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Cold Air Follows Early Week Rains, But Moderation is Expected

Announced Change in Minnesota WeatherTalk

 Minnesota WeatherTalk is now officially an Extension Blog.  It will continue to be released in newsletter form each Friday following the broadcast of Minnesota Public Radio's "Morning Edition" news program.  But in addition, periodic WeatherTalk blogs highlighting current significant weather events and impacts, along with climate science research will appear at this place on the web.

Wringing the atmosphere, September 9-10 rains:

 A strong low pressure system moved across Minnesota earlier this week over September 9-10, bringing strong winds, significant rains, and a dramatic drop in temperatures and dewpoints.  Early in the week dewpoints ranged into the mid 60s F with temperatures in the 70s F.  This cold front passage brought a drop of 20-30 degrees F in dewpoints and temperatures, along with 35-40 mph wind gusts.

Most observers reported less than an inch of rainfall from this storm, but some received record-setting amounts including 1.20" at Hibbing on the 9th.  Those setting new records on September 10th included: 2.10" at Hutchinson, 1.59" at Preston, 1.55" at Litchfield, 1.37" at Bruno, 1.25" at Austin, and 1.19" at both Floodwood and Wolf Ridge Environmental Learning Center (north shore).  

Invasion of cold air:

Following the cold front passage on September 9-10, the coolest air mass of the season so far spread over Minnesota.  Cool northwest winds, along with persist cloud cover kept daytime temperatures very low on Wednesday, September 10th.  Some climate stations reported new record low daytime maximum temperatures including 44 degrees F at Embarrass, 46 degrees F at Ely, Eveleth, and Wright, 51 degrees F at Ottertail, 52 degrees F at Wheaton, and 54 degrees F at Kabetogama.  On Thursday, September 11tth a few more record cold maximum temperatures were reported, including 46 degrees F at Grand Marais, 48 degrees F at Crane Lake, and 49 degrees F at Cook.  In addition on Thursday morning Orr tied their daily record low temperature (2006) with a reading of 28 degrees F.

Weekly Weather Potpourri:

The NOAA-National Weather Service Forecast Office in Rapid City, SD reported the earliest measurable September snowfall in history this week over the 10th and 11th.  Rapid City reported about 2 inches, but nearby Custer, SD reported 8 inches of snowfall and Mount Rushmore saw 7 inches.

 In addition Environment Canada reported this week that Calgary, Albert received over 11 inches of snowfall, causing some travel difficulties as well as some power outages.

A recent NOAA report assesses groundwater conditions in California in the context of the three year drought there.  It clearly points to the fact that one of the driest three-year periods in the state has produced a significant decline in groundwater supplies as well.

Another news release this week from NOAA documents how new technologies deployed in the use of Doppler Radar systems are helping forecasters with detection and warnings for severe convective weather, including tornadoes.  The technology applied is called SAILS which stands for Supplemental Adaptive Intra-Volume Low-Level Scans and it speeds up the radar scan rate at the lowest levels in the atmosphere.  This technology has been deployed effectively in our region of the country since last May. 

An inventory of global carbon dioxide emissions was described this week in a research paper from Arizona State University.  The paper appears in the Journal of Geophysical Research and describes how researchers estimated hourly carbon dioxide emissions over the past 15 years.  This is the most detailed source of emissions data yet derived for use in assessing human impact on climate change.  Science Daily features a description of this paper.

Tropical Storm Odile off the west coast of Mexico is expected to become a hurricane this weekend and bring heavy rains to coastal regions of Mexico.  Odile is the 15th named storm of the Eastern Pacific Tropical Storm season.  In the Western Pacific Tropical Storm Kalmaegi was expected to become a typhoon east of the Philippines and bring extreme weather to that country by early next week.
Earlier this week on September 8th the central portion of Arizona, particularly the Phoenix area received some torrential downpours causing widespread flash flooding.  Some areas received 3-4 inches of rainfall in less than 12 hours.  The Phoenix Sky Harbor Airport reported 3.29 inches in only 7 hours, the largest quantity of rainfall in one day ever recorded there.

MPR listener question:

Back in the early summer you and Cathy spoke about how many climate observers in Minnesota were on pace to record their wettest year in history.  Then Mother Nature slowed down the pace and quantity of rainfall over the summer.  Are any places still expected to set annual precipitation records this year?


 For the most part the frequency and quantity of precipitation has diminished during the second half of 2014 and few if any observers are expected to set any new annual precipitation records.  Those who still have a shot at setting by year's end include: Mora with 36.03" (currently ranked 9th wettest year); Rushford with 36.26" (currently ranked 8th wettest year); Kabetogama with 28.70" (currently ranked 5th wettest year); Chaska with 39.63" (currently ranked 4th wettest year); and Little Falls with 34.16" (currently ranked 3rd wettest year).  Normal or above normal monthly precipitation for the rest of this year would likely establish new annual records at these locations.

 Twin Cities Almanac for September 12th:

The average MSP high temperature for this date is 72 degrees F (plus or minus 10 degrees F standard deviation), while the average low is 53 degrees F (plus or minus 7 degrees F standard deviation).

MSP Local Records for September 12th:

MSP weather records for this date include: highest daily maximum temperature of 94 degrees F in 1908 and 1948; lowest daily maximum temperature of 55 degrees F in 1886, 1923, and 1974; lowest daily minimum temperature is 36 degrees F in 1878 and 1940; highest daily minimum temperature of 73 F in 1931; record precipitation of 4.96 inches in 1903; and there has been no snow on this date.

Average dew point for September 12th is 52 degrees F, with a maximum of 72 degrees F in 1909 and a minimum of 26 degrees F in 1923.

All-time state records for September 12th:

The state record high temperature for this date is 102 degrees F at Beardsley (Big Stone County) in 1931. The state record low temperature for this date is 17 degrees F at Kelliher (Beltrami County) in 2000. State record precipitation for this date is 4.96 inches at Komiska (an early Czech community in McLeod County) in 1869; and a trace of snow fell at Warroad and Roseau on this date in 1923.

Past Weather Features:

 By far the coldest September 12th in history occurred in 1902 bringing an end to the agricultural season statewide.  Half of the climate observers in the state reported lows in the 20s F, with virtually every corner of the state experiencing a frost.  It was just 27 degrees F in St Peter.

One year later (1903) brought one of the wettest spells of September weather as strong thunderstorms crossed the state over the 12th and 13th bringing 2 to 3 inches of rainfall to many areas.  Widespread flooding occurred in many areas including Shakopee, St Paul, Farmington, Minneapolis, and Red Wing where over 5 inches of rainfall was reported.

The warmest September 12th in state history was in 1931.  Actually the entire week of September 6-12 that year was one of the warmest ever in September.  Ever location in the state except for Grand Marais and Two Harbors surpassed the 90 degrees F mark, with 10 communities reporting afternoon readings of 100 degrees F or higher.  September of 1931 proved to be the warmest in state history as well.


The weekend will start with patchy frost around the state, depending on cloud cover early Saturday morning.  Temperatures will continue cooler than normal, but moderate slowly towards normal later next week.  There is a chance for showers Sunday night into Monday, but most of next week looks to be dry.

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