October Winter Forecast October 29, 2011 Pete Parsons, ODF Meteorologist Pete Parsons, ODF Meteorologist oregon.gov/oda/nrd/weather.shtml#weather_forecastsoregon.gov/oda/nrd/weather.shtml#weather_forecasts PWODT/OMSI Exclusive Presentation! Exclusive Presentation!PWODT/OMSI

Best Prediction Since 1996

Winter Prediction … Packers will overcome injuries and win the Super Bowl! Packers will overcome injuries and win the Super Bowl!

February 6, 2011

Back to the Weather!

November 2010 ( Forecast Issued October 16, 2010) Forecast Precipitation Actual Precipitation Data courtesy of the National Climatic Data Center (NCDC)

November 2010 ( Forecast Issued October 16, 2010) Forecast Temperatures Actual Temperatures Data courtesy of the National Climatic Data Center (NCDC)

December 2010 ( Forecast Issued October 16, 2010) Forecast Precipitation Actual Precipitation Data courtesy of the National Climatic Data Center (NCDC)

December 2010 ( Forecast Issued October 16, 2010) Forecast Temperatures Actual Temperatures Data courtesy of the National Climatic Data Center (NCDC)

January 2011 ( Forecast Issued October 16, 2010) Forecast Precipitation Actual Precipitation Data courtesy