Atlantic Hurricane Headlines

 

Hurricane Laura, August 2020  (Source: WUSA9)

The World Meteorological Organization met earlier this month and made key changes that will impact future Atlantic hurricane seasons.  It falls under the purview of the WMO to retire the names of hurricanes that are extraordinarily destructive or deadly (e.g. Andrew, Katrina, and Maria).  Retired names are replaced on the rotating 6-year list of names that are used to name tropical storms and hurricanes in the Atlantic.

WMO retired a total of four names: Hurricane Dorian (2019) and Hurricanes Laura, Eta and Iota (2020).  Dorian was a Category 5 monster that decimated the Bahamas in September 2019 but the name was only retired this month.  That’s because retiring names wasn’t on the agenda at the WMO meeting a year ago due to the developing COVID emergency.

More named storms developed in the tropical Atlantic last season than any previous season on record (30).  That meant 2020 joined the epic 2005 season as only the second one to use all 21 names on the list and required storms to be named with letters from the Greek alphabet.  The letters Q, U, X, Y & Z aren’t used due to the dearth of names that began with those letters.  

To reduce confusion going forward, the Greek alphabet will not be used when the original list of names is used up.  Instead, a supplemental list of names with letters A-Z will be used.  Any of the names on the supplemental list could be retired, as needed, the same way names have historically been retired. 

It’s important to emphasize that using up all 21 names on the original list is extraordinarily rare and has only happened twice, in 2020 and 2005.  Last season was the first time named storms that developed after the original list was used up were destructive and/or deadly enough to be retired.  That created the unprecedented circumstance the WMO had to address.  Going forward, however, there is now a new protocol in place should a similar situation present itself again. 

Although the 2021 Atlantic hurricane season doesn’t begin until June 1, the last six seasons have each had at least one named storm develop before then.  Not since 2015 has there been a below average Atlantic hurricane season.  According to NOAA’s most recent La Nina Advisory, there is a 60% chance a transition to ENSO neutral conditions will occur this spring.  That means neither La Nina or El Nino conditions are present.  That would be a significant development in the upcoming Atlantic hurricane season.

A Look Back at DC’s March 2021 Weather

 

This month has featured some memorable weather in the DC Metro Area.  Starting with DC’s longest stretch without measurable rainfall in 18 months, to record warmth and rainfall, among other things.  While this month will finish warmer than average March, it hasn’t been as warm as last March, which finished as DC’s fifth warmest.  Depending on how much rain occurs today, this month could also become DC’s fifth drier than average March in the last six years.

Washington, DC had no measurable precipitation from March 2 – March 17.  That 16-day stretch was DC’s longest since a 17-day stretch at National Airport (DC’s official weather reporting site) in September 2019.  It was a particularly welcome dry stretch for many DC Area residents, following what was a particularly wet February. 

Less than a week after DC’s dry stretch ended, record rainfall occurred at National and BWI Airports on March 24.  The 1.69” of rain that fell at National Airport made it DC’s rainiest March day since 2019.  Despite having only 0.66” of rain through March 23, DC’s record March 24 rainfall removed any chance this month had to rank among DC’s 10 driest on record.

There have been some appreciable temperature differences this month.  While temperatures in the Nation’s Capital fell to 32° or colder on eight occasions, 17 of the first 27 days of the month were warmer than average.  That will allow March 2021 to finish more than 3° warmer than average.  While three of DC’s five warmest March’s occurred during just the last decade, it’s noteworthy that seven of DC’s coldest March’s occurred in the late 1800s. 

March is often one of DC’s most varied weather months.  It can have appreciable snowfall and extreme cold, such as what occurred in March 2014 that finished with 12.7”.  It can also be downright warm as March 2012 that finished 10° warmer than average to become DC’s warmest on record.  DC’s coldest temperature this month was 28° on March 5 and March 7, while the warmest temperature was 84° on March 26, 2021.  While not a record for the date, it was DC’s warmest temperature since September 8 (87°) and DC’s warmest March temperature since 2006!

DC’s Warmest March’s (Source: NOAA)

1.  56.8° (2012)
2.  56.2° (1945)
3.  55.5° (1921)
4.  53.5° (2016)
5.  53.2° (2020)
6.  53.0° (1946)
7.  52.7° (1977)
8.  51.7° (2000)
9.  51.5° (1979)
10.  51.3° (1976)

---

DC’s Coldest March’s (Source: NOAA) 

1.  34.5° (1885)
2.  35.4° (1872)
3.  35.6° (1960)
4.  37.4° (1888)
5.  37.6° (1906, 1883)
7.  37.7° (1892)
8.  37.9° (1916)
9.  38.5° (1896, 1887)

DC’s Record March Rainfall

 

DC’s March 24 rainfall total of 1.69” was not only a daily record, but was also DC’s rainiest day so far in 2021.  It also eliminated any chance March 2021 had for finishing among DC’s driest.  Prior to yesterday, a rainfall total of only 0.66” had occurred since March 1.

The record rainfall yesterday was not only DC’s wettest day since November 30, 2020 when 2.39” fell, but also DC’s wettest March day since March 21, 2019 (1.96”).  While not common, such heavy rain does occur periodically in the DC Metro Area during this time of the year.  DC’s wettest March day on record occurred on March 9, 1881 (2.79”).

Unlike February 2021 that had 15 days with measurable rainfall, DC had three days with measurable rainfall so far this month.  DC’s record rainfall yesterday was double the heaviest daily rainfall to occur during all of last month (0.84” on February 28).  Despite yesterday’s rainfall, this month has an ongoing rainfall deficit of 0.27”.  That’s the result of DC’s longest dry stretch in 18-months, which recently ended.

The 16 days without measurable precipitation in the Nation’s Capital between March 2 and March 17 was the longest since a 17-day stretch in September 2019.  That month finished as one of DC’s driest Septembers on record.  However, with several more rain chances before the end of the month, March 2021 should finish as a wetter than average month.  Additional rainfall is good news for allergy sufferers hoping for a respite from the rising levels of tree pollen.

If March 2021 finishes wetter than average month, then it would be a relatively rare occurrence.  Four of the last five March’s, through 2020, were drier than average in Washington, D.C.  However, that had little bearing on total rainfall in 2018 and 2020 because they finished as DC’s wettest and seventh wettest years on record, respectively.  According to NOAA’s 30-year average from 1981-2010, the Nation’s Capital has averaged 3.48” of March rainfall.  NOAA will release updated climate data later this spring, which will be for the 30-year period from 1991-2020.

DC’s Ten Wettest March’s (Source: NOAA)

1.  8.84” (1891)
2.  8.45” (1994)
3.  7.43” (1953)
4.  7.24” (1884)
5.  6.82” (1993)
6.  6.61” (1881)
7.  6.45” (1932)
8.  6.41” (1886)
9.  6.17” (1924)
10.  6.14” (1984, 1912)

DC’s Ten Driest March’s (Source: NOAA)

1.  0.05” (2006)
2.  0.57” (1910)
3.  0.74” (1986)
4.  0.84” (1945)
5.  0.98” (1894)
6.  1.02” (2012, 1947)
8.  1.07” (1915)
9.  1.16” (2016)
10.  1.27” (1927)