2018 Atlantic Hurricane Season


Tiny Beryl Becomes the First Hurricane of the 2018 Atlantic Hurricane Season

Updated July 6, 2018 @ 12:44 pm EST

We have our first hurricane of the 2018 Atlantic Hurricanes Season and it is a very tiny storm.

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This tiny cluster of thunderstorms is Hurricane Beryl as it travels on a primarily westward direction at about 15 mph. Despite its size it has managed to intensify and continues to do so. As of the 11am advisory from the National Hurricane Center, Beryl has strengthened its winds to 80 mph still maintaining a solid Category 1 strength on the Saffir-Simpson Hurricane Wind Scale. However, Beryl is heading into trouble which could help spare the Windward and Leeward Islands in the Caribbean.

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Top Image: Upper level wind shear values and intensities. Bottom Image: Saharan dust levels in the atmosphere

Relating to the top image, a patch of intense wind shear lies just in front of Beryl and is blocking the storm from the Caribbean Islands. This patch will help to tear the tiny storm apart and potentially weaken it to a low end Category 1 or a Tropical Storm before it impacts the islands late this weekend. Additionally, if Beryl holds together and exits into the Caribbean Sea it is still not out of trouble. There is a larger plume of wind shear to the south of the Dominican. If this area continues to harbor intense winds this will likely be the end of Beryl. Hurricane Beryl also has to worry about the moisture in the air to keep itself together. The second image above shows how much Saharan dust is in the atmosphere over the Atlantic Basin. Over the past few months we have seen an increase in Saharan dust traveling over the Atlantic and this hinders hurricane formation. Beryl is tracing the southwest corner of this large swath of dry air and avoiding it for the most part, but to reach the Caribbean Beryl will have to interact with some of this dry air which could help to weaken the system.  This dry air prevents Beryl from evaporating more ocean water and condensing it into clouds, in one way the air is chocking the storm to death.

Due to the small size of Beryl this storm is very fragile and any change in the atmosphere surrounding this storm will significantly affect the evolution of the hurricane. Unlike a large hurricane which can create its own “micro” climate and affect other weather systems near the storm, a smaller hurricane is at the mercy of other surrounding elements and will weaken faster than a larger hurricane. If Beryl were a large system it would likely survive the wind shear and dry air and potentially last for a longer period of time. However Beryl is tiny. Likely one for the record books.

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Tropical Storm (orange) and Hurricane Force (Purple) Estimated Wind Areas.

The National Hurricane Center and forecasters are estimating that the eye of Beryl is only 5 miles wide and the wind field is about 60 miles in diameter. To put that in perspective above, Beryl is about the size of some of the islands in the Lesser Antilles (only taking into consideration the wind). Beryl could likely keep its hurricane strength as it approached the eastern Caribbean Islands late Sunday night but with the interaction of the wind shear Beryl could weaken fast to a Tropical Storm as it pushed through the Lesser Antilles and into the Caribbean Sea.

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Track Forecast Provided by the National Hurricane Center

If the larger plume continues to be in the south Dominican, it can help destroy the remains of Beryl once it enters into the Caribbean Sea. However, there is a chance that Beryl can maintain its tropical storm or tropical depression status and continue its journey across the Caribbean Islands, and this is where is could get interesting. The more time Beryl stays over land, the more likely it will dissipate, especially if it continues to be a smaller storm. However, if it can avoid the island of Cuba and stay over the open water it could maintain Tropical Storm strength. While unlikely, it is possible. Hurricane Harvey last year traveled in a similar direction to Beryl and became a remnant low in the south Caribbean sea until the remains exited into the Gulf of Mexico and rapidly intensified to be a Category 4 hurricane before coming ashore near Rockport, Texas. Beryl is different though and we don’t want to think about another Harvey repeat. However, the possibility always remains that Beryl can continue to survive and maintain its tropical status. However, because of its small and fragile state Beryl is not going to make a historical comeback like Harvey.

Tropical Storm Watches and Warnings will likely be issued as early as tonight for the Lesser Antilles. Regardless of intensity the islands will receive gusty winds and heavy rainfall for Sunday and Monday with the Dominican expected to see these same affects for Monday and Tuesday.


June 1st! Opening of the Atlantic Hurricane Season!

Updated June 1, 2018 @ 1:26 am EST

June 1st is here and it is known as the official opening date to the Atlantic Hurricane Season. Already we are off to an early start with the first storm of the season already formed in late May making this the 4th consecutive year for cyclones forming before the official start of the season.

Subtropical Cyclone Alberto formed late last week near the Yucatan Peninsula and slowly traveled northward into the Gulf of Mexico before making landfall along the panhandle of Florida on Memorial Day (May 28).

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Left: Subtropical Storm Alberto nearing landfall in Florida on May 28, 2018. Right: Path and strength of Subtropical Storm Alberto (Courtesy of NOAA).

Although not designated as a “tropical” system Alberto brought heavy rains to Florida, Alabama, Mississippi, the Carolinas, and Georgia for several days and traveled far inland. Alberto maintained Tropical Depression status and became one of only eleven cyclones to reach Lake Huron in recorded history (Wenckstern, 2018).

With the formation of Alberto in the month of May many may be wondering if this is a sign of things to come. Alberto was lucky to evolve into a cyclone and it all had to do with its location. During the month of May the majority of the North Atlantic sea surface temperatures are below the threshold for hurricane formation (80°F/ 26.5°C). However, the Caribbean and the Gulf of Mexico generally stay warmer than the open ocean due to the shallow depth and surrounding landmasses.

