Record Rainfall on July 13For some Minnesota citizens the early morning hours (4 am to 8 am) on Saturday, July 13th were quite noisy, with thunder, high winds, and very heavy rainfall. The rainfall amounts ranged from 1 to 3 inches across many east-central counties, and were even higher in parts of Scott, Rice, Steele, and Waseca Counties. Some National Weather Service observers reported new daily record amounts for July 13th, including 3.80 inches at Wells, 3.02 inches at Chanhassen, 2.79 inches at MSP Airport, 2.75 inches at Rosemount, 2.44 inches at Brainerd, 2.30 inches at Faribault, 2.23 inches at Rockford, and 1.82 inches at Owatonna.
These rains caused the National Weather Service to issue a number of flood warnings for areas along the Vermillion, Straight, and Cannon Rivers, and flash flood warnings for many communities, including Wells, Faribault, Northfield, New Market, Dundas, and Shakopee. You can read more about this storm here.
Further, the Midwest Climate Center informs us that the first six months of 2013 (January-June) has been the wettest in history for Michigan (20.80" statewide average), Iowa (24.93" statewide average), Wisconsin (21.85" statewide average), and Illinois (29.11" statewide average). In Minnesota it has been the 3rd wettest first six months of the year averaging 16.93 inches statewide (this trails only 17.31 inches in 1908 and 17.83 inches in 1896). Harmony, MN (Fillmore County) has reported nearly 35 inches of precipitation so far this year and their annual normal is 34.63 inches!
Record rainfall in NE MN on July 18-19Late in the day on Thursday, July 18th and overnight into Friday, July 19th strong thunderstorms trained over far northeastern Minnesota bringing damaging winds, hail, and intense rainfall. Flood warnings had to be issued by the National Weather Service for a number of rivers, as well as for the city of Grand Marais. Among the observers reporting record amounts of rainfall were International Falls with 2.15 inches, Kabetogama with 1.63 inches, Gunflint Lake with 3.23 inches, and Grand Marais with 3.53 inches. The amount of rainfall at Grand Marais was the 5th highest 24-hour total ever measured there.
July HeatTuesday, July 16 through Thursday, July 18 brought numerous 90 degrees F readings to southern Minnesota counties, and widespread Heat Advisories issued by the National Weather Service. Dew points were very high as well touching 70 degrees F or higher on 5 consecutive days and helping to push the Heat Index values near 100 F or higher. On Tuesday, July 16 at least 20 cooperative observers reported highs in the 90s F, Wednesday (July 17) that number jumped to 56 observers, and Thursday (July 18) at least 65 cooperative observers reported high temperatures of 90 degrees F or greater. Fortunately a cold front brought relief from the heat on Friday, and further relief was expected into the weekend.
Weekly Weather potpourriA recent paper in the International Journal of Climatology documents how tropical storms can intensify even after they make landfall when the surrounding soil is wet enough to provide evaporative fuel (latent heat) for the storm. Under such conditions "the land essentially mimics the moisture-rich environment of the ocean, where the storm originated," says Theresa Andersen from the University of Georgia, one of the paper's co-authors. You can read more about this study of tropical storms here.
This week NASA's Earth Observatory is showing images of the melt season on the Greenland ice sheet as the ponds forming across the ice have accelerated in recent days. The melt season did not start as early as it did in 2012, nor is it expected to be as intense, but it is still on a faster pace than average for the period from 1981-2010. You can see more and read more about this here.
MPR listener questionAs a life long resident of the Twin Cities I wondered if there is a day of the year that has seen significantly less frequency of precipitation than any other day of the year. If so, what day is it?
Answer: That is an interesting question I had never considered. Our State Climatology Office examined the Twin Cities climate record back to 1871 (142 years) and found that February 8th has brought precipitation the fewest number of times (17 percent) just 24 days, while November 6 is a close second with (18 percent) just 26 days. The day of the year which has recorded the highest precipitation frequency is June 14 with 48 percent, or 68 days.
As a sidebar to this answer the State Climatologist in California informs me that June 21st has never brought a rain to Fresno (133 years of record), and that July 7th has never brought a rain to San Francisco (164 years).
Twin Cities Almanac for July 19thThe average MSP high temperature for this date is 84 degrees F (plus or minus 8 degrees F standard deviation), while the average low is 64 degrees F (plus or minus 6 degrees F standard deviation).
MSP Local Records for July 19thMSP weather records for this date include: highest daily maximum temperature of 100 degrees F in 1940 and 1977; lowest daily maximum temperature of 63 degrees F in 1877 and 1902; lowest daily minimum temperature of 46 F in 1873; highest daily minimum temperature of 79 F in 1977; and record precipitation of 1.75 inches in 1957; No snow has been recorded on this date.
Average dew point for July 19th is 61 degrees F, with a maximum of 82 degrees F in 2011 and a minimum of 41 degrees F in 1958.
All-time state records for July 19thThe state record high temperature for this date is 108 degrees F at Canby (Yellow Medicine County) in 1932 and at Redwood Falls (Redwood County) in 1934. The state record low temperature for this date is 29 degrees F at Tower (St Louis County) in 2000. State record precipitation for this date is 8.97 inches at Fosston (Polk County) in 1909; and no snow has fallen on this date.
Past Weather Features:Strong thunderstorms in northern Minnesota brought flash flooding to some areas over July 19-20, 1909. Bagley and Beaulieu reported over 10 inches of rain, while Fosston reported 9 inches and Walker 6 inches. In some areas the small grain harvest was delayed because of wet ground.
On July 19, 1912 ground frost was reported at a number of northern Minnesota locations, including Bagley, Roseau, Pokegama Dam, Cloquet, Virginia, and Littlefork. Overnight lows were in the low to mid 30s F, while daytime highs were in the 60s and 70s F during the week.
July 19th brought high temperatures of 100 degrees F or greater to parts of Minnesota in 1926, 1932, and 1934. In 1926 a 7-day Heat Wave prevailed in southern MN bringing 90 plus F temperatures each day over July 15-21. In 1932 an 11-day Heat Wave prevailed over July 12-22. In 1934 a Heat Wave began on July 19th and lasted until the 27th, bringing consecutive days with 100 degrees F or greater to many western and southern Minnesota communities.
July 17-21, 1999 was extremely wet in southern Minnesota counties with daily thunderstorms and large rainfalls. Austin, Preston, Spring Grove, Hokah, Winnebago, Wells, Harmony, and Albert Lea all reported 5 to 6 inches of rainfall. Grand Meadow reported nearly 8 inches. July of 1999 was the wettest in history for southeastern counties with total monthly rainfall averaging nearly 9 inches among all observers.
Some of the highest Heat Index values ever measured in our region occurred on July 19, 2011. Temperatures were primarily in the 90s F with dewpoints in the 80s F. Some of the more remarkable Heat Index readings that day included: 107 F at Montevideo, 110 F at Morris, 111 F at Fergus Falls, 112 F at Olivia and Appleton, 113 F at Redwood Falls, 114 F at New Ulm, 115 F at Marshall and Ortonville, 116 F at Fargo, ND, 117 F at Willmar, St Cloud, and Benson, 119 F at MSP, and 130 F at Moorhead. These were the warmest spots in North America that day.