Other Factors: MJO Index

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Other Factors MJO Index
Madden Julian Oscillation (MJO) A 40- to 60-day
period of alternately strong or weak trade winds
that normally blow west. It is named after Roland
Madden and Paul Julian, two scientists from the
National Center for Atmospheric Research who in
1971 were studying wind patterns in the tropical
Pacific. For unknown reasons, these tropical
winds sometimes weaken, and the Sun-warmed pulse
of ocean water that they usually cause to drift
west drifts east. As this pulse of warm water,
called a Kelvin wave, moves east-from the coast
of Africa across the Indian and Pacific Oceans-it
carries changed air patterns above it.

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MJO Data Links

• Current MJO Data and Archives (CPC)
• Archived MJO (Historical Images)

Click here for current MJO Phase
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Other Factors MJO Index
When the wave crashes into South America, the
water stops, but the air pattern continues over
land northeastward, into the Caribbean atmosphere
and across the Atlantic Ocean. Before this cycle
is complete, another pulse has already started in
the Indian Ocean. Scientists are still studying
the MJO. Most agree, however, that when the MJO
cycle speeds up and warm Kelvin waves pile up in
the Pacific Ocean, we have the start of an El
Niño. The MJO usually brings flooding rains
(also known as the "Pineapple Express") to the
Pacific Northwest and California. In an active
hurricane season on the East Coast, it can mean
several hurricanes within a few weeks, followed
by a long spell with no hurricanes. MJO Tutorial
Site

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Other Factors MJO Index

For the East coast of the United States, the
impact of the MJO during the winter months is
uncertain. We know the MJO goes through phases,
8 to be exact.

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Other Factors MJO Index

Although much is uncertain, phases 8 and 1 of the
MJO appear to be the most favorable for large
scale East coast snowstorms due to the above
heights (high pressures) over and near Greenland
which in turn impacts the negative NAO. Click
here for current MJO Phase

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Other Factors MJO Index
According to HM (Eastern US Weather Forum), MJO
does not have to be in Phase 8 all the time to
get SECS (Significant East Coast Snowstorms). It
is one tool to the general equation. It is not
until phase 4-7 when the MJO alignment favors a
ridge back east. Click here for current MJO Phase

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Other Factors MJO Index

500mb Height Anomalies for each MJO phase for
every month

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Other Factors MJO Index (Thanks to NWJ)

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Other Factors MJO Index (Thanks to NWJ)

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Phase 4 (March 2007)
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MJO Phase (Blizzard of 2006)