Atlantic tropical update

 

Saffir-Simpson Hurricane Wind Scale (Source: WUSA9)

Atmospheric and environmental conditions reach their annual peak for tropical storm and hurricane development across the Atlantic Ocean in September.  September 2023 has lived up to its billing as the most active month of the Atlantic hurricane season. 

Tropical Storm Rina developed on September 28 and that was the 18^th storm of 2023.  An unnamed subtropical storm developed in January giving 2023 a total-to-date of 18 storms (17 named), with 6 hurricanes and 3 “major” hurricanes.  A “major” hurricane has maximum sustained winds of at least 111 mph that makes it a Category 3 storm.

When NOAA issued its early August update to its seasonal hurricane forecast, they increased the number of storms from what was forecast at the start of the season in June.  The major question was would near-record high sea-surface temperatures offset the El Nino conditions that have developed?  The short-answer is, yes, given how busy the tropical Atlantic has been over the last six weeks.

When Rina was named a tropical storm, it became the 13^th named storm in the Atlantic since August 20.  According to a tweet from Colorado State University hurricane expert, Dr. Philip Klotzbach, “That's the most on record to form between August 20 - September 28, breaking old record of 12 Atlantic named storm formations set in 2020.”  Fortunately, not all of these storms were intense or had direct impacts on the United States.

However, Hurricane Idalia made landfall in Florida as a Category 3 storm and Tropical Storm Ophelia made landfall in North Carolina.  Ophelia’s remnants brought beneficial rainfall to the Mid-Atlantic Region.  Hurricane Lee also became the Atlantic’s first Category 5 hurricane since Lorenzo in 2019.  Fortunately, it had no direct impacts on the United States.  Lee weakened before it made landfall in Atlantic Canada as a strong extratropical, or non-tropical storm.

If no more named storms were to develop in 2023, then this season would finish with an above average number of named storms, but a near average number of hurricanes.  An “average” Atlantic hurricane season has 14 tropical storms, of which 7 develop into hurricanes with 3 major hurricanes.

If anything, though, the last few seasons have illustrated that October and November can still be active in the tropical Atlantic.  Hurricane Nicole made landfall in Florida as a Category 1 storm last November.  Meanwhile, Hurricanes Eta and Iota both reached Category 4 intensity in November 2020.  Hurricane Michael also made landfall in the Florida panhandle as a Category 5 storm in October 2018.  This illustrates why it’s important to monitor the tropics until the season ends on November 30.

Weather Quiz

 

Key Bridge in the distance from Roosevelt Island

With six days in the 90s, September 2023 has had the most such days in the nation’s capital since ?

A.  1998

B.  2010

C.  2016

D.  2019

Ophelia’s impacts in the nation’s capital

 

"Ophelia" brought plenty of rain to the DC Metro Area

Tropical Storm Ophelia was a high impact weather system for the Mid-Atlantic Region.  Although it was a touch below hurricane status with 70 mph sustained winds when it made landfall at peak intensity on September 23 in North Carolina, its impacts were still significant and far-reaching. 

Heavy rain and gusty winds enveloped the nation’s capital and entire DMV (“District of Columbia, Maryland and Virginia”).  Widespread 2” – 4” rainfall totals were common as Ophelia tracked north.  Although it weakened to a non-tropical or “post-tropical cyclone” by the time it reached the immediate DC Metro Area, its impacts were no less significant. 

Temperatures have also felt more like late-October than late-September over the last two days.  That’s a far cry from the record heat that Washingtonians endured to start the month.  The past two days featured highs of 65° and 69°, respectively, at National Airport.  That made for DC’s first such instance of consecutive daily high temperatures in the 60s during the month of September since 2020. 

While no additional heavy rain is expected this week, my colleagues and I on the WUSA9 weather team expect shower chances to continue for much of the week with below average temperatures.

Rainfall Totals from “Ophelia”  (Source: National Weather Service)

3.86” – Prince Frederick, Maryland
3.25” – Chantilly, Virginia
2.86” – Dulles Airport, Sterling, Virginia
2.81” – Damascus, Maryland
2.56” – Leesburg, Virginia
2.51” – Culpeper, Virginia
2.47” – Washington, D.C.
2.25” – National Airport, Arlington, Virginia
2.15” – Alexandria, Virginia
2.04” – BWI Airport, Baltimore, Maryland
2.00” – Garrett Park, Maryland
1.25” – Chestertown, Maryland