Spotty Rainfall Pattern This Month

Spotty Rainfall Pattern This Month:

July has begun with generally warmer than normal temperatures over much of the state, and several days with dew points in the sticky upper 60s F or low 70s F. Rainfall has been below normal in most areas of the state, but some have seen heavy thunderstorms deliver over 2 inches of rain through the first week of the month. The heaviest rains occurred over several southern counties near the Iowa border, though there were some significant rainfalls (over 1 inch) in north-central and northeastern counties as well.
Some record rainfalls for July 5th included:
3.16 inches at Worthington
2.40 inches at Kabetogama
1.91 inches at Austin
1.33 inches at Owatonna
1.30 inches at Spring Valley

Then on July 6th some other long term climate stations reported record rainfalls as well, including:
3.35 inches at Bricelyn
2.80 inches at Worthington
2.16 inches at Blue Earth
2.09 inches at Hokah
1.80 inches at St James

According to the U.S. Drought Monitor all or part of 24 central and southern counties in Minnesota are abnormally dry, with portions of Faribault County in Moderate Drought. According to the NOAA Climate Prediction Center most medium range forecast models favor drier than normal conditions for Minnesota through July 21st. Thankfully according to the USDA NASS reports 75 to 80 percent of Minnesota is still showing adequate to surplus stored soil moisture for crops.

Weekly Weather Potpourri:

According to the BBC Italy has declared a state of emergency in five northern regions surrounding the Po River because of the worst drought in 70 years. Water rationing is a policy being used in many municipalities, while a significant area of agriculture is expected to see reduced production. About a third of Italy’s agricultural production comes from the Po Valley.

According to a recent study published in Geophysical Research Letters, the Arctic region of the Northern Hemisphere is warming at a pace that is 4 times faster than the rest of the globe. They point out the one period of rapid warming around 1986 was due to external forcing of the climate, while another rapid warming around 1999 was due to internal forcing. The climate models did not pick up this measured variation in the data.

AGU offers an online quiz for those who wish to test their knowledge about Earth and space science. The quiz is based on science news from the most recent months and covers a broad range of topics,

MPR listener question:

From a climate perspective can you explain why most cities in Minnesota recommend watering gardens and lawns in the early morning or late evening hours?

Answer:

Measurements from several climate stations across the state show that the hourly rate of evaporation from both vegetation and soils varies immensely. Afternoon hourly evaporation rates can be ten times or more higher than those in the early morning or late evening. So in terms of delivering water to be stored in the soil and used by lawns and gardens it is much more efficient to utilize the morning or evening hours. In addition, wind speeds tend to be lower in the early morning or late evening hours, so that if you use sprinkler systems, you achieve better distribution of the water that is applied.

During the summer season there is also generally a higher probability for shower activity in the afternoon and early evening, than there is in the morning. Plants can more efficiently use the moisture from watering to grow in the morning than the afternoon and evening.

Twin Cities Almanac for July 8th:

The average MSP high temperature for this date is 84 degrees F (plus or minus 7 degrees F standard deviation), while the average low is 65 degrees F (plus or minus 6 degrees F standard deviation).

MSP Local Records for July 8th:

MSP records for this date: highest daily maximum temperature of 101 degrees F in 1974; lowest daily maximum temperature of 65 degrees F in 1997; lowest daily minimum temperature of 51 degrees F in 1958; highest daily minimum temperature of 82 degrees F in 1936; record precipitation of 3.07 inches in 1925. No snow has been reported on this date.

Average dew point for July 8th is 58°F; the maximum dew point on this date is 78°F in 1916; and the minimum dew point on this date is 34 degrees F in 2001.

All-time state records for July 8th:

The state record high temperature for this date is 110 degrees F at Fosston (Polk County) in 1936. The state record low temperature for this date is 25 degrees F at Kelliher (Beltrami County) in 2003. The state record precipitation for this date is 6.03 inches at White Rock Dam (Traverse County) in 1950. No measurable snowfall has occurred on this date.

Past Weather Features:

By far the warmest July 8th in state history was in 1936 when. Everywhere in the state except Grand Marais reported afternoon temperatures in the 90s F or higher. Over 40 climate stations reported a maximum temperature of 100°F or greater. The overnight low at Albert Lea was 83°F.

Severe thunderstorms developed over southeastern Minnesota on July 8, 1955. Many areas reported 2 to 4 inches of rain with some localized flooding of roads and highways. Portions of Goodhue, Dakota, and Carver Counties reported over 5 inches of rainfall. Several climate stations in Minnesota ended up reporting over 10 inches of rainfall in July of 1955.

July 8, 1961 brought a chilly morning for campers in northern Minnesota. In St Louis, Cass, Carlton, Beltrami, and Itasca Counties temperatures were in the 30s F. At Cook in St Louis County the temperature started out in the morning at freezing (32°F) but warmed up to 81°F by late afternoon.

Outlook: 

Continued dry into the weekend with near seasonal temperatures. A good chance for scattered showers and thunderstorms Sunday and Monday, some of which could be severe. Then drier for Tuesday through Thursday next week, with near seasonal temperatures. A warming trend is seen towards next weekend.