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Extension > Mark Seeley's WeatherTalk > August starts dry, then widespread rains

Friday, August 7, 2015

August starts dry, then widespread rains

August starts dry, then widespread rains:



Except for portions of northern Minnesota last weekend (Aug 1-2), most agricultural areas of the state had started out August with little or no rainfall over the first week.  Several climate stations in southern and central parts of the state had not reported measurable rainfall for at least 8 days, the longest such spell since early March of this year. 

Thankfully, Thursday, August 6th brought the first measurable rainfall of the month to many agricultural areas, with rainfall amounts from a half inch to one inch very common across much of the state.  Some observers reported record-setting rainfall values including the following:
1.42 inches at International Falls
2.25 inches at Baudette
2.32 inches at Warroad
3.30 inches at Waskish
3.55 inches at Wright
2.31 inches at Sandstone
2.48 inches at Forest Lake
2.21 inches at Chisago City
1.60 inches at Glenwood
4.20 inches at Kimball
4.39 inches at Becker

Along with the rainfall there were brief tornado touchdowns in Swift and Kandiyohi Counties, and large hail in Blue Earth County.

It is important to note that soil moisture reserves are adequate to surplus for most of Minnesota’s agricultural counties, so not many fields are showing any signs of dryness affecting yield potential for this year’s crop.  With corn in the grain filling stage and soybeans setting seeds in their pods, these additional rainfalls will be most helpful in getting through the August growth period stress-free.

Most of the climate models favor warm and dry weather for the balance of August after scattered showers this weekend, so that means the stored soil moisture will be greatly utilized by crops as they finish out their growth and maturation.  Most of the opinion expressed at FarmFest this week was that Minnesota may have the best crops in the Midwest this year, as a result of an ideal growing season.  Many will not be surprised by record yields.

Camelot Climate Index favors Embarrass this summer:

 


Excerpt from Camelot by Alan Jay Lerner (1960)
CAMELOT
It's true!  It's true!
The crown has made it clear:
The climate must be perfect all the year.
A law was made a distant moon ago here,
June, July and August cannot be too hot;
In Camelot. 
The rain may never fall till after sundown,
By eight the morning fog must disappear.
In short, there's simply not,
A more congenial spot
for happy everaftering than here
In Camelot.
There is indeed a Camelot Climate Index designed around climate variables that relate to human comfort: day and night temperatures; humidity; sunshine; and rain. 

This index uses 75 F as an ideal daytime high (great for outdoor activity without stress), and 45 F as an ideal nighttime low (sleeping comfort mostly).  It also uses humidity, precipitation, and sunshine in the determination of the index.
Just taking the temperature portion of the index and comparing climate stations in Minnesota for the summer months so far (June 1 to August 7) proved interesting to me.  I used 75 F plus or minus 5 F as the ideal range for daytime highs and 45 F plus or minus 5 F As the ideal range for nighttime lows.  Here is what I found:
In Grand Marais, 20 summer days have scored well in the comfort zone for daytime highs, while Embarrass has reported 41 such days.  Grand Marais has reported 41 nights with temperatures good for sleeping comfort, while Embarrass has reported 36 such nights.  For context the urban heat island of the Twin Cities has recorded zero nights with temperatures in the 40s F this summer, and only 22 days with daytime temperatures of 75 F plus or minus 5 F. 
I find it interesting that Embarrass, the coldest place in the state (and often coldest in the nation), has had such a magnificent summer on the Camelot Climate Index.  Perhaps the citizens of Embarrass are closer to Camelot than most of us.

Weekly Weather Potpourri:

ScienceDaily reported this week that NASA scientists have determined that drought since 2012 has brought a cumulative loss of precipitation to California that is equivalent to a year's worth, 20 inches.  Even with the current El Nino episode expected to bring above normal precipitation to California this winter, scientists think it will take several year’s of above normal precipitation to recover from the current drought.


Typhoon Soudelor in the Western Pacific Ocean was packing winds well over 115 mph and heading towards Taiwan this week.  It had generated sea waves of 35-40 ft.  Damaging winds, heavy rains, and coastal storm surge are expected to hit Taiwan this weekend.  In the Central Pacific Ocean Tropical Storm Guillermo was expected to track north of Hawaii and perhaps bring strong winds to Maui, along with big waves to the northern coastal areas of that state.
http://www.usno.navy.mil/NOOC/nmfc-ph/RSS/jtwc/satshots/13W_071132sair.jpg 


NOAA scientists reported this week that well above normal sea surface temperatures in the northern Pacific Ocean have likely contributed to a record-setting bloom of toxic algae along the Alaskan Coast.  This bloom may have some detrimental impact on marine organisms along the coast.  You can read more at climate.gov.



NOAA also released this week a well done teaching module about spatial and temporal climate variations and how they are related to both natural and man-made process.  You can read more at the NOAA Teaching Essential Principles web site.


