Global Precipitation & Temperature Outlook April 2021

5 April 2021

OVERVIEW
The forecast for April 2021 indicates exceptionally hotter temperatures in a vast expanse of Russia from the Ural Mountains through Siberia, along with precipitation surpluses in much of the Arctic region. The bulk of central Brazil will also be much hotter than normal, but drier.

PRECIPITATION OUTLOOK
In South America, precipitation deficits are forecast for the bulk of central Brazil in the southern Amazon Basin and will stretch through the easternmost states to the Atlantic Coast. Anomalies will be extreme to exceptional in Amapá, Maranhão, Pará, Mato Grosso, Tocantins, and coastal Bahia. Eastern and southeastern Bolivia can also expect deficits which could be extreme south of Sucre, downgrading as they reach into Argentina. Some areas of moderate deficit are forecast in Chile and skirting Peru’s coast.

Surpluses of varying intensity are forecast through nations that form the northern arc of the continent, moderate overall but severe to exceptional in western Colombia from Medellin to Cali. Surpluses are also expected in northeastern Peru’s large Loreto region leading into the western Amazon region of Brazil, and in a line following the Cordillera Central Mountains through Peru and into Bolivia. Anomalies will be exceptional in the central Ucayali River Watershed.

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… — 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.

Few precipitation anomalies are expected in Central America and the Caribbean - some moderate surpluses in southeastern Nicaragua and Belize, and some moderate deficits across the Upper Coco River Watershed along the Honduras/Nicaragua border. Moderate deficits are forecast for pockets of Mexico in the northwest, northeast, and the central Pacific region. Deficits may be severe near the Rio Grande in northern Coahuila.

The United States Southwest will be drier than normal as will Southern California and much of Texas outside of the Panhandle. Deficits will be moderate in SoCal, moderate to severe in Arizona and New Mexico, but will reach extreme to exceptional intensity spanning the southern Colorado/Utah border. In Texas, deficits are expected to be severe from San Antonio to Houston and north past Dallas, where the Dallas-Fort Worth region could see extreme dry anomalies. Louisiana, southern Arkansas, and the Florida Panhandle will be moderately drier than normal. Likewise, northern Illinois and southern Michigan will see moderately drier conditions, while northeastern Montana can expect to be moderately wetter than normal. Moderately wetter conditions are also forecast for central Alaska in the Upper Kuskokwim River Watershed.

In Canada, precipitation will be greater than normal in Labrador and easternmost Quebec. Moderately drier conditions are forecast for western Quebec, most of Ontario, and into eastern Manitoba. Deficits could be severe along the Great Whale River in Quebec as it reaches Hudson Bay. Surpluses are forecast in the eastern portion of Northwest Territories and in much of the vast expanse of Nunavut.

Europe can expect relatively normal precipitation though moderate surpluses are forecast from northern Norway into Sweden.

The forecast for East Africa includes surplus anomalies in southern Ethiopia, Somalia, Kenya, northeastern Uganda, and the Upper Wami River region of Tanzania. Surpluses will be primarily moderate but could be severe or extreme in Kenya and Uganda. Moderate precipitation deficits are predicted for the Sinai Peninsula, northern Ethiopia, Eritrea, Djibouti, and western Somaliland. Moderate deficits are also forecast throughout Zambia but deficits will be severe in nearby regions of southern Democratic Republic of the Congo and in northern Mozambique leading into Tanzania. Other areas with a forecast of moderate deficit include pockets in northwestern Botswana, Malawi, Namibia, Angola, and Lesotho.

The Middle East will be drier than normal with moderate deficits in many regions, including northern Syria, northern Iraq, Jordan, Saudi Arabia, western Yemen, and Iran. Deficits will be extreme east of the Jordan River, pockets of Saudi Arabia, and northeastern Iran.

