2.0 Climate Forecasts

CLIMATE FORECAST

The Climate Hazards Center (CHC) of the University of California Santa Barbara (https://www.chc.ucsb.edu/) provides GEOGLAM Crop Monitor with global and regional climate outlooks. These assessments are based on weather and seasonal climate forecasts from a variety of international and national sources. Regional climate outlooks in the CM4EW draw attention to abnormal rainfall and temperature conditions (observed and forecast) that may impact food production or pose other risks to society, with a focus on food insecure regions.

 

December 5th, 2019
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Global Climate Outlook

ENSO neutral conditions likely to continue through June 2020 

El Niño-Southern Oscillation (ENSO) conditions are neutral and are most likely to remain neutral through June 2020. The Indian Ocean Dipole (IOD) is in a strong positive state and is forecast to remain positive through the rest of 2019, potentially into January 2020. A positive IOD tends to enhance rainfall in parts of East Africa and suppress rainfall in Australia.

 
East Africa Outlook:

Above-average rainfall is expected to continue across the region along with increased flood risk

Much of East Africa received higher than normal rainfall in the past two months, and average to above-average rainfall is forecast during December. The October to December 2019 season is on track to be one of the top three wettest on record, since 1981, for many areas. Figure 1 (left) shows an outlook for percent of normal October 1st to December 15th rainfall, based on a combination of estimated and forecast amounts. Season-to-date amounts may be 150% to higher than 200% of average.

According to the two-week forecast, issued December 1st, average to above-average rainfall is expected for the first half of December in most in-season areas. Substantially higher than average rainfall is forecast in central and western Kenya, the Lake Victoria region, northern Tanzania, and parts of southern Tanzania. The forecast also shows a potential for atypically high rainfall amounts in northeastern Kenya and southwestern Ethiopia in the second week. In eastern Somalia and southeastern Ethiopia, there is potential for heavy rain and winds associated with a tropical cyclone that may develop during the first week of December. Given the severe impacts of recent flooding on communities across the region, updated forecasts should be monitored.

During December the bulk of rains is expected to move southward and intensify in Tanzania, but some equatorial areas may also see above-average rainfall for the month (Figure 1-right). This outlook is in line with the latest forecast for a positive Indian Ocean Dipole (IOD) mode into January. A strong IOD helped to produce the very wet conditions in October and November. It has recently weakened in strength but is likely to still promote enhanced rainfall in East Africa during the next several weeks.

 

Figure caption: Outlook for October 1st to December 15th, 2019 rainfall and a 30-day forecast. On the left is the UCSB Climate Hazards Center Early Estimate for October 1st to December 15th, based on final CHIRPS for Oct. 1-31, preliminary CHIRPS for Nov. 1-30, and an unbiased GEFS forecast for Dec. 1-15. The image shows how the combined total compares to the 1981-2018 CHIRPS average, in terms of the percent of average. On the right is a 30-day forecast from November 27th. The image shows the forecast difference from average according to five Subseasonal Experiment (SubX) model forecasts available on that day. The anomaly is based on the 1999 to 2016 model average. Skill assessments of SubX can be accessed at http://cola.gmu.edu/kpegion/subx/index.html.

 

Southern Africa Outlook:

Rainfall deficits are expected to continue across central and southern areas

Above-average October to mid-December rainfall is anticipated in northern areas of Southern Africa while below-average amounts are anticipated in some central and southern areas, according to rainfall estimates and a two-week forecast issued December 1st (Figure 1-left). Areas with potential moderate to large deficits, ranging from 50 mm to 100+ mm below average, include southeastern South Africa and Lesotho and also in an area from southeastern Angola into southwestern Zambia, northern Botswana, and the Caprivi Strip in Namibia. Southern Tanzania, Malawi, central and northern Mozambique, and southern DRC are among the areas showing potential for moderate to large season-to-date surpluses. Some of these surpluses are coming from the two-week forecast, which shows above-average rainfall in Tanzania and surrounding areas. Other areas may see mixed conditions during these two weeks. In northern Madagascar, Comoros Islands, and Seychelles Islands there is potential for heavy rain and winds associated with a tropical cyclone that may develop during the first week of December.

The latest 30-day outlook points to a continued tendency for drier than average conditions in southeastern areas and wetter than average conditions northeastern areas (Figure 1-right). While this multi-model forecast is unlikely to depict actual 30-day outcomes, the regional pattern is consistent with other model forecasts that were released in early November and showed below normal December to February rainfall in southern areas. Given the consistency in models and a drier than normal season thus far in parts of South Africa and in Lesotho, the situation remains a concern.

 

Figure caption: Outlook for October 1st to December 15th, 2019 rainfall and a 30-day forecast. Both depict rainfall in terms of the difference from average. On the left is the UCSB Climate Hazards Center Early Estimate for October 1st to December 15th, based on final CHIRPS for Oct. 1-31, preliminary CHIRPS for Nov. 1-30, and an unbiased GEFS forecast for Dec. 1-15. The image shows how the combined total compares to the 1981-2018 CHIRPS average. On the right is a 30-day forecast from November 27th. The image shows the average across five Subseasonal Experiment (SubX) model forecasts available on that day. The anomaly is based on the 1999 to 2016 model average. Skill assessments of SubX can be accessed at http://cola.gmu.edu/kpegion/subx/index.html.

 

Indonesia Outlook

Rainfall deficits are expected to continue across Indonesia

Moderate to large rainfall deficits are possible by mid-December across much of southern and eastern Indonesia, according to preliminary data and a two-week forecast. Here, and in other areas of Southeast Asia, October and November were drier than average. Figure 1 (left) shows an outlook for October 1st to December 15th rainfall in terms of the difference from the historical average.

According to the two-week forecast, issued December 1st, much of southern and eastern Indonesia will continue to see below-average rainfall. Forecast rainfall totals range from 50 mm to 150 mm. Higher amounts and locally wetter than average conditions are forecast in northern and western Sumatra and western Borneo. Wet conditions are also forecast for southern Malaysia and the northern Philippines. Below-average rainfall is forecast in northern and eastern Australia. According to a longer-term outlook, drier than normal conditions will persist through much of December in the southern Indo Pacific region (Figure 1-right).

Figure caption: Outlook for October 1st to December 15th, 2019 rainfall and a 30-day forecast. Both depict rainfall in terms of the difference from average. On the left is the UCSB Climate Hazards Center Early Estimate for October 1st to December 15th, based on final CHIRPS for Oct. 1-31, preliminary CHIRPS for Nov. 1-30, and an unbiased GEFS forecast for Dec. 1-15. The image shows how the combined total compares to the 1981-2018 CHIRPS average. On the right is a 30-day forecast from November 27th. The image shows the average across five Subseasonal Experiment (SubX) model forecasts available on that day. The anomaly is based on the 1999 to 2016 model average. Skill assessments of SubX can be accessed at http://cola.gmu.edu/kpegion/subx/index.html.

For previous forecasts and assessments, please see the report archive page.