**MADDEN-JULIAN OSCILLATION (MJO)**

**DIAGNOSTIC DISCUSSION**

**issued by**

**CLIMATE PREDICTION CENTER/NCEP**

**September 12, 2005**

**[Synopsis:]{.underline}** The MJO is expected to remain weak-moderate
for the next 1-2 weeks.

Earlier in the year from mid-March through mid-May the MJO was strong
with areas of enhanced and suppressed tropical rainfall propagating
eastward across the global tropics with a period of approximately 45
days. From late May through early July, however, the MJO was virtually
inactive with enhanced convection becoming quasi-stationary generally in
the region of Southeast Asia (Fig. 1). There has not been any additional
Kelvin wave activity since April (Fig. 2).

The MJO strengthened in early July, however, with eastward propagation
of enhanced (suppressed) convection (Fig. 3) and upper-level divergence
(convergence) (Fig. 4) across the global tropics. The MJO is anticipated
to continue at similar strength for the next 1-2 weeks (Fig. 5). During
week 1, potential benefits/hazards in the global tropics associated with
a stronger MJO signal include an increased chance of above (below)
average rainfall across Indonesia / western Pacific Ocean (western
Atlantic across Africa) due to the enhanced (suppressed) phases of an
eastward propagating MJO. As a result of increased tropical convection
in the Pacific Ocean (resulting in increased vertical wind shear in the
Atlantic Basin) and large scale suppressed convection across the
Atlantic sector there is an increased chance of below average tropical
cyclone activity in the central Atlantic. On the other hand, an
increased chance of above average tropical cyclone activity is expected
in the western Pacific Ocean as a result of the eastward shifting MJO.
Also, there is an increased chance of tropical cyclone activity across
the eastern Pacific Ocean due to the enhanced phase of the MJO. Other
benefits/hazards during week 1, not specifically related to the MJO,
include an increased chance of above average rainfall, strong winds, and
greater than normal wave heights associated with Hurricane Ophelia
across the eastern US coast. There is an increased chance of above
normal rainfall in Northeast Brazil associated with low-latitude frontal
system.

During week 2, an increased chance of above (below) rainfall across
sections of Central America (southern Indonesia region), an increased
chance of tropical cyclone activity in the Eastern Pacific ocean, and
increased chance of below average tropical cyclone activity across the
eastern Atlantic Ocean associated with the continued eastward
propagation of the MJO. There is also a possibility of enhanced tropical
cyclone activity in the Caribbean Sea.

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 19 September 2005. 

**Climate Prediction Center**

**National Centers for Environmental Prediction**

**NOAA/National Weather Service**

**Camp Springs, MD 20746-4304**

![](media/image1.png){width="4.8381944444444445in"
height="5.836805555555555in"}

**[Figure 1:]{.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/image2.png){width="4.46875in" height="5.592361111111111in"}

**[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="5.477083333333334in"
height="5.7340277777777775in"}

**[Figure 3:]{.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 or westerlies by orange/red shading.**
>
> ![](media/image4.png){width="2.73125in" height="3.5104166666666665in"}

**[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 realtime version of the NCEP/NCAR Reanalysis. Contour interval
is 3 x 10^6^ m^2^ s^-1^ with the brown (green) shading indicating areas
of upper-level convergence (divergence) respectively.**

![](media/image5.png){width="5.997916666666667in"
height="5.998611111111111in"}

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