El Niño Update – Separating Hype from Probability

The following is an excerpt of the Browning World Climate Bulletin, a key source of information in describing the relationship between macro weather-related trends and their potential impact upon energy, commodities, and the wider global economy. To subscribe to her monthly newsletter, click here.

Summary: Expect a strong El Nino this winter to warmer conditions in the northern tier of states and most of Canada. This should lead to lower heating demand, as well as fewer travel and transportation difficulties. The southern tier of states should get cooler, wetter conditions, usually enough to end drought conditions in all but Southern California. California should expect more precipitation but not enough to end the drought.

El Niño may be the only climate event that needs its own press agent. Once it was determined that there will be a strong El Niño, it has dominated the headlines. Some of these headlines are intelligent warnings and others are exercises in attention-grabbing hyperbole. Let’s separate the probability from the hype.

The Danger of Analog Years

One of the great dangers of some of the current headlines is that many of the reporters are comparing this upcoming El Niño event to the huge El Niño of 1997/1998. While both years have powerful El Niños dominating the Tropical Pacific, they have a number of climate factors that do not match.

Remember – you cannot use single factor analysis for running a business or making a weather forecast.

Climate probability is a mosaic of factors. North American winters are shaped by what is happening in the Atlantic and Arctic as well as the Pacific. Even in the Pacific, El Niño is not the only factor affecting the West Coast.

The West Coast – The Region Most Affected by El Niño

Some of the wildest headlines have been from the West Coast, where many view the event as a possible salvation from the four-year long drought. A few good ones are:

  • “Will El Nino End California’s Water Saving?” BBC Business Matters
  • “Super El Niño Means Super Rain?” Liveweatherblogs.com
  • and, just in case floods and landslides are not scary enough, “El Niño delivers venomous sea snakes to California beaches,” San Jose Mercury News.

Readers of the Browning Bulletin know that historical evidence gives a more than 90% probability that there will be good rainfall in California this winter but it will only partially relieve drought conditions. The four-year drought and groundwater drainage has led to a giant shortfall, 6.5 trillion gallons back in April and much greater now. In Central California an area greater the state of Rhode Island has sunk as much as 6 feet (183 cm), wrecking and damaging irrigation and water supply infrastructures. Coastal areas have had sea water surge into aquafers to replace the missing fresh water.

The problems that the West Coast faces in order to end the drought are:

  1. Heavy El Niño rains are a mixture of heavy tropical precipitation and normal Pacific storms from the Northwest. The tropical moisture has reached Mexico and should take several weeks to work its way up the coast. Most experts expect only near-normal rainfall this November and most of December with above average heat increasing evaporation.
  2. The main reservoir of California is its snowpack which dropped to almost nothing this year. Its water system is geared to pour snow melt into storage reservoirs. Even heavy precipitation will not restore a giant snowpack when temperatures are high.
  3. California's major reservoirs are in the north and only 3 of the seven large El Niños since 1950, less than 50%, had heavy precipitation in this key area. The reservoirs in the southern areas that typically get reliable El Niño rainfall are small.

History suggests that Central and Southern alifornia should have heavy rainfall while Northern California good rainfall. Historically much of this rainfall comes in the form of torrential rains and flash flooding from tropical streams of moisture called atmospheric rivers. Meanwhile, the coastal Pacific Northwest and British Columbia get heavy rains with occasional “Pineapple Expresses”. Inland, the Northwest and Alberta and Saskatchewan, have an 80% chance of a warm, dry winter.

The following is an excerpt of their November 2015 newsletter. To become a subscriber or learn more about the Browning World Climate Bulletin, click here to visit their site.

Co-authored by James Garriss