Too Early to think about the Tropics ?

 

Hurricane Ian making landfall in 2022 (Source: WUSA9)

NOAA recently announced that while a weak episode of La Nina remains present, ENSO (El Nino Southern Oscillation) neutral conditions are expected to develop over the next couple of months.  “ENSO-neutral conditions” simply refers to the absence of El Nino or La Nina conditions.  While impacts from El Nino or La Nina have heightened significance in the United States during the winter months, they can also impact the Atlantic hurricane season.

On February 9, NOAA said: “There are increasing chances of El Niño at longer forecast horizons…”  The time frame for that would be later in the summer and early fall.  El Nino conditions, particularly moderate to strong El Nino’s, create less favorable conditions for hurricane development in the tropical Atlantic.  Such conditions include cooler sea surface temperatures, combined with an increased amount of wind shear (winds that change direction with altitude). 

However, five of the last six summers have featured weak to moderate intensity La Nina’s.  Consequently, four of the last six years have seen active Atlantic hurricane seasons.  An exception was last season that finished with an average number of Atlantic tropical storms and hurricanes, the majority of which were weaker, more short-lived systems that combined to create the lowest ACE score for an Atlantic hurricane season since 2015.

Some may recall that the last very strong El Nino developed in 2015 and it was a significant contributor to the last below average Atlantic hurricane season.  Of course, there are other factors that play a role in how active an Atlantic hurricane season is such as the status of the North Atlantic Oscillation (NAO) and the amount of dust present in the atmosphere that blows from Africa’s West Coast into the tropical Atlantic.  High concentrations of atmospheric dust tend to preclude widespread tropical development.

If climate experts at NOAA expect an episode of El Nino to develop during the middle or second half of the Atlantic hurricane season, then that could impact seasonal hurricane forecasts.  Since at least one named storm has developed prior to the official June 1 start of the season in seven of the last eight years, it isn’t too early to start talking about the upcoming season.

It’s also important to not lose sight of the fact that all tropical storms and hurricanes are potentially dangerous, even during a quieter than average hurricane season.  Hurricane Alicia (1983) and Hurricane Andrew (1992) were each the only major hurricanes of their below average seasons, but both rank among the most destructive U.S. hurricanes of their respective decades.

Challenges of Severe Weather in February

 

NOAA's Severe Weather Outlook for February 16

 “Severe weather” is defined as a thunderstorm that contains any of the following: hail 1”/+ in diameter; wind gusts of 58/+ mph; or a tornado.   Severe weather is less common in the United States during the colder winter months than it is during the rest of the year.  However, it’s more frequent during February as compared to December or January.  

When severe weather does occur in February, it can most often be found on or near the Gulf Coast.  That’s because weather conditions there are often more favorable than in other parts of the country.  Nevertheless, some February outbreaks have occurred in other parts of the United States that made them unusual.

2020:  An exceedingly rare February tornado outbreak occurred on February 7 in the D.C. Metro Area.  A total of six tornadoes touched down in Maryland and Virginia between 7:00 a.m. and 10:00 a.m.  Four of the six tornadoes were ranked as EF-1’s with winds between 86 mph and 110 mph.  Although some tree and structural damage was reported, it was fortunate that no injuries or fatalities occurred.
 
An EF-0 occurred in Loudoun County, Virginia, in the town of Leesburg and had winds of 85 mph.  It was on the ground for three minutes and had a track of 3.3 miles.  According to National Weather Service records, this tornado broke the record of April 16 (1993, 2011) for earliest Loudoun County tornado by more than two months.  Tornado intensity is measured on the Enhanced Fujita Scale that ranges from EF-0 to EF-5. 

2016:  A larger tornado outbreak with 33 confirmed tornadoes from Florida to Pennsylvania occurred on February 24, 2016.  Three deaths were reported from one of the tornadoes that touched down in Sussex County, Virginia.  Only one tornado occurred in the D.C. Metro Area during this outbreak with an EF-0 in St. Mary’s County, Maryland.

2008:  A severe weather outbreak from February 4 – 6 was unusual for several reasons.  The three-day total included over 600 reported cases of severe weather, with more than 130 confirmed tornadoes.  The most active of the three days was February 5, with over 500 cases of severe weather from Texas to West Virginia.  A severe weather outbreak that covers that much geography is more common in April or May.  What made this outbreak especially tragic was that 28 fatalities were reported.

1998:  Another significant outbreak occurred in central Florida on February 22 – 23.  NOAA reported that the 42 lives lost in this disaster made it one of Florida’s deadliest.  The tornadoes occurred between 10:55 p.m. and 2:30 a.m. when most people were asleep.  This underscores the need to get weather alerts on your phone or to have a NOAA weather radio which provides the latest weather watches and warnings for your area 24/7.

Weather Quiz

 

Lexie and "Blue," February 2015

How many snowier than average months has Washington, D.C. had in the seven years since the record January 2016 blizzard ?

A.  3

 

B.  4

 

C.  8

 

D. 12