**THE MADDEN JULIAN OSCILLATION: ITS POTENTIAL FOR WEEK TWO FLOOD
OUTLOOKS AND RESERVOIR**

**MANAGEMENT DECISIONS IN CALIFORNIA**

**David W. Reynolds**

**National Weather Service**

**WFO San Francisco Bay Area**

# Monterey, CA

1\. **Introduction**

It has been noted (Mo and Higgins, 1998) that tropical influences can
have a profound impact on California precipitation. Specifically,
hydrologically significant events can occur along the West Coast during
the cool season when the negative or convective phase of the
intratropical seasonal oscillations (Madden Julian Oscillation or MJO)
occur near 120E and eastward. It has been observed that during ENSO
neutral years there is a higher frequency of occurrence of the MJO.
During this past cool season, a well-defined 30 to 60 day cycle of the
MJO began in December, 2003 and has continued up until November, 2004.
This paper will highlight what might be an opportunity to provide up to
two weeks lead-time to water managers and reservoir operators to
potential flooding. However, it will be necessary to improve the
confidence of these outlooks before reservoir operators can utilize them
to make critical decisions, (e.g., water releases in anticipation of
capturing the floodwaters, versus the risk of not refilling the
reservoirs if the event fails to materialize).

2**. MJO IDENTIFICATION**

As stated, during this past cool season, the occurrence of the negative
phase of the MJO was closely monitored using NOAA's Climate Prediction
Center's (CPC) MJO index page.

<http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_mjo_index/mjo_index.html>

These five-day running mean charts shown on what is called a Hovmoller
diagram, allows the forecaster to track the eastward progression of the
200 hPa velocity potential moving out from the Indian Ocean. Figure 1
shows the diagram from May of 2004. This diagram however does not
indicate the actual intensity of the convective response to the MJO as
this relates to other features such as SSTs. The Climate Diagnostic
Center has developed a 3-day filtered running mean of the Outgoing
Longwave Radiation (OLR) anomalies which, via the number of solid blue
contours, indicates the strength of the anomaly and better depicts the
convective response to the MJO as it moves eastward, Figure 2. The
convective phase of the MJO are shaded in warmer colors (opposite from
the CDC MJO index). Note that the CDC index quite often dissipates out
near the dateline. This is indicative of cooler SSTs

The occurrence of the negative (convective) phase of the MJO is not
sufficient by itself to cause flooding along the West Coast. As CPC has
noted, there appears to be a favored

![](media/image1.png){width="3.479861111111111in" height="4.125in"}

Figure 1 5-day running mean of the MJO Index from CPC. Blue shading
denotes negative (enhanced convection) of the MJO cycle. The three
cycles during the cool season are noted. The date is along the Y-axis
and the longitude is along the X-axis.

![](media/image2.png){width="3.3756944444444446in"
height="3.3368055555555554in"}

Figure 2 CDC 3-Day running OLR filtered anomaly with a 7 to 14 day
forecast. The contours suggest the strength of the anomaly. The green,
black and brown lines indicate convectively coupled equatorial waves.
see http://www.cdc.noaa.gov/map/clim/olr_modes/hovEa.html for further
discussions.

![](media/image3.png){width="2.2555555555555555in"
height="3.0416666666666665in"}

Figure 3 conceptual patterns of large scale flow field and a scenario
that would allow the MJO to enhance rainfall to potentially extreme
amounts along the West Coast. Taken from CPC MJO Tutorial.

large-scale synoptic pattern, Pacific North American or PNA, Figure 4,
that, when in the positive phase, provides a favored flow pattern for
the MJO to increase the mid-latitude westerly flow or jet stream into
the West Coast. This is shown conceptually in Figure 3 from CPC's web
site.

![](media/image4.png){width="3.877083333333333in"
height="3.509027777777778in"}

Figure 4 Positive Phase of the PNA pattern as depicted at 500 mb. Red
areas denote positive height anomalies and blue areas denote negative
height anomalies. '

3.  **Application of the MJO to Week Two Forecasts**

For this past cool season, the MJO index was monitored closely along
with the

output from the Global Forecast Model or GFS and its ensembles. Since
the GFS and its ensembles are now run out to 15 days it is possible to
analyze the model output with respect to the pattern identified in
Figure 3 to determine whether, when the MJO negative phase approaches
120E longitude, there could be potential heavy rain 7 to 14 days later
in California. Note in Figure 3 that the below normal height anomalies
in the northern Pacific and the above normal height anomalies in the
tropical and sub-tropical Pacific infer a strong zonal jet stream over
the central Pacific. It is the enhancement of this jet by the tropical
convection associated with the MJO out near the dateline that allows the
jet to undercut the ridge over western North America, an hence allowing
the jet core to move directly into California with enhanced moisture
content through entrainment of the tropical to sub-tropical moisture.

