**MADDEN-JULIAN OSCILLATION (MJO)**

**DIAGNOSTIC DISCUSSION**

**issued by**

**CLIMATE PREDICTION CENTER/NCEP**

## July 5, 2004

**[Synopsis:]{.underline}** MJO activity is expected to continue to
weaken during the next 2-4 weeks.

During June the eastward progression of the MJO slowed considerably as
the period of the MJO increased. By the end of the month MJO-related
enhanced convection was located near the international dateline while
MJO-related suppressed convection was located over Indonesia and the
west Pacific (Fig. 1).

Consistent with this, weaker than average easterlies (westerly
anomalies) are located in the western Pacific and stronger-than-average
easterlies are located in the central and east-central Pacific (Fig. 2).

Over the past several months fluctuations in equatorial easterly winds
have contributed to month-to-month variability in the surface and
subsurface temperatures in the equatorial Pacific. In particular,
MJO-related weakening of the equatorial easterly winds initiated
eastward-propagating oceanic Kelvin waves in early January and in early
April 2004 (Fig. 3). The weakening of the equatorial easterly winds
throughout the latter part of June has not initiated the development of
an eastward propagating Kelvin wave (Fig. 3).

During mid-June the pattern of tropical convection exhibited a
stationary wavenumber 1 pattern, with enhanced convection focused from
the Bay of Bengal (100°E) to the Western Pacific (160°E) and suppressed
convection from 60° E to 60°W (Fig. 4). Near the end of June this
pattern of convection has become more disorganized (Fig. 4), consistent
with further weakening of MJO activity. During late June it was hard to
distinguish MJO-related enhanced convection from intense convection
associated with two typhoons in the tropical western Pacific.

Both statistical and dynamical model forecasts indicate that MJO
activity will continue to weaken during the next 2-4 weeks (Figs. 5-6).
The Empirical Wave Propagation (EWP) model forecasts an area of enhanced
convection over the east-central Pacific to propagate eastward and
weaken (Fig. 5). An area of suppressed convection over the far-western
Pacific is forecast to propagate eastward toward the central Pacific and
maintain its intensity during the next two weeks (Fig. 5). The GFS shows
a similar eastward propagation of the area of enhanced convection over
the east-central Pacific over the next two weeks, but it does not show
eastward propagation of the area of suppressed convection over the
western Pacific. Given the observed atmospheric patterns discussed
above, it is likely that MJO activity will continue to weaken during the
next 2-4 weeks.

Weekly updates of SST, 850-hPa wind, OLR and features of the equatorial
subsurface thermal structure are available on the Climate Prediction
Center homepage at:

[http://www.cpc.ncep.noaa.gov.]{.underline}

**Climate Prediction Center**

**National Centers for Environmental Prediction**

**NOAA/National Weather Service**

**Camp Springs, MD 20746-4304**

![](media/image1.png){width="5.75in" height="6.107638888888889in"}

**Figure 1. Time-longitude section (5°N-5°S) of anomalous Outgoing
Longwave Radiation (OLR) (W m^-2^). The base period for computing
anomalies is 1979-1995. 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/image2.png){width="5.75in" height="6.29375in"}

**Figure 2. 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/image3.png){width="4.864583333333333in"
height="7.572222222222222in"}

Figures 3. Time-longitude section (5°N-5°S) of anomalous depth of the
20^o^C isotherm in the Pacific Ocean. The contour interval is 6 m, with
positive anomalies (greater depths) indicated by orange/red shading and
negative anomalies (reduced depths) indicated by blue shading.

![](media/image4.png){width="3.5in" height="2.25in"}

![](media/image6.png){width="3.5in" height="2.1666666666666665in"}

![](media/image8.png){width="6.875in" height="0.4166666666666667in"}

**Figure 4. Daily IR Temperatures (K) and 200-hPa velocity potential
anomalies (10^6^ m^2^s^-1^) on 15 June, 20 June, 25 June and 30 June.
Velocity potential anomalies are proportional to divergence with green
(brown) contours corresponding to regions in which convection tends to
be enhanced (suppressed).** **The base period for computing anomalies is
1971-2000.**

![](media/image9.png){width="5.729166666666667in"
height="7.356944444444444in"}

**Figure 5. Forty-day forecast of 200-hPa velocity potential anomalies
(10^6^ m^2^s^-1^) based on EWP (Empirical Wave Propagation) zonal
harmonics.**

![](media/image10.png){width="5.729166666666667in"
height="3.5319444444444446in"}

![](media/image11.png){width="4.666666666666667in"
height="0.6048611111111111in"}

**Figure 6. Fifteen-day forecast of 200-hPa velocity potential anomalies
(10^6^ m^2^s^-1^) based on the NCEP GFS.**