Global Precipitation & Temperature Outlook September 2019

4 September 2019

OVERVIEW
The September Outlook indicates warmer than normal temperatures in many parts of the world, but anomalies forecast in the northern environs are worth noting. Arctic Russia is expected to be much warmer than normal as are Alaska in the U.S. and Baffin Island, Canada. Xinjiang Province in northwestern China will be much wetter than normal.

PRECIPITATION OUTLOOK
As noted above, northwestern China is forecast to be much wetter than the norm, with anomalies reaching exceptional intensity. Moderate to extreme wet anomalies are expected in southwestern Mongolia as well. China’s southeastern Provinces of Guangdong, Shangxi, and Fujian will be moderately wetter than normal. Wet anomalies are also forecast for South Korea and will be moderate to severe. Exceptional precipitation surpluses are forecast for coastal Myanmar; some moderate wet anomalies are forecast elsewhere in Southeast Asia.

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.

Precipitation in Malaysia and Indonesia will be significantly less than normal, especially in Malaysia. Moderate precip deficits are forecast for New South Wales and Queensland in eastern Australia.

In South Asia, moderate to extreme wet anomalies are forecast for northwestern India from Gujarat into western Uttar Pradesh, and along India’s western coast trailing south to Kerala. Anomalies will be extreme in Haryana. Severe dry anomalies are forecast at the northern borders of Uttar Pradesh and Bihar near Nepal. Northwestern Pakistan will be wetter than normal with moderate to severe anomalies and these conditions will reach across the border to Kabul, Afghanistan.

Central Asia can expect moderately drier than normal conditions in western Kazakhstan along with some severe pockets. Primarily moderate dry anomalies are expected in Russian regions northwest of the Caspian Sea and in much of the Volga River Basin and part of the Ob Basin. Moderate wet anomalies are forecast for southeastern Kazakhstan, Kyrgyzstan, and northwestern Tajikistan. Dry anomalies are expected across northern Turkey and into western Georgia and could reach extreme to exceptional intensity along the eastern shore of the Black Sea.

In the Middle East, some pockets of primarily moderate wet anomalies are forecast in Syria and northern Iraq, and severe wet anomalies in eastern Oman. Some wet anomalies are also forecast for southwestern Saudi Arabia along with dry anomalies in southern Riyadh Region.

On the African continent, wetter than normal conditions are forecast for: Uganda and western Kenya; pockets of southern and eastern Ethiopia; Somalia; northern Algeria and Tunisia; and pockets of Cameroon, coastal Nigeria and its western neighbors, and Congo and Democratic Republic of the Congo. Areas with a forecast of moderate dry anomalies include pockets of Zimbabwe, Madagascar, Chad, and Sudan.

The outlook for Europe indicates moderate to severe wet anomalies in the Czech Republic and surrounding areas of Austria and Germany as well as a pocket around Malmo, Sweden.

The U.S. Rocky Mountain States can expect moderately wetter than normal conditions which will reach into Nevada and Arizona. Wet anomalies of similar intensity are forecast around Bristol Bay, Alaska. Moderate dry anomalies are forecast for Alabama, trickling northeast into West Virginia. Relatively normal precipitation is expected in Canada with some moderately wetter than normal conditions in the Moose River region of northern Ontario.

Northern Baja, Mexico will be moderately wetter than normal. Dry anomalies are expected in southern Mexico from the Gulf of Mexico through Nicaragua with intense conditions around the Bay of Honduras. Moderate wet anomalies are forecast for western Panama. Haiti and Jamaica will be drier than normal.

In South America, dry anomalies are forecast along a path following the Andean Range from Venezuela through Ecuador, with intense anomalies around Caracas, and anomalies of varying intensity from there leading southwest through central Colombia and in much of Ecuador. Moderate to severe dry anomalies are expected from northern Guyana through Suriname, French Guiana, and across Amapá, Brazil. Primarily moderate dry anomalies are expected in scattered pockets of central and southwestern Brazil, central Peru, pockets of Bolivia, central and southern Chile and across the border into Argentina. Anomalies may be severe in southern Chile. Moderate wet anomalies are forecast for northern Santa Catarina State in southern Brazil and a pocket in Maranhão State in northeastern Brazil.

TEMPERATURE OUTLOOK
Temperatures across nearly all of Russia are forecast to be warmer than normal, with anomalies in Arctic Russia ranging from severe to exceptional; anomalies in European Russia primarily severe to extreme; and moderate anomalies elsewhere. As in European Russia, temperatures in Eastern Europe will be warmer than normal, including extreme to exceptional anomalies in Ukraine. Primarily moderate warm anomalies are forecast for Finland, southern Norway, the Baltics, Denmark, Poland, Slovakia, and Hungary, though some severe pockets are also possible. Moderately cooler than normal temperatures are expected in western Aragon, Spain, and moderately warmer conditions along the southern border of Spain and Portugal.

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.

Warm anomalies of varying intensity are forecast across the Sahara Desert in northern Africa and exceptional anomalies in the Sahel. Warm anomalies reaching exceptional intensity are also forecast in the Ethiopian highlands and eastern Ethiopia, and in a path from southern Somalia through southern Kenya, Tanzania, northern Mozambique, and across the Mozambique Channel into Madagascar’s northern half. Also in the region, warm anomalies are forecast for Kenya’s northwestern corner and northern Tanzania. Pockets of moderately warmer than normal temperatures are expected in southern Africa, and warm anomalies ranging from moderate to extreme in the west around the Gulf of Guinea from Guinea through westernmost Democratic Republic of the Congo (DRC). Anomalies will be severe to extreme in Guinea, Sierra Leone, Cameroon, Equatorial Guinea, and coastal Gabon, Congo, and DRC. Warm anomalies will also reach into the center of the continent in Central African Republic and southern Chad, but much cooler than normal temperatures are forecast for eastern South Sudan and moderate cool anomalies in eastern Uganda and southeastern DRC.

In the Middle East, severe to exceptional warm anomalies will blanket much of the Arabian Peninsula reaching into western and southern Iraq and around the Persian Gulf in Iran. Moderate warm anomalies are expected in the Levant. Conditions in Turkey are forecast to be cooler than normal along the Black Sea Coast but warmer than normal in the south.

In Central and South Asia, cooler than normal temperatures are expected in Kyrgyzstan and from western Afghanistan into eastern Turkmenistan. Intense warm anomalies are forecast for southern Pakistan, including Karachi. Primarily moderate warm anomalies are forecast for India’s southern third and in Odisha on the Bay of Bengal; severe anomalies in the Far North; and severe to extreme anomalies in the northeast. Northeastern Uttar Pradesh is expected to be much cooler than normal, and cool anomalies are also forecast for eastern Rajasthan. Western Nepal will be much warmer than the norm, and warm anomalies are also forecast for Bhutan and Bangladesh.

Much of the Tibetan Plateau in China will be exceptionally warmer than normal; moderate to severe warm anomalies are forecast for northeastern China and the Korean Peninsula; and moderate warm anomalies in southeastern China. In Japan, primarily moderate warm anomalies are expected. Southeast Asia can expect temperatures above normal as well, with anomalies ranging from moderate to severe.

Intense warm anomalies are forecast for peninsular Malaysia, Sumatra, Indonesian Borneo, and parts of Java.

Warmer than normal temperatures are forecast for much of Australia, with moderate anomalies overall; severe anomalies in a vast expanse at the intersection of Northern Territory, South Australia, Queensland, and New South Wales; and severe to exceptional anomalies in the east from Rockhampton through Brisbane and south to Sydney.

In North America, warmer than normal temperatures are forecast for a vast area reaching from Alaska through Canada’s western territories and provinces, and throughout the western U.S., and will be intense in coastal Alaska, southern Yukon, and pockets of the U.S. Southwest. Northern Nunavut Territory in Canada is expected to be much warmer than normal, including Baffin Island. Warm anomalies are also forecast for Greenland. In the U.S., severe warm anomalies are forecast for southern Florida and a pocket in northeastern Louisiana.

Cooler than normal conditions are expected in northwestern mainland Mexico, but the Baja Peninsula can expect severe warm anomalies. Intense warm anomalies are forecast along the Pacific Coast from Nayarit to Acapulco, and around the Gulf Coast, southern states, and Yucatan. Severe to exceptional warm anomalies are forecast in Central America and in many regions of the Caribbean.

In South America, warm anomalies of varying intensity are forecast for many parts of the northern half of the continent, moderate overall but with numerous intense pockets. Areas of extreme to exceptional anomalies include: Mato Grosso, northern Tocantins, and Amapá, Brazil; northern Guyana and French Guiana; central Colombia north of Bogotá; western Ecuador surrounding Quito; and throughout the Cordillera Central Mountains in Peru. Severe warm anomalies are forecast for the Atacama Desert region of northern Chile. Cooler than normal temperatures are expected in the center of the continent in central Bolivia, Paraguay, northeastern Argentina, Uruguay, and Rio Grande do Sul, Brazil. Anomalies will be extreme in northern Santa Fe Province, Argentina and at the intersection of Bolivia, Paraguay, and Argentina.

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 September 3, 2019 which includes forecasts for September 2019 through May 2020 based on NOAA CFSv2 forecasts issued August 25 through August 31, 2019.

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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Many analyses reported in ISciences-authored blog posts are based on data generated by the ISciences Water Security Indicator Model (WSIM). Other sources, if used, are referenced in footnotes accompanying individual posts. WSIM is a validated capability that produces monthly reports on current and forecast global freshwater surpluses and deficits with lead times of 1-9 months at 0.5°x0.5° resolution. This capability has been in continuous operation since April 2011 and has proven to provide reliable forecasts of emerging water security concerns in that time-frame. WSIM has the ability to assess the impacts of water anomalies on people, agriculture, and electricity generation. Detailed data, customized visualizations, and reports are available for purchase.

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