March delivers two distinct patterns of weather

March delivers two distinct patterns of weather:

With a clear and evident change in the weather expected to dominate the second half of March, we will historically describe this month having two distinct and opposite weather patterns. Through the first 16 days, warm and dry, with temperatures averaging from 12°F to 14°F above normal around the state. On a statewide basis this marks the 2nd warmest first half of March in history, trailing only 2016 by half a degree. In addition, the first half of March was exceptionally dry, with many climate observers reporting zero precipitation. The statewide average precipitation was only 0.08 inches, marking the 2nd driest first half of March in history (first half of March only delivered 0.02 inches of precipitation statewide in 1910).

Conversely the second half of this March will clearly be wetter (snowy) and cooler than normal. Since the 16th many northern climate stations have reported morning low temperatures in the single digits (Baudette reported just 1°F on Wednesday, March 20th). Ten day forecast guidance suggests that the balance of the month will see temperatures that average between 6°F and 9°F below normal. The other weather feature change is more snow and rain for the balance of the4 month. In fact, many places are likely to see a month’s worth of precipitation (1.5 to 2.0 inches) over the next week, much in the form of heavy, wet snow.

One feature of the March weather that will remain rather constant is higher than normal wind speeds. Many climate stations have already reported 10 or more days with wind gusts over 30 mph, including:

Brainerd 10 days
Duluth 11 days
Moorhead 11 days
Redwood Falls 11 days
MSP 13 days
Rochester 14 days

According to forecast guidance, there will be several more days this month with wind gusts of 30 mph or greater. Perhaps March will be even windier than April (normally our windiest month) this year.

Weekly Weather Potpourri:

Earlier this week Aljazeera reported on the record Heat Wave that blanketed parts of Brazil. The Heat Index values (effect of temperature and humidity) ranged from 120°F to 140°F. In fact a record high Heat Index of 144°F was reported from Rio de Janeiro on Sunday, March 17th. Air temperatures were over 100°F but with dew points in the mid to upper 80s F. Citizens flocked to the Ipanema and Copacabana beaches seeking some relief in the ocean waters. Fortunately, rain was expected this weekend with cooler temperatures.

Speaking of Heat Index Values, a recent paper published in Environmental Research Letters documents that climate change is provoking an even larger rise in Heat Index Values than air temperature values. The interaction of air temperature and atmospheric water vapor is changing with climate change, especially in certain landscapes. A case study of the changing climate in Texas showed that summer Heat Index Values there have changed as much as 8°F to 11°F since the 1970s.

This week’s AGU-EOS Bulletin features an interesting article (published in Science) about the declining seasonal variability in flow volume of northern hemisphere watersheds (north of 50 degrees latitude). This is due to climate change modifying the seasonality of moisture deposition on the landscape. “In northern North America, about 40% of gauge stations showed decreasing seasonality. In southern Siberia, the number was 32%, whereas in northern Europe, about 19% of gauge stations showed decreasing seasonality.”

MPR listener question:

I heard that we may get from 8 inches to 12 inches of snowfall in western Minnesota this Sunday and Monday. We live in Fergus Falls and we are wondering what our record snowfalls are for March 24 and March 25. Thought you might know.

Answer:

Yes, the National Weather Service is suggesting that March 24-25 could bring the most snowfall of the entire snow season to many places, perhaps doubling the seasonal snowfall total for some. Your climate records at Fergus Falls go back to 1892. Snowfall record for March 24 is 12.0 inches in 1975. The snowfall record for March 25th is 10.2 inches in 1927. I doubt that these records will be broken by this storm, but you never know.

BTW the statewide record snowfall for March 24 is 15.0 inches at Winona and Bird Island in 1937 and at Waseca in 1966. The corresponding record for March 25th is 14.0 inches at Bemidji in 1914. You can see if these records fall.

Twin Cities Almanac for March 22nd:

The average MSP high temperature for this date is 45 degrees F (plus or minus 12 degrees F standard deviation), while the average low is 28 degrees F (plus or minus 10 degrees F standard deviation).

MSP Local Records for March 22nd:

MSP records for this date: highest daily maximum temperature of 71 degrees F in 1945; lowest daily maximum temperature of 10 degrees F in 1888; lowest daily minimum temperature of -14 degrees F in 1888; highest daily minimum temperature of 56 degrees F in 2012, and record precipitation of 1.40 inches in 1952. There was a record 13.7 inches of snowfall also in 1952.

Average dew point for March 22nd is 23°F; the maximum dew point on this date is 60°F in 2012; and the minimum dew point on this date is -10 degrees F in 1974.

All-time state records for March 22nd:

The state record high temperature for this date is 81 degrees F at Pipestone (Pipestone County) in 1939. The state record low temperature for this date is -30 degrees F at Pokegama Dam (Itasca County) in 1888. The state record precipitation for this date is 3.00 inches at Elk River (Sherburne County) in 1865. The state snowfall record is 14.6 inches at Fairmont (Martin County) also in 1952.

Past Weather:

The coldest March 22nd was in 1888, as nearly all locations in Minnesota reported subzero morning low temperatures. In central and northern Minnesota, low temperatures ranged from -20°F to -30°F. With nearly a foot of snow on the ground, the afternoon high temperature at Rochester only reached -6°F.

March 22nd in 1939 was the warmest in state history, with 21 counties reporting afternoon temperatures of 70°F or greater. After a morning low of 26°F, Windom saw an afternoon high of 80°F, under bright sunshine and with moderate south winds.

A major winter storm brought a mixture of rain, sleet and snow to parts of southern and central Minnesota over the weekend of March 22-23 of 1952. Many climate stations reported 10 to 17 inches of snowfall. There were a number of road closures in southern counties.

Outlook:

Generally cloudy, with cooler than normal temperatures over the weekend. Chances for linger snow early on Saturday over southern sections of the state. Increasing cloudiness late Saturday and into Sunday with chances for significant snowfall mixed with rain in some areas. Many areas of central and southern Minnesota will see over 6 inches of snowfall, and some areas could get a foot. There will be continuing chances for precipitation through Tuesday of next week, then more settle weather will also bring warmer temperatures.