Winter Outlook ( ) 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
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
El Niño vs. La Niña La Niña El Niño
La Niña vs El Niño Precipitation La Niña Temperature El Niño Temperature Precipitation Based on NOAA data
Current ENSO Current ENSO Status Tropical conditions may resemble a weak El Niño at times, but ENSO-neutral conditions will persist into As of 8 November Warm Neutral
Sea Surface Temperatures (SST) SST have decreased since July SST have decreased since July But rose slightly in October But rose slightly in October
Climate Model Predictions ENSO-neutral conditions favored through Spring El Niño ñ La Niña ENSO-neutral
Temperature Precipitation NOAA’s U. S. Seasonal Outlooks December 2012 – February 2013 Favors Warmer Favors Drier Favors Wetter Favors Cooler
Monthly Precipitation at PDX But Likely to Finish Wetter than Average Near Average Rainfall in most of Winter
ENSO Rain Signal * 15 October through 15 March
ENSO and Flood Events
Portland Snow Data In ‘Warm Neutral’ Years Average Portland Winter Snowfall ~5.0 inches (2.6”) (1.9”) (12.4”) (12.3”) (2.9”) (0”) (8.3”) (14.1”) (0.6”)
ENSO Lowlands Snow Signal
Portland Snowfall History Top 10 snowiest winters: 34.0” El Niño 24.2” ENSO Neutral 22.4” La Niña 20.3” ENSO Neutral 17.4” ENSO Neutral 16.3” ENSO Neutral 14.7” La Niña 13.4” ENSO Neutral 12.3” ENSO Neutral 12.0” El Niño 10.5” ENSO Neutral data
PDX Snowfall History 1951 to 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 ( ) * Can be very mild ( and )
ENSO and Portland Snow Events
So, will there be a lot of rain or snow this Winter? Cartoon used with permission by T. McCracken
Winter 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?
POC: Clinton Rockey, NWS Portland x242 or POC: Tyree Wilde, NWS Portland x223 Questions?