Global Precipitation & Temperature Outlook May 2021

4 May 2021

OVERVIEW
The May 2021 Outlook includes a forecast of exceptionally hotter than normal temperatures in a vast expanse of Russia from Siberia through much of the Russian Far East. Wetter than normal conditions are expected in northern Ethiopia and Angola.

PRECIPITATION OUTLOOK
In Africa, precipitation surpluses of varying intensity are forecast in northern Ethiopia and are expected to reach exceptional intensity in the northern Rift Valley. Surpluses of generally lesser intensity will extend into Somaliland, Eritrea, Djibouti, Sudan, and South Sudan. Africa’s mid-Atlantic coast will also see precipitation surpluses from Cameroon through Namibia. Anomalies will be especially widespread in Angola and will be exceptional from the southern coast of the Republic of the Congo through northwestern Angola and in a pocket east of Lubango in southern Angola. Moderate precipitation surpluses are forecast for southwestern Botswana, eastern Zambia, central Tanzania, and some pockets in west-central Democratic Republic of the Congo.

Precipitation outlook. Reds indicate below normal monthly total precipitation. Blues indicate above normal monthly total precipitation. The darker the color, the more extreme the anomaly relative to a 1950-2009 climatic baseline. Colors are based on the expected return period of the anomalies.

Southern Uganda will be drier than normal particularly in the south near Lake Victoria and into Tanzania. Central Kenya will also see precipitation deficits. In North Africa, moderate deficits are forecast in coastal Libya east of Benghazi.

Turkey will be somewhat drier than normal with moderate deficits in the north and southeast along with a few severe pockets. In the Middle East, mild to moderate dry anomalies are expected in the Levant, northern Saudi Arabia, and western Iran. Iran’s far southwest will be much wetter than normal and moderately wetter conditions are forecast from the center of the country to the Caspian Coast.

Relatively normal precipitation is forecast for Europe with some areas of moderate surplus in northern France and Belgium near the Strait of Dover and in Scotland. Moderately drier conditions are expected in Greece around the Aegean Sea and in southern Bulgaria.

In Central Asia, Turkmenistan, Uzbekistan, eastern Kazakhstan, and central Kyrgyzstan will be drier than normal with moderate to severe deficits. Eastern Tajikistan will be much wetter. The TransVolga region of Russia will be moderately wetter than normal as will the Yamal Peninsula in the Arctic. Somewhat drier than normal conditions are forecast in a long belt from the Upper Ob River region through southern Siberia to the Sea of Okhotsk where deficits will become more intense, reaching past the Kamchatka Peninsula.

In East Asia, some moderate precipitation surpluses will skirt northern Mongolia into northeastern China. Some mild to moderate deficits are forecast for southwestern Mongolia. Xinjiang in western China will be drier than normal and will include pockets of severe to extreme precipitation deficit. Western Tibet will be moderately wetter than normal but moderate deficits are forecast in its eastern extent, reaching into Yunnan.

Moderate to extreme deficits are predicted for India’s Far Northeast, and some pockets of moderate deficit in Bhutan and Nepal. Far northern and northwestern India will be wetter than normal. Elsewhere in South Asia, many regions of Pakistan and Afghanistan will see precipitation surpluses, generally moderate in Pakistan but extreme to exceptional in central Afghanistan. Moderate deficits are forecast near Afghanistan’s western border.

Precipitation deficits are expected throughout much of Myanmar in Southeast Asia, with extreme to exceptional deficits in the north. Surpluses are forecast for Cambodia, the Mekong Delta, Peninsular Malaysia’s east coast, northern Malaysian Borneo, Brunei, and Sumatra’s northern tip. Moderate surpluses are expected on Papua New Guinea’s northern coast.

Australia can expect some pockets of moderate deficit scattered across the far north and some pockets of moderate surplus in the southeast. Moderately drier than normal conditions are forecast for New Zealand’s central west coast on Cook Strait. New Caledonia will be somewhat wetter than normal.

