Worried About the Drought
As we enter winter I am concerned about the dry weather persisting into winter as we’ve had a near record dry fall. But, as I finish this, we just got 8.4 inches of snow on November 29th -- more on that later.
The winter prediction from NOAA for December 2022 through February 2023 shows a chance of being colder than normal and now slightly above normal for precipitation. The drought is supposed to continue as even if we get an average snow year of about 50 inches that will not put a dent in the drought as we are currently over 9 inches of precipitation below normal for the year. We need precipitation next spring to relieve the drought.
This will also be the third year in a row with La Nina conditions which partially accounts for the slightly colder than normal prediction. Past winters with 3 La Nina winters in a row include 1973-74 through 1975-76 and 1998-99 through 2000-01. (NOAA El Nino-La Nina records go back to 1950).
The La Nina winters of 1973-74 through 1975-76 averaged 56.6 inches of snow and 99 natural snow ski days (2 inches on the ground - from the MDNR Twin Cities Climate data for the TC Airport with monthly records for snow depth going back to 1885-86 and daily snow depth records since 1899-1900). The 1970s were the decade with the most ski days (the 1980’s had more snowfall). The La Nina winters of 1998-99 through 2000-01 averaged almost the same for snowfall at 56.2 inches but averaged 74 ski days which is just slightly above the overall average of about 70 ski days (10 weeks) per winter.
The past two winters had 48.7 and 50.2 inches of snow and 70 and 86 ski days respectively.
Looking at the historical records comparing where we are with the low precipitation with other years that were dry. This year June through October and September and October were both the second driest for those periods in the 150 plus years of precipitation records (started in 1871).
Precipitation from June through October was 7.06 inches this year (average is 16.41) and is the second driest behind 1910 which had 6.93 inches for that period. The winter following the dry 1910 had 37.4 inches of snow and 37 ski days. The third driest year for the June through October period was 1936 (7.32 inches) which was followed by 44.6 inches of snow and 83 ski days. The next two dry years were 1894 and 1889 with 7.79 and 8.82 inches respectively and followed by 16.2 and 37 inches of snow respectively (no ski day records as they were before daily snow depth records were kept). The next 3 dry years for that period with daily snow depth records were 1948, 1933 and 1989 (8.93, 9.26 and 9.27). The following winters had 38.3, 25.6 and 35.5 inches of snow and 69, 26 and 31 ski days respectively. The driest 5 years on record for June through October with following daily snow depth records averaged 34.7 inches of snow and 49 ski days (3 weeks less than the average).
The next 5 years when it was dry from June through October with ski day data are, in order, 1964, 1950, 1977, 1970 and 1974 (June through October precipitation ranged from 9.27 to 10.38 inches). Here is where it gets interesting. Those 5 years had following snow that ranged from 50.7 inches to 88.9 inches or about average to well above average. The following ski days ranged from 105 (1977) to 132 (1950). The winter of 1950-51 is the all-time record for ski days with 132 starting on November 23, 1950 and ending on April 3, 1951 -- imagine that -- almost double the average of 70 ski days. The winter of 1964-65 is the second highest with 131 ski days starting on November 28, 1964 and ending on April 7, 1965. I remember ’64-’65 as that was the first time that school (Mpls.) was called off (a couple of days in March as I recall) in my school years. These 5 winters averaged 66.4 inches of snow and 117 ski days or almost 7 weeks longer than normal.
What a contrast between the driest 5 and the second driest 5.
Combining the 10 driest June through October years with following daily snow depth records the average following snow is 44.8 inches with an average of 83 ski days – almost 2 weeks above normal. But, what a difference between the first 5 and the second five.
For the dry September and October there is a different scenario. The year 1952 is the driest on record for that period with 0.43 inches. This year had 0.48 inches of precipitation in September and October combined.
The winter of 1952-53 was followed by 42.9 inches of snow (about 8 inches below average) but had 110 ski days -- kind of an overachiever with that lower total snowfall -- just cold enough to keep the snow but not really a cold winter. The late fall of 1952 had a temperature of 75 on October 24 and 61 on November 14. On November 25 there was 5.3 inches of snow and 2 inches on the ground. Another 4.5 inches fell the next day and then there was 8 inches on the ground. The snow depth remained above 2 inches until March 11, 1953 but then more snow fell and there were 3 more ski days that ended on March 18, 1953.
The next 3 years with dry September through October periods were 1953, 2011 and 1944 with 0.7, 1.06 and 1.23 inches respectively. (I left out 1889 which had 0.57 inches as it didn’t have following daily snow depth records). Those following winters had 25.7, 22.3 and 33.9 inches of snow and 16, 21 and 60 ski days respectively. The winter 1953-54 with the low snow and ski days is in contrast to the winter of 1952-53 discussed above.
As I mentioned at the start we just received 8.4 inches of snow and now 7 inches on the ground after settling. Looking at the historical records for November 30th there were 15 years (out of 123 on record) with 6 inches or more on the ground on November 30th. All except two were followed by winters with well above the average ski days. In fact, 9 of the 15 were followed by 100 ski day plus winters and averaged 99 ski days. (Max. was 126 ski days in 1978-79). Of the 15 above winters those preceded by dry falls include 1952-53 (driest Sept-Oct. – 110 ski days), 1975-76 (8th driest Sept.-Oct. – 94 ski days) and 1977-78 (10th driest June – Oct. – 126 ski days).
The two of the above 15 winters with fewer ski days were 1994-95 with 36 and 2001-02 with 39. Both of those winters had low snow and melting with temps in the 40s during the winter.
After yesterday’s snowfall I’m optimistic about this coming winter. I wonder where we’ll end up this year -- near the low end or the high end or somewhere in between. It remains to be seen and is unpredictable.