NOAA Long Term Winter Forecast for 2020-21 ~~~ ENSO, El Niño, & La Niña – Explained ~ Open Snow

ENSO-neutral is favored to continue through the summer, with a 50-55% chance of La Niña development during Northern Hemisphere fall 2020 and continuing through winter 2020-21 (~50% chance). … Overall, the combined oceanic and atmospheric system is consistent with ENSO-neutral.Jul 14, 2020

NOAA Long Term Winter Forecast 2020-2021 | 55% Chance …

The US National Oceanic and Atmospheric Administration (NOAA) makes long-range forecasts each month.

We are going to show you their forecast for the upcoming winter, but first, a warning.

WARNING: Long-range forecasts are rarely accurate. These forecasts cover three months but we know that skiing quality improves and degrades with storm cycles that last a few days to a week.

Paying attention to the 1-10 day forecast (All-Access only) is the way that you’ll find powder and give you the best information for your weekend trip or destination ski vacation.

Temperature Forecast During December, January, & February

Warm. This outlook is based on a general trend of increasing temperatures during the past years and decades.

Precipitation Forecast During December, January, & February

The northern half of the United States is in the “Probability of Above” zone, which means that the odds of above-average precipitation is higher.

The middle of the country is in the “Equal Chances” zone, which basically means that the odds of average, above-average, or below-average precipitation is about the same.

