Global Precipitation & Temperature Outlook December 2020

3 December 2020

OVERVIEW
The Outlook for December 2020 indicates exceptionally hotter than normal temperatures in Arctic Russia, and severe warm anomalies blanketing much of Canada’s vast northern environs. Arctic regions can also expect more precipitation. Indonesia, India, and south-central Brazil will be much warmer as well.

PRECIPITATION OUTLOOK
In Arctic Russia, precipitation surpluses will range from severe to exceptional, with exceptional conditions in the watersheds of the Olenyok and Khatanga Rivers and east of the Yenisei River around Norilsk and Lakes Keta and Khantayskoye. Surpluses will extend into parts of the Central Siberian Plateau and will be intense near Lensk on the Lena River. Moderate to severe precipitation deficits are forecast from the Middle Volga River Basin through the Transvolga region, reaching across the Ural Mountains. Similar conditions are forecast from the Upper Ob River region through the Tom River Watershed and into the Upper Yenisei River area.

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.

Western Kazakhstan will be moderately drier than normal, as will parts of Uzbekistan and western Turkmenistan. Surpluses are forecast for eastern Kyrgyzstan and Tajikistan.

Surpluses will reach into western Xinjiang, China. Severe to exceptional precipitation surpluses are forecast in northern Qinghai and Gansu Provinces, downgrading in Inner Mongolia. Some moderate deficits are expected in the Middle Yangtze River Basin south of the river, primarily in Hubei Province. In China’s Northeast, moderate precipitation deficits will be widespread with some pockets of severe intensity. Moderate deficits are also forecast for the Korean Peninsula and much of Japan, along with some severe pockets.

Southeast Asia can expect pockets of surplus in central Laos, Vietnam, and peninsular Thailand. Surpluses are forecast in parts of the Philippines, northeastern Borneo (Malaysia), eastern Java, the Lesser Sunda Islands, and New Guinea. Moderate deficits are expected in Sumatra and Borneo’s northwestern quadrant, but conditions may reach severe intensity in a pocket of southwestern Sumatra.

Moderate surpluses are forecast for Western Australia with severe surpluses around Kalgoorlie. Moderate surplus are also expected in pockets across the northern reaches of the nation, and in the east between the Buckland Tableland and Darling Downs in Queensland and near the northeast coast of New South Wales.

South Asia will see some wetter than normal conditions in southern India, western Sri Lanka, northern Bangladesh, eastern Nepal into Bhutan, and northern Afghanistan.

In the Middle East, moderate wet surpluses are forecast for central Iran, Kuwait, and near the Persian Gulf in Saudi Arabia. Primarily moderate deficits are forecast for northwestern Saudi Arabia, northern Syria, and throughout Georgia.

Relatively normal precipitation is expected in most of Europe though surpluses are forecast for Italy, eastern Romania, and southern Norway.

In Africa, surpluses of varying intensity are forecast surrounding Lake Tanganyika, and moderate surpluses in Tanzania, southern Kenya, northern Uganda, Zambia, southeastern Mozambique, and other pockets in the region. Drier than normal conditions are expected in northern and southwestern Angola and western Namibia. Deficits will be intense in southwestern Angola. Other regions with a forecast of some surplus include central Morocco and isolated small pockets spanning the border of Sudan and South Sudan.

In North America, Arctic Canada will see surpluses of varying intensity. Similar conditions are expected in other vast regions of the far north and in northern Manitoba and northwestern British Columbia. Surpluses will be exceptional in BC’s northwestern corner and into the Alaskan Panhandle, moderating as they reach west well past Anchorage. Surpluses are also forecast in northern Alaska west of Barrow and east of Prudhoe Bay. Eastern Canada can also expect wetter conditions in eastern Quebec, New Brunswick, and Nova Scotia.

Wet conditions will reach into Maine, but many other parts of the United States will be somewhat drier than normal including the Northern Plains, Michigan’s Upper Peninsula, the southwestern quadrant of the nation, and Georgia and South Carolina in the Southeast.

Mexico, too, will be moderately drier than normal throughout the bulk of the northwest. Moderate to extreme surpluses are forecast for Costa Rica and moderate surpluses for western Panama. Nearly normal conditions are expected in the Caribbean.

In South America, precipitation surpluses of varying intensity are forecast from Venezuela into the northern reaches of the Amazon Basin in Brazil and many regions of Colombia, Ecuador, and Peru. Surpluses will be exceptional in eastern Colombia, southeastern Ecuador, and pockets of northern Peru. Brazil’s central and eastern states can expect deficits, primarily moderate but reaching severe intensity in pockets of the east. In southern Brazil, moderate to exceptional surpluses are forecast in southern Paraná, Santa Catarina, and northern Rio Grande do Sul. Surpluses will extend west into southern Paraguay and northeastern Argentina. Some moderate deficits are expected in south central Bolivia. Deficits of greater intensity are forecast for Argentina’s northwestern corner along with surpluses slightly east.

TEMPERATURE OUTLOOK
Much of the vast expanse of Arctic Russia and the Central Siberian Plateau will be warmer than normal with exceptionally warmer temperatures in the coastal Arctic. Kazakhstan, southern Mongolia, and Inner Mongolia (China) will be somewhat cooler than normal. Northeast China’s Heilongjiang Province can expect warm anomalies ranging from moderate to extreme. Likewise - though far removed - the eastern Tibetan Plateau will be warmer than normal with exceptionally warmer temperatures in western Yunnan, moderate to extreme anomalies in eastern Tibet, and moderate to severe anomalies in Qinghai. In Japan, central Honshu will be moderately warmer than the norm.

