A Peaceful Close to an Unsettling Year

 

One of the final sunsets of 2020

December 2020 has kept with the overall pattern of 2020 being warmer and wetter than average in the Nation’s Capital.  DC’s average monthly temperature (combining daily high/low temperatures) is 1.4° above average through December 30.  There has been 4.96” of rain so far this month, making it DC’s ninth wetter than average December of the last 10 years.

A few showers are possible this afternoon, but won’t add up to the 0.2” of rain that DC needs to tie 1948 for sixth wettest year.  A total of 57.34” of rain has occurred at Reagan National Airport since January 1.  Oddly enough, four of the first six months of 2020 were drier than average in the Nation’s Capital.  However, there have been three days just this month with an inch of more of rain.  That’s compared to only two such days in December 2018, which capped off DC’s rainiest year on record. 

Washingtonians may wonder what typical New Year’s Eve weather is like.  Based on NOAA’s 30-year average from 1981-2010, DC’s “average” December 31 high/low temperatures are 44°/29°.  Dulles Airport is a touch colder with averages of 43°/24°.  There has been some very mild December 31 weather in the DC Metro Area such as in 2011 with a high/low of 62°/46° or 2015 (57°/44°).  There have also been frigid conditions in the Nation’s Capital on New Year’s Eve such as in 2017 with a high/low of only 23°/16°.

Measurable rainfall has only occurred five times in the last 20 years on New Year’s Eve in Washington, D.C. with the last being 2018.  Official weather measurements for the Nation’s Capital are kept at National Airport.  Dulles Airport in nearby Sterling, Virginia has had some even colder New Year’s Eve weather.  The high/low temperature at Dulles on December 31, 2017 was 21°/10°, compared to the balmy 2004 high/low of 60°/40°.  DC’s weather last New Year’s Eve featured an above average high/low of 54°/43° and dry conditions.

NOAA is getting ready to update the time period used for measuring “average” weather in the United States.  Starting next month, the 30-year time period will shift to 1991-2020.  Meteorologists will be able to see a discernable difference once that change is made.  Daily low temperatures, in particular, should be warmer in the Nation’s Capital and other urban/suburban areas.  

Weather Quiz

 

Photo Courtesy of Robin Beal

When was the last time high temperatures in the Nation’s Capital remained below freezing on New Year’s Eve ?

 

A.  2017

B.  2009

C.  1998

D.  1993

The Epic 2020 and 2005 Atlantic Hurricane Seasons

 

Hurricane Eta, November 2020 (Source: TropicalTidbits.com)

One of 2020’s major weather stories is how busy the Atlantic hurricane season was.  For a sixth consecutive season there was at least one named storm before its official start on June 1.  Two tropical storms, Arthur and Bertha, developed in May 2020.  Although a busier than average season was forecast by NOAA, no one expected it to be as busy as it was.

A total of 30 named storms developed of which 13 became hurricanes, including six major hurricanes.  That’s in contrast to the 2005 Atlantic hurricane season that finished with 28 named storms, 15 hurricanes – with seven major ones.  While this season’s total of 30 named storms set a record, the 15 hurricanes and seven major hurricanes in 2005 remain a record.  A “major” hurricane is a Category 3 or higher on the Saffir-Simpson Hurricane Wind Scale with 111/+ mph sustained winds.

The 2020 season got off to a fast start and ended in mid-November when Hurricane Iota dissipated after making landfall in Central America.  That was consistent with the official end of the hurricane season on November 30.  In contrast, the 2005 season saw two active storms continue after November 30.  Tropical Storm Epsilon developed on November 29 and became a Category 1 hurricane on December 2.  Tropical Storm Zeta didn’t dissipate until early January 2006.

Three major hurricanes (Katrina, Rita and Wilma) developed in August and September 2005, with a total of five through September 30 (including Dennis and Emily in July 2005).  By comparison, the first major hurricane of 2020, Laura, didn’t develop until the second half of August, with only two through the end of September.  Two major hurricanes developed during the month of October in both 2005 and 2020.

A key difference between 2005 and 2020 is what happened during the month of November.  No major hurricanes developed on or after November 1 in 2005.  By comparison, November 2020 was an especially active month in the tropical Atlantic.  Hurricane Eta became a major Category 4 hurricane with sustained winds of 150 mph last month.  It was the first major hurricane with a name from the Greek Alphabet.  While the 2005 Atlantic season had four Category 5 hurricanes, none developed in 2020 – until Hurricane Iota reached Category 5 intensity on November 16.  That made November 2020 the first on record with two major Atlantic hurricanes.

The 2005 hurricane season was much more damaging for the United States due to catastrophic hurricanes Katrina, Rita and Wilma.  However, the United States had a record number of landfalling tropical systems in 2020.  The key difference is that many of the landfalling storms in 2020 were either weaker than in 2005 or made landfall in less densely populated areas.  The World Meteorological Organization (WMO) will meet this winter to determine which storms from the 2020 Atlantic hurricane season will have their names retired.