|Above: The deadliest disaster of April 2018 was flooding in Kenya that claimed at least 72 lives—the deadliest flood in Kenya since 2006, when 114 people died in an October flood. Kenya has been experiencing periodic flooding due to heavy rainfall since March 2018, and damage is estimated at $350 million--including $200 million in damage to the nation’s infrastructure. According to EM-DAT, the international disaster database, this is Kenya’s most expensive natural disaster in recorded history. The total number of internally displaced people was at least 211,000, according to the UN Office for the Coordination of Humanitarian Affairs. Above: Pedestrians use a metal fence to cross a flooded road on their way to work following heavy rainfall, on March 15, 2018 in Nairobi, Kenya. Image credit: SIMON MAINA/AFP/Getty Images.|
April 2018 was the planet's third-warmest April since record keeping began in 1880, said NOAA's National Centers for Environmental Information (NCEI) on Thursday. NASA also rated April 2018 as the third-warmest April on record. Both agencies found that the only warmer April months were in 2016 and 2017. Occasional differences in rankings between NASA and NOAA are mostly due to how they handle data-sparse regions such as the Arctic, where few surface weather stations exist.
The rankings for April were cooler than we've seen in the last couple of years largely because of the presence of colder weather than average over most of North America, plus the presence of cool ocean temperatures over the Eastern Pacific from a weak La Niña event that ended in April.
Global ocean temperatures during April 2018 were the third warmest on record, and global land temperatures were the ninth warmest on record, according to NOAA. Global satellite-measured temperatures in April 2018 for the lowest 8 km of the atmosphere were the seventh or sixth warmest in the 40-year record, according to the University of Alabama Huntsville (UAH) and RSS, respectively.
|Figure 1. Departure of temperature from average for April 2018, the third-warmest April for the globe since record keeping began in 1880. Record warmth was observed over land across parts of central South America, eastern Europe, southern Africa, Papua New Guinea, and Australia. Record cold for April occurred over parts of the U.S. Midwest (see our national climate roundup for details). Image credit: National Centers for Environmental Information (NCEI).|
Two billion-dollar weather disasters in April 2018
Two billion-dollar weather-related disaster hit the Earth last month, according to the April 2018 Catastrophe Report from insurance broker Aon Benfield: severe winter weather in China that caused $1.5 billion in damage to agriculture, and a severe weather outbreak in the U.S. that cost $1.25 billion. Here is the list of the seven billion-dollar weather disasters so far in 2018:
- Drought, Argentina and Uruguay, 1/1 – 3/31, $3.9 billion, 0 killed
- Winter Storm Friederike, Western & Central Europe, 1/18, $2 billion, 13 killed
- Winter Storm Riley, Eastern U.S., 3/1 – 3/3, $2 billion, 9 killed
- Winter Weather, China, 4/2 – 4/18, $1.5 billion, 0 killed
- Severe Weather, Plains, Midwest, Southeast, Northeast U.S., 4/13 – 4/17, $1.25 billion, 6 killed
- Winter Storm Eleanor & Carmen, Western & Central Europe, 1/1 – 1/4, $1.25 billion, 7 killed
- Winter Storm Grayson, Central & Eastern U.S., 1/3 – 1/5, $1.1 billion, 22 killed
- Winter Weather, China, 1/24 – 1/29, $1.1 billion, 2 killed
|April Billion-Dollar Disaster 1. Extended cold and snow in China during the first half of April affected 1.5 million acres of cropland, causing $1.5 billion in damage. Above: A March 15, 2018 aerial view of the Beiling Park after snowfall in Shenyang in China's northeastern Liaoning province. Image credit: AFP/Getty Images.|
|April Billion-Dollar Disaster 2. A major springtime storm system (Xanto) swept across the Plains, Midwest, Southeast, Mid-Atlantic, and the Northeast, bringing periods of severe thunderstorms, flooding rains, and heavy snow from April 13-17. At least six people were killed and many others injured. The most significant damage resulted from nearly 70 tornado touchdowns, up to baseball-sized hail, and straight-line winds. Blizzard conditions and freezing rain also led to anomalous snowfall accumulations in the Upper Midwest and New England. Dry air and gusty winds behind the system additionally helped fuel significant wildfires across parts of Oklahoma, leaving two people dead and numerous structures destroyed. Total economic losses were estimated at $1.2 billion. Above: Visible satellite image of the sprawling storm dubbed Xanto at 10 am EDT April 13, 2018. Image credit: NOAA, via NCAR/RAL.|
La Niña ends
La Niña conditions no longer existed in the tropical Pacific Ocean by early May, with neutral conditions prevailing, said NOAA’s Climate Prediction Center (CPC) in its May 10 monthly advisory. The weak La Niña event that began in August 2017 is now over, something the Australian Bureau of Meteorology concurred with in their April 13 biweekly report. The bureau uses a more stringent threshold than NOAA for defining La Niña: sea-surface temperatures in the Niño3.4 region of the tropical Pacific must be at least 0.8°C below average, vs. the NOAA benchmark of 0.5°C below average.
