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Seasonal Climate Forecast Dec. 2012 – Feb. 2013 (Issued: November 15, 2012). 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 ForecastDec. 2012 – Feb. 2013(Issued: November 15, 2012) 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://cms.oregon.gov/ODA/NRD/Pages/weather.aspx
El Niño Southern Oscillation (ENSO) • ENSO-neutral (near normal) conditions are continuing. However, central and western tropical Pacific Ocean sea-surface temperatures (SSTs) remain above normal. • A full-fledged weak El Niño event is becoming less likely this winter, with the most recent trends in the opposite direction (towards ENSO-neutral conditions). • The previously issued “El Niño Watch” has been discontinued by the Climate Prediction Center (CPC). • The official CPC forecast is now for ENSO-neutral conditionsto continue through this winter. Courtesy: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.html
Tropical Pacific OceanAnimated (in PowerPoint only) SSTs (top) / Anomalies (bottom) Courtesy: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_update/sstanim.shtml
Tropical Pacific Ocean“ENSO Neutral” conditions are continuing… Courtesy: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_update/sstweek_c.gif
ENSO Indices (2008-09;2000-01; 1950-51) La Niña El Niño
ENSO Indices (2008-09;2000-01; 1950-51) El Niño La Niña
ENSO Predictive ModelsMost models predict continued slow cooling in the central tropical Pacific Ocean El Niño ENSO-neutral conditions are most likely through mid-2013 La Niña Courtesy: http://iri.columbia.edu/climate/ENSO/currentinfo/SST_table.html
ENSO Predictive ModelsThe CPC/IRI consensus forecast ENSO-neutral conditions are most likely through mid-2013 Courtesy: http://portal.iri.columbia.edu/portal/server.pt?open=512&objID=945&mode=2
December 2012 Forecast Temperatures Precipitation • Stormy periods likely. Cooler than normal with near to above normal precipitation. Increased chance of Arctic outbreaks late in the month. • Diverse weather during the analog years (some mild and stormy and others with significant cold episodes) lowers forecast confidence.
January 2013 Forecast Temperatures Precipitation • ENSO-neutral conditions favor stormy and mild periods alternating with cold and dry stretches (often with Arctic outbreaks and valley snow). • Overall temperatures will depend on the severity of any cold snaps. • Diverse weather during the analog years lowers forecast confidence.
February 2013 Forecast Temperatures Precipitation • Seasonal temperatures with below normal precipitation. • Most analog years had El Niño episodes, which would typically yield a mild and dry February. However, ENSO-neutral conditions are likely this year, so precipitation totals may be closer to normal than indicated.
Dec. 2012 – Feb. 2013 Forecast Temperatures Precipitation • Mild and stormy periods alternating with cool and drier periods. Severity of any cold snaps will strongly influence overall departures. • ENSO-neutral conditions favor Arctic intrusions and valley snow events, mainly from mid-December through January.
Winter 2012-13 Highlights • There are no excellent analog matches for this winter (looking back over the past 100+ years). • It is rare to have back-to-back La Niña winters (the past two) followed by ENSO-neutral conditions (forecast for this winter). This year is also unique due to the recent decay of what appeared to be a developing El Niño episode. • ENSO-neutral winters tend to produce stormy and mild periods alternating with cool and dry periods (often Arctic outbreaks). The transitions can bring valley snow & ice. • The favored ENSO-neutral period for Arctic outbreaks and valley snow events is from mid-December through January.
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 Mary Jane Schaffer