Good Morning all good people visiting the zoomradar.com site. I am going to write today on the MJO or Also Known as the Madden Julian Oscillation.  In recent years more Meteorologists have been studying and monitoring this oscillation that propagates around the globe. Today I will touch on aspects on the MJO, what it is and how it effects our weather in the United States and around the Globe.

First I will provide you with a definition or some background information on the MJO.

1. MJO – The Madden Julian Oscillation is essentially a “envelope” of deep convection that circumnavigates the equator. It generates Rossby Train Waves which are meridional patterns in the Jetstream oriented North-South or in that general Direction. This is mainly due to Diabatic (adding heat) heating and latent heat(hidden) release from convection or thunderstorms. Under normal conditions, especially during the Northern Hemisphere winter, there normally is a fairly strong Jetstream over the central pacific. The convection from the MJO creates an anti-cyclonic or a high pressure just to the Northwest of the maximum convection. This anti-cyclone can enhance the jet and even create a jetstreak within the Jetstream. (A Jetsteak is a band of very strong winds within the envelope of the jetsteam which is normally fast winds). This has strong implications for the mid-latitude weather between 35-60 degrees N+S LAT.

I am going to display for images to illustrate my key points

The MJO and Kelvin Ocean Wave if intense can enhance or strengthen the Subtropical Jetstream by adding heat(diabatic and latent) into the tropsphere. A strong MJO coupled with a Very strong El Nino like we are observing this year can heat the globe by a degree celsius or so which have big implications. I mean witness this year East of Mississippi River. We don’t know if it is Christmas or Easter.

2 MJO and ENSO 

As far as the MJO and ENSO or El Nino Southern Oscillation , it’s very possible that the Madden Julian oscillation is an important component of the ENSO as the graphic above depicts. In a neutral ENSO state, the warmest water is in the Central Pacific or CPAC. The MJO, which has strong WESTERLY WINDS associated with it, can provide what are called WESTERLY WIND BURSTS (WWBs). These WWBs enact stress on the ocean surface which may, in a sense, move the warm water eastward. Even more important is these WWBs are a likely cause of oceanic Kelvin Waves, which are depicted on the graph above, which have been associated with the ENSO!!  If warm water from the CPAC moves eastward, the SST anomalies will be positive(warm water in an area where there isn’t usually warm water) and that’s a common signature of El Nino. The next graphic will show you the signature of ENSO and MJO together.


In recent years Meteorologists have been looking at the MJO in connection with tropical cyclone development all over the world since the MJO can enhance tropical cyclone development by convection, lowering of surface pressure, and promoting rising air motions. However, the MJO has its part in other processes as well. Take a look:

1. Most Prominent Connection to Phase of ENSO – The MJO can enhance the ENSO. Lets do a simple comparison here. Lets say a man is riding a stationary bike continously for many hours, soon or later he is going to get tired(ENSO). The MJO is gatorade to provide fuel and energy for this man riding his bike so he can keep going. The ENSO is stationary and the MJO is always moving around the globe, which enhances what is already established. I hoped that help, I had to dig deep for that one. LOL

2. West Coast Weather – A week to days days before a Low Pressure system affects the West Coast of the U.S. convection is observed in the SW Pacific near Australia and Indonesia, with a Strong Blocking High sprawled across the Pacific Northwest, with a strong polar jetstream poised north of the area of convection. Three to five days from a Low Pressure affecting the West Coast, The Retrogrades goes moves further west and the jetstream splits still strong to the north and one to the South to capture the convection and Low Pressure. Finally the Jetstream propagates further South enhancing the Low Pressure System and driving it into the West Coast. I will attempt to get an image up to I can show you visually.

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3. Modulation of Tropical Systems in the Main Development Region of the Atlantic During Summer – The convectively active phase of the MJO and the phases immediately following them are typically associated with above-average tropical cyclone frequencies for every tropical cyclone ocean basin, whiole to dry phase of the MJO is associated with below normal frequencies of Tropical Cyclones throughout the ocean basins. Finally, the number of rapid intensification periods are also shown  to increase when the convectively active phase of the MJO  is impacting a particular tropical ocean basin. This is a segway to the next part dry vs convection MJO


3. DRY vs WET MJO – 

A. The MJO consists of two parts, or  PHASES. 

1. The Enhanced rainfall or the Convective Phase

2. The Dry or Suppressed Rainfall Phase 

Strong MJO activity usually splits the globe into halves. One half into the convective phase or enhanced rainfall and the other half into the dry and suppressed rainfall phase. These two phases produce entirely opposites in rainfall, clouds and temperatures and this entire dipole propagates EASTWARD. The location of the Convective and Dry phases are often grouped geographically into based stages which climate scientists number 1-8. I will show you what a chart looks like but first I am going to tell you what the chart actually means.

Note right now, the blue line ends in Phase 3, which implies that the MJO is somewhere over the Indian Ocean, entering the Maritime Continent area. The Circle corresponds to an MJO amplitude of 1. Anything less than 1 (inside circle) is often considered inactive, but this is a rather arbitrary distinction, there is NOTHING special about the value of “1”.

GFS MJO index ensemble plume

NOAA – Source. and Mississippi State University – Source.

You can clearly see the NCEP model from NOAA showing the MJO convective phase forecasted to move from the Maritime/Comtinent region of the Indian Ocean to the Western Pacific. Which is phase 3-5 to phase 6-7.

Thank you all for listening I hoped this helped everyone who is interested in this underrated teleconnection. The weather and climate are always changing and there are a lot of players in the weather. so may processes that are very dynamic. Happy holidays everyone

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