Sagar Pounds Somalia; New Cyclone May Threaten Oman

Early reports suggest widespread damage and suffering from Tropical Cyclone Sagar, which made landfall on Saturday as the strongest tropical storm ever recorded in Somalia. Packing heavy rain and top sustained winds of 60 mph, Sagar made landfall further west than any tropical cyclone in 52 years of recordkeeping for the North Indian Basin.

Sagar struck at around noon local time Saturday about 100 miles southeast of the city of Djibouti, along the flat, arid coastal plain of far western Somalia. As Sagar tracked inland, satellite imagery indicated widespread rains across western Somalia, the nation of Djibouti, and far northeast Ethiopia.

The aftermath of #Cyclone #Sagar this morning in #DjiboutiCity #Djibouti pic.twitter.com/RTgfGK1OYN

— Abdirahman Ahmed Hussein (@AbdirahmanSk) May 20, 2018

The disaster management authority NADFOR reported at least 16 deaths from Sagar in the Awdal region of far western Somalia, according to Abdirashed Ibrahim, director general of Somalia’s Ministry of Planning and National Development. At least 35 homes were destroyed as Sagar passed by northeast Somalia, according to reliefweb. The website also noted reports from humanitarian agencies of disruption in villages along the coastal plain of western Somalia, including 15 shelters reportedly destroyed at Ceel Sheek and a number of people missing in Bulaxaar. One woman was killed in a home fire on Friday during evacuations in Khor Maskar, Yemen, just north of Sagar’s path.

Surface observations were not immediately available from Djibouti or western Somalia. According to satellite-based surface wind estimates from the Joint Typhoon Warning Center (JTWC), Sagar’s top sustained (1-minute) winds peaked at 65 mph near the end of the storm’s remarkable four-day journey across the narrow Gulf of Aden.

According to insurance broker Aon Benfield, Sagar's rains in Somalia arrived on the heels of a month of unusually heavy rains. Nearly 700,000 people were affected by flooding in Somalia in April, and at least five people were killed. Among the hardest-hit regions were Gedo, Bakool, Bay, Hiraan, and Horseed, as flash flooding and overflowing rivers inundated vast areas of land. Local officials reported significant damage to agriculture and infrastructure.

Somalia's strongest and westernmost tropical cyclone on record

Since the advent of satellite monitoring in the 1960s, only two other tropical cyclones have been observed to make it into the western Gulf of Aden:

•  Cyclone Megh, which passed just north of the northern tip of Somalia as a Category 1 cyclone and made landfall as a tropical depression in Yemen in November 2015

•  Tropical Cyclone 1A, which reached western Somalia at weak tropical storm strength in May 1984

Only five other tropical cyclones are known to have hit Somalia since accurate satellite measurements began in 1966: Tropical Cyclone ARB02 of 2016, Tropical Cyclone ARB01 of 2013 (the nation’s deadliest cyclone on record, with at least 162 fatalities), Tropical Cyclone Murjan of 2012, Tropical Cyclone ARB02 of 1994, and Tropical Cyclone 4B of 1984. Notably, all five of these were post-monsoon (autumn) cyclones rather than springtime systems, and all of them struck the east coast of Somalia rather than its north coast.

Somalia’s previous record-highest wind speed at landfall, according to Joint Typhoon Warning Center data at the International Best Track for Climate Stewardship website, was the 45 knots (55 mph) with TC ARB01 in 1994.

Figure 1. Only three tropical cyclones have tracked into the western Gulf of Aden in historical records dating to 1966. Sagar’s landfall was the westernmost of the three, and its top sustained winds at landfall were the highest. Image credit: NOAA Historical Hurricane Tracks, via weather.com.