The southern half of the United States is in the “Probability of Below” zone, which means that the odds of below-average precipitation is higher.

~~~~~~  ~~~  ~~~~~~~  ~~~~

But remember, 3-6 month forecasts have little to no value so don’t get too excited or upset by where your favorite areas fall on this map.

What about El Niño or La Niña?

A strong El Niño or La Niña (which refers to ocean water temperatures in the central Pacific Ocean) can help us predict snowfall patterns during the winter.

For the upcoming 2020-2021 winter season, there’s a ~50% chance that water temperatures will reach below-average (blue bar = La Niña), a less than 10% chance that water temperatures will be above-average (red bar = El Niño), and a ~40% chance that water temperatures will be near-average (grey bar = Neutral).

These model forecasts provide us with a signal for a La Niña event during the 2020-2021 winter season.

The official Climate Prediction Center outlook is similar to these model forecasts, calling for a 60% chance of La Niña for fall and a 55% chance for La Niña to continue through the 2020-2021 winter season.

Since long-range forecasts are rarely accurate or useful for finding great snow, here is a quick recap of our strategy for finding the deepest powder:

If you want the highest odds of deep powder, here are our six tips:

1) Live in a location that’s close to mountains with the deepest snow.

2) If you can’t live close to deep powder, wait until 7-10 days before booking your trip.

3) Even if you wait until 7-10 days before booking your trip, consider only booking to a general area.

4) If you have to book a trip far in advance, pick locations that statistics show have the deepest powder.

5) If you can’t execute any of the above strategies, change your expectations for your ski trip.

You often hear weather forecasters begin their discussion about the upcoming winter forecast by looking at the current state of the El Niño-Southern Oscillation (ENSO). So what is ENSO, El Niño, and La Niña?

What is ENSO?

El Niño-Southern Oscillation (ENSO) refers to the year-to-year variations in sea-surface temperatures, convective rainfall, surface air pressure, and atmospheric circulation that occur across the equatorial Pacific Ocean.

El Niño and La Niña represent opposite extremes in the ENSO cycle, while ENSO-Neutral refers to the state between El Niño and La Niña.

ENSO is one of the most important climate phenomena on Earth due to its ability to change the global atmospheric circulation, which in turn, influences temperature and precipitation across the globe.

What is El Niño?

The term El Niño refers to the large-scale ocean-atmosphere climate phenomenon linked to periodic warming in sea-surface temperatures across the central and east-central equatorial Pacific.

El Niño represents the warm phase of the ENSO cycle and means that the ocean water temperatures are warmer than average.

El Niño was originally recognized by fishermen off the coast of South America in the 1600s, with the appearance of unusually warm water in the Pacific Ocean.

The name El Niño, or ‘Christ child’, was chosen because these warm-water events happened to around the Christmas holiday.

What is La Niña?

The term La Niña refers to the large-scale ocean-atmosphere climate phenomenon linked to periodic cooling in sea-surface temperatures across the central and east-central equatorial Pacific.

La Niña represents the cool phase of the ENSO cycle and means that the ocean water temperatures are cooler than average.

What is ENSO-Neutral?

The term ENSO-neutral refers to periods when El Niño and La Niña are not present and typically occur during the transition between El Niño and La Niña events.

The ocean water temperatures over the equatorial Pacific Ocean are near the long-term average.

Images of El Niño & La Niña

The images below (courtesy of NOAA) show ocean water temperature compared to average in the Pacific Ocean.

The top image is La Niña, showing cooler than average ocean water temperature. The bottom image is El Niño, showing warmer than average ocean water temperature.

How do we measure ENSO?

The first ENSO indicator is the Southern Oscillation Index (SOI), which is calculated using the pressure differential between Tahiti and Darwin. The SOI is negative during El Niño years and positive during La Niña years.

The second ENSO indicator comes from the National Oceanic and Atmospheric Administration (NOAA). NOAA maintains monitoring buoys called the Tropical Atmosphere Ocean (TAO) Array across the equatorial Pacific Ocean.

The buoys record and transmit sea surface and sub-surface temperatures, atmospheric conditions, water currents, and wind data to scientists and researchers around the world in real-time.

El Niño & La Niña Alert System

On the second Thursday of each month, scientists with NOAA’s Climate Prediction Center, in collaboration with forecasters at the International Research Institute for Climate and Society (IRI), release an official update on the status of the El Niño-Southern Oscillation (ENSO).

Watch: Issued when conditions are favorable for the development of El Niño or La Niña conditions within the next six months.

Advisory: Issued when El Niño or La Niña conditions are observed and expected to continue.

Final Advisory: Issued after El Niño or La Niña conditions have ended.

Not Active: ENSO Alert System is not active. Neither El Niño nor La Niña are observed or expected in the coming 6 months.

El Niño Criteria

1) The average sea surface temperatures in the Niño-3.4 region of the equatorial Pacific Ocean were at least 0.5°C (0.9°F) warmer than average in the preceding month.

2) The average anomaly of at least 0.5°C (0.9°F) has persisted or is expected to persist for 5 consecutive, overlapping 3-month periods.

La Niña Criteria

1) The average sea surface temperatures in the Niño-3.4 region of the equatorial Pacific Ocean were at least 0.5°C (0.9°F) cooler than average in the preceding month.

2) The average anomaly of at least -0.5°C (-0.9°F) has persisted or is expected to persist for 5 consecutive, overlapping 3-month periods.

Why do we care about El Niño & La Niña?

Ocean water temperatures across the world influence the tracks of winter storms.

One area of ocean water temperature that has the biggest impact on winter storms in North America is the central Pacific Ocean. This is the location of El Nino and La Nina.

Thanks to decades of research, scientists now have a decent ability to predict the strength of El Nino and La Nina months in advance.

This means that even now in late summer, we are looking ahead to the temperature of the ocean during the upcoming winter, and it’s these water temperatures that can influence the tracks of our winter storms.

Typical El Niño & La Niña Winter Weather Patterns

The following maps (courtesy of NOAA) illustrate the typical impacts of El Niño and La Niña on the United States during the winter.

During La Niña, the Pacific jet stream often meanders high into the North Pacific and is less reliable across the southern tier of the United States. Southern and interior Alaska and the Pacific Northwest tend to be cooler and wetter than average and the southern tier of U.S. tends to be warmer and drier than average.

During El Niño, the Pacific jet stream will often dip further south across the southern tier of the United States. The southern states tend to be cooler and wetter than average, while the northern half of the U.S. becomes warmer and drier than average.

Keep in mind that one or more of these climate patterns have occurred during many El Niño and La Niña events in the past. That doesn’t mean that all of these impacts happen during every episode as every event is different.

Final Thoughts

You will come across numerous winter forecasts. These 1-6 month forecasts are rarely accurate.

If your main goal is to enjoy deep, fresh powder, you’ll need to watch the forecast closely through the season. Forecasts out to 7-14 days can guide you to areas where the weather is trending cold and snowy, and then you can nail down the exact day and location of the best snow about 1-3 days in advance.

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