The Greater Horn of Africa is often associated with famine and drought but this time, it captured headlines with a different kind of extreme event in mid-May 2018: a landfalling tropical cyclone. Tropical cyclone Sagar was the strongest cyclone to ever make landfall in Somalia. It is quite rare for a system to track this far west, traversing the entire Gulf of Aden between the Arabian Peninsula and the Horn of Africa. Since satellite surveillance of tropical cyclones began in mid-1960s, only two other tropical cyclones have moved into the western Gulf of Aden, according to NOAA's historical hurricane tracks database. Cyclone Megh, hammered Socotra Island, east of Somalia, making landfall along the Yemeni coast in November 2015. Before that, Tropical Cyclone 1A traversed almost the entire Gulf of Aden before landfalling in northwest Somalia on May 28, 1984. None of them however, were as strong as Tropical cyclone Sagar.
On 19 May 2018, Tropical Cyclone Sagar slammed into northern Somalia near Djibouti border with heavy rains and winds of around 60 mph making Sagar the strongest landfalling tropical storm on record for Somalia. Taking advantage of a favorable environment, low wind shear and sea surface temperatures up to 31 degrees Celsius, the system gained in much strength. However, according to local news reports, 31 people died as a result of Sagar with thousands of people and livestock affected by flash flooding. The coastal villages of Yago and Garyaara have reportedly been damaged extensively.
Such storms are rare but if they do form, they tend to be generated in the Arabian Sea in Spring and Autumn, during the transition periods between the strong southwest flow of the summer monsoon and the strong northeast flow that predominates in Winter. Outside of these transitional seasons, the Indian Ocean is dominated by the southwest flow of the summer monsoon and conversely the intense northeast flow that occurs in Winter. So, while ocean temperatures are warm enough year-round to sustain tropical cyclones, it is generally during the Spring and Autumn when atmospheric conditions are conducive for the development of tropical cyclones in the North Indian Ocean. Any storm that forms and begins to move west towards the Arabian Peninsula and the Greater Horn of Africa, when approaching the coast, begins to ingest dry air and this usually weakens the storms rapidly before they make landfall.
This area of northern Somalia also known as Somaliland, has been experiencing drastic drought over the past five years. With the additional damage done by this storm, including the destruction of farmland and infrastructure and livestock loss, food security concerns will rise. Also, the heavy rainfall that occurred across Western Yemen is likely to promote cholera infection rates.
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© 2018 Meteorologist Daneeja Mawren
DISCUSSION: There is no question that as we approach the 2018 tropical Atlantic hurricane season, a primary thought for many millions of people living along the coastlines of the United States is whether they will be impacted the season by a landfalling tropical cyclone. This is often a very difficult question to answer since it can often be very challenging to pinpoint the exact location of a given landfall at a given time during the tropical Atlantic hurricane season before the season has even gotten underway. Having said that, there are indeed approaches that hurricane forecasters will take from a more fundamental standpoint to better anticipate involving tropical cyclones threats during a given hurricane season.
From a purely fundamental standpoint, it is reasonably well-known across both within and beyond the atmospheric science community that hurricane formation and maintenance chiefly rely upon the presence of both warmer oceanic sea surface temperatures along with weak to moderate vertical wind shear. The reason for this is because the warmer oceanic sea-surface temperatures act as the main source of “fuel” for a developing and/or maturing tropical cyclone. In addition, the presence of weak to moderate vertical wind shear is also critical since this effectively allows the storm to develop and intensity as opposed to having the critical thunderstorm near the center of the storm be torn apart. This point is reflected by the graphic above which was shared by FEMA Meteorologist Michael Lowry.
Therefore, during periods of time in which there is stronger wind shear present across portions of the tropical Atlantic basin as well as greater vertical wind shear values, this type of dynamic set up is not typically favorable for the development and/or intensification of tropical cyclones. Hence, when tropical forecasters see either below-normal sea-surface temperatures and/or greater-than-normal magnitudes of vertical wind shear, this is often an initial “red flag” to not anticipate any tropical low-pressure systems which do try to develop to blossom into all-out tropical cyclones.
However, if a given tropical cyclone which tries to develop does happen to both begin its lifetime or move into and then quickly out of a more unfavorable atmospheric environment during the earlier part of its existence, this is a different story. In such situations, if the center of the storm’s circulation does manage to remain out over warm ocean water for a long enough time, then a tropical system may sometimes have the time and ability to further develop into a more formidable tropical cyclone despite being situated in a more hostile environment earlier on in its lifetime. Hence, it is important during a given hurricane season (regardless of what basin you are concerned about) to never completely write off a given storm even while it is going through a hostile environment since storms can and have been known to “bounce back and surprise.”
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© 2018 Meteorologist Jordan Rabinowitz
DISCUSSION: As we get closer and closer to the 2018 Tropical Atlantic hurricane season, it is always interesting to look back and reflect on tropical cyclone season's past. In looking back to the Tropical Atlantic hurricane season of 1951, we find the strongest hurricane on-recorded which occurred during the month of May. Over the course of the past 60 to 70 years of relatively reliable archiving of tropical cyclone events, there have most definitely been major improvements made to the ways and methods by which tropical cyclone track and intensity data is obtained and recorded. Thus, it is crucial to recognize the fact that May is not notoriously known for producing powerful tropical cyclones, but it can and does happen as is shown in the track of Hurricane Able (1951) as shown above.
It is worth noting that, as is always the case, it only ever takes that one tropical cyclone to shatter a record and forever leave it's mark on a region for generations to come. Hence, even though, we are not quite yet at the official start of the Tropical Atlantic's hurricane season timeline, it is imperative to always remain vigilant so you are never caught off-guard in any way when a tropical cyclone is bearing down on your home-base. As unlikely as a major hurricane realistically is during the month of May from a climatological standpoint, it is always so important to be prepared so you are ready for if and when a tropical cyclone of any intensity threatens your hometown. This can be done with simple steps as fundamental as even just having an evacuation plan in place, should you ever need it. And, of course, having basic emergency supplies such as a 4 to 7 day supply of water, energy bars, batteries, basic medications, a couple of blankets, and a basic first aid kit are all important to have at the ready as well.
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© 2018 Meteorologist Jordan Rabinowitz