Another tropical cyclone may affect the Arabian Sea this week

On Sunday, the HWRF and GFS forecast models indicated that a disturbance dubbed 92A could develop into an intense hurricane-strength cyclone this week, possibly threatening Oman by late in the week. The disturbance is predicted to track west before hooking sharply northward toward Oman. Sea surface temperatures of around 30°C (about 1°C above the seasonal norm) along the projected track of 92A are more than warm enough to support tropical development, and wind shear is projected to remain weak to moderate (about 10-15 knots) through at least Tuesday. Mid-level relative humidity is around 80%, which would support robust development of convection (showers and thunderstorms).

The 12Z Sunday run of the HWRF develops 92A into the equivalent of a Category 4 hurricane by Thursday, weakening the cyclone to Category 2 strength at the end of the forecast period (Saturday) just a few hours from reaching Oman. The 12Z GFS brings 92A into the Oman coast as a Category 2 equivalent on Saturday.

Figure 2. MODIS satellite view of Cyclone Gonu at Category 4 strength in the northwestern Arabian Sea as it approached the northeast coast of Oman at 0635Z on June 5, 2007. Image credit: NASA.

Tropical cyclone history in the northwest Arabian Sea

Tropical cyclones are most common 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. There are signs that pre-monsoon (springtime) Arabian Sea cyclones have gotten stronger in the last 20 years, as we discussed in a 2015 post on Chapala.

The region’s two strongest tropical cyclones on record both occurred in November 2015. Cyclone Chapala came ashore on the south end of the Arabian Peninsula on November 4 as the first hurricane-strength cyclone ever recorded in Yemen. Just four days later, Cyclone Megh passed just north of Socotra Island east of Somalia with Category 3 winds of 110 mph, destroying hundreds of homes and killing at least 18 people.

Tropical cyclones often weaken as they approach Oman and ingest dry desert air from the Arabian Peninsula. However, Oman is not invulnerable to cyclone disaster. In June 2010, Cyclone Phet came shore in far eastern Oman as the equivalent of a Category 3 storm, with top winds of 110 mph, according to JTWC. At least 24 deaths were reported in Oman, with 23 other fatalities occurring in India and Pakistan as Phet moved by in a much-weakened state. Phet left an estimated $780 million (2010 USD) in damage in Oman. In 2007, Oman was struck in 2007 by Cyclone Gonu, which peaked as a Category 5 equivalent before striking the eastern tip of Oman and going on to become the first tropical cyclone on record to make landfall in Iran. Gonu was the strongest cyclone ever recorded in the Arabian Sea; in Oman, it caused at least 50 deaths and wreaked at least $4.2 billion in damage (2007 USD). Prior to Gonu, the last significant tropical cyclone to affect Oman was in 1890, when a storm hit the Gulf of Oman coast and Muscat, killing 700 people. Lesser cyclones affected the area in 1945 and 1977. (Note: This paragraph has been updated from Sunday's original post.)

Figure 3. An outbreak of desert locusts in southwest Morocco in November 2004. Image credit: Magnus Ullman, via Wikimedia Commons.

Cyclone landfalls can set the stage for desert locust plagues

In addition to flash flooding, the Food and Agriculture Organization (FAO) of the United Nations warned that the heavy rains from Sagar could cause favorable breeding conditions for desert locusts. Plagues of these voracious locusts are a major threat to Middle East food security.

"Monitoring tropical cyclones in the Arabian Sea and Gulf of Aden is a very important part of [our forecast] strategy because historically they have been the origin or trigger of desert locust plagues," Keith Cressman, the FAO’s senior locust forecasting officer, said in an email. Cressman has been operating FAO’s early warning system for desert locust outbreaks for the past 30 years.

According to the FAO, an adult desert locust can consume roughly its own weight in fresh food per day—about two grams, or 0.07 ounce. That may not sound like much, but the locusts can spawn up to five generations per year. Swarms of tens of millions of locusts can travel with the wind up to 100 miles a day. Even a very small swarm eats the same amount of food in one day as about 35,000 people. Multiyear desert locust plagues tend to occur in the Middle East every couple of decades, with the most recent being in 2003-05.

Dr. Jeff Masters contributed to this post.