Seasonal Climate Forecast Nov – Jan (Issued: October 20, 2014) This Product is Published by the Oregon Department of Agriculture (ODA), in Cooperation with the Oregon Department of Forestry (ODF). Contact: ODF Meteorologist Pete Parsons at Get related Seasonal Climate Forecast information at: This Product is Published by the Oregon Department of Agriculture (ODA), in Cooperation with the Oregon Department of Forestry (ODF). Contact: ODF Meteorologist Pete Parsons at Get related Seasonal Climate Forecast information at:

Forecast Method Notes… Analog years were obtained by tracking and comparing a variety of indices over the past several years (see Forecasting Methods). Priority was given to years from a “Cool Phase” period of the Pacific Decadal Oscillation (PDO) with sea-surface temperatures (SSTs) most closely matching the current SSTs in the equatorial Pacific Ocean. Analog years were obtained by tracking and comparing a variety of indices over the past several years (see Forecasting Methods). Priority was given to years from a “Cool Phase” period of the Pacific Decadal Oscillation (PDO) with sea-surface temperatures (SSTs) most closely matching the current SSTs in the equatorial Pacific Ocean. Forecasting Methods Forecasting Methods The analog years (2009; 1968; 1951) used to create this forecast are all from “Cool Phase” periods of the “PDO” and are unchanged from last month. The analog years (2009; 1968; 1951) used to create this forecast are all from “Cool Phase” periods of the “PDO” and are unchanged from last month. “Moderate El Niño” conditions developed during the autumn/winter seasons in each of the top analog years. “Moderate El Niño” conditions developed during the autumn/winter seasons in each of the top analog years.

El Niño Southern Oscillation (ENSO) Current Status and Forecast ENSO-neutral (average) conditions continue across the equatorial Pacific Ocean, although sea-surface temperatures (SSTs) are mostly above average. ENSO-neutral (average) conditions continue across the equatorial Pacific Ocean, although sea-surface temperatures (SSTs) are mostly above average. The Climate Prediction Center (CPC) favors “El Niño” development in the next 1-2 months…lasting into the spring of The Climate Prediction Center (CPC) favors “El Niño” development in the next 1-2 months…lasting into the spring of The “analog years” used in this forecast also support the development of “El Niño” this late-autumn. The “analog years” used in this forecast also support the development of “El Niño” this late-autumn. A weak or moderate strength El Niño is most likely for this coming late-autumn/winter. A weak or moderate strength El Niño is most likely for this coming late-autumn/winter.

Tropical Pacific Ocean Animated (in PowerPoint only) SSTs (top) / Anomalies (bottom) Courtesy:

Tropical Pacific Ocean SSTs remain mostly warmer than average Courtesy:

ENSO Indices El Niño La Niña ( ; ; ) ENSO-Neutral

La Niña La Niña conditions developed, during the winter, in 1 of the top 3 analog years. El Niño El Niño conditions developed, by late-autumn, in each of the top 3 analog years. El Niño ENSO Indices ( ; ; ) ENSO-Neutral La Niña

Model forecasts favor ENSO-neutral conditions through spring 2014; followed by El Niño development. ENSO Predictive Models Computer models favor weak El Niño development Courtesy: La Niña El Niño ENSO-neutral

November 2014 Forecast TemperaturesPrecipitation No significant departures from “average” temperatures and precipitation indicated. No significant departures from “average” temperatures and precipitation indicated. Mountain snowpacks to begin earlier than average (mid-month). Mountain snowpacks to begin earlier than average (mid-month). Increased potential for stormy weather, especially along the coast. Increased potential for stormy weather, especially along the coast.

December 2014 Forecast TemperaturesPrecipitation Consensus among the analog years is for below average temperatures. Consensus among the analog years is for below average temperatures. Two of the top analog years (1951 & 1968) were very stormy with above average precipitation, but the third year (2009) was quite dry. Two of the top analog years (1951 & 1968) were very stormy with above average precipitation, but the third year (2009) was quite dry. Heavy valley snow in December 1968 but not in 1951 nor in Heavy valley snow in December 1968 but not in 1951 nor in 2009.

January 2015 Forecast TemperaturesPrecipitation Extreme variation of weather among the analog years…ranging from very cold and wet (1969) to very mild and somewhat dry (2010). Extreme variation of weather among the analog years…ranging from very cold and wet (1969) to very mild and somewhat dry (2010). Graphics are skewed cold and wet by the extreme conditions of 1969, but a mild and dry January is more typical with El Niño. Graphics are skewed cold and wet by the extreme conditions of 1969, but a mild and dry January is more typical with El Niño.

Nov – Jan Forecast TemperaturesPrecipitation Look for an early start to mountain snowpacks (mid-November). Look for an early start to mountain snowpacks (mid-November). Tremendous variation among analog years for December and January increases forecast uncertainty. A “classic” El Niño produces warmer and drier than average weather, but the opposite extremes can occur… Tremendous variation among analog years for December and January increases forecast uncertainty. A “classic” El Niño produces warmer and drier than average weather, but the opposite extremes can occur…

Nov – Jan Highlights It appears that either a weak or moderate El Niño is likely to develop, which commonly produces cool and stormy conditions in late-autumn, then relatively mild and dry winter weather…below average mountain snow and minimal valley snow. It appears that either a weak or moderate El Niño is likely to develop, which commonly produces cool and stormy conditions in late-autumn, then relatively mild and dry winter weather…below average mountain snow and minimal valley snow. However, this scenario is not always the case… However, this scenario is not always the case… In stark contrast to the current Climate Prediction Center (CPC) Forecasts, the analog method used here shows that extremely cold and wet weather can’t be ruled out for this December and January. In stark contrast to the current Climate Prediction Center (CPC) Forecasts, the analog method used here shows that extremely cold and wet weather can’t be ruled out for this December and January. Dec – Jan. 1969, (one of the top analogs for this year) produced multiple Arctic outbreaks with heavy snowfall across much of the state. Dec – Jan. 1969, (one of the top analogs for this year) produced multiple Arctic outbreaks with heavy snowfall across much of the state.

Some Helpful Resources CPC Official US Three-Month Forecasts (Graphics): CPC Official US Three-Month Forecasts (Graphics): h ttp:// CPC US 30-Day & 90-Day Forecasts (Discussions): CPC US 30-Day & 90-Day Forecasts (Discussions): CPC Weekly & Monthly ENSO Discussions: CPC Weekly & Monthly ENSO Discussions: Australian Government Weekly Tropical Climate Note: Australian Government Weekly Tropical Climate Note: Australian Government ENSO Wrap-Up: Australian Government ENSO Wrap-Up: IRI ENSO Quick Look: IRI ENSO Quick Look: NRCS Western Snowpack Data & Water Supply Forecast: NRCS Western Snowpack Data & Water Supply Forecast:

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