In South America, Brazil will be see deficits in a vast belt south of the Amazon with moderate deficits overall but some severe pockets as well. From eastern Venezuela into Guyana, precipitation surpluses are forecast, exceptional in the Caroni River Watershed in the southeast and extreme in the Orinoco Delta. Some moderate deficits are expected in northwestern Venezuela. Moderate to severe precipitation deficits will reach through the Andes Mountains from southwestern Colombia through the Cordillera Oriental Range in Peru. Deficits of similar intensity are forecast for northern and central Bolivia. Northeastern Argentina and the eastern Pampas will be moderately drier than normal, but Mendoza Province in the west will be moderately wetter. Moderate precipitation deficits are forecast for southern Chile, bleeding across the border into southern Argentina.

Relatively normal precipitation is expected in Central America with some moderate deficits in Dominican Republic. Northern Mexico will be moderately drier than normal and drier conditions are also forecast for states along the Gulf and inland with some pockets of severe deficit in San Luis Potosi and Hidalgo.

In the United States, moderate deficits are forecast for western Texas, New Mexico, southwestern Colorado, central Arizona, Southern California, and Utah’s southern tip. Some pockets of severe deficit are expected in north-central New Mexico. Moderate precipitation surpluses are forecast in the Ohio River Watershed. The Black Hills of South Dakota will also be moderately wetter than normal. In northern Alaska, moderate to extreme surpluses are forecast for the Brooks Range.

Southern Ontario will be moderately wetter than normal, but moderately drier conditions are forecast for far northern Ontario. Moderate precipitation deficits are expected in the northern extent of Canada’s Northwest Territories.

TEMPERATURE OUTLOOK
A vast expanse of Russia from Siberia through much of the Russian Far East will be exceptionally hotter than normal. Framing this area, temperatures will be warmer than normal reaching to the nation’s southern border with China and Mongolia and west to the Ural Mountains. In European Russia, the tundra region will see moderate to severe warm anomalies. In Central Asia, Turkmenistan, Uzbekistan, eastern Tajikistan, and south-central Kyrgyzstan will be moderately warmer than normal. Kazakhstan, too, can expect moderate warm anomalies in large pockets of the northeast, south, and southwest.

Temperature outlook. Reds indicate above normal monthly average temperature. Blues indicate below normal monthly average temperature. The darker the color, the more extreme the anomaly relative to a 1950-2009 climatic baseline. Colors are based on the expected return period of the anomalies.

In South Asia, India will be much warmer than normal in regions along its Arabian Sea Coast and in the south, with exceptionally hotter temperatures in Gujarat and coastal Maharashtra. India’s Far Northeast will be moderately to extremely warmer than normal with moderate conditions reaching into eastern Bangladesh. Moderately cooler than normal pockets are forecast between Bhutan and Nepal, and in northern Chhattisgarh and central Afghanistan.

Much of China will be warmer than normal with moderate anomalies overall but more intense conditions in pockets of Yunnan, Shaanxi, Qinghai, and Xinjiang. Other regions in East Asia can also expect warmer than normal temperatures. Anomalies will be moderate in South Korea and much of Mongolia but will be severe to extreme in the northern half of Honshu, Japan, and moderate elsewhere in Japan.

Temperatures in Southeast Asia are forecast to be exceptionally hotter in much of Myanmar, severe in central Vietnam and southern Laos, and moderate in northern Laos and pockets of Thailand. Malaysia, Indonesia, and Papua New Guinea will be much warmer than normal. In the Philippines, warm anomalies are forecast to be exceptional in the central region, severe in the south, and moderate in the north.

In Australia, temperatures will be warmer than normal in the east and southeast with severe to extreme anomalies in Tasmania, and severe anomalies in eastern New South Wales and eastern Victoria. Some pockets elsewhere will be warmer than normal also including Arnhem Land and the Cape York Peninsula in the far north. Extreme to exceptional warm anomalies are expected to cover South Island, New Zealand. Temperatures in New Caledonia will be exceptionally hotter.

The Middle East is forecast to experience warmer than normal temperatures of varying intensity in Turkey, the Levant, the Arabian Peninsula, Iraq west of the Euphrates, and from southern Iraq into Iran. Anomalies will be intense in many regions, especially across southern Turkey. Iran’s Persian Gulf Coast will also be warmer than normal, as will the region north of Lake Urmia. Intense warm anomalies are expected in Georgia.

