Global Precipitation & Temperature Outlook for April 2017

3 April 2017

Overview
The April 2017 Outlook indicates much wetter than normal conditions in mainland Southeast Asia and Russia's Central Siberian Plateau. Temperatures are forecast to be warmer than normal in many parts of the world, particularly across much of Russia, Alaska, the Arabian Peninsula, and southern India.

Precipitation Outlook
The precipitation forecast for April shows moderate to extreme wet anomalies stretching across much of northern Russia, which are expected to be particularly extensive in the Central Siberian Plateau. Moderate to extreme wet anomalies are also projected for Thailand, southern Laos, Cambodia, southern Vietnam, and eastern Borneo

In South America wet anomalies of varying severity are expected in an arc extending from northwestern Bolivia down through north-central Argentina to the country's central coast in southern Buenos Aires province. Moderate wet anomalies are forecast for Paraguay, and scattered wet anomalies are forecast in a line through central Ecuador into northern Peru.

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.

Drier than normal conditions are forecast in a patchwork across central Africa. These anomalies are forecast to reach exceptional severity in northeastern Democratic Republic of the Congo and Rwanda, surrounded by moderate to severe dry anomalies in Uganda, Burundi, northern Tanzania, Kenya, southern South Sudan, and southern Ethiopia.

Moderate dry anomalies are forecast for southern Saudi Arabia, Yemen, south-central Iran, southern Afghanistan, Turkey's north central coast, Java, and a wide swath reaching from Shanghai, China into the central interior provinces. Moderate to severe dry conditions are expected in Australia's southwestern tip, and in a pocket of northern Brazil's Roraima state.

Temperature Outlook
The vast meandering dark red blob on the temperature map below immediately captures our attention, indicating an expanse of exceptionally warmer than normal temperatures across Russia's Central Siberian Plateau and across the Bering Strait into Alaska, Yukon Territory, and Northwest Territories. Much of the remaining expanse of northernmost regions of the world is forecast to experience moderate to extreme warm anomalies stretching throughout northern Europe, Western European Russia, Mongolia, Northeast China, and much of Canada. Moderate warm anomalies are forecast for much of Europe with severe anomalies in Eastern Europe.

Extreme to exceptional warm anomalies are expected on the Arabian Peninsula; southern India; southern Myanmar; Sulawesi and West Papua, Indonesia; eastern Madagascar; northern Democratic Republic of the Congo; Niger; Sardinia and Corsica, Italy; Puerto Rico; the southern Cordillera Central Mountains in Peru and into Bolivia; and Brazil's eastern tip.

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 of varying severity are forecast in Africa from the Mediterranean through the southern Sahel; Cameroon, Gabon, Congo; and southern Namibia and South Africa.

Moderate to extreme warm anomalies are expected in the US from the Rockies to the Gulf Coast states and seeping through northern Mexico down to Jalisco, picking up again in Chiapas, Tabasco, and Yucatan. Temperatures in Guatemala and Belize are forecast to be moderately to severely warmer than normal, as is much of the northern half of South America.

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 April 3, 2017 which includes forecasts for April 2017 through December 2017 based on NOAA CFSv2 forecasts issued March 25 through March 31, 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.