Consolidated Seasonal Rainfall Guidance for Africa, June 2013 Initial Conditions

Issued 9 July 2013

• Forecast maps

• Forecast Background– ENSO update– Current State of the global climate– SST Forecasts

• Summary

Methodology• The forecasts are subjectively derived from canonical correlation analysis

(CCA) seasonal forecast runs, the NCEP CFS, the National Multimodel Ensemble (NMME) forecasts, and the International Multimodel Ensemble (IMME) forecasts

• Polygons are drawn for areas, where there is an agreement between the models to tilt the odds to favor one category over another. Preference is sometimes given to the CCA when skill is moderate to high.

• The NMME models include: the NOAA CFS, the Canadian models, NOAA GFDL, NCAR, NASA

• The IMME models include: the ECMWF, the UK MO, and Meteo France

• Forecasts are expressed in probabilistic terms to convey uncertainty.

Seasonal Rainfall Guidance for Africa, Jun IC, Issued 9 July 2013, Valid Jul-Sep 2013 and Aug-Oct 2013

Jul-Sep 2013, Zero Month lead Aug-Oct 2013, One Month lead

For Jul-Sep, the forecasts call for a slightly elevated chance for above average rainfall over the central areas of the Sahel, including eastern Burkina Faso and southwestern Niger.

For Aug-Oct, there is an increased chance for above average rainfall over western Kenya and eastern Uganda.

Seasonal Rainfall Guidance for Africa, June IC, Issued 9 July 2013, Valid Sep-Nov 2013 and Oct-Dec 2013

Sep-Nov 2013, Two Months lead Oct-Dec 2013, Three Months lead

For both Sep-Nov and Oct-Dec, the forecasts call for an elevated chance for above average rainfall over western Kenya and eastern Uganda.

CPC ENSO Update

• CPC ENSO Alert System Status: Not Active(updated 5 July 2013)

• Synopsis: ENSO-neutral is favored through the Northern Hemisphere summer 2013.

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml

Below normal SST persisted across the eastern Pacific.

SST was slightly above-average across the equatorial Atlantic.

Current State of the Global Ocean

SST Anomaly (top) for June 2013 and Tendency (bottom) for June minus May

SST tendency was negative over Bay of Arabian Sea and Bay of Bengal, while positive tendencies were observed over central and southern Indian Ocean.

Positive SST anomalies persisted across western Pacific and eastern Indian Ocean.

SST tendency was positiveAcross portions of equatorial easternPacific.

Last Month

SST slightly decreased Across southwestern Indian Ocean

SST was belownormal in the equatorial easternPacific.

Positive SST anomalies persisted in the eastern sector of the tropical North Atlantic.

Current State of the Global Ocean

Positive SST anomalies were present in the eastern Indian Ocean and western Pacific.

Weekly SST Anomaly 30 June – 6 July 2013 andTendency for 30 June – 6 Jul minus 23 – 29 June

SST tendency was positive over the eastern tropical Pacific.

Last Week

OLR Anomaly, June 2013

Negative OLR anomalies (enhanced convection and precipitation, blue shading) were observed over India, the Arabian Sea and Bay of Bengal, parts of the Maritime Continent region, extending into eastern Indian Ocean and Australia, and portions of Peru, Bolivia and Brazil.

Precipitation was suppressed (orange-red shading) over equatorial Africa, Central Indian Ocean, and the tropical central and eastern Pacific.

Low Level 850 mb Wind Anomaly

Stronger than normal cross-equatorial flow was observed over northwestern Indian Ocean. Weak easterly (westerly) wind anomalies were present over the equatorial western (eastern) Pacific.

There was an amplification of the subtropical ridges across both hemispheres over the Atlantic as evidenced by the anomalous anticyclonic circulation in the northern and southern Atlantic.

200hPa

Upper Level 200 mb Wind Anomaly

The 200 hPa wind anomaly map features a strengthening of the Mascarene high pressure system with the presence of an anomalous anticyclonic circulation over the southern Indian Ocean. Also, noticeable is the strengthening of the Tibetian High as evidenced by the anomalous anticyclonin circulation over Asia and Africa.

Time

Longitude

Monitoring the Madden Julian Oscillation

Moderate MJO has been observed over the past several weeks.GEFS bias corrected indicates a gradual weakening of the current MJO signal.

Summary of State of the Global Ocean in June 2013

• Neutral ENSO state continued to prevail in June. Equatorial sea surface temperatures (SST) anomalies were slightly negative across the eastern Pacific.

• Positive SST anomalies but weakened over the tropical North Atlantic and the western Pacific. SST was above normal over the south central Indian Ocean, but below normal along coastal East Africa.

• SST anomalies over the past week featured warming along coastal West Africa and cooling over the equatorial eastern Pacific.

• Precipitation was significantly above average over India and parts of southeast Asia, while moderately enhanced over portions of tropical central Africa. Precipitation was suppressed along the Gulf of Guinea and parts of equatorial central Africa.

- Most of the models predicted ENSO-neutral in the coming Northern Hemisphere summer and autumn.- The consensus forecast favors ENSO-neutral conditions in the summer-autumn 2013.

IRI/CPC NINO3.4 Forecast Plume

Global SST Outlook: NCEP CFS.v2 Forecast Initial Conditions 21 – 30 June 2013

Jul-Sep 2013

Aug-Oct 2013

Sep-Nov 2013

Oct-Dec 2013

Caution: Ocean areaswith skill less than 0.3are shaded in gray

CFS.v2 predicts neutral ENSO conditions to persist through the northern hemisphere fall season. Additional forecast resources are found here:http://www.cpc.ncep.noaa.gov/products/african_desk/cpc_intl/index.shtmlhttp://origin.cpc.ncep.noaa.gov/products/people/wwang/cfsv2fcst/

Nov 2013-Jan 2014

Global SST Outlook: NMME (left) and IMME (right)JAS JAS

ASO ASO

http://www.cpc.ncep.noaa.gov/products/NMME/seasanom.shtml

JAS JAS

ASO ASO

http://www.cpc.ncep.noaa.gov/products/NMME/seasanom.shtml

Global Precipitation Outlook: NMME (left) and IMME (right)

Summary• Neutral El Nino Southern Oscillation (ENSO) conditions continue to

prevail. Sea surface temperature (SST) was slightly above normal along coastal West Africa and over the western Pacific.

• SST predictions favor ENSO-neutral to continue through the northern hemisphere summer and autumn of 2013.

• Precipitation forecasts are mostly driven by regional SST and not ENSO. They are expressed in probabilistic terms to convey uncertainty.

• Additional forecast resources can be found here: http://www.cpc.ncep.noaa.gov/products/african_desk/cpc_intl/index.shtmlhttp://www.cpc.ncep.noaa.gov/products/NMME/http://origin.cpc.ncep.noaa.gov/products/people/wwang/cfsv2fcst/