Drier than normal conditions are forecast in Central Asia throughout Turkmenistan, and in eastern Uzbekistan, northeastern and southern Kazakhstan, southern Kyrgyzstan, and Tajikistan. Deficits will be moderate overall with some more intense pockets, particularly in Tajikistan. Russia will be drier than normal in a wide path northeast of Kazakhstan following the Mongolian border and reaching Northeast China. Northern Russia, however will be wetter than normal in a vast expanse from the Pechora River in the Arctic reaching past Siberia. Surpluses will be intense in the region of the Lower Lena River.

In South Asia, dry anomalies will extend throughout Afghanistan and into Pakistan’s Northern Areas. India can expect moderate surplus precipitation from northern Rajasthan into Haryana, and in Gujarat. Sri Lanka, however, will be drier than normal with severe to exceptional anomalies in the south. Moderate surpluses are forecast for the interconnecting river regions of southern Bangladesh.

In East Asia, some pockets of moderate deficit are forecast in Mongolia and in Xinjiang, China. Western Tibet will be wetter than normal, as will Qinghai and southern Gansu, and Yunnan in the south and southern Sichuan. A few isolated pockets of moderate deficit are forecast in eastern coastal provinces. Parts of Japan will experience precipitation deficits, moderate in western Hokkaido but severe in some areas of Honshu on the Sea of Japan.

Most of Southeast Asia will be wetter than normal. Sumatra and western Borneo will see drier than normal conditions with severe anomalies overall. Surpluses are forecast for northern Sulawesi, the Maluku Islands, and New Guinea’s north central coast. Moderate deficits are expected in pockets of Papua, Indonesia.

Nearly normal precipitation is forecast for Australia though the Cape Yorke Peninsula can expect moderate surpluses. Conditions in New Zealand will be normal, while New Caledonia will be wetter.

TEMPERATURE OUTLOOK
Notable in the temperature map below is the forecast for warmer than normal temperatures throughout Russia, particularly a vast expanse from the Ural Mountains through Siberia shown in dark red indicating exceptionally hotter conditions - a return period greater that 40 years. Much of Central Asia can expect warm anomalies of varying intensity including extreme anomalies in Kazakhstan north of the capital, Nur-Sultan (Astana) and in eastern Tajikistan; and severe anomalies in western Turkmenistan.

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 t… — 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, warmer than normal temperatures are also forecast, with extreme anomalies in the Hindu Kush of Pakistan and into Jammu and Kashmir in India. Temperatures are expected to be normal in northern Punjab, Pakistan; in the Gangetic Plain; and in most of Nepal, Bhutan, and Bangladesh, with somewhat cooler conditions between Nepal and Bhutan. Warm anomalies will be severe to exceptional in Gujarat, along India’s entire east coast, and in Sri Lanka. India’s Far Northeast will see moderate to severe warm anomalies.

In East Asia, Mongolia and Northeast China can expect severe warm anomalies overall, becoming extreme in eastern Heilongjiang. The Korean Peninsula and Japan will be much warmer than normal with severe to extreme anomalies. Moderately warmer than normal temperatures are forecast for eastern and Southeast China though anomalies may be severe in a pocket of northeastern Jiangxi. Warm anomalies will also be severe at the intersection of Sichuan, Tibet (Xizang), and Yunnan. Somewhat cooler than normal conditions are forecast in northern Tibet. Farther north, Inner Mongolia and eastern Xinjiang will be moderately warmer than the norm.

Myanmar will be warmer than normal, particularly regions along the Bay of Bengal where anomalies will be extreme. In Southeast Asia, pockets of moderately warmer than normal temperatures are expected in Vietnam’s Central Highlands, west of the Tonlé Sap River in Cambodia, several regions of Thailand, and Peninsular Malaysia. From Indonesia through New Guinea however, conditions are forecast to be much warmer including extreme to exceptional anomalies in Sumatra, Sulawesi, and Papua, Indonesia. Likewise, the central Philippines will be exceptionally warmer with anomalies of lesser intensity in the south.