Africa, too, is forecast to be warmer than normal across the vast expanse of the north, in much of West Africa, and around the Gulf of Guinea. Anomalies will be exceptional in many areas including Mauritania, Mali, and Cote D’Ivoire. Moderate to severe warm anomalies will skirt the Atlantic Coast from southeastern Angola through Namibia, and are also expected in the western half of South Africa. Northeastern Madagascar will be much hotter than normal. Other regions with a forecast of warmer than normal temperatures include pockets in southwestern Ethiopia, Eritrea, southern Somalia, Rwanda, Burundi, southern Kenya, Central African Republic, and northern Democratic Republic of the Congo (DRC).

Cooler than normal temperatures are forecast from southeastern Sudan into Eritrea and Ethiopia, and in South Sudan, the central Rift Valley, south-central DRC, and pockets of western Tanzania and Mozambique. Cool anomalies will be exceptional in DRC and central South Sudan.

In Europe, moderately warmer than normal temperatures are forecast in France’s southern half and across the border into Spain, near Madrid, and in Switzerland, southern Germany, many regions of Italy, southern Austria, Slovenia, Croatia, the Balkan Peninsula, Romania, and Bulgaria. Some pockets in the Balkans will be of severe intensity. Moderately cooler than normal temperatures will span the central border of Norway and Sweden.

Much of the northern half of South America will be warmer than normal with anomalies of varying intensity. Warm anomalies will blanket nearly all of Brazil with the exception of its southern states. Widespread, exceptionally hotter temperatures are forecast in central and south-central Brazil. Many regions of the Guianas will be warmer than normal as will southern and northwestern Venezuela, but Venezuela’s northeastern quadrant will see cooler than normal conditions. Warm anomalies will be intense through the Andes Mountains. Southwestern Bolivia will be warmer than normal as will southern Argentina and Tierra del Fuego.

In Central America and the Caribbean, western Cuba and the Bahamas will be exceptionally hotter than normal. Warm anomalies of lesser intensity are expected in many other pockets throughout the region. Central and northern Mexico will be warmer than normal. Anomalies will be exceptional from Jalisco north into Zacatecas, and along the Pacific Coast in Colima and Michoacán. Extreme anomalies are forecast for Coahuila and into nearby states.

The United States Southeast, Gulf Region, Texas, and Southwest are forecast to be warmer than normal. Much of Peninsular Florida will be extremely to exceptionally warmer, as will a pocket in southwestern Mississippi. From the Big Bend region of West Texas into central New Mexico warm anomalies will be extreme. Much of Alaska’s northern half will be warmer than normal with widespread exceptional anomalies in the far north.

Though temperatures in much of Canada will be normal, reaching well into the northern half of the U.S., the northern extremes will be warmer with anomalies ranging from moderate to exceptional in northern Quebec and the territories. Some moderately warmer temperatures are forecast in British Columbia, primarily in pockets of the north.

NOTE ON ADMINISTRATIVE BOUNDARIES
There are numerous regions around the world where country borders are contested. ISciences depicts country boundaries on these maps solely to provide some geographic context. The boundaries are nominal, not legal, descriptions of each entity. The use of these boundaries does not imply any judgement on the legal status of any territory, or any endorsement or acceptance of disputed boundaries on the part of ISciences or our data providers.

ABOUT THIS BLOG POST
Each week, ISciences processes an ensemble of 28 seasonal temperature and precipitation forecasts issued by the National Oceanic and Atmospheric Administration's Climate Forecast System Version 2 (CFSv2). We present our results in a proprietary weekly report titled Global Water Monitor and Forecast: Precipitation and Temperature Outlook. This blog post summarizes our Outlook released May 2, 2021 which includes forecasts for May 2021 through January 2022 based on NOAA CFSv2 forecasts issued April 24 through April 30, 2021.

Technical details:

Each CFSv2 forecast is bias corrected by:
- Constructing probability density functions from CFSv2 hindcasts.
- Fitting the hindcast probability distribution functions to a generalized extreme value distribution.
- Using an inverse lookup to an extreme value distribution fitted to the observed temperature and precipitation record (Fan & van den Dool 2008, Chen et al. 2002).
The map colors depict the return period of the median forecast anomaly.
Regions where the interquartile range of the ensemble spans both above normal and below normal conditions are hashed as having uncertain direction.
Regions where the interquartile range of the ensemble divided by the median forecast is large (>0.4) are hashed as having uncertain magnitude.
Results are reported in terms of return period using a 1950-2009 baseline.

Subscribe to our monthly Water Watch List

Search blog categories

Search blog tags