Excerpts from the weekly drought briefing by USDA's Brad Rippey: ".....  The Plains, Midwest, and Northeast remain largely free of drought, but hot, dry conditions have resulted in drought development in parts of the South.  Portions of eastern Texas, which experienced the worst flooding in at least 25 years in late May and early June, received little or no rain during July and have witnessed flash drought conditions that have increased stress on pastures and shallow-rooted crops.  In addition, significant drought continues in most areas west of the Rockies....worsening drought in the Northwest led to sharp increases in the coverage of extreme to exceptional drought (D3 to D4) between June 30 and August 4 in Washington (from 0 to 32%); Idaho (6 to 22%); Montana (0 to 14%); and Oregon (34 to 48%)....the Northwestern drought situation was exacerbated by persistent heat; locations such as Salem, Oregon, and Seattle, Washington, experienced not only their hottest July, but also their hottest month on record.  By August 6, nearly three dozen large wildfires, in various stages of containment, were actively burning in the Pacific Coast States."

MPR listener question:

Someone at FarmFest said that August holds the statewide record for rainfall in Minnesota.  That is hard to believe as I remember the Twin Cities received 17.90 inches of rainfall in July of 1987, and Redwood Falls reported 14.24 inches of rainfall in June of 2014.

Answer:


The person at FarmFest was probably from southeastern Minnesota which had the remarkable flash flood in August of 2007.  That month delivered 23.86 inches of rainfall to Hokah (Houston County), MN setting the statewide record for monthly rainfall.  So it is a correct statement to say that August has delivered more rainfall to the state at one location than any other month in history.  On the other end of the spectrum for August rainfall, Crookston reported just a trace amount in 1915, and Le Sueur just a trace amount in 1896.

Twin Cities Almanac for August 7th:


The average MSP high temperature for this date is 82 degrees F (plus or minus 8 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 7th:

MSP weather records for this date include: highest daily maximum temperature of 98 degrees F in 2001; lowest daily maximum temperature of 61 degrees F in 1917: lowest daily minimum temperature is 45 degrees F in 1972; highest daily minimum temperature of 76 F in 2001; record precipitation of 2.29 inches 1984; and no snowfall has been recorded on this date.

Average dew point for August 7th is 60 degrees F, with a maximum of 77 degrees F in 2001 and a minimum of 42 degrees F in 1989.

All-time records for August 7th:


The state record high temperature for this date is 104 degrees F at Alexandria (Douglas County) in 1983. The state record low temperature for this date is 29 degrees F at Brimson (St Louis County) in 1989.  State record precipitation for this date is 8.62 inches at St Peter (Nicollet County) in 1968; and there has not been any snowfall on this date.   

Past Weather Features:


1955 The climate record of George W. Richards of Maple Plain ends. He recorded weather data with lively notations on phenology and weather events. He began taking observations when he was eleven in 1883. He continued to take observations for 72 years, with 66 years as a National Weather Service Cooperative Observer, an outstanding record of service.

On August 6-7, 1968 very heavy thunderstorms brought high winds, hail, and flash floods to southern Minnesota communities. Hail damage to crops occurred from Murray and Nobles Counties east to Freeborn and Sibley Counties. Wind speeds between 60 and 70 mph we associated with these thunderstorm, notably 66 mph at Rochester. St Peter (8"), North Mankato (7"), Albert Lea (6"), and Janesville (5") all reported flash floods, closed or washed out roads, and flooded basements.

Historically, one of the worst outbreaks of tornadoes in northern Minnesota occurred on August 6, 1969. As many as 12 different tornadoes were observed and reported between 1:15 and 7:00 pm across Cass, Crow Wing, Aitkin, St Louis, and Lake Counties. Many farms, homes and lake cabins were destroyed, while 15 people were killed and over 100 injured. The worst of these tornadoes, an F-4 (winds 207-261 mph), was on the ground for 33 miles, and at times was a 1/2 miles wide as it leveled thousands of trees.
 



August 6-7, 1983 brought a heat wave to many areas of Minnesota. Many thermometers hit the century mark, including 104 F at Alexandria, Argyle, and Crookston, 103 F at Ada, 102 F at Browns Valley, Red Lake Falls, and Georgetown, 101 F at Cass Lake, Mahnomen, Orwell Dam, Baudette, Wheaton, and Cambpell, and 100 F at Redwood Falls, Montevideo, Thief River Falls, Hawley, and Elbow Lake. These temperatures combined with dew points in the 70s F to produce Heat Index Values that ranged from 105 to 112 degrees F. The heat produced additional stress on Minnesota's corn crop which had been hit earlier in the growing season by one of the worst ever outbreaks of European Corn Borer.

Word of the Week: Isoerodent

This is not a type of rodent, nor is it a meteorological term. It is a term from soil science and means a line connecting points on a map which have an equal erosivity index. The average erosivity of soils (loss of soil in sediment runoff) is computed from the Universal Soil Loss Equation partially based on the long term historical rainfall and rainfall intensity. Many other soil characteristics are considered as well. The relative differences in the erosivity index across a landscape can be compared by mapping these values using isoerodents (lines of equal value). With such data state and federal agencies can better advocate for conservation practices that help minimize soil erosion where the risks are high.

Outlook:


Chance of scattered showers and thunderstorms around the state Saturday through early Monday, with near normal temperatures for this time of year.  Drier for Tuesday through Friday next week with temperatures climbing to above normal values and plenty of sunshine.


 

 









 



 


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