To: Minnesota WeatherTalk for MPR's Morning Edition From: Mark Seeley, Dept of Soil, Water, and Climate Re: Topics for MPR's Morning Edition, Friday, July 29, 2005 Headlines: -Cool air arrives for a few days -Preliminary climate summary for July -Multi-million dollar rains on July 25th -Tropical heat on the 23rd sets records -Worst late July heat wave? How about 1917 -Question about 24-hr rainfall records -Almanac for July 29th -What's a scarf, cap, or hood cloud? -Outlook Topic: Finally some cool, Canadian air While many of the eastern and southern states continued to swelter, Tuesday through Friday mornings this week (July 26-29) brought the coolest temperatures of the month to MN. Many locations reported lows in the 40s and 50s F. Embarrass reported a low of just 32 degrees F on the 27th, tying the all-time record state low for the date set at Sawbill Camp in Cook County in 1937. Hibbing with 34 degrees F and Eveleth with 37 degrees F also set new local record minimum temperatures for the 27th. International Falls reported record lows of 43 degrees F on the 28th and 36 degrees F on the 29th. Also on the 29th, Embarrass reported a low of just 30 degrees F, tying the state record low for the date (held by Tower in 1903). Cook tied their record low on Friday with 36 degrees F, It is noteworthy to mention that the reading of 30 degrees F at Embarrass was the nation's lowest temperature on the 29th and the first time that Minnesota has reported the nation's lowest reading in over two months. The last time was a reading of 25 degrees F at Bigfork on the 16th of May. Topic: Preliminary Climate Summary for July, 2005 July was dominated by hot days and warm nights, consequently, most places reported average monthly temperatures that were 2 to 4 degrees F warmer than normal. For the Twin Cities July of 2005 is ranked in the warmest 15 percent of all time, while for both Rochester and St Cloud it is ranked in the warmest third historically. The highest reading for July came from Winona where it was 99 degrees F on the 18th. The lowest reading came from Embarrass with 30 degrees F on the 29th. Rainfall was lacking in most places, especially up north. There were a number of southern locations that reported above normal rainfall. Winona, Caledonia and Preston in the southeast reported over 5 inches, with the Winona Dam receiving 4.71 inches on the 25th. Duluth will likely report one of the driest Julys in history. With just 0.82 inches so far this month, July 2005 ranks among the driest along with 1936, 1946, and 1947. The record lowest for July at Duluth is just 0.47 inches in 1875. Strong winds were reported on the 3rd, 7th, 17th, 23rd, and 25th of the month. The winds on the 23rd and 25th exceeded 60 mph in a number of places, topping out at 85 mph near Morris in Stevens County. In fact there were 33 reports of high wind damage (mostly broken tree limbs) in Minnesota on the 23rd. Topic: Record million dollar rains on July 25th Monday, July 25th brought some much needed moisture to many areas of Minnesota. Both morning and evening thunderstorms provided a much needed boost to the state's row crops, which are in the moisture sensitive reproductive growth stage. Many areas reported an inch or more of rainfall. Some communities received record setting amounts for the date, including Rochester 3.48" Twin Cities 1.56" Preston 1.49" Winona 3.20" New Ulm 2.00" Windom 1.68" LaCrescent 1.62" Spring Valley 1.53" Minnesota City 3.41" Decorah, IA 1.75" Winona Dam 4.71" During the reproductive growth stage of corn, each inch of rainfall can translate to 5 to 10 bushels in yield. Similarly for soybeans each inch of rainfall can mean an additional 2 to 4 bushel in yield. With approximately 7 million acres of each crop planted this year, and $2.00/bu corn prices and $6.50/bu soybean prices, it is easy to see how a one or two inch rainfall across even a part of the state can mean tens of millions of dollars to the agricultural economy of our Minnesota. Topic: A tropical like air mass on July 23rd sets records.... Saturday, July 23rd brought very hot, humid air to the region. A new state record high dewpoint value of 86 degrees F was observed at Pipestone and at St James. This broke the record dewpoint reading of 84 degrees F set in July of 1999 and July of 2002 at other southern Minnesota locations. Though a stormy day for many (there