Global Precipitation & Temperature Outlook October 2020

2 October 2020

OVERVIEW
The October Outlook indicates warmer than normal temperatures in many regions around the world, notably the U.S. West where conditions will be exceptionally warmer in the Southern Rockies, Southwest, and Southern California. Central and Northern Europe can expect to be wetter than normal and the Tibetan Plateau will be drier.

PRECIPITATION OUTLOOK
Much of Central and Northern Europe will see precipitation surpluses. In France, surpluses will range from moderate to severe along with some extreme pockets, and conditions will reach into Switzerland, western Germany, Luxembourg, and Belgium. The U.K. and Denmark will be moderately wetter than normal but Sweden and southeastern Norway can expect surpluses to reach severe or extreme intensity. Spain’s northern coast will be moderately to severely wetter than normal. Around the Mediterranean, southern Italy and southern Greece will see moderate to severe precipitation deficits.

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.

Generally mild precipitation deficits are forecast for the Middle East with moderate to severe pockets in north-central Saudi Arabia; the intersection of Iraq, Jordan, and Saudi Arabia; southeastern Oman and southwestern Yemen; and along the eastern coast of the Black Sea in Turkey and Georgia.

Northern Africa will see mild precipitation deficits punctuated by moderate deficits in Tunisia, across the border into Algeria, and in northeastern Libya. Eritrea, the Ethiopian Highlands, and Somaliland will be moderately drier than normal. Dry pockets of great intensity are forecast near Sudan’s border with Ethiopia and in South Sudan spanning the central Ethiopian border. Precipitation surpluses are expected from southeastern South Sudan into Uganda, Kenya, and Tanzania - primarily moderate but more intense in South Sudan. Mozambique will see mild precipitation surpluses. Mild surpluses are also predicted in pockets around the Gulf of Guinea and in the southern Sahel. Surpluses are also forecast from Cameroon through coastal Congo and will be extreme to exceptional from southern Gabon into Republic of the Congo.

In South Asia, India’s Far North will be drier than normal with severe deficits, while scattered moderate deficits are expected elsewhere in the north and in the Gangetic Plain. Precipitation deficits in Nepal and Bhutan are expected to be widespread and will reach extreme intensity in some regions.

In China, the Tibetan Plateau will be dry with deficits ranging from moderate in the west to exceptional in the central and eastern regions. Precipitation surpluses are forecast from Shanghai reaching inland in a broad path through the southern reaches of the North China Plain past the Qinling Mountains and into eastern Qinghai. Surpluses will be severe in the mountain region of Shaanxi. Guizhou in southwest China will be moderately drier than normal. Hainan in the south will be wetter. Conditions on the Korean Peninsula will be moderately drier. Likewise, much of Japan will be somewhat drier than normal with some surpluses north of Sapporo in Hokkaido.

Generally moderate precipitation surpluses are forecast for Vietnam, southern Laos, and eastern Thailand. Some pockets of moderate surplus are expected in the northern Philippines and Indonesia.

The precipitation forecast for Australia indicates surpluses in the Kimberley Plateau reaching extreme intensity, and generally mild surpluses from South Australia into Western Australia. Some mild deficits are expected in North Island, New Zealand.

In Russia, mild to moderate precipitation deficits are forecast in the northwest from the White Sea to the Pechora Sea and in the Ob River Basin. The Kamchatka Peninsula in the far east will be moderately drier. Some pockets of mild surplus are expected across the Arctic.

In South America, scattered pockets of surplus are forecast in an arc across the northern nations. The bulk of central and southern Brazil will be drier than normal with moderate deficits overall but deficits will be severe in Mato Grosso and Mato Grosso do Sul. Moderate deficits will reach into eastern and central Bolivia and across the border into Paraguay as well. In Peru, drier than normal conditions will extend through the Cordillera Oriental Range, but some surpluses are expected in southern Peru from Cusco to Lake Titicaca. Central Chile will be moderately drier than normal. Argentina’s Chaco region in the north will be moderately wetter, as will coastal Rio Grande do Sul in southern Brazil.

In Central America, moderate precipitation surpluses are forecast for Costa Rica and moderate deficits for Honduras, El Salvador, and Guatemala.

Southern Mexico will be drier than normal with extreme to exceptional deficits in the Balsas River Watershed of Michoacán and Guerrero, and severe deficits around the city of Oaxaca and in coastal Chiapas. Moderate deficits are forecast in northern states along the Gulf of Mexico. The Yucatan will be wetter along its Gulf Coast.

Drier than normal conditions are forecast in a vast expanse of the U.S. covering all of Texas and reaching north through the Southern Plains into Iowa, and east through Louisiana, Arkansas, Mississippi, and the Lower Ohio River Basin into the Mid-Atlantic States. Deficits will be moderate overall with severe pockets in Tennessee, Louisiana, and eastern Texas. In Alaska, conditions near Kodiak in the south will be moderately wetter than normal, while moderately drier conditions are expected south of Fairbanks between the Tanana and Susitna Rivers.

The precipitation outlook for Canada is nearly normal with some moderate deficits in Nova Scotia.

TEMPERATURE OUTLOOK
The U.S. West will be warmer than normal with exceptionally warmer temperatures in California, Nevada, Utah, Arizona, Wyoming, Colorado, and New Mexico. Anomalies will be only slightly less intense from the Pacific Northwest through western Montana. Mild warm anomalies are forecast for the Northern Plains States and normal temperatures for much of the rest of the contiguous U.S. Alaska will be moderately warmer than the norm.

