Metering Out Snow Moisture Content

Metering Out Snow Moisture Content:

Despite some mixed light precipitation across the state this week (1-3 inches of snow across SE Minnesota), the month of March continues to run warmer and drier than normal. This has been a real blessing for many areas of the state that saw a high risk of spring flooding on the horizon about a month ago. Temperatures have been averaging 5-9°F warmer than normal, and only small doses of precipitation have been recorded so far.

A month ago according to snow surveys done by the National Weather Service many areas of Minnesota showed 4 to 6 inches of water in the surface snow cover, a large quantity to discharge into our already high flowing rivers and streams as the spring thaw began. However similar surveys this week show that much of southern Minnesota now has no snow cover, and where there is snow, the water content is less than one inch. Even in northern counties, especially the Red River Valley the water content has declined significantly to about 2-3 inches. This has certainly helped to alleviate the flood threat for many areas.

Frost has begun to come out of the soil with many areas showing thawing out down to 8 inches or deeper. The soil has it begins to dry will have some ability to take in more precipitation, if it comes in light amounts. Still, gaged flow volume measurements from the USGS still show many southern Minnesota rivers are running at higher than normal volume for this time of year (90th percentile historically), so their ability to tolerate a high volume of runoff is diminished.

No major spring storms are in sight yet, so perhaps we can expect a continuation of the gradual metering out of the overwinter snow cover across the state.

Weekly Weather Potpourri:

Earlier this week NOAA reported on the erratic distribution of precipitation across the nation during the month of February. Many areas of the west and north-central USA were near record dryness for February, while some areas of the SE USA reported close to record-setting wetness.

A recent report from the BBC Science Department describes the accelerated loss of ice from both the Greenland Ice Cap as well as Antarctica, as measured over the years by satellite-based systems. Both are now losing ice mass at six times the rate they were in the 1990s.

There is an interesting article this week posted by Bob Henson of the Weather Underground about the relationships of the Northern Hemisphere seasons with the spread of the flu virus. Apparently atmospheric moisture content is an important variable. At higher atmospheric water vapor levels the virus appears to be less stable, as the virus-bearing droplets attract more water vapor and fall out of the air more quickly before infecting someone.

MPR listener question:

Please settle a bet we had in Mancini’s restaurant of St Paul this week. Many remembered the unusually warm St Patrick’s Day of 2012 (80°F in St Paul), but I said we often see at least one 70°F day during the month of March. Am I right?

Answer:

Not exactly……since 1873 (147 years) the Twin Cities have seen at least one day in March reach 70°F or higher in only 34 years (about 23 percent of the time). However, over just quarter of a century 10 years have brought a 70°F or higher temperature in March to the Twin Cities, a frequency of 40 percent. Perhaps this was what you were thinking of.

Twin Cities Almanac for March 13th:

The average MSP high temperature for this date is 40 degrees F (plus or minus 11 degrees F standard deviation), while the average low is 23 degrees F (plus or minus 12 degrees F standard deviation).

MSP Local Records for March 13th:

MSP records for this date include: highest daily maximum temperature of 67 degrees F in 2012; lowest daily maximum temperature of 12 degrees F in 1906; lowest daily minimum temperature of -9 degrees F in 1895; highest daily minimum temperature of 47 degrees F in 2016; record precipitation of 0.78 inches in 2006. Record snowfall is 9.9 inches also in 2006.

Average dew point for March 13th is 22°F; the maximum dew point on this date is 54°F in 1995; and the minimum dew point on this date is -11°F in 1960.

All-time state records for March 13th:

The state record high temperature for this date is 80 degrees F at Waseca (Waseca County) in 1927. The state record low temperature for this date is -36 degrees F at Campbell (Wilkin County) in 1896 and at Embarrass (St Louis County) in 2009. The state record precipitation for this date is 1.85 inches at Winona (Winona County) in 1997. Record snowfall for this date is 18.0 inches at Cloquet (Carleton County) in 1940.

Past Weather Features:

An Arctic air mass brought record setting cold temperatures to Minnesota on March 13, 1896. Subzero temperatures prevailed, except for far southern Minnesota. Many areas reported morning lows of -20°F or colder, while portions of Polk, Roseau, Norman, and Wilkin Counties reported lows of -30F or colder. The daytime high temperature at Crookston was only 5°F.

Over March 12-14, 1940 a slow moving low pressure system brought a prolonged winter storm to Minnesota delivering very heavy amounts of snow. Many portions of the state reported 10-17 inches of snowfall, while Collegeville (Stearns County) and Minnesota City (Winona County) reported over 20 inches. March 13, 1990 was the warmest on a statewide basis with many climate stations reporting daytime highs in the 60s F. Portions of southern Minnesota saw temperatures climb into the 70s F and overnight lows remain in the 40s F.

Outlook:

Partly sunny skies and dry over the weekend but starting out cooler than normal. Warming up into the low to mid 40s F for Monday through Wednesday. Slight chances for some rain on Monday and Wednesday in areas of the state, with the heavier rain possible on Wednesday. Temperatures will moderate around normal.