For this past cool season, December through March, it was possible, by
analyzing the charts noted above, to begin an open discussion among the
West Coast forecasters some ten days ahead that a major pattern change
was possible and could lead to a significant hydrologic event. The 120E
longitude line was used as a threshold to begin these discussions. Since
the MJO moves on average of about 7 degrees longitude per day a rather
specific date could be given as to the pattern change. Additionally, the
numerical models do not usually handle the breakdown of the large West
Coast ridge patterns very well. One reason for this is the models do
poorly in simulating the MJO and its impacts. Thus in situations when
the models are continuing what would be a dry pattern in 7 to 10 days,
the forecaster, by recognizing the pattern, can have more confidence
that the models in error at this time frame and can add significant
value to the forecast process by forecasting a breakdown of the ridge
and a turn to potentially much wetter conditions.

Twice during the past cool season this scenario was followed. The first
event came in December of 2003. The second event occurred in February of
2004. Referring back to Figure 1, this would be what was called MJO #1
and MJO #2. Figure 5 shows a hydrograph for the Napa River at St Helena
for a period running from 1 December, 2003 through 19 February, 2004.
The red line denotes the flood stage for the Napa River. Annotated on
the chart are the dates when the negative phase of the MJO was noted at
120E longitude.

![](media/image5.png){width="5.125694444444444in"
height="2.861111111111111in"}

Figure 5 Hydrograph for the Napa River at St Helena in the north San
Francisco Bay Area showing two periods of flooding believed to be
correlated with the MJO\'s identified some 12 to 14 days earlier.

Figure 6 shows the 500 mb height field for 10 February, 2004. This is
indicative of a positive PNA pattern. This pattern, as referenced
earlier, is thought to be more conducive to the impacts of the MJO on
precipitation in California.

![](media/image6.png){width="3.377083333333333in"
height="2.7493055555555554in"}

Figure 6 500 mb height field for 10 February, 2004. This pattern is
indicative of a positive PNA pattern.

Figure 7 shows the hydrograph for the Russian river at Guerneville. This
is the largest river in the San Francisco hydrologic service area. Note
that for the February MJO, flood stage was attained on the 17^th^.

![](media/image7.png){width="4.503472222222222in"
height="2.6881944444444446in"}

Figure 7 Hydrograph for the Russian river at Guerneville for the period
December 1 through February 19, 2004. The red line indicates flood
stage.

Figure 8 shows an image of the total precipitable water from the SSMI
instrument on the NOAA polar orbiter satellite. It shows a narrow plume
of high PWs extending back to the tropical Pacific near Hawaii. It has
been noted in the past that very heavy rains in California have what has
been coined a "pineapple connection" (relating to the extension of
clouds back to near the Hawaiian Islands).

![](media/image8.png){width="4.374305555555556in"
height="3.7993055555555557in"}

Figure 8 SSMI total precipitable water image for 16 February, 2004. The
location called CZD is located in the Russian river watershed. IWV here
stands for Integrated Water Vapor.

The December and February cases stand out as excellent cases where
identifying the MJO out near 120E, and identifying that the synoptic
regime might be more conducive to the influence of the MJO, may provide
a week two heads up to water managers.

As you can see from Figure 1 there was a third MJO in March. However
there was no impact on California rainfall from this MJO. One possible
reason for this is that the large-scale flow regime was not
representative of the positive PNA pattern. Figure 9 is the 500 mb chart
for March 12, 2004. It indicates that the westerlies have receded north
in Canada and that there is no full latitude West Coast ridge
representative of the positive PNA pattern. It may also indicate a
preferential season such as December through February when the MJO
impacts California. Bond and Vecchi (2003) found such a seasonal
relationship for MJO impacts on precipitation in the Pacific Northwest.

![](media/image9.png){width="3.4972222222222222in"
height="2.8520833333333333in"}

Figure 9 500 mb chart for March 12, 2004. This pattern is not
representative of the positive phase of the PNA pattern.