were 33 reports of high winds from MN and 66 reports of high winds from WI), bright sun and strong southerly breezes ushered in very hot, humid air on Saturday, pushing the Heat Index well past the 100 F mark for many. In fact Pipestone tied the state record Heat Index Value with a late afternoon reading of 125 degrees F (temp 93 F, dewpoint 86 F), which had previously occurred at Red Wing on July 30, 1999. Some of the most extreme Heat Index readings Saturday included... Pipestone 125 F St James 122 F New Ulm 114 F Windom 114 F Willmar 113 F Waseca 113 F Redwood Falls 113 F Austin 111 F Albert Lea 111 F Owatonna 111 F Fairmont 111 F Faribault 111 F Luverne 110 F Marshall 110 F Topic: The hottest last week of July? 1917 is the winner! Though July of 1936 brought the worst heat wave ever to parts of MN, it was the last week of July 1917 that produced the greatest month ending heat. Unlike the hot and humid conditions of July experienced in recent years, 1917 brought very dry heat, manifested by the large swings in daily temperature. Below are the daily highs and lows for the last week of July, 1917 at Beardsley (Big Stone County). Date High Temp Low Temp 7/25 104 F 64 F 7/26 104 F 66 F 7/27 104 F 50 F 7/28 113 F 51 F 7/29 114 F 60 F 7/30 101 F 61 F 7/31 89 F 56 F Fortunately the dry air allowed considerable overnight cooling and sleeping in the non-air conditioned environment was not a problem. However, daytime heat stress caused a number of heat prostration cases in Minnesota which required treatment. Across the nation the heat wave caused scores of deaths that year, but this was lost in the headlines of WWI, and subsequently lost in the history books in comparison to the 600,000 deaths from the flu epidemic in 1918. MPR listener question: The media reported that the Indian Monsoon has brought extreme 24-hr rainfalls lately, including up to 37 inches near Bombay, India. What are the record 24-hr rainfall totals for Minnesota, North America, and the World, respectively? Answer: According to the Minnesota State Climatology Office the record 24-hr rainfall for Minnesota is 10.84 inches on July 22, 1972 at Fort Ripley. According to the National Weather Service the record 24-hr rainfall for North America is 43 inches at Alvin, TX on July 26, 1979. According to the World Meteorological Organization the world record 24-hr rainfall is 72 inches at La R'union Island in the Southern Indian Ocean on January 8, 1966. This world record amount is equivalent to a day-long rainfall intensity of 3 inches/hour which equates to the 100-year rainfall rate in Minnesota.....quite remarkable. Twin Cities Almanac for July 29th: 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 63 degrees F (plus or minus 6 degrees F standard deviation). MSP Local Records for July 29th: MSP weather records for this date include: highest daily maximum temperature of 98 degrees F in 1933, 1975, and 1999; lowest daily maximum temperature of 70 degrees F in 1971 and 1996; lowest daily minimum temperature of 47 degrees F in 1971; highest daily minimum temperature of 80 degrees F in 1917; record precipitation of 1.11 inches in 1989. Average dew point for July 29th is 61 degrees F, with a maximum of 79 degrees F in 1955 and a minimum of 35 degrees F in 1936. All-time state records for July 29th: Scanning the state climatic data base: the all-time high for this date is 114 degrees F at Beardsley (Big Stone County) in 1917; The all-time low for this date is 30 degrees F at Tower (St Louis County) in 1903. The all-time state record for precipitation on this date is 4.12 inches at Aitkin in 1963. Word of the Week: Cap, Hood, or Scarf Cloud This is an accessory cloud form associated with cumulus or cumulonimbus clouds. This cloud is generally of small horizontal extent and is positioned just about the larger cumuloform cloud, sometime penetrated by it. Formation is caused when moist air aloft is lifted over the cumulus cloud form and a thin layer of cirrus forms. Scarf, cap, and hood clouds, so named as they appear like head coverings, are generally short-lived. They are far more frequently seen in the summer months. Outlook: Partly cloudy and warmer over the weekend with a small chance for showers and thunderstorms, particularly late on Saturday. Generally sunny and warm most of next week with another chance for showers and thunderstorms by Thursday and Friday.