Over the past week, sea surface temperatures (SSTs) in the benchmark Niño 3.4 region (in the equatorial Pacific) rose to about 0.2°C below average, which is outside the 0.5°C to 1.0°C-below-average range that is required to qualify as a weak La Niña. Odds for an El Niño event to form are predicted to increase as we head towards the fall and winter of 2018, with the latest CPC/IRI Probabilistic ENSO Forecast calling for a 38% chance of an El Niño event during the August-September-October peak of the Northern Hemisphere hurricane season. El Niño events typically reduce Atlantic hurricane activity, due to an increase in wind shear over the tropical Atlantic.
|Figure 2. Sea surface temperatures (SSTs) in the benchmark Niño 3.4 region (in the equatorial Pacific) have risen to about 0.2°C below average over the past week, outside of the 0.5° - 1.0°C below average range required to be classified as weak La Niña conditions. Image credit: Levi Cowan, tropicaltidbits.com.|
Arctic sea ice falls to 2nd-lowest April extent on record
Arctic sea ice extent during April 2018 was the second lowest in the 40-year satellite record, behind the record set in April 2016, according to the National Snow and Ice Data Center (NSIDC). "Given the uncertainty in measurements, NSIDC considers 2016 and 2018 as tying for lowest April sea ice extent on record," the center said in a report on May 3.
The most dramatic lack of ice extent was across the Bering Sea, which experienced major ice loss in February and never fully recovered. Ice extent across the Bering Sea in April was less than half of its previous record for the month, set in 1989.
Notable global heat and cold marks set for April 2018
Hottest temperature in the Northern Hemisphere: 50.2°C (122.4°F) at Nawabshah, Pakistan, 30 April
Coldest temperature in the Northern Hemisphere: -51.2°C (-60.2°F) at Geo Summit, Greenland, 4 April
Hottest temperature in the Southern Hemisphere: 43.7°C (110.7°F) at Roebourne, Australia, 3 April
Coldest temperature in the Southern Hemisphere: -73.1°C (-99.6°F) at Dome Fuji, Antarctica, 6 April
(Courtesy of Maximiliano Herrera.)
Major weather stations that set (not tied) new all-time heat or cold records in April 2018
Subic Bay (Philippines) max. 39.2°C, 15 April
(Courtesy of Maximiliano Herrera)
One all-time national heat record broken in 2018
So far in 2018, one nation has broken an all-time record for its hottest temperature in recorded history: Palau, which hit 95°F (35°C) at Koror on April 22. This beat the record set (most recently) back in February 2018: 93.9°F (34.4°C). No nations have set an all-time cold temperature record so far in 2018. Most nations do not maintain official databases of extreme temperature records, so the national temperature records reported here are in many cases not official. I use as my source for international weather records researcher Maximiliano Herrera, one of the world's top climatologists, who maintains a comprehensive list of extreme temperature records for every nation in the world on his website. If you reproduce this list of extremes, please cite Maximiliano Herrera as the primary source of the weather records.
Nineteen national monthly/territorial heat records so far in 2018
January: Marshall Islands
February: Marshall Islands, Falkland Islands, Kuwait, Qatar, Saudi Arabia, Palau.
March: Marshall Islands, Qatar, Armenia, Madagascar, Pakistan, Iraq, UAE, Turkmenistan, Tajikistan, Uzbekistan.
April: Albania, Montenegro
(Courtesy of Maximiliano Herrera.)
National monthly cold records in 2018: none
No national monthly records for cold were set in April 2018.
Continental/Hemispheric records in 2018
Highest temperature ever recorded in April in Asia: 50.2°C (122.4°F) at Nawabshah, Pakistan, 30 April
Bob Henson co-wrote this post.