Relatively normal temperatures are forecast for much of Australia though moderate to extreme anomalies are expected near Brisbane and at the tip of the Cape York Peninsula in Far North Queensland. Moderately warmer temperatures are predicted for the southeast from Newcastle past Canberra and in Tasmania, and also in the nation’s southeastern corner. South Island, New Zealand will be moderately warmer than normal, but New Caledonia will be extremely warmer.

Western and Central Europe will see relatively normal temperatures with some moderately warmer conditions in southern France reaching into Spain and the western Alps. Moderate to severe warm anomalies are forecast in southern Italy, and moderate anomalies in the Balkans, particularly widespread in Romania and Bulgaria. In Northern Europe, warm anomalies will be moderate in southern Norway and central Sweden, but will reach extreme intensity in Finnish Lapland. Estonia and Belarus will be somewhat warmer than normal, and primarily moderate warm anomalies are forecast in Western European Russia.

In the Middle East, Turkey, the Caucasus, and the western Levant will be moderately warmer than normal, but the Arabian Peninsula, Iraq, and Iran can expect more intense anomalies. Exceptionally warmer temperatures are forecast for southern Iraq, central Saudi Arabia, and around the Persian Gulf reaching well into Iran through Fars and Kerman Provinces and trailing east.

Warm anomalies ranging from severe to exceptional are forecast for nations along the Gulf of Guinea in Africa, and in the northwest from Mauritania through Mali, Algeria, and nearby regions of neighboring countries. Primarily moderate anomalies are expected elsewhere in the north though anomalies will be extreme on the Mediterranean Coast. Extreme warm anomalies are also forecast for Eritrea and northeastern Sudan. Warm anomalies will also be extreme in Somaliland, and anomalies of greater intensity are forecast in Ethiopia. Other regions with a forecast of warmer temperatures, primarily moderate, include Central African Republic, northwestern Democratic Republic of the Congo, Uganda, Burundi, coastal Kenya, and South Africa. Northern Madagascar will be much warmer than normal with moderate anomalies elsewhere. Cool anomalies are expected in pockets of central and southern Africa including South Sudan, central Tanzania, south-central DRC, and from northern Namibia through central Mozambique.

Canada can expect warmer temperatures that will be moderate to exceptional in Quebec and the eastern provinces, and moderate in Southern Ontario though severe to extreme in the vast northern regions of the province. Manitoba will see severe warm anomalies in the south and extreme to exceptional anomalies north of Lake Winnipeg. Southeastern Saskatchewan will be moderately warmer with more intense anomalies in the north. Anomalies in the nation’s vast northern territories will range from moderate to extreme.

In the United States, the Northern Plains and Upper Midwest can expect severe to extreme warm anomalies with exceptional conditions in eastern North Dakota. The Rockies and the Southwest will be moderately to extremely warmer than normal, most intense in central Colorado and central New Mexico. West Texas will be moderately warmer than the norm, as will the region from Kansas reaching east through northern Ohio. New England will be somewhat warmer than normal, with severe anomalies in southern Maine.

Though normal temperatures will prevail in Mexico’s Gulf states, a vast portion of the north and west can expect to be warmer than normal. Anomalies will be intense in many regions including exceptional anomalies from Durango through northern Guerrero. In Central America, Guatemala and El Salvador will be warmer, with anomalies reaching into Chiapas, Mexico. Warm anomalies of varying intensity are expected in the Caribbean with exceptional anomalies in Jamaica.

Brazil jumps out on the map with a vast extent of exceptionally warmer than normal temperatures in the bulk of the nation. Warm anomalies of lesser intensity - moderate to severe - are forecast in the western portion of the Brazilian Amazon Basin. Elsewhere in South America, warm anomalies of varying intensity are expected to trace a path through the Andes Mountains. Southern Venezuela and southern Colombia will be warmer than normal, as will French Guiana and pockets of Bolivia and Argentina. Central Venezuela will be cooler than normal in the central Orinoco River Watershed.

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 April 2, 2021 which includes forecasts for April 2021 through December 2021 based on NOAA CFSv2 forecasts issued March 25 through March 31, 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.

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