Regional Rainfall Forecast maps Summary Consolidated Seasonal Rainfall Guidance for Global Tropics, April 2015 Initial Conditions Issued 10 April 2015 Forecast Background ENSO update Current State of the global climate SST Forecasts Regional Rainfall Forecast maps Summary

CPC ENSO Update CPC ENSO Alert System Status: El Niño Advisory Synopsis: There is an approximately 70% chance that El Niño will continue through Northern Hemisphere summer 2015, and a greater than 60% chance it will last through autumn. (Updated on April 9, 2015) http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml

Current State of the Global Ocean Last Month SST Anomaly (top) for March 2015 and Tendency (bottom) for March 2015 minus February 2015 Positive SST anomalies were observed across the central and southern Indian Ocean. Equatorial SSTs were above average across the western Pacific. SST tendency was positive across the western and southern Indian Ocean. Changes in equatorial SST anomalies were negative across the equatorial Pacific.

Current State of the Global Ocean Last Week Weekly SST Anomaly 29 March – 4 April 2015 and Tendency for 29 March – 4 April 2015 minus 22 - 28 March 2015 SST was above average across the equatorial eastern and central Pacific, with larger anomalies present near the Date Line. Positive SST anomalies were present over much of the Indian Ocean. SST tendency was positive over the western Indian Ocean. Positive SST tendency was observed over the eastern Pacific.

OLR Anomaly, March 2015 Negative OLR anomalies (enhanced convection and precipitation, blue shading) was observed along the Gulf of Guinea coastline, central Africa, and parts of southern Africa. Convection was also enhanced over western Australia, the central Pacific, and parts of South America. Precipitation was suppressed (orange-red shading) over northern southern Africa, eastern Indian Ocean, the Maritime Continent, and the eastern Pacific Ocean. .

Low Level 850 mb Wind Anomaly Anomalous low-level (850-hPa) westerly winds were located over the western and central equatorial Pacific.

Upper Level 200 mb Wind Anomaly Anomalous upper-level (200-hPa) westerly winds were apparent over the eastern Pacific, while anomalous easterlies were observed near the Date Line.

Monitoring the Madden Julian Oscillation Time The GFS ensemble RMM Index forecasts depict a weakening of the signal over the next week, as destructive interference grows between the ENSO signal and the subseasonal variability. Recently, eastward propagation of a strong negative (positive) OLR anomalies propagating over the Maritime Continent and far West Pacific. Negative anomalies persisted near the Date Line. 8

Evolution of Indian Ocean SST Indices The Indian Ocean Dipole (IOD) returned to near average values in late March and early April, with the latest weekly index value as of 5 April 2015 0.05 °C.

Summary of State of the Global Climate in March 2015 El Niño conditions are present. The most recent Ocean Nino Index (ONI) value (January – March 2015) is 0.6oC. Positive sea surface temperature (SST) anomalies continued across the central Pacific. Above-average SSTs were observed across the central and southern Indian Ocean. The Indian Ocean Dipole (IOD) returned to near neutral values in late March and early April. Enhanced precipitation was observed along the Gulf of Guinea coastline, central Africa, and parts of southern Africa. Convection was also enhanced over western Australia, the central Pacific, and parts of South America. Convection was suppressed over northern southern Africa, eastern Indian Ocean, the Maritime Continent, and the eastern Pacific Ocean.

Eq. Subsurface temperature Anomalies Nino region SST departures The latest weekly SST departures : Recently, negative anomalies in the eastern Pacific have diminished in strength and extent. Niño 4 0.9ºC Niño 4 = 1.1ºC Niño 3.4 = 0.7ºC Niño 3 = 0.6ºC Niño 1+2 = 1.4ºC Niño 3 0.9ºC Niño 1+2 0.5ºC

IRI/CPC NINO3.4 Forecast Plume Season La Niña Neutral El Niño MAM 2015 ~0% 26% 74% AMJ 2015 29% 71% MJJ 2015 1% 70% JJA 2015 2% 69% JAS 2015 30% 68% ASO 2015 3% 33% 64% SON 2015 5% 34% 61% OND 2015 6% 60% NDJ 2015 7% 59% About half of the models indicate Niño 3.4 SST anomalies will remain greater than or equal to +0.5C through the end of 2015. Many other models (mostly statistical models) predict ENSO-neutral conditions.

