Global Patterns & Forecasts

Long Wave Cycles are global scale weather patterns. These are observed higher in the atmosphere at jet stream level. They last longer periods of time, and can produce the ‘trends’ in the weather we see at the surface.

Here is a brief look at the Polar Vortex, Arctic Oscillation, North Atlantic Oscillation, and ENSO (El Nino/Southern Oscillation).

Long Range Pattern Forecasts

Polar Vortex
Northern Hemisphere: 500mb Past 30 days

The Polar Vortex is a naturally occurring flow of air around the North Pole.

In normal conditions, the coldest air is locked up within it. But a weak Polar Vortex can be disrupted to wobble or split, allowing arctic air to spill southward into North America, Europe, and Asia.

Arctic Oscillation

The Arctic Oscillation is an index in essence connected to the normal easterly winds in the higher latitudes.

When they weaken or reverse, a NEGATIVE index would be measured. This would allow colder air to spill southward.

North Atlantic Oscillation

North Atlantic Oscillation is a measure of the slow or blocking of winds in the North Atlantic.

When a Block develops, often in Greenland, then arctic air has a better chance to reach the eastern US.

This also disrupts the jet stream to produce more frequent and perhaps stronger coastal storms.

Global 200 mb Past 30 Days

Global circulation can often be seen as waves of ridges and troughs. We measure them aloft at constant pressure levels to see how the height changes.

This 200mb level is located roughly 39,000 Feet above the ground.

Ridges are seen in Orange/Red.
Troughs are seen in Blue

El Nino/Southern Oscillation

Animations

Sea Surface Temperatures (SST)

Sea Surface Temperatures are obtained from remote buoys and satellite measurements.

SST Anomalies

Anomalies are a comparison of measurements to a 30 year average.

This is valuable in determining warming or cooling trends, that can identify an El Nino or La Nina.

Sea Surface Temperature Anomalies

The tropical Pacific is broken down into regions. Compare the numbered plots to the locations in this map.

Sea Surface Temperature Forecast

Standardized Anomaly

Forecast

Temperature Forecast

Forecast

Historical Chart: Cold (La Nina) and Warm (El Nino) Episodes

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MJO – Madden/Jullian Oscillation

From NOAA:

MJO is an eastward moving disturbance of clouds, rainfall, winds, and pressure that traverses the planet in the tropics and returns to its initial starting point in 30 to 60 days, on average. This atmospheric disturbance is distinct from ENSO, which once established, is associated with persistent features that last several seasons or longer over the Pacific Ocean basin. There can be multiple MJO events within a season, and so the MJO is best described as intraseasonal tropical climate variability (i.e. varies on a week-to-week basis).

The MJO consists of two parts, or phases: one is the enhanced rainfall (or convective) phase and the other is the suppressed rainfall phase. Strong MJO activity often dissects the planet into halves: one half within the enhanced convective phase and the other half in the suppressed convective phase. These two phases produce opposite changes in clouds and rainfall and this entire dipole (i.e., having two main opposing centers of action) propagates eastward. The location of the convective phases are often grouped into geographically based stages that climate scientists number 1-8.

HiRes GFS

Regions 7, 8, and 1 are historically more favorable to feed a storm track to the west coast of the US. Sometimes coordinating for east coast storms as well.

GEFS OLR Map

Forecast

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