Sunday, April 19, 2020

Winter 2019-20: fairly normal temperatures but much wetter than normal

Meteorological winter consists of December, January, and February.  Overall, this past winter was slightly milder and much wetter than normal.  The mildness of this winter was entirely due to December, which was much warmer than normal, while February was slightly cooler than normal.  In terms of precipitation, December was slightly wetter than normal, but January, and to a lesser degree February, were much wetter than normal.

The mean temperature this past winter at Victoria Gonzales was 6.0 degrees, compared with the 30-year average of 5.8 degrees.  Winter began with a mild December, which was 1.1 degrees above normal.   January experienced normal temperatures overall, while February was 0.4 degrees cooler than normal.      

The chart below shows the daily maximum and minimum temperatures at Victoria Gonzales during winter 2019-20, compared with the 30-year averages.  You can see that temperatures in December were generally above average.  January started out mild, experienced a short but sharp cold spell in the middle of the month, then returned to above normal temperatures towards the end of the month.  In February, temperatures were generally below average, especially at the beginning of the month.  The mildest day of the winter was 13.5 degrees on January 31.  The coldest day of the winter was January 14, when the temperature dipped to -5.7 degrees overnight, and the high temperature was only -2.0.  There was one stretch of 6 days from January 12-17 when the overnight temperature dipped below freezing, but there were no other days during the winter with below freezing temperatures.  On average, Victoria Gonzales gets 7.6 days with below freezing temperatures during meteorological winter.



Daily vs. average Max & Min temperatures, winter 2019-20 in Victoria




Victoria received 419 mm of precipitation during the December to February period.  That's nearly 60% more than the 30-year average winter precipitation of 264 mm, making it the 10th wettest winter on record at Victoria Gonzales (with 107 years of record-keeping), and the wettest winter in more than 20 years.  Precipitation was slightly above average in December (112 mm versus the normal 96 mm), but nearly double the normal in January (204 mm versus 107 mm) and 67% above normal in February (102 mm versus 61 mm).  

There were 55 days with measurable precipitation this winter, with 16 days in December, 25 days in January, and 14 days in February.  That's above the normal of 45 days with measurable precipitation that Victoria typically sees during the winter.  Victoria also saw a lot of really wet days this winter: it experienced 5 days with more than 25 mm of precipitation, versus the normal average of 1.6 such days.  There have only been 5 winters in 107 years at Victoria Gonzales with 5 or more days with 25 mm of precipitation.


The chart below shows daily precipitation during winter 2019-20, and compares the cumulative precipitation with the 30-year average.   Precipitation levels were generally close to the average during December, but quickly surged ahead of normal during January.  The wettest day of the winter was February 1st, with 33.8 mm of rain.  Four other days had more than 25 mm: 29.4 mm on December 20, 30.6 mm on December 31, 27 mm on January 6, and 28 mm on January 31.



Daily & cumulative precipitation, winter 2019-20 in Victoria


The chart below compares the precipitation amounts in Victoria this winter with other locations in the region.  As is typically the case, Victoria Gonzales had the lowest amount, with a total of 419 mm.  However, the difference in precipitation levels between Victoria and other locations was less than usual.  That's because winter precipitation was nearly 60% higher than normal at Victoria Gonzales, but only 17% above normal at Vancouver Airport, 37% above normal at Victoria Airport, and 47% above normal at Seattle.  

2019-20 Winter precipitation in Victoria and nearby locations

Victoria received 22 cm of snow during winter 2019-20, higher than the average winter snowfall of 16 cm.  (Victoria averages 20 cm of snow annually, but some of that falls during November and March, which are not part of meteorological winter).  All of this winter's snowfall was during 4 days in mid-January, which was much snowier than the average January snow total of 3.4 cm.  There was 5 days this winter with snow on the ground in Victoria, very close to the average of 4.8 days each winter with snow on the ground.

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