2019/20 North Atlantic Hurricane Force Wind Events

An ever present danger to all mariners -- from fishermen, recreational boaters, to transoceanic shipping -- is the possibility of encountering extreme winds created by powerful mid-latitude cyclones. These violent winds quickly build dangerous seas, posing life-threatening hazards to vessels on the open ocean.

Hurricane force (HF) wind warnings are issued by the Ocean Prediction Center (OPC) when non-tropical sustained winds of 64 kt (74 mph) or greater are being observed, or are forecast to occur within 48 hours. These warnings represent the highest wind warning category issued by OPC and the National Weather Service.

Accurate and reliable weather forecasts are critical to provide mariners adequate time to plan safe, economically sound routes days in advance, thereby minimizing exposure to the strongest winds and roughest seas, ultimately keeping the crew, vessel, and cargo as safe as possible. OPC, as part of the National Weather Service, helps fulfill the NOAA mission of providing weather, water, and climate data, forecasts and warnings for the protection of life and property and enhancement of the national economy.

The slide show below highlights the exact kind of extreme seas mariners avoid for safety of crew and cargo. As an intense low pressure produced hurricane force winds, the altimeter instrument aboard the Jason-3 satellite detected significant wave heights up to 51 feet. Use the right arrow key to step through the slide show.

During the June 2019 to May 2020 season, OPC analyzed 42 hurricane force low pressure systems and wind events across the North Atlantic area of responsibility. 

Each of the 118 circles on the interactive map represents the low pressure location or placement of hurricane force winds, and are color coded by pressure; the warmer the colors, the deeper the pressure. Clicking on the circle will provide more information, including the date, position, and the corresponding surface analysis produced by the forecasters on watch at the Ocean Prediction Center. For tip jet events where no discernible central low pressure was analyzed, a zero pressure was assigned.

The distribution heat map below provides another view of the most recent 2019-2020 season, in particular the most concentrated areas of low pressure development. With the middle slider bar pulled right, you'll notice the Gulf Stream track along the U.S. East Coast, and of course the hot spot maximum we see season after season, year after year off the southeast coast of Greenland. Pull the slider bar left to view the individual locations of the hurricane force winds events, the same web map as above.

Accumulation graphs provide a quick diagnosis of the most recent season, and helps put into context how the finally tally compares to recent history. The graphs provide visual cues to monthly trends, active periods, and seasonal totals.

A common characteristic of all graphs of all seasons are the steep slopes during the winter months. In other words, December, January, and February typically account for the vast majority of all hurricane force wind events across the North Atlantic.

Putting a bow on seasonal illustrations and climatology, the following graph charts all hurricane force wind events per date, starting at the onset of the June 1 2005 season. Notice the steady increase in events with the approach and arrival of Fall, followed by a surge in early to mid December, before reaching the climatological peak on February 14. After, it's a sharp and quick decline into the relatively quieter months of late Spring and Summer.

Generally speaking, as the central pressure of a low decreases, the intensity of the wind field increases. In other words, the lower the pressure, the stronger the system.

From February 5 to 17, the Atlantic basin produced a series of mid-latitude cyclones resulting in some of the lowest pressures ever analyzed by the forecasters at the Ocean Prediction Center. This active period included:

• 13 storm force low pressure systems (winds between 48-63 kt)
• 4 hurricane force low pressure systems (winds > 63 kt)
• 4 low pressures at or below 933 mb, ranking among some of the lowest pressures on record for the basin
• 920 mb low analyzed on 18 UTC February 15th is the lowest pressure analyzed from forecasters at OPC (it is widely accepted the "Braer Storm" of 1993, before OPC was established, reached 916 mb)
• relentless rounds of hazardous seas; the altimeter instrument aboard Sentinel-3A captured significant wave heights to near 20 meters (64.52 ft) at 2301 UTC February 13th

A few of the more noteworthy low pressure systems are highlighted during this stretch, all seen via GOES-East RGB Air Mass imagery:

The first hurricane force low rapidly intensified to an incredible 930 mb on the Feb 7, centered southeast of Greenland. At the time of analysis, the 930 mb central pressure was among the top-6 of lowest pressures analyzed since 2005. There would be 2 more storms to eclipse that central pressure.

This system primed the basin for the subsequent hyper-active low track and the other remarkable pressure falls. It also helped to propel the next hazardous system toward Ireland and the UK.

Dubbed Storm Ciara by the UK Met Office, on Feb 9, a 945-mb storm force low lashed Ireland and the UK with gusts to 84 kt (97 mph), causing extensive damage and flooding. On the far right of the animation, look for the baroclinic leaf off the elongated front and atmospheric river, then the curl as it passes just NW of Ireland.

On Feb 12 a low pressure passed south of Nova Scotia and Newfoundland, then rapidly intensified into the central Atlantic deepening from 996 mb to 929 mb over the span of 48 hours. Look for the deepening reds and oranges indicative of warm, dry, ozone-rich descending stratospheric air associated with the jet stream and potential vorticity (PV) anomalies. This low produced winds to at least 85 kt, confirmed in Advanced Scatterometer (ASCAT) overpasses. The altimeter instrument aboard Sentinel-3A captured significant wave heights to near 20 meters (64.52 ft ) at 2301 UTC February 13th ( link ).

Finally, on Feb 14, another low pressure system explosively intensified from the central Atlantic to south of Iceland, named Storm Dennis by the UK Met Office. The pressure dropped 50 mb in just 24 hours on Feb 14, then even at 944 mb, continued to rapidly intensify to 920 mb on Feb 15, 18z.

920 mb is the lowest central pressure analyzed by forecasters at OPC, and is generally accepted as one of the lowest pressures ever recorded for a mid-latitude cyclone across the North Atlantic basin.

Below is another animation containing all of the OPC surface analysis charts from Feb 5-17, culminating in the historic 920 mb low.

If any of the statistical graphs are too small to legibly view on your device, linked below are the full size versions:

• Accumulation graphs:  https://go.usa.gov/xfvcM 
• Seasonal HF wind event totals:  https://go.usa.gov/xfvce 
• Average monthly HF wind events:  https://go.usa.gov/xfvxq 
• The 15-year HF wind event quilt:  https://go.usa.gov/xfvxc 
• North Atlantic HF wind even frequency, by date:  https://go.usa.gov/xfvxx 

ADDITIONAL LINKS, HELPFUL INFO:

•  CSV file  containing all metadata that was used to create this story map (downloads automatically)
• Learn more about altimeters  following this link. 
• During major events, and as time allows, OPC forecasts post interesting satellite and analysis information to our social media feeds.  This link will take you to all of our tweets  pertaining to hurricane force lows.
• Want to learn more about marine weather, or see other story maps, articles, and presentations?  Check out our publications page! 
• Finally, the graphic below explains some of the technical differences between tropical and non-tropical systems (or hurricane vs hurricane force winds). They develop and intensify by very different meteorological processes!