Western Canada is expected to be warmer than normal with moderate anomalies dominating but severe to extreme anomalies in southern British Columbia. On the other side of the country, eastern Quebec will be moderately warmer than normal with severe anomalies spanning the border with Labrador. Warm anomalies will be severe in Newfoundland and moderate in New Brunswick and Nova Scotia.

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 Mexico, exceptionally warmer than normal conditions are forecast for Baja and across the Gulf of California into northwestern Sonora. Temperatures will also be significantly warmer along the central Pacific Coast and will include exceptional anomalies in Nayarit. Southern Chihuahua will be moderately warmer than the norm. Somewhat cooler than normal temperatures are forecast in a path down the center of the nation with a large pocket around Mexico City. The eastern Yucatan will be moderately warmer than normal.

Many regions of Central America and the Caribbean will be warmer than normal, and anomalies will be exceptional in the Bahamas, Haiti, Jamaica, and central Nicaragua.

In South America, the bulk of central and eastern Brazil is forecast to be warmer than normal with exceptional anomalies in Tocantins and severe anomalies in Ceará, Mato Grosso, central Goiás, Mato Grosso do Sul, and northern São Paulo State. Warm anomalies of varying intensity will trace a path following the Andes Mountains from northwestern Venezuela through the Atacama Desert in Chile. Anomalies will be exceptional from western Bolivia into northern Chile and Argentina, and in the south-central Andes in Peru. Paraguay will be moderately warmer than normal with anomalies reaching through eastern Bolivia and into the western Brazilian states of Acre and Amazonas. Cooler than normal temperatures are forecast in the Marañón River Basin in northern Peru and also in Patagonia.

Western Europe can expect nearly normal temperatures but conditions in Scandinavia, Finland, the Baltics, Eastern Europe, and the Balkans will be warmer than normal. Anomalies will be extreme in the Baltics and severe in eastern Europe and much of the Balkan region. Some intense warm anomalies are also forecast in southern Italy and along Spain’s Mediterranean Coast south of Valencia.

The vast expanse of northern Africa be warmer than normal with extreme to exceptional anomalies in Algeria, northern Mali, northeastern Egypt, and northern Sudan. Intense warm anomalies are also forecast for Eritrea, Somaliland, and parts of Ethiopia. South Sudan will see much cooler than normal conditions, and cooler than normal temperatures are also forecast along its border with Sudan. Eastern Uganda will be moderately cooler than the norm, while neighboring Kenya can expect exceptionally warmer temperatures in its northwest corner and in the southeast.

Warm anomalies will continue from Kenya through eastern Tanzania into northern Mozambique and will be severe to exceptional. Likewise, much of Madagascar will see intense warm anomalies. Elsewhere in Africa, warm anomalies ranging from moderate to extreme are forecast from Guinea, around the Gulf of Guinea, reaching inland into central Africa, and continuing south through nearly all of Angola. Zambia and western South Africa will also be warmer than normal.

In the Middle East, intense warm anomalies will dominate in the Levant and west of the Euphrates River in Iraq. Warm anomalies of varying intensity are expected in Turkey and much of Saudi Arabia, and exceptional anomalies in Yemen. Western Oman will be warmer than normal. Warm anomalies will be intense around the Persian Gulf and reaching inland into Iran.

Nearly normal temperatures are forecast in central Asia, but moderate to severe warm anomalies are forecast for European Russia and moderate to exceptional anomalies in the east from the Laptev and East Siberian Seas in the Arctic to the Sea of Okhotsk.

In South Asia, temperatures will be much warmer than normal in southern India, Sri Lanka, and coastal Pakistan and Gujarat. Severe warm anomalies are forecast in Indian regions along the Bay of Bengal from Andhra Pradesh through Odisha, moderating in West Bengal. India’s Far North and Far Northeast will also be warmer, but Eastern Uttar Pradesh will be much cooler than normal. Warm anomalies of varying intensity are expected in much of Nepal, Bhutan, and Bangladesh.

Likewise, warm anomalies are expected in Southeast Asia, the Philippines, Indonesia, and Papua New Guinea. Anomalies will be exceptional in many regions including Myanmar, northwestern Thailand, southern Cambodia through the Mekong Delta, the Philippines, and Sumatra.

Though much of China will see normal temperatures, a vast region encompassing the Tibetan Plateau, western Sichuan, and Yunnan can expect intense warm anomalies. Southeastern China will be moderately warmer than normal from Shanghai through Fujian, but anomalies in Taiwan will be exceptional. Southwestern Mongolia will be moderately cooler than the norm and most of Japan will be moderately warmer.

Australia, too, will be warmer than normal in many regions. Moderate to severe anomalies are forecast in the southeast and Tasmania. A pocket west of Brisbane will be extremely warmer than normal. South Australia will be moderately warmer with conditions becoming more intense through the Outback, and reaching exceptional intensity in Northern Territory in a block near Katherine. Warm anomalies will also be intense in Western Australia’s Kimberley Region. Conditions in New Zealand will be moderately warmer than normal, especially on South Island.

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 October 2, 2020 which includes forecasts for October 2020 through June 2021 based on NOAA CFSv2 forecasts issued September 24 through September 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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