Consolidated Seasonal Rainfall Guidance for Global Tropics, May 2015 Initial Conditions

Issued 14 May 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 90% chance that El Niño will continue through Northern Hemisphere summer 2015, and a greater than 80% chance it will last through 2015.

(Updated on May 14, 2015)

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

Equatorial SSTs were above average across the eqauaterial central and eastern Pacific.

Current State of the Global Ocean

SST Anomaly (top) for April 2015 and Tendency (bottom) for April 2015 minus March 2015

Positive SST anomalies were observed across much of the Indian Ocean.

Changes in equatorial SST anomalies were positive across the equatorial eastern Pacific.

Last Month

SST tendency was positive across the western Indian Ocean.

SST was above- average across the equatorial central and eastern Pacific.

Positive SST anomalies were present over much of the Indian Ocean.

Weekly SST Anomaly 3 – 9 May 2015 andTendency for 3 – 6 May 2015 minus 26 Apr - 2 May 2015

Last Week

SST tendency was negative over the western Indian Ocean.

Current State of the Global Ocean

OLR Anomaly, April 2015

Negative OLR anomalies (enhanced convection and precipitation, blue shading) was observed over the Greater Horn of Africa and the Lake Victoria regions. Convection was also enhanced over Indonesia, much of Australia, equatorial central Pacific, and parts of South America.

Precipitation was suppressed (orange-red shading) over many places in the Gulf of Guinea and Central Africa countries, southeastern Africa, the Maritime Continent, and western Pacific Ocean.

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Low Level 850 mb Wind Anomaly

Anomalous low-level (850-hPa) westerly winds were located over the western and central equatorial Pacific. Anomalous anti-cyclonic circulation prevailed over the northern and West Africa.

Upper Level 200 mb Wind Anomaly

Anomalous upper-level (200-hPa) easterlies were observed across equatorial central and eastern Pacific.

Monitoring the Madden Julian Oscillation

The RMM MJO index indicated an incoherent signal during the past 7 days (left panel). The GFS ensemble RMM Index forecasts depict week signal over the coming two weeks (right panel).

Evolution of Indian Ocean SST Indices

The Indian Ocean Dipole (IOD) showed positive values in late April and early May, with the latest weekly index value as of 10 May 2015 is 0.15 °C.

Summary of State of the Global Climate in April 2015

• El Niño conditions are present. The most recent Ocean Nino Index (ONI) value (February – April 2015) is 0.6oC.

• Positive sea surface temperature (SST) anomalies continued across the central and eastern Pacific.

• Above-average SSTs were observed across much of the Indian Ocean. The Indian Ocean Dipole (IOD) positive values in late April and early May.

• Enhanced precipitation was observed over the Greater Horn of Africa and the Lake Victoria regions. Convection was also enhanced over Indonesia, much of Australia, equatorial central Pacific, and parts of South America.

• Convection was suppressed over many places in the Gulf of Guinea and Central Africa countries, southeastern Africa, the Maritime Continent, and western Pacific Ocean.

Nino region SST departuresEq. Subsurface temperature

Anomalies

Niño 4 0.9ºC

Niño 3 0.9ºCNiño 1+2 0.5ºC

The latest weekly SST departures :Niño 4 = 1.2ºC Niño 3.4 = 1.0ºC

Niño 3 = 1.2ºC Niño 1+2 = 2.3ºC

Recently, negative anomalies have increased at depth in the western Pacific.

- The majority of the models indicate Niño 3.4 SST anomalies will remain greater than or equal to +0.5C through the end of 2015.

IRI/CPC NINO3.4 Forecast Plume

Season La Niña Neutral El NiñoAMJ 2015 ~0% 5% 95%MJJ 2015 ~0% 7% 93%JJA 2015 ~0% 10% 90%JAS 2015 1% 10% 89%ASO 2015 1% 13% 86%SON 2015 2% 13% 85%OND 2015 2% 15% 83%NDJ 2015 3% 15% 82%DJF 2015 3% 17% 80%

Global SST Outlook: NCEP CFS.v2 Forecast Initial Conditions 3 – 12 May 2015

Jun - Aug 2015

Jul - Sep 2015

Aug - Oct 2015

Sep - Nov 2015

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

Oct - Dec 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.shtmlhttp://www.cpc.ncep.noaa.gov/products/CFSv2/htmls/glbSSTe3SeaMask.html

Global SST Outlook: NMME (May 2015 Initial Conditions)

Jun - Aug 2015 Jul - Sep 2015

NMME models predict higher than normal SST across the equatorial central and eastern Pacific Ocean.

Aug - Oct 2015 Sep - Nov 2015

IOD Outlook (source: Australian Bureau of Meteorology)

The average Model outlooks suggest that the Indian Ocean dipole (IOD) will remain near average through the northern hemisphere summer 2015.

Rainfall Guidance, Africa: NMME, Precipitation Skill Masked Std. Anomalies, (01 – 08 May 2015 IC)

Jun - Aug 2015 Jul – Sep 2015

Aug – Oct 2015 Sep – Nov 2015

The forecasts call for climatology over much of Africa. There is a slight to moderate tilt in the odds to favor below-average rainfall over portions of the Gulf of Guinea countries in Jun to Aug and Jul to Sep seasons. In contrast there a slight tilt in the odds to favor above-average rainfall over portions of the Sahel region and Somalia.

Individual model forecasts can be found here:http://www.cpc.ncep.noaa.gov/products/international/nmme/nmme1.shtml

Gray shade indicates areas where skill is lower than 0.3.

Rainfall Guidance, CAM and Caribbean: NMME, Precipitation Skill Masked Std. Anomalies, (01 – 08 May 2015 IC)

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.

Individual model forecasts can be found here:http://www.cpc.ncep.noaa.gov/products/international/nmme/nmme1.shtml

Gray shade indicates areas where skill is lower than 0.3.

Jun - Aug 2015 Jul – Sep 2015

Aug – Oct 2015 Sep – Nov 2015

Rainfall Guidance, South America: NMME, Precipitation Skill Masked Std. Anomalies, (01 – 08 May 2015 IC)

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.

Individual model forecasts can be found here:http://www.cpc.ncep.noaa.gov/products/international/nmme/nmme1.shtml

Gray shade indicates areas where skill is lower than 0.3.Jun - Aug 2015 Jul – Sep 2015

Aug – Oct 2015 Sep – Nov 2015

Rainfall Guidance, Central Asia: Precipitation Skill Masked Std. Anomalies, (01 – 08 May 2015 IC)

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 Iran and Afghanistan. In contrast, there a slight tilt in the odds to favor below-average rainfall over portions of India and Pakistan.

Individual model forecasts can be found here:http://www.cpc.ncep.noaa.gov/products/international/nmme/nmme1.shtml

Gray shade indicates areas where skill is lower than 0.3.

Jun - Aug 2015 Jul – Sep 2015

Aug – Oct 2015 Sep – Nov 2015

Summary• El Niño conditions are present. Above-average Sea surface

temperatures (SST) was observed over the central and eastern Pacific Ocean. Positive SST anomalies were observed over much of the Indian Ocean.

• There is an approximately 90% chance that El Niño will continue through Northern Hemisphere summer 2015, and a greater than 80% chance it will last through 2015.

• 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/