**MADDEN-JULIAN OSCILLATION (MJO)**

**DIAGNOSTIC DISCUSSION**

**issued by**

**CLIMATE PREDICTION CENTER/NCEP**

**May 17, 2005**

**[Synopsis:]{.underline}** Suppressed convection will influence the
Indian Ocean and western Indonesia during the period.

During mid March the MJO became active and strong while completed one
cycle around the global tropics with a period of approximately 45 days.
Westerly anomalies (Fig.1) during mid-April associated with this MJO
activity did not extend far enough east to initiate another Kelvin wave
(Fig. 2). The warming along the South America Coast from the previous
Kelvin wave has peaked.

During the past week, the MJO has weakened and become less coherent. The
convective phase of the MJO is contributing to enhanced convection
across South America/Central America and the Caribbean while suppressed
convection is influencing eastern Africa and the Indian Ocean (Fig.
3-4). Based on the latest evolution of the MJO and statistical model
forecasts (Fig. 5), it is likely during the next week that enhanced
convection will continue to impact the western hemisphere and suppressed
convection can be expected in the Indian Ocean.

Impacts in the global tropics include the chance of above average
rainfall across northern South America and southern Central America into
the Caribbean (week 1) with drier than average conditions across the
eastern Africa, the Indian Ocean and Indonesia (week 1). Due to the
current uncertainty of the MJO, any impacts in the global tropics during
week 2 are unclear.

This discussion is a consolidated effort of NOAA and its funded
institutions. Weekly updates for SST, 850-hPa wind, OLR and features of
the equatorial subsurface thermal structure are available on the Climate
Prediction Center web page at
[http://www.cpc.ncep.noaa.gov](http://www.cpc.ncep.noaa.gov/). The next
MJO Diagnostics Discussion is scheduled for 24 May 2005.

**Climate Prediction Center**

**National Centers for Environmental Prediction**

**NOAA/National Weather Service**

**Camp Springs, MD 20746-4304**

![](media/image1.png){width="5.211805555555555in"
height="5.666666666666667in"}

**[Figure 1:]{.underline} Time-longitude section (5°N-5°S) of anomalous
850-hPa zonal wind (m s^-1^) (GDAS).**

> **Contour interval is 2 m s^-1^. Dashed contours indicate negative
> anomalies. The base period for computing anomalies is 1979-1995.
> Stronger-than-average easterlies are indicated by blue shading and
> weaker-than-average easterlies by orange/red shading.**
>
> ![](media/image2.png){width="4.345138888888889in"
> height="5.583333333333333in"}

**[Figure 2:]{.underline} Time-longitude section (5°N-5°S) of upper
ocean (0-300 m) heat content anomalies (^o^C) in the Pacific Ocean taken
from GODAS (Global Ocean Data Assimilation System). Greater heat content
(orange/red shading); lower heat content (blue).**

> ![](media/image3.png){width="4.6305555555555555in"
> height="5.583333333333333in"}

**[Figure 3:]{.underline} Time-longitude section (7.5°N-7.5°S) of
anomalous Outgoing Longwave Radiation (OLR) (W m^-2^). Negative OLR
anomalies (wetter-than-normal conditions) are indicated by blue shading
while positive OLR anomalies (drier-than-normal conditions) are
indicated by orange/red shading.**

![](media/image4.png){width="4.554166666666666in"
height="5.666666666666667in"}

**[Figure 4:]{.underline} Five day running mean time longitude sections
of the 200-hPa velocity potential anomalies averaged from 5°N to 5°S
from the Global Data Assimilation System (GDAS). Contour interval is 2 x
10^6^ m^2^ s^-1^ with the orange/red (blue) shading indicating areas of
upper-level convergence (divergence) respectively.**

> ![](media/image5.png){width="5.75in" height="5.75in"}

**[Figure 5]{.underline}: Prediction of MJO-associated anomalies using
lagged linear regression with the real-time multivariate MJO index
(RMM1) and (RMM2) as predictors.**