and below normal precipitation for the state. August precipitation normals range from about two-and-a-half inches in northwest Minnesota to about five inches in southeastern counties. The August temperature outlook leans towards below normal temperatures across all of Minnesota, especially in the south. Normal August high temperatures are around 80 degrees to start the month, dropping to the mid-70s by month's end. Normal lows are around 60 degrees early in the month, falling to the mid-50s by late August.
[see: Climate Prediction Center 30-day Outlook | August Temperature Normal Map]
- The 90-day precipitation outlook for August through October indicates equal chances of below-normal, near-normal, or above-normal conditions across eastern Minnesota, with a slight tendency for above normal precipitation in the west central and south west. The August through October temperature projection also has equal chances of below-normal, near-normal, or above-normal conditions across Minnesota, with a slight tilt to above normal temperatures in northern Minnesota.
[see: Climate Prediction Center 90-day Outlook]
- The National Weather Service produces long-range probabilistic river stage and discharge outlooks for the Red River, Minnesota River, and Mississippi River basins. These products address both high flow and low flow probabilities.
[see: National Weather Service - North Central River Forecast Center]
From the author:
- What does this winter look like? El Niño was present in early August. A transition from El Niño to ENSO-neutral is expected in the next month or two, with ENSO-neutral most likely to continue through the Northern Hemisphere fall and winter. The current three month outlook from December-February from the Climate Prediction Center has a tendency for above normal temperatures for all of the lower 48 states, including Minnesota. The December-February precipitation outlook has equal chances for above, below and normal precipitation. [see: Climate Prediction Center Dec 19-Feb 20]
Upcoming dates of note:
- August 15: National Weather Service releases 30/90 day temperature and precipitation outlooks
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