Spotty But Heavy Rainfalls Continue

Spotty But Heavy Rainfalls Continue:

This week brought more heavy rainfalls to some areas of the state, especially in the north. Many areas of the state saw 1 to 2 inches of rainfall on August 16, 17, and 18. Some long-term climate stations even reported daily record rainfalls, including:
Big Falls (Koochiching County) with 2.40 inches on the 16th
Winnibigoshish Dam (Itasca County) with 3.11 inches on the 17th
And on the 18th new record rainfalls were reported from Mora (Kanabec County) with 2.14 inches, Wright (Carlton County) with 2.70 inches, and Cambridge (Isanti County) with 4.32 inches.

With the heavier rains in northern Minnesota this month, some Minnesota communities like International Falls, Chisholm, Thorhult, Tower, and Grand Portage remain on a pace to record one of their wettest years in history.

Overall total rainfalls of 3 inches or greater have fallen this month over about 20 to 30 percent of the state helping to hold the drought areas in check. About 12 percent of the state landscape remains in Moderate to Severe Drought according to the U.S. Drought Monitor. Drought has been more widespread and extreme in the central and southern Plains States.

Despite some wide variation week to week, temperatures so far this month have averaged close to the monthly normal. Extremes for the month so far range from 101°F at Marshall (Lyon County) on the 3rd to just 39°F at Brimson (St Louis County) on the 12th.

MPR State Fair Minnesota Weather Quiz Broadcast:

It’s time once again to test how much you know about Minnesota weather and climate. Cathy Wurzer and I will present the annual Minnesota State Fair Weather Quiz Event on Minnesota Public Radio News and Information Service from noon to 1pm August 25, 2022. We will be located on the State Fairgrounds at the MPR booth on the corner of Judson and Nelson. The quiz will also be posted on the MPR web site, so if you cannot be there, but want to test your knowledge you can go to the web site. The quiz has questions related to Minnesota history, recent weather events, record weather events, weather jargon, and climate change. Have fun!

Weekly Weather Potpourri:

The NOAA Climate Prediction Center release a new fall season outlook this week. For the September through November period, the outlook models favor warmer than normal and drier than normal conditions to prevail across Minnesota, especially in the southern half of the state.

According to Reuters mountainous portions of the South Island of New Zealand received up to 19 inches of rainfall over last Wednesday through Friday, sending a torrent of water downstream which flooded many towns and villages. Many homes were evacuated in short order from the flash flooding that occurred as an “atmospheric river” of water vapor fed into the storms causing record-setting rainfalls in many areas.

A recent paper published in the journal Nature by scientists from Cambridge documents success with a floating lightweight, leaf-like structure which converts solar energy with efficiencies that are scalable enough to consider as alternative clean fuel sources. These could be deployed in sufficient numbers on oceans and waterways to produce another option for generating solar based fuel systems to compete with other energy sources.

This week’s AGU-EOS Bulletin features an article about the effects of wildfires on snowpack in the western states of the USA. A recent study shows that in vast areas where wildfires have occurred the water content of the winter snowpack is no longer as great as it was in the past and the melting of the seasonal snowpack has become more accelerated than in the past. This has may have implications for reservoir water supplies in many areas.

MPR listener question:

This morning I’m watching bands of rain moving south at a rate of at least 15 mph over the Twin Cities. But winds at my house are calm and weather app shows wind velocity of zero. Can you explain this ‘contradiction’ between radar “velocity” and local wind velocities? Thanks much.

Answer:

Sure. Reported wind velocities from climate stations in Minnesota are measured by anemometers on a 10 meter tower (about 33 feet above the ground level). Wind direction and velocity varies with height and it is probably the least uniform (most variable) measurement used by meteorologists. Each vertical layer of the atmosphere over us may have a different pattern of pressure differences affecting it, with different size eddies or streams of wind interacting. As a consequence, wind speeds and directions commonly vary with height, and sometimes to an extreme. You can view this by going to one of the National Weather Service web sites that shows the measured wind direction and speed with height.

Twin Cities Almanac for August 19th:

The average MSP high temperature for this date is 80 degrees F (plus or minus 7 degrees F standard deviation), while the average low is 62 degrees F (plus or minus 7 degrees F standard deviation).

MSP Local Records for August 19th:

MSP records for this date: highest daily maximum temperature of 97 degrees F in 1976; lowest daily maximum temperature of 61 degrees F in 1997; lowest daily minimum temperature of 39 degrees F in 1967; highest daily minimum temperature of 75 degrees F in 1900; record precipitation of 3.19 inches in 1997. No snow has been reported on this date.

Average dew point for August 19th is 59°F; the maximum dew point on this date is 76°F in 1998; and the minimum dew point on this date is 33 degrees F in 1950.

All-time state records for August 19th:

The state record high temperature for this date is 107 degrees F at Browns Valley (Traverse County) in 1976. The state record low temperature for this date is 27 degrees F at Tower (St Louis County) in 1977. The state record precipitation for this date is 15.10 inches at Hokah (Houston County) in 2007. No measurable snowfall has occurred on this date.

Past Weather Features:

August 19, 1976 was the hottest in state history. Most communities reported an afternoon high temperature in the 90s F. A maximum of 100°F or greater occurred in 30 Minnesota counties. The overnight low at Wheaton (Traverse County) only dropped to 81°F.

On August 19, 1977 frosts were reported in portions of St Louis, Roseau, Lake of the Woods, and Marshall Counties. The growing season ended at Tower with a reading of 27°F. 

Fifteen years ago, over August 19-20, 2007 perhaps the most intense flash flood in Minnesota history occurred over portions of Houston, Winona, Olmsted, Fillmore, and Dodge Counties in southeastern Minnesota. Many climate stations reported 8 to 16 inches of rainfall. The town of Rushford (Fillmore County) was entirely inundated with water and residents made their way around to help each other in boats. The Minnesota State Climatology Office provided a complete briefing on this storm.

Outlook: 

Lingering chances for showers and thunderstorms on Saturday with cooler than normal temperatures. A drier pattern will begin on Sunday and last through Wednesday with near normal temperatures. There will be increasing chances for showers and thunderstorms to return by Thursday and Friday of next week.