Weather!

[Ban my account ffs!]

So there is an El Niño coming and while it's too early to say for sure, indications are that this will be a significant or "strong" event.  The amount of warm water that has built up under the surface in recent weeks in the western equatorial Pacific is migrating both eastward and upward towards the surface very quickly.

When it reaches the surface, this warmer than usual water changes the broad weather pattern across the Pacific which impacts the entire world.

Here is an image depicting the global Walker Circulation.  The circulation of air over the tropical regions.


It is important to point out that the reason the circulation occurs this way with more thunderstorms near Australia and over Africa and the Amazon.... because of geographic features.

For one, the ocean currents approximate the air currents at the surface near the equator... because of the placement of South America and Panama.  Ocean water cannot move freely from the Atlantic to the Pacific... so it goes around South America.  This drives cool water towards the equator along the coast of western South America.

The Andes mountains then act as the same barrier for the atmosphere.  A perfect storm, so to say.  The air cannot flow over the Andes mountains easily... so with the relatively cold water for being so tropical, and the natural inclination for air to sink just west of the Andes (since the main tropical flow is east to west), means that this area of the tropics is unusually dry.

But that keeps that part of the ocean cloudless too, which allows the intense sun to heat the water as it flows westward.  By the time it gets to Indonesia... it's 86F rather than 68F.

This means the big warm spot north of Australia gets more thunderstorms and rain than is typical for a tropical area.

This is where El Niño and La Niña come in.

La Niña, which we've experienced more of in recent years, is basically the process described above on steroids.  Faster winds at the equator cause more cold water to upwell which creates even sunnier conditions which pushes the water westward where the now warmed up water is forced under the surface.  This creates a "bubble" of warm water under the surface that expands thermally so the ocean surface is higher in the western Pacific by about a foot than the eastern Pacific.

El Niño is the unusual conditions that occur every 3-7 years when this warm pool moves eastward across the ocean and upward to the surface.  Depending on how big the pool of warm water was determines how big the El Niño event is.

This warm water, now at the surface, releases its heat into the atmosphere.  This causes the normally high pressure and sinking air in the eastern Pacific to reverse... because now there is 80F water near the surface which increases humidity, warms the air, causes rising, and eventually thunderstorms.  Areas that can go years without precipitation might see a massive deluge of tropical thunderstorms that cause the deserts of Peru and Chile to bloom.

At the same time... the warm water sloshing to the eastern side of the ocean causes the wind direction to change across the entire Pacific... flowing west to east instead of east to west.

The sinking high pressure is, instead, located exactly where the low pressure usually is.  So the monsoons and thunderstorms fail over India, SE Asia, and the maritime continent (Indonesia).

This is a bad thing since these areas are covered in lush tropical forests that rely on that rising warm air to produce thunderstorms.  Instead they get baked under day after day of hot sun with no rain.

Also, ocean levels can fall by up to 2 feet, exposing coral to the air and killing it.

But the impacts are wider.  This tends to also change the position of the jet stream and low and high pressure systems over the rest of the world... since if you completely reverse the largest and singly most important circulation in the atmosphere on earth (the tropical Pacific is an enormous portion of the globe)... it will impact every other system.

This sets off a cascade.  The warmth and reversed circulation in the tropical Pacific causes high pressure usually present over the central Pacific to migrate north and eastward into Alaska and western Canada.  But the flow of moisture and warmth from the tropics also dramatically strengthens the subtropical jet stream causing it to move southward and become laden with moisture.  This is why southern California and the normally arid parts of the U.S. do well during El Niño.

The placement of frigid Arctic air is often displaced out into the Pacific ocean during El Niño, and subsequently... the mild Pacific air is displaced eastward into the U.S. leading to warm winter conditions in the north, but cooler summer conditions.

These are the impacts one would typically expect for summer 2014 going into fall and winter provided a moderate to strong El Niño event is underway by summer (increasingly likely):

Plenty of rain across the western and central U.S. during summer with an increased moisture source due to being directly north of the eastern tropical Pacific, which is where the biggest disruption from the norm occurs.

Dry weather occurs during winter in the Pac NW and Ohio and Tennessee river valleys with wet weather along the entire southern tier and along the east coast. 

Drought tends not to be an issue during El Niño in the U.S.  But will be a big problem since it can occur in the Amazon and across SE Asia, India, and portions of southern/central China.

In any case, get ready for a year of more extreme weather!

[Ban my account ffs!]

Also I realize I posted this in FC and not OT.