Global Precipitation & Temperature Outlook for July 2017

3 July 2017

Overview
Though there are several regions with a July forecast of significant precipitation anomalies - India's Western Ghats will be much drier than normal and northern Argentina will be much wetter - the temperature forecast has more severe and widespread anomalies. The African Sahel, Saudi Arabia, and Mongolia are among the numerous regions forecast to see much warmer than normal temperatures.

Precipitation Outlook
India's western coast is forecast to be much drier than normal with extreme to exceptional dry anomalies tracing the Western Ghats from Maharashtra through Goa and Karnataka. Eastern Cambodia can expect conditions nearly as severe, along with a few isolated pockets in central Ethiopia.

Dry anomalies ranging from moderate to severe are expected in a large block of southern British Columbia, Canada, reaching south into Washington state; in Mexico from central Sonora down the western coast to Puerto Vallarta; and also trailing through Oaxaca in the south. Conditions may be extreme near Puerto Vallarta. In South America moderate to severe dry anomalies are forecast in northwestern Peru; in the far western parts of Acre and Amazonas, Brazil; and central Chile into western Argentina.

Other regions of the world where drier than normal conditions are forecast include: Equatorial Guinea; western Kazakhstan, northeastern Turkey; a wide band of south-central India from Maharashtra eastward; central Thailand; and Myanmar's southernmost region of Tanintharyi.

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.

Severe to exceptional wet anomalies are forecast for: northern Argentina from Cordoba north to Bolivia; a band across Venezuela along the Río Orinoco; a band through central Democratic Republic of the Congo to Uganda; and eastern Tajikistan.

Significant wet anomalies are also expected in: the eastern Yucatan Peninsula; Belize; Brazil's easternmost tip; the Lower Yangtze River and the central Pearl River Basin in China; central Myanmar; Seoul, South Korea; and eastern Arnhem Land in Australia's Northern Territory.

Temperature Outlook
The most noticeable warm temperature anomalies on the July forecast map below include extreme to exceptional anomalies extending across Africa's Sahel, southern Africa, and eastern Madagascar; Saudi Arabia, southern Iraq, Turkey, and other parts of the Middle East; southern India; and a vast stretch of Mongolia, northern China, the Korean Peninsula, and Japan.

Moderate to extreme warm anomalies anomalies are expected in a large block of the US Northwest trailing down through the Southwest into Baja and Sonora, Mexico, and northward through much of western Canada. Exceptional warm anomalies are forecast in northern Louisiana. Southern Florida, Connecticut, and Maine are expected to be warmer than normal, and similar temperatures may extend into Nova Scotia, Canada.

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… — 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 reaching extreme intensity are forecast for Mexico's central west coast, southern coast, Yucatan, and into Guatemala, El Salvador, western Honduras, Costa Rica, Panama, and western Cuba.

Similar warm anomalies are expected across northern Brazil, Guyana, Suriname, French Guiana, western Peru, and northern Chile into Bolivia and Argentina.

In Southeast Asia and the Pacific moderate to severe warm anomalies are forecast. Primarily moderate warm anomalies are forecast for Australia's northern half, but more intense warm anomalies are forecast for South Island, New Zealand.

Much cooler than normal temperatures are forecast for central Democratic Republic of the Congo and central South Sudan.

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 July 2, 2017 which includes forecasts for July 2017 through March 2018 based on NOAA CFSv2 forecasts issued June 24 through June 30, 2017.

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.