Global SST Outlook: NCEP CFS Global SST Outlook: NCEP CFS.v2 Forecast Initial Conditions 29 March 2015 – 07 April 2015 May - Jul 2015 Aug - Oct 2015 Caution: Ocean areas with skill less than 0.3 are shaded in gray Jun - Aug 2015 Sep - Nov 2015 Jul - Sep 2015 CFS.v2 predicts higher than normal SST across equatorial central and eastern Pacific Ocean. Additional forecast resources are found here: http://www.cpc.ncep.noaa.gov/products/african_desk/cpc_intl/index.shtml http://www.cpc.ncep.noaa.gov/products/CFSv2/htmls/glbSSTe3SeaMask.html

Global SST Outlook: NMME (top panel) & IMME (bottom panel) May - Jul 2015 Jun - Aug 2015 Jul - Sep 2015 NMME IMME NMME and IMME models predict higher than normal SST across the equatorial central and eastern Pacific Ocean.

IOD Outlook (source: Australian Bureau of Meteorology) Model outlooks suggest that the Indian Ocean dipole (IOD) will remain near average through the northern hemisphere spring and summer 2015.

Rainfall Guidance, Africa: NMME, Precipitation Skill Masked Std Rainfall Guidance, Africa: NMME, Precipitation Skill Masked Std. Anomalies, (01 – 08 April 2015 IC) Gray shade indicates areas where skill is lower than 0.3. May - Jul 2015 Jun - Aug 2015 The forecasts call for climatology over much of Africa. There is a slight tilt in the odds to favor above (below) average rainfall over portions of the Sahel (Guinea coast) in Jul to Sep and Aug to Oct seasons. Jul – Sep 2015 Aug – Oct 2015 Individual model forecasts can be found here: http://www.cpc.ncep.noaa.gov/products/international/nmme/nmme1.shtml

(01 – 08 April 2015 IC) May - Jul 2015 Jun - Aug 2015 Jul – Sep 2015 Rainfall Guidance, CAM and Caribbean: NMME, Precipitation Skill Masked Std. Anomalies, (01 – 08 April 2015 IC) Gray shade indicates areas where skill is lower than 0.3. May - Jul 2015 Jun - Aug 2015 The forecasts call for a slight to moderate tilt in the odds to favor below-average rainfall over portions of Central America and the Caribbean. Jul – Sep 2015 Aug – Oct 2015 Individual model forecasts can be found here: http://www.cpc.ncep.noaa.gov/products/international/nmme/nmme1.shtml

(01 – 08 April 2015 IC) May - Jul 2015 Jun - Aug 2015 Jul – Sep 2015 Rainfall Guidance, South America: NMME, Precipitation Skill Masked Std. Anomalies, (01 – 08 April 2015 IC) Gray shade indicates areas where skill is lower than 0.3. May - Jul 2015 Jun - Aug 2015 The forecasts call for a slight to moderate tilt in the odds to favor below average rainfall along the northern coast of South America. In contrast, there is a slight to moderate tilt in the odds to favor above-average rainfall over portions of Bolivia, Paraguay and Brazil. Jul – Sep 2015 Aug – Oct 2015 Individual model forecasts can be found here: http://www.cpc.ncep.noaa.gov/products/international/nmme/nmme1.shtml

(01 – 08 April 2015 IC) May - Jul 2015 Jun - Aug 2015 Jul – Sep 2015 Rainfall Guidance, Central Asia: Precipitation Skill Masked Std. Anomalies, (01 – 08 April 2015 IC) Gray shade indicates areas where skill is lower than 0.3. May - Jul 2015 Jun - Aug 2015 The forecasts call for climatology over much of Central Asia, except for a slight to moderate tilt in the odds to favor above average rainfall over Turkey, northern Iran, southern Turkmenistan, northern Afghanistan and the neighboring areas in May to Jul season. In contrast, there a slight to moderate tilt in the odds to favor below-average rainfall over portions of Pakistan and southern Iran. Jul – Sep 2015 Aug – Oct 2015 Individual model forecasts can be found here: http://www.cpc.ncep.noaa.gov/products/international/nmme/nmme1.shtml

Summary El Niño conditions are present. Above-average Sea surface temperatures (SST) was observed over the central Pacific Ocean. Positive SST anomalies were observed over the central and southern Indian Ocean. There is an approximately 70% chance that El Niño will continue through Northern Hemisphere summer 2015, and a greater than 60% chance it will last through autumn. Additional forecast resources can be found here: http://www.cpc.ncep.noaa.gov/products/african_desk/cpc_intl/index.shtml http://www.cpc.ncep.noaa.gov/products/NMME/ http://origin.cpc.ncep.noaa.gov/products/people/wwang/cfsv2fcst/