First Autumn Rain/Snow Mix With a Winter Storm

First Autumn Rain/Snow Mix With a Winter Storm:

October 10-11 brought the first seasonal mixture of rain and snow to many parts of Minnesota. Most of the snow was reported in northwestern counties, which were under a Winter Storm Watch Thursday night. Some areas of the Red River Valley were expected to get 4 to 8 inches of snowfall by Saturday, along with winds over 40 mph. Rain fell across much of the rest of the state (in some areas more than one inch) pushing monthly totals past 4 inches at over two dozen climate stations in Minnesota.

Early Look at Change in Climate "Normals"

By the end of 2020 we will complete climate record keeping for the second complete decade of the new millennium. By international agreement all of the government weather services will calculate new climate “normals” for locations that have measured daily climate histories. We know already for Minnesota that the climate trends of the past decade have been upward (positive) with respect to both temperature and precipitation. But what magnitude of change might we expect in the new “normals” for the 1991-2020 period, as they replace the 1981-2010 period?

We have some evidence from preliminary data for selected cities in Minnesota. For MSP the annual average precipitation will go up again by about 2 percent over the previous period (1981-2010), which will continue the upward trend seen since 1941. Likewise for Duluth the annual average precipitation will go up by about 2 percent over the previous period. The largest single month increase at MSP has occurred in May with about 15 percent more rainfall, while the largest single month increase at Duluth has been 9 percent more rainfall in June.

For changes in temperature “normals” we find that MSP will see about a 0.7°F increase in the annual mean temperature, while Duluth will see a change in the annual mean value of temperature that is about 0.4°F. Again, these are positive trends that started nearly a century ago. At MSP the biggest change in monthly mean temperature has occurred in September, with an increase over 1.0°F, while at Duluth the biggest increase in monthly mean temperature has occurred in December with an increase of over 1.5°F.

I am sure we will hear more about the continuation of these trends throughout the next year.

Weekly Weather Potpourri:

NOAA features this week an article about the reconstruction of historical weather maps using historical observations of the weather. It provides for another way to look at the geographic distribution of weather elements during some of the most significant historical events.

There is also an interesting article by NOAA’s Tom Di Liberto concerning the rapid development of drought across some of the southeastern states during the month of September. This occurred at such a rapid pace, it is termed a “flash drought.”

In the Western Pacific Ocean Typhoon Hagibis was expected to hit portions of Japan on Friday and Saturday this week with strong winds, heavy rainfall, and large waves. Areas around Tokyo were bracing for the storm. At one time it produced winds over 150 mph and sea wave heights of 55 feet, but it was expected to weaken as it approached the coast.

There was an interesting article in the Washington Post this week about the dramatic climate changes being observed in Siberia and the impacts on natural resources and communities there.

MPR listener question:

A couple of weeks ago you mentioned that the statewide monthly record for snowfall in October was 19 inches, and that occurred in multiple years. But what is the statewide daily snowfall record for the month of October and do you think we might break it this month?

Answer:

The all-time daily record snowfall for October is 16 inches which occurred on October 18, 1916 at Baudette, MN (Lake of the Woods County). As for breaking it this month, it would take a strong winter storm that is slow moving, and I don’t see that happening.

Twin Cities Almanac for October 11th:

The average MSP high temperature for this date is 61 degrees F (plus or minus 11 degrees F standard deviation), while the average low is 41 degrees F (plus or minus 8 degrees F standard deviation).

MSP Local Records for October 11th:

MSP weather records for this date include: highest daily maximum temperature of 85 degrees F in 2015: lowest daily maximum temperature of 39 degrees F in 1959; lowest daily minimum temperature is 22 degrees F in 1876; highest daily minimum temperature of 63 degrees F in 1997; record precipitation of 1.36 inches in 1881; and record snowfall of 0.5 inches in 1977.

Average dew point for October 11th is 41 degrees F, with a maximum of 67 degrees F in 1962 and a minimum of 11 degrees F in 2012

All-time state records for October 11th:

The state record high temperature for this date is 95 degrees F at Moorhead (Clay County) in 2015. The state record low temperature for this date is 10 degrees F at Ada (Norman County) in 1935. State record precipitation for this date is 3.28 inches at Litchfield (Meeker County) in 1983; and record snowfall is 10.0 inches at Mount Iron (St Louis County) in 1909.

Past Weather Features:

Early winter gripped the state on October 11, 1876 when northern and central Minnesota counties reported temperatures in the teens, while even southern Minnesota counties saw morning temperatures fall into the low 20s F.

An early winter storm hit northern Minnesota with a mixture of rain and snow over October 10-12, 1909. Many areas received over an inch of rain, while Baudette and Two Harbors received over 2 inches. Other areas of northeastern Minnesota reported 2-4 inches of snow, and Mount Iron reported 10 inches.

October 11, 2015 brought summer-like conditions to most places with temperatures in the 80s F. Over 20 northern and western communities reported afternoon highs in the 90s F. The cool spot in the state was Grand Marais, with a high of only 58 degrees F.

Outlook:

Sharply colder this weekend with a rain/snow mix on Saturday. It will be dry on Sunday and Monday, but temperatures will remain cooler than normal. Chance for precipitation returns on Tuesday. A warming trend should start towards the end of next week bringing temperatures back closer to normal.