**MADDEN-JULIAN OSCILLATION (MJO)**

**DIAGNOSTIC DISCUSSION**

**issued by**

**CLIMATE PREDICTION CENTER/NCEP**

**June 28, 2004**

**[Synopsis:]{.underline}** MJO activity in the Western Pacific is
expected to move eastward and weaken in the next 2-4 weeks.

After a quiet May, enhanced convection flared over Indonesia and the
tropical Western Pacific during mid-June consistent with renewed MJO
activity. MJO-related weakening of the equatorial easterly winds
occurred across Indonesia and the far western Pacific through mid-June
and shifted eastward to the western Pacific (near 160°E by late June)
(Fig. 1). Westerly anomalies have not extended beyond the international
date line. Consistent with this, enhanced convection has been restricted
to the region west of the international date line through the end of
June (Fig. 2).

The fluctuations in equatorial easterly winds have contributed to
month-to-month variability in the surface and subsurface temperatures in
the equatorial Pacific. In particular, the MJO-related weakenings of the
equatorial easterly winds initiated eastward-propagating oceanic Kelvin
waves in early January and in early April 2004 (Fig. 3).

-   Positive temperature anomalies in the upper-ocean have tended to
    weaken in the equatorial western and central Pacific in recent weeks
    consistent with a return to near normal easterly winds across the
    basin. At the present time there is no indication that MJO activity
    will contribute to the development of an eastward propagating
    oceanic Kelvin wave.

During mid-June 2004, the pattern of tropical convection exhibited a
wavenumber 1 pattern, with enhanced convection from the Bay of Bengal
(100°E) to the western Pacific (160°E) and suppressed convection from
60° E to 60°W (Fig. 4). Subsequently, the area of enhanced convection
shifted east to the equatorial West-Central Pacific, while the area of
subsidence moved east to cover much of Africa. The convective activity
west of the date line remains strong with some indication of eastward
propagation as evidenced by renewed convective activity over the eastern
Equatorial Pacific late in the month.

Both statistical and dynamical model forecasts indicate that the MJO
activity over the western Pacific will move east and weaken during the
next 2-4 weeks (Figs. 5-6). The Empirical Wave Propagation (EWP)
forecast shows an area of suppressed convection (subsidence) over
India/East Africa that is forecast to propagate eastward to the
equatorial Pacific while in the Tropical Atlantic overall subsidence is
forecast to be replaced by rising motion later in July (Fig. 5). The GFS
has a similar area of subsidence over India/East Africa but eastward
propagation is slow. As in the EWP model, the GFS forecasts rising
motion to develop across the Tropical Atlantic during July. Given the
observed atmospheric patterns discussed above and the recent trends in
the strength of the MJO, it is likely that the MJO will continue to
weaken as it moves east 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](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="6.191666666666666in"}

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

**Contour interval is 2 ms^-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="5.75in" height="6.022222222222222in"}

**Figure 2. Time-longitude section (5°N-5°S) of anomalous Outgoing
Longwave Radiation (OLR) (Wm^-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/image3.png){width="4.875in" height="7.21875in"}

Figures 3. Time-longitude section (5°N-5°S) of anomalous depth of the
20C isotherm in the Pacific Ocean. The contour 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="4.0in" height="2.748611111111111in"}

![](media/image6.png){width="4.166666666666667in" height="3.0in"}

![](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 June 13, June 18, June 23, and June 28.
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="6.667361111111111in"}

![](media/image9.png){width="5.08125in" height="0.3145833333333333in"}

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

![](media/image10.png){width="5.729166666666667in"
height="3.359722222222222in"}

![](media/image10.png){width="5.729166666666667in"
height="0.5395833333333333in"}

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