4.0 **Summary**

NOAA's Climate Prediction Center has outlined a set of circumstances
whereby the negative phase of the MJO can interact with the mid-
latitude westerlies to produce heavy to extreme rainfall in Central and
Northern California. The more extreme of these events have been coined
the "pineapple connection" in reference to a tap to the deep tropical
moisture near and south of Hawaii. As part of the National Weather
Service's new Climate Services Program (NWS, 2003), this study is an
attempt to develop a climate-weather connection that can be used in a
weather forecast office to provide up to two weeks notice of a potential
significant hydrologic event. One can think of this as similar to the
identification of a strong EL Nino such as those of 1982-83 and 1997-98
that had profound influences on California's precipitation. The MJO
however provides a more specific time frame then do the seasonal El Nino
forecasts such that if confidence is sufficient, water managers may be
able to utilize this information to more efficiently manage reservoir
operations to both benefit flood control, hydro power generation, and
water supply needs. However it is anticipated that a much better
understanding of the interactions of the MJO with the mid-latitudes is
needed before confidence can be raised to a level that reservoirs can be
more efficiently managed. The hope in this paper is to stimulate further
studies by the research and climate communities that may help the
operational forecaster have more confidence in issuing week two flood
outlooks that in turn can be used by water managers to take action.

During this coming cool season, the CPC and CDC MJO indices will
continue to be monitored. In addition one can monitor the forecast of
the PNA pattern using the CPC web site that displays various time ranges
of the PNA pattern out to day 14.

<http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/new.pna_index_ensm.html>

Figure 10 is an example of using the GFS ensembles to denote the pattern
currently existing and expected to develop.

![](media/image10.png){width="4.375in" height="5.677083333333333in"}

Figure 10 Ensemble observed and forecast phase of the Pacific North
American pattern as per Figure 3.

A forecaster should look for a positive PNA pattern near the time the
MJO is near 120E with a forecast to shift to a negative phase of the PNA
indicating the models agree with a breakdown in the ridge and the
westerlies pushing into California. If one looks at Figure 10 in
combination with Figure 2 one might speculate that around mid November a
wet cycle may occur in California.

In summary it can be said that not all floods in California occur with
an MJO and not all MJO's induce flooding. There are certainly seasonal
variations of the impacts of MJO on mid-latitude circulations as noted
by Bond and Vecchi (2003). Figure 11 shows a comparison of the CDC
Multivariate ENSO Index (MEI) of Wolter and Timlin (1998) (positive El
Nino, negative La Nina), and MJO activity using the MJO multivariate
index following Wheller and Hendon, (2004) for the past 30 years. As
noted earlier one can see that the MJO is most active when ENSO is near
neutral.

Several other noteworthy features in Figure 11are that the last two
major statewide floods in California, February 1986 and January 1997
both occurred during active periods of the MJO. Secondly the two
strongest El Nino events, 1982-83 and 1997-98, were both preceded by
active MJO years. McPhaden (2004) suggests that frequent westerly wind
reversals in the tropics brought about by the MJO can accelerate or
initiate El Nino.

![](media/image11.png){width="6.05625in" height="6.59375in"}

Figure 11 Plot of MJO activity (Wheller and Hendon, 2004) per year with
the regions above 2 indicating active MJO years.

5.0 **References**

Bond, N.A. and G.A. Vecchi, 2003: The Influences of the Madden-Julian
Oscillation on Precipitation in Oregon and Washington. *Wea. and Fcst*.,
**18**, 600-613.

McPhaden, M.J., 2004: Evolution of the 2002/2003 El Nino. *Bull. Amer.
Meteor. Soc.*, **85**, 677-695.

Mo, K.C. and R. W. Higgins, 1998: Tropical convection and precipitation
regimes in the western United States. *Jour. Clim,* Vol 11, **9**,
2404-2423.

NWS, 2003: National Weather Service Regional and Local Climate Services.
[http://www.nws.noaa.gov/om/csd/Pres/Plan.pdf](http://www.nws.noaa.gov/om/csd/Pres/)

Wheller, M and H.H. Hendon, 2004: An All-Season Real-time Multivariate
MJO Index: Development of an Index for Monitoring and Prediction. *Mon.
Wea. Rev*., **132**, 1917-1932.

Wolter, K. and M.S. Timlin, 1998: Measuring the strength of ENSO -- how
does 1997/98 rank? *Weather*, **53**, 315-324.