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A Significant Mid-April Winter Storm

A Significant Mid-April Winter Storm:

A large and deep low pressure system crossed the plains from Colorado to Wisconsin during the middle of the week bringing a mixture of precipitation along a 900 mile frontal boundary, and producing widespread winds of 40 to 50 mph. The winds ushered in a great deal of dust and soils from the southern states, notably TX and NM, such that many in the region observed a brownish or yellow tinge to the snow that fell. And plenty of snow fell over April 10-12 this week. Many areas of the state picked up from 6 to 20 inches. Some of the snowfall totals from this storm were quite impressive, including

20.0 inches at Madison (Lac Qui Parle County)
18.0 inches at Ortonville (Big Stone County)
17.0 inches at Canby (Yellow Medicine County)
14.0 inches at Milan (Chippewa County)

Even larger numbers were observed in eastern South Dakota with Watertown reporting 23.2 inches and Clear Lake reporting 26.3 inches.

This snow had a high water content as well, bending and breaking many tree branches with its weight, as well as power and telephone lines. Many in southern and western counties were without power, and a number of roads and highways were closed due to blizzard conditions.

Some of those climate stations reporting new daily snowfall records for April 10th included:
Milan with 6.0 inches, Hokah with 6.1 inches, Rochester with 4.1 inches, and Eau Claire, Wi with 3.9 inches. In addition Hokah and Luverne reported new record daily precipitation amounts for April 10th with 1.26 inches, and 0.76 inches, respectively.

For April 11th a number of other new daily record amounts were reported, including:
11.0 inches at Montevideo and Dawson; 10 inches at Canby, Marshall, and Brownton; 9.5 inches at Chanhassen; 9.2 inches at New Ulm; 8 inches at Rosemount; 7.6 inches at Wabasha; 7.5 inches at Faribault; and 6.8 inches at Redwood Falls. In addition with such high water content many new daily precipitation records were reported, including: 1.57 inches at Bird Island; 1.64 inches at Marshall; 1.45 inches at Winona; and 1.36 inches at La Crescent. In fact many areas reported from 1 to 2 inches of liquid water content in the snow.

With the abundant snow from this storm three western Minnesota communities have now set new seasonal snowfall records during the 2018-2019 snow season. They are:

Granite Falls with 92.5 inches
Canby with 90.4 inches
Marshall with 88.8 inches

Weekly Weather potpourri:


NASA release some images of the dust storm generated by the passage of the low pressure system (described above) earlier this week through the central USA. Winds of 60 to 70 mph across New Mexico and Texas on April 10th generated a great deal of dust and reduced visibility to near zero on many roads and highways. You can view the satellite images at the University of Wisconsin SSEC web site.

Climate models present a range of possible scenarios—some show more extremes than others, which can make it difficult for cities, states, and countries to plan ahead. Now, however, in a new study, Padron et al, suggest a way to reduce uncertainty using precipitation patterns from the past. You can read more about this study in this week’s AGU-EOS newsletter.

Saturday, April 13th is Citizen Science Day and NOAA highlights some exemplary citizen science projects this week on their web site. The projects involve oceans, atmosphere, and old weather records. There are also links to other resources for citizen science projects.

More than a foot of rain fell on portions of Rio de Janeiro, Brazil this week, bringing flash flooding to many areas. Some roads were washed out and many homes were flooded. More from the BBC Weather Centre.

MPR listener question:


With this week’s storm of mixed precipitation in the Twin Cities I was wondering how often does a one or multi-day storm deliver an inch or more of water during the month of April? It seems to me to be quite rare in occurrence, and I have been keeping rain gage records since 1959.

Answer:


Indeed this is unusual. The storm of April 10-12 this week delivered several inches of snow, combined with sleet, and even rain. At MSP airport the total snowfall was 9.7 inches with a liquid water content of 1.02 inches. Below is a list of the historical April storms in the Twin Cities climate record (135 years) that have brought mixed precipitation (snow, rain, and sleet) that produced over an inch of liquid water:

April 13-14, 1983 brought 13.6 inches of snow and 1.93 inches of water
April 19-21, 1893 brought 10 inches of snow and 1.67 inches of water
April 29-30, 1984 brought 9.7 inches of snow and 1.63 inches of water
April 14-17, 1961 brought 7.2 inches of snow and 1.52 inches of water
April 13-15, 2018 brought 15.7 inches of snow and 1.32 inches of water
April 13-14, 1949 brought 9.3 inches of snow and 1.25 inches of water
April 6-7, 1923 brought 9.4 inches of snow and 1.05 inches of water
April 10-12, 2019 brought 9.7 inches of snow and 1.02 inches of water

Twin Cities Almanac for April 12th:


The average MSP high temperature for this date is 56 degrees F (plus or minus 12 degrees F standard deviation), while the average low is 36 degrees F (plus or minus 8 degrees F standard deviation).

MSP Local Records for April 12th:

MSP weather records for this date include: highest daily maximum temperature of 83 degrees F in 1931; lowest daily maximum temperature of 28 degrees F in 1950; lowest daily minimum temperature is 12 degrees F in 1962; highest daily minimum temperature of 60 degrees F in 1941; record precipitation of 0.67 inches in 1983; and there was a record 6.0 inches of snowfall in 1962.

Average dew point for April 12th is 31 degrees F, with a maximum of 61 degrees F in 1941 and a minimum of -1 degrees F in 1950.

All-time state records for April 12th:

The state record high temperature for this date is 90 degrees F Beardsley (Big Stone County) in 1931. The state record low temperature for this date is -7 degrees F at Warroad (Roseau County) in 1924. State record precipitation for this date is 3.74 inches at Grand Meadow (Fillmore County) in 2001; and record snowfall is 11.8 inches at Madison (Lac Qui County) in 1995.

Past Weather Features:

By far the warmest April 12th in state history was in 1931 when over 30 climate stations reported high temperatures of 80 degrees F or greater. The overnight temperature never fell below 58 degrees F at Montevideo and Redwood Falls.

April 12, 1950 was a cold and blustery day across the state. After morning lows that were subzero in the north and single digits in many other areas the daytime highs remained in the 20s F with Wind Chill values in the single digits. At Red Lake Falls the daytime high was only 19 degrees F.

Outlook:

A dry weekend coming up with temperature well below seasonal normals. Temperatures will begin to warm up closer to normal by Monday through Wednesday of next week, but still a few degrees shy of seasonal averages. There will be a chance for rain on by Wednesday and Thursday.





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