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 Southeast Asia, temperatures will be relatively normal with moderately warmer temperatures in central Vietnam. Warm anomalies are forecast throughout Myanmar, moderate in the east but severe to exceptional in the west. Malaysia, Indonesia, the southern Philippines, and New Guinea will be warmer than normal and extreme to exceptional conditions will be widespread.

Warm anomalies are forecast for Queensland, Australia, moderate overall but intense in Far North Queensland and severe in the east stretching from Brisbane. Intensely warmer temperatures will follow the coast of Top End at the tip of Northern Territory. Moderately warmer temps are expected in the Tanami Desert; near Alice Springs in the Outback; spanning the western edge of the Great Sandy Desert in Western Australia; and in Tasmania’s western half. New Caledonia will be exceptionally warmer.

Warm anomalies of varying intensity will blanket many parts of South Asia including nearly all of India, Sri Lanka, and Bangladesh; vast areas of Pakistan; and a large pocket of Afghanistan surrounding Kabul. Afghanistan’s northern neighbors, Tajikistan and Kyrgyzstan, will also be warmer than normal with extreme anomalies in eastern Tajikistan.

Relatively normal temperatures are forecast overall in the Middle East. The Levant will be moderately warmer than normal with exceptionally warmer temperatures in Cyprus. Some moderate warm anomalies are also expected in pockets of Turkey, particularly in the west, though coastal Antalya Province could be exceptionally warmer. Northern Saudi Arabia will be moderately warmer; anomalies in Riyadh Province in the central south could reach severe intensity; and somewhat cooler than normal conditions are expected in a pocket of the Rub’ al Khali Desert. Intense warm anomalies are forecast in Yemen’s western tip, and moderate warm anomalies in southern Iran.

In Europe, southern Italy will be exceptionally warmer, while moderately warmer temperatures are expected in the north and in Switzerland. The Balkans will be moderately warmer with some severe pockets. Similar conditions are forecast in western Ukraine, Romania, and Bulgaria though the extent of severe anomalies will be greater. Northern Europe will be warmer as well, with primarily moderate anomalies overall in Denmark, Norway, and Sweden, but exceptionally warmer temperatures in northern Finland and Arctic regions of its neighbors.

Warmer than normal temperatures are forecast for many nations in North and West Africa and around the Gulf of Guinea. Conditions will be exceptionally warmer in southeastern Algeria and northeastern Libya, and extremely warmer in northwestern Egypt. The Horn of Africa can also expect to be warmer with exceptional anomalies in southeastern Ethiopia and pockets of Somalia. In the center of the continent, cooler than normal temperatures are forecast for: eastern Central African Republic into Democratic Republic of the Congo (DRC); central DRC; South Sudan into southwestern Ethiopia; and eastern Uganda. Temperatures will be exceptionally cooler in eastern South Sudan. Farther south, Namibia’s central coast regions can expect cooler than normal temperatures.

Though normal temperatures are forecast for many regions in southern Africa, moderately warmer than normal temps are forecast for: western DRC, Rwanda, Burundi, southern Kenya, northern Mozambique, central and southwestern Angola, from Swaziland west past Johannesburg, and Northern Cape, South Africa. Temperatures in most of Madagascar, however, will be much warmer than normal, with exceptional anomalies in the east encompassing the capital, Antananarivo.

In South America, Brazil’s Center-West, Northeast, and Southeast Regions will be much warmer than normal with widespread exceptional anomalies in Tocantins, Goiás, Minas Gerais, and Rio de Janeiro States. From southwestern Bolivia into Argentina, temperatures will be moderately to extremely warmer than normal through the Andes Mountains. Warm anomalies of generally lesser intensity are forecast in other pockets of the continent. Anomalies will be moderate to severe in Guyana, French Guyana, and Suriname; and moderate in northwestern Venezuela, western Colombia, central Ecuador, the central Peruvian Andes, Paraguay, northern Patagonia in Argentina, and border regions of west-central Argentina past Santiago, Chile. A few areas of the continent will be cooler than normal including Los Llanos in Venezuela, the Marañón River Basin in northern Peru, and Madre de Dios Department in southeastern Peru.

Moderately warmer than normal conditions are expected in some pockets of Central America, particularly southern Guatemala. In the Caribbean, eastern Cuba and Dominican Republic will be moderately warmer, but anomalies will be exceptional in Jamaica, extreme in Turks and Caicos, and moderate to severe in other regions.

Mexico’s central Pacific Coast state of Nayarit will be much warmer than normal. In southern Baja, warm anomalies will reach severe intensity, and moderate anomalies are forecast in the north-central states.

The United States can expect warmer than normal temperatures in the Northern Plains States, Rocky Mountain States, parts of the West and Southwest, and New England. Anomalies will be severe to exceptional in the Northern Plains and New England, and moderate to severe in the other regions mentioned.

Though northern Quebec will be spared, much of the remaining extent of Canada will be blanketed with warmer than normal conditions. A vast column of severe warm anomalies will stretch from the southern border regions of the Prairie Provinces reaching north through the northern territories and into the Arctic region. Anomalies will be extreme from southeastern Saskatchewan into Manitoba and south of Great Bear Lake in Northwest Territories. In eastern Canada, warm anomalies will be moderate to extreme in the Maritimes, Newfoundland, and south of the St. Lawrence River. Much of southern Quebec, Southern Ontario, and eastern Northern Ontario will be moderately warmer, with severe anomalies beginning in Ontario’s Kenora District. In western Canada, anomalies will be moderate in British Columbia.

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 December 2, 2020 which includes forecasts for December 2020 through August 2021 based on NOAA CFSv2 forecasts issued November 24 through November 30, 2020.

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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