1. Winter Outlook (2012-2013) Oregon Museum of Science and Industry AMS Oregon Chapter Meeting 17 November 2012 Oregon Museum of Science and Industry AMS Oregon Chapter Meeting 17 November 2012 Clinton Rockey NOAA/National Weather Service

2. El Niño vs. La Niña La Niña Below-normal sea surface temperatures in equatorial Pacific Ocean El Niño Above-normal sea surface temperatures in equatorial Pacific Ocean Nov 1997 Feb 1999

3. El Niño vs. La Niña La Niña El Niño

4. La Niña vs El Niño Precipitation La Niña Temperature El Niño Temperature Precipitation Based on 1950-2010 NOAA data

5. Current ENSO Current ENSO Status Tropical conditions may resemble a weak El Niño at times, but ENSO-neutral conditions will persist into 2013. As of 8 November Warm Neutral

6. Sea Surface Temperatures (SST) SST have decreased since July SST have decreased since July But rose slightly in October But rose slightly in October

7. Climate Model Predictions ENSO-neutral conditions favored through Spring 2013. El Niño ñ La Niña ENSO-neutral

8. Temperature Precipitation NOAA’s U. S. Seasonal Outlooks December 2012 – February 2013 Favors Warmer Favors Drier Favors Wetter Favors Cooler

9. Monthly Precipitation at PDX But Likely to Finish Wetter than Average Near Average Rainfall in most of Winter

10. ENSO Rain Signal * 15 October through 15 March

11. ENSO and Flood Events

12. Portland Snow Data In ‘Warm Neutral’ Years Average Portland Winter Snowfall ~5.0 inches 1993-94 (2.6”) 1990-91 (1.9”) 1979-80 (12.4”) 2003-04 (12.3”) 1958-59 (2.9”) 1960-61 (0”) 1989-90 (8.3”) 1992-93 (14.1”) 1952-53 (0.6”)

13. ENSO Lowlands Snow Signal

14. Portland Snowfall History Top 10 snowiest winters: 34.0” 1968-69 El Niño 24.2” 2008-09 ENSO Neutral 22.4” 1955-56 La Niña 20.3” 1959-60 ENSO Neutral 17.4” 1992-93 ENSO Neutral 16.3” 1979-80 ENSO Neutral 14.7” 1970-71 La Niña 13.4” 1964-65 ENSO Neutral 12.3” 2003-04 ENSO Neutral 12.0” 1994-95 El Niño 10.5” 1953-54 ENSO Neutral 1950-2011 data

15. PDX Snowfall History 1951 to 2010 18 snow-shutout winters: (Trace or 0 snowfall) 8 were El Niño winters 7 were ENSO Neutral winters 3 were La Niña winter So…in recent years, for low elevations, ENSO Neutral: - Wide Range of possibilities. * Can have a moderately snowy winter (2003-04) * Can be very mild (1992-93 and 2001-02)

16. ENSO and Portland Snow Events

17. So, will there be a lot of rain or snow this Winter? Cartoon used with permission by T. McCracken

18. Winter 2012-13 Outlook Temperatures Near average. Precipitation Slightly drier than Average February may trend to slightly wetter than average. Lowland Snow Potential Low to Moderate in January and February. More likely would be a Mixed Precipitation Event (Sleet, Snow and/or Freezing Rain) But…. Weather in ENSO Neutral years is Highly Variable. Will we be shut out, or shut in due to snow?

19. POC: Clinton Rockey, NWS Portland clinton.rockey@noaa.gov 503.326.2340 x242 or POC: Tyree Wilde, NWS Portland tyree.wilde@noaa.gov 503.326.2340 x223 Questions?