HydroClim Minnesota for Early September 2022
A monthly electronic newsletter summarizing Minnesota's climate conditions and the resulting impact on water resources. Distributed on the first Thursday of the month.
State Climatology Office - DNR Division of Ecological and Water Resources, St. Paul
distributed: September 9, 2022
What happened in August 2022:
- Minnesota continued to be on the dividing line between the hot dry conditions over the Great Plains and somewhat cooler and wetter conditions across Minnesota. August 2022 brought some welcome relief to the drought across the central and southern parts of the state. The rains were still hit or miss though, with a wide range of precipitation totals. One of the largest August 2022 rainfalls found so far from a National Weather Service Cooperative Observer was seven miles northwest of Two Harbors in lake County with 7.13 inches or 3.48 inches above normal. One of the drier locations was at Crookston in Polk County with .57 inches or 2.40 inches below normal. The preliminary statewide average precipitation was 4.05 inches or .37 inches above normal.
[see: August 2022 Precipitation Total Map | August 2022 Precipitation Departure Map | August 2022 Climate Summary Table | August 2022 Percent of Normal Precipitation Map] - The notable rain and storm events in August 2022 happened during the first and last week of the month. Thunderstorms moved across central and southern Minnesota on Saturday August 6, with pockets of intense rains forming and reforming across the far south throughout the day and into the night. A second batch of showers and thunderstorms moved across many of the same areas on evening of Sunday August 7. This second round was generally less intense and more evenly distributed. Between the two events, rainfall totals ranged from one to three inches across the southern third of the state, with scattered higher amounts reported in Renville, Kandiyohi, and McLeod Counties, and also along and south of I-90 in far southern Minnesota.
[see: (Mostly) Beneficial Rains for Southern Minnesota] - On August 27th, a Quasi-Linear Convective System “QLCS” or, in simpler terms, “a strong line of thunderstorms that is not perfectly straight” hit the Twin Cities. A 61 mph gust was measured at the Grandstand of the Minnesota State Fair. Five weak tornadoes were reported in the Twin Cities.
[see: August 27 Tornadoes] - For the third August in a row, Minnesota finished with above normal temperatures, but the preliminary average was only .6 (six tenths) of a degree above normal. August 2 stood out as a very hot and muggy day. With air temperatures in the mid-90s and dew point temperatures in the middle to upper 70s, heat index values surged to the 105 to 115F range. Hutchinson had the highest heat index value at 115 degrees F, and the Twin Cities International Airport had a heat index of 109. The warmest air temperature seen in August was 101 degrees on August 2 (reported on August 3) at Marshall in Lyon County, and the coldest temperature was 39 degrees at Waskish in Beltrami County on August 11.
[see: August 2022 Climate Summary Table | 2022 August Departure from Normal Temperature Map]
Where we stand now:
- Seasonal precipitation totals (April 1 through September 6) ranked above the historical median north of a line from Breckenridge though St. Cloud and east to North branch, to generally below the median south of this line. One major exception is over southeast Minnesota where some areas were in the 85th percentile.
[see: Seasonal Precipitation Ranking Map] - The U. S. Drought Monitor map released on September 8 depicts 17% of the state in the Abnormally Dry category, 8% in the Moderate Drought category and 1% in the Severe Drought category. Last year at this time there was only 5% of the state that was free of any drought designation. 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 to be near normal to above normal across much of the state, with a few exceptions. There are much below normal stream flows on the Sauk River at St. Cloud and the Vermillion River near Empire in Dakota County. There is much above normal flow on the Thief River near Thief River Falls and at the Root River near Houston.
[see: USGS Stream Flow Conditions] - Water levels on Minnesota lakes vary depending on lake and location in the state. Mille Lacs was at 11.13 feet, about half a foot higher than this time last year and close to the 26 year median for early September. On September 8, Minnetonka was at 928.13 feet, .27 feet lower than this time last year. Gray's Bay Dam closed on July 21. On September 9, White Bear Lake was at 923.15 feet, .62 feet lower than in early September 2021. Rainy Lake continues to fall from the record level set in June and is now in the normal band. Lake Superior was forecasted to be at 602.43 feet on September 9, four inches above the early September average and 2 inches lower than early August, 2022. The lake level in Superior is forecast for a continued slow fall 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 September 6 reports that topsoil moisture across Minnesota is 6 percent Very Short, 23 percent Short, 68 percent Adequate, and 3 percent Surplus. Available soil water at Lamberton on September 1 was approximately 3.2 inches, an improvement since mid-August, but still short of the median by nearly an inch.
[see: Agricultural Statistics Service Crop Progress and Condition | U. of M. Southwest Research & Outreach Center (Lamberton)] - The potential for wildfires rated by DNR Forestry on September 9, as Low across central and southern Minnesota. Moderate potential exists over northern Minnesota, with Historically, 80 percent of all wildfires in Minnesota occur during April and May. There was a small ten acre fire reported on September 7, southeast of Lake Three and north of Horseshoe Lake in the Boundary Waters Canoe Area Wilderness.
[see: Fire Danger Rating Map]
Future prospects:
- The September precipitation outlook has a tendency for below normal precipitation across the state. September precipitation normal values range from about one-and-a-half inches in northwest Minnesota to about four inches in northeast and southeastern counties.
[see: Climate Prediction Center 30-day Outlook | September Precipitation Normal Map] - The September temperature outlook also has a tendency for above normal temperatures. Looking at central Minnesota, seven of the past eight Septembers have seen above normal temperatures. In the Twin Cities, eight of the last ten Septembers from 2012 to 2021 were above normal for average temperature. Normal September high temperatures are in the middle to upper 70's degrees to start the month, dropping to the low to mid 60's by month's end. Normal lows are in the 50's early in the month, falling to the middle 30's to mid-40s by late September.
[see: Climate Prediction Center 30-day Outlook | September Temperature Normal Map] - The 90-day precipitation outlook for September through November indicates an equal chance for above, below and normal precipitation in northern and central Minnesota, with a tilt to below normal precipitation in the south. The September through November temperature projection offers a tendency for above-normal conditions statewide.
[see: Climate Prediction Center 90-day Outlook] - The Winter Outlook (December-February) from the Climate Prediction Center depicts equal chances for below-normal, near-normal, or above-normal temperature and precipitation statewide. The last two winters (December-February) saw above normal average temperatures in 2020-2021 and below normal average temperatures in 2021-2022. The last two winters have had La Niña conditions and it appears La Niña will be in place for this winter as well.
[see: Climate Prediction Center 3.5 month 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:
- The 2022 preliminary count of tornadoes is approximately 70 for Minnesota. In 2021 there were 64 tornadoes in 2020 there were 59, and in 2019 there were 54. The total for 2022 is the highest tornado count since 2010 when 110 tornadoes.
[see: Year-by-Year Tornado Statistics for Minnesota 2010-2021]
Upcoming dates of note:
- September 15: National Weather Service releases 30/90 day temperature and precipitation outlooks
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Pete Boulay;DNR Climatologist