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Current sea surface temperatures for the Gulf of Mexico and western Caribbean for May 30, 2018 (Courtesy NOAA).

Currently the Gulf of Mexico is maintaining prime temperatures for cyclone development and this is what Alberto utilized last week as it impacted the Gulf Coast. Regardless of the warm sea surface temperatures in the Gulf of Mexico there is generally a high amount of wind shear still present in the atmosphere during the month of May and June. This wind shear is left over from the winter months and helps to tear forming thunderstorms apart and prevent them from growing and expanding to form a low pressure center (the beginning stages of tropical storm formation).

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Wind shear map for North Atlantic Basin for June 1, 2018. Green depicts areas favorable for tropical cyclone development (less wind shear); red is unfavorable for formation (high wind shear).

The past few weeks have shown unfavorable conditions in the Gulf of Mexico, particularly to the west. As Alberto moved into this area the west side of the storm was sheared and portrayed very little cloud cover. However the east side of the Gulf of Mexico and over the state of Florida showed little wind shear and the majority of the cloud cover from Alberto was secluded to the east side of the center of low pressure which gave the storm an “uneven shape” and helped to designate it as a subtropical storm.

Currently from the wind shear map above there is very little chance for any additional storms to form in the coming days. Wind shear is taking up most of the Gulf, Caribbean, and open Atlantic Ocean preventing any formation. This is so far a good sign for the beginning of June. Usually these strong wind shear values do not die down until July and August.

Moving onto what to expect for the 2018 Hurricane Season. Earlier in the year meteorological agencies released their forecasts on what to expect this year, with many calling for another active season similar to 2017.

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April 2018 hurricane prediction numbers for the 2018 Atlantic Hurricane Season provided by Colorado State and The Weather Channel.

The Weather Channel forecasted a more average hurricane year with 13 total named storms, 2 of which could be major (Category 3 or higher). Colorado State increased their numbers slightly to a total of 14 storms, 3 of which could be major hurricanes.

However, Colorado State released their new forecast for the 2018 Hurricane Season today (June 1) and dropped their predictions to 14 named storms, 6 hurricanes, and only 2 major storms, thus making this a near average season.

One of the reasons for this change has to do with the current sea surface temperatures being experienced in the open North Atlantic Basin.

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Sea surface temperature anomalies for the month of May 2018. (Courtesy NOAA).

The tropical North Atlantic and areas near the equator, where hurricane formation is likely, are cooler than average for this time of the year; especially off the west coast of Africa where temperatures are close to 2 degrees cooler than normal. According to Philip Klotzbach these cool temperatures have not been seen since 1994 and could have major impacts on the 2018 Atlantic Hurricane Season. This could be a major reason as to why forecast models and meteorological agencies are lowering their hurricane forecasts.

Additionally, there is still the idea of an el Niño forming later into the fall season. If this happens it will suppress formation of hurricanes at the time of the peak activity months (September and October). With the open Atlantic experiencing cold temperatures and the possibility of an el Niño forming it could be a potentially quiet hurricane season. However, chances of an el Niño developing are quite low due to the lingering la Niña still in place in the eastern Pacific.

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Sea surface temperature anomalies globally. Take note of the cooler temperatures off the west coast of South America (Courtesy Weather Underground).

Relating to the image above. Notice the blue swirl pattern coming off west South America. This is a la Niña event which cools the Pacific and hinders cyclone formation in this region. This “cool phase” has been in place since last hurricane season (2017) and produced less cyclone frequency in the Pacific basin. However, this has the opposite affect in the Atlantic. Instead of cool sea surface temperatures, the Atlantic warms up and we see an increase in frequency and strength of hurricanes in the Atlantic during a la Niña year. This phenomenon is what helped the 2017 Atlantic Hurricane Season to become so active and destructive. Once this la Niña transforms into an el Niño event (the swirl off South America will turn red in colour) the opposite will occur. The Atlantic will become less active while the Pacific becomes more active with hurricane formation.

What could happen is that we have a quiet start to the season (Alberto being the exception). June and maybe July could be less active as sea surface temperatures slowly warm up. August is generally where the North Atlantic starts producing higher amounts of cyclones and even major hurricanes. If the la Niña persists in the Pacific this may be the time that hurricane activity will increase across the ocean basin. However, if by some lucky chance an el Niño begins to take shape it may help to suppress the formation of hurricanes further for the peak months of September and October. Unfortunately there is no guarantee of this happening as meteorologists and climatologists have a minimal understanding on the el Niño and la Niña phenomenon (known as the El Niño Southern Oscillation). Throughout the season meteorologists and forecasters will continue to monitor the sea surface temperatures, wind shear levels, and potential el Niño formation and update their hurricane forecasts. Currently we are expecting a near average season and the possibility of a moderately active one for 2018. There is no way to forecast where these storms will form or where they will impact. Even during quiet seasons, one major hurricane can form and cause immense devastation, as seen in 1992 with Hurricane Andrew which formed during a quiet hurricane season. Therefore, regardless of how active a season is forecasted to be there is always the chance of a powerful hurricane coming ashore. The best advice is to prepare now. The 2017 Atlantic Hurricane Season is still fresh in our minds, especially for the victims of Hurricane’s: Irma, Harvey, Maria, and Nate. 2017 proved that we need to always be prepared for the next storm.

Citations:

  • Wenckstern, E (2018). The strangeness of Alberto: Making history over Great Lakes. The Weather Network.

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