Published On: Thu, Sep 12th, 2019

Hurricane tracker: Dangerous activity to SLAM into US – what is Madden-Julian Oscillation? | World | News


The NOAA’s National Hurricane Center (NHC) is currently monitoring a churning system over Atlantic waters, which currently has a predicted 50 percent chance of forming into a cyclone within 48 hours. According to reports, the storm may impact on the American states of Florida and Alabama, as well as other parts of the US Gulf Coast, later this week into early next week. The disturbance – likely to be named as Tropical Storm Humberto – is currently tracking near the Caribbean.

The NHC said in their weather outlook for the disturbance: “Although limited development of this system is anticipated today, conditions are forecast to become a little more conducive for tropical cyclone formation over the weekend, and a tropical depression is likely to form as the system moves northwestward at 5 to 10 mph across the Florida Straits and southern Florida, and into the eastern Gulf of Mexico.

“This disturbance will likely produce periods of locally heavy rainfall and gusty winds across the Bahamas through Friday, and across Florida during the weekend.”

The Washington Post reported heavy rainfall and winds could accompany the system, and that the potential cyclone formation could well be possible – largely due to a phenomenon known as Madden-Julian Oscillation.

What is Madden-Julian Oscillation (MJO)?

According to the Met Office, the Madden-Julian Oscillation is characterised by “an eastward spread of large regions of enhanced and suppressed tropical rainfall”.

The MJO lifts air to the west and drops it to the east, and on the west side of the MJO the air is more susceptible to rising – which causes the development of hurricanes.

There are eight phases of MJO, and each cycle lasts for approximately 30 to 60 days.

Ever year, the MJO contributes to extreme weather events in the USA, including Arctic air outbreaks during the winter months.

How does Madden-Julian Oscillation affect weather patterns?

MJO can create favourable weather conditions for tropical cyclone activity, and is an important factor to take into consideration when tracking potential Atlantic hurricanes.

The increase in rainfall associated with MJO can also catalyse Monsoon seasons around the world.

What is El Nino and La Nina?

Both El Nino and La Nina are types of the Earth’s climate systems.

The term El Nino describes the warming of the sea surface temperature, and it occurs every few years.

El Nino is when sea temperatures in the tropical eastern Pacific rises 0.5C above the long-term average.

The system creates stronger wind-shear and more stable air over the Atlantic, which can suppress hurricane formation.

El Nino ended in August 2019 this year, leading to NOAA increasing their chances of an “above-normal” hurricane season this year.

La Nina occurs when sea surface temperatures in the central Pacific Ocean drops to below-average levels.

It is thought that although MJO doesn’t cause El Nino or its counterpart system, La Nina, evidence suggests it can contribute to the intensity and speed of development of the climate systems.



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