Exceptionally high temperatures are expected to dominate the global outlook for July 2015. (For data sources see "About this blog post" below.) As visualized in the first map below which lights up in red, many areas of the world may see much higher than normal temperatures including: Western US and Canada; Central America, west coast of South America, and Brazil; much of Europe; southern Africa; northeast India and Myanmar; Indonesia and Malaysia; and, northeast Siberia.
Temperature outlook for July 2015. 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.
The July outlook for global precipitation (below) shows both exceptional surpluses and deficits. Large areas of the US Southwest, US Central Plains, and northwestern Mexico are expected to be wetter than normal, with some areas of exceptional wetness as indicated by the dark blue areas. In contrast, extreme dryness is forecast for southern Mexico, parts of Central America, and parts of northern South America. Surpluses are expected in Western Amazonia and southern Brazil. As we switch our attention to the rest of the world, precipitation deficits (dryness) are forecast for: Central and Eastern Europe; the Horn of Africa and Yemen; Indonesia, Malaysia, Papua New Guinea, the Philippines, and northern China. Precipitation surpluses (wetness) are expected in northern Australia.
Precipitation outlook for July 2015. 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.
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, 2015 which includes forecasts for July 2015 through March 2016 based on NOAA CFSv2 forecasts issued June 24 through June 30, 2015.
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.