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Seasonal Climate Forecast Nov. 2014 – Jan. 2015 (Issued: October 20, 2014)

Seasonal Climate Forecast Nov. 2014 – Jan. 2015 (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 503-945-7448 pparsons@odf.state.or.us

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Seasonal Climate Forecast Nov. 2014 – Jan. 2015 (Issued: October 20, 2014)

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  1. Seasonal Climate ForecastNov. 2014 – Jan. 2015(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 503-945-7448 pparsons@odf.state.or.us Get related Seasonal Climate Forecast information at: http://www.oregon.gov/ODA/programs/NaturalResources/Pages/Weather.aspx

  2. 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. • 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.

  3. 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. • The Climate Prediction Center (CPC) favors “El Niño” development in the next 1-2 months…lasting into the spring of 2015. • 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. http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

  4. Tropical Pacific OceanAnimated (in PowerPoint only) SSTs (top) / Anomalies (bottom) Courtesy: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_update/sstanim.shtml

  5. Tropical Pacific OceanSSTs remain mostly warmer than average Courtesy: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_update/sstweek_c.gif

  6. ENSO Indices (2008-09;1967-68; 1950-51) La Niña ENSO-Neutral El Niño

  7. ENSO Indices (2008-09;1967-68; 1950-51) El Niño conditions developed, by late-autumn, in each of the top 3 analog years. El Niño ENSO-Neutral La Niña La Niña conditions developed, during the winter, in 1 of the top 3 analog years.

  8. ENSO Predictive ModelsComputer models favor weak El Niño development Model forecasts favor ENSO-neutral conditions through spring 2014; followed by El Niño development. El Niño ENSO-neutral La Niña Courtesy: http://iri.columbia.edu/climate/ENSO/currentinfo/SST_table.html

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

  10. December 2014 Forecast Temperatures Precipitation • 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. • Heavy valley snow in December 1968 but not in 1951 nor in 2009.

  11. January 2015 Forecast Temperatures Precipitation • 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.

  12. Nov. 2014 – Jan. 2015 Forecast Temperatures Precipitation • 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…

  13. Nov. 2014 – Jan. 2015 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. • 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. • Dec. 1968 – Jan. 1969, (one of the top analogs for this year) produced multiple Arctic outbreaks with heavy snowfall across much of the state.

  14. Some Helpful Resources • CPC Official US Three-Month Forecasts (Graphics): http://www.cpc.ncep.noaa.gov/products/predictions/long_range/seasonal.php?lead=01 • CPC US 30-Day & 90-Day Forecasts (Discussions): http://www.cpc.ncep.noaa.gov/products/predictions/long_range/fxus07.html • CPC Weekly & Monthly ENSO Discussions: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory • Australian Government Weekly Tropical Climate Note: http://www.bom.gov.au/climate/tropnote/tropnote.shtml • Australian Government ENSO Wrap-Up: http://www.bom.gov.au/climate/enso • IRI ENSO Quick Look: http://portal.iri.columbia.edu/portal/server.pt?open=512&objID=945&mode=2 • NRCS Western Snowpack Data & Water Supply Forecast: http://www.wcc.nrcs.usda.gov/cgibin/westsnowsummary.pl

  15. Updated Monthly(around the 20th) Your Feedback is Welcome Contact: Pete Parsons, ODF Meteorologist 503-945-7448 pparsons@odf.state.or.us ODA Production support from Diana Walker and Andy Zimmerman

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