Tropical rainfall exhibits strong variability on time scales shorter than the seasonal El Niño Southern Oscillation. These fluctuations in tropical rainfall often go through an entire cycle in 30-60 days, and are referred to as intraseasonal oscillations. (For more information see Frequently Asked Questions)

The intraseasonal oscillations are a naturally occurring component of our coupled ocean-atmosphere system. They significantly affect the atmospheric circulation throughout the global Tropics and subtropics, and also strongly affect the wintertime jet stream and atmospheric circulation features over the North Pacific and western North America.

As a result, they have an important impact on storminess and temperatures over the United States During the summer these oscillations have a modulating effect on hurricane activity in both the Pacific and Atlantic basins. Thus, it is very important to monitor and predict intraseasonal activity, since this activity has profound implications for weather and short-term climate variability through the year.

Key monitoring tools are:

Animations

• 3-day Satellite Infrared (IR) Temperatures
• 3-day Satellite Water Vapor
• 30-day 200-hPa Heights
• 30-day Northern Hemisphere 500-hPa Heights
• 30-day Southern Hemisphere 500-hPa Heights
• 30-day IR/Velocity Potential

5-day Means

• 200-hPa Heights and Wind Speed
• 500-hPA Heights and Anomalies

Time-Longitude Sections

Equatorial

• Filtered OLR Anomalies (5°S-5°N)
• 200-hPa Velocity Potential (5°S-5°N)
• 850-hPa Zonal Wind Anomalies (5°S-5°N)
• Ocean Heat Content Anomalies (Equator)

Mid-Latitude

• 500-hPa Height Anomalies (45°N-60°N)
• 500-hPa Height Anomalies (45°S-60°S)

High-Latitude

• 500-hPa Height Anomalies (60°N-90°N)
• 500-hPa Height Anomalies (60°S-90°S)