Global Precipitation & Temperature Outlook for September 2016

September 2, 2016

Overview
Temperature anomalies dominate the September Outlook, especially a wide expanse of exceptionally warmer temperatures in eastern Russia. Exceptionally wetter than normal conditions are forecast for the Taklamakan Desert in western China. (For data sources see "About This Blog Post" below.)

Temperature Outlook
As seen in the Temperature map below, warm anomalies are forecast for many parts of the world, but eastern Russia draws attention with a wide expanse of exceptional (greater than 40 years) warm anomalies. Warm anomalies of lesser severity are forecast for much of the remaining area of the country.

Red also lights up Europe on the map. Moderate to extreme warm anomalies are forecast throughout Central, Eastern, and Northern Europe, which may be particularly widespread and severe in Germany, the Netherlands, and Corsica.

In the Middle East the Arabian Peninsula stands out in dark red. Moderate to exceptional warm anomalies are expected across Saudi Arabia, Yemen, much of Oman, and United Arab Emirates; and also in southern Iraq and southern Iran. Cool anomalies are forecast across northern coastal Turkey.

Warm anomalies are forecast for much of Mongolia and China, Taiwan, the Korean Peninsula, Southeast Asia, Malaysia, and much of Indonesia. In South Asia, warmer than normal temperatures are expected in southern and far eastern India, Bangladesh, Sri Lanka, and western Nepal.

Likewise, warm anomalies are forecast for northern Australia and from Brisbane south to Melbourne; in Tasmania; and New Zealand.

In Africa moderate to extreme warm anomalies are forecast for much of the western and some of the southern region of the continent. Cool anomalies are forecast in South Sudan, central Democratic Republic of the Congo, and northern Kenya.

Much of the US east of the Mississippi River is forecast to experience warmer than normal temperatures, as is eastern Canada, though most anomalies will be moderate. The exceptions: Pockets of extreme warm anomalies are forecast for Michigan's Upper Peninsula, southern Maine, and along the central border of Louisiana and Mississippi.

Cool anomalies are forecast in northeastern Chihuahua, Mexico, while exceptional warm anomalies are expected near Puerto Vallarta. Warm anomalies are also forecast for the Yucatan, Guatemala, Honduras, Costa Rica, Panama, and the Caribbean.

Warm anomalies, including exceptional anomalies, are forecast for a large area of eastern Brazil. Warm anomalies also forecast in Chile and southern Argentina. Much of Bolivia, Paraguay, and the surrounding regions are expected to experience cooler than normal temperatures.

Precipitation Outlook
The deep blue patch in western China on the Precipitation map below indicates a forecast of exceptionally wetter than normal conditions (greater than 40 years expected frequency of occurrence) in the Taklamakan Desert and westward into Tajikistan and Kyrgyzstan. In China's southern provinces of Yunnan, Guangxi, and Guangdong abnormal to moderate wet anomalies are expected which may also reach into northern Myanmar, Laos, and Vietnam. Drier than normal conditions are forecast in Tibet northwest of Nepal in an area that is the source of many of the region's major rivers.

Shades of green and blue on the Precipitation map also call our attention to much of Australia. Modernate to extreme wet anomalies are forecast for much of Australia's eastern two-thirds, with greatest severity in the eastern Outback from northwestern Queensland to central New South Wales.

Severe to exceptional dry anomalies are forecast across northern Turkey, coastal Georgia, and Abkhazia.

In Africa, dry anomalies are expected in Chad, which may be extreme (20 to 40 years) in the southeast. Cameroon's Northwest Province is forecast to be wetter than normal.

Southern Alberta and Saskatchewan in Canada are forecast to be moderately wetter than normal, as is northwestern Minnesota in the US. Moderate dry anomalies are expected in the Lower Mississippi River Basin, which may extend into the Ohio River Basin.

In South America, moderate wet anomalies are forecast in the central Amazon Basin in Brazil; the states of Rio de Janeiro and Paraná in Brazil; Paraguay; and Formosa, Argentina. Moderate to severe dry anomalies are forecast for southern Chile.

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 2, 2016 which includes forecasts for September 2016 through May 2017 based on NOAA CFSv2 forecasts issued August 25 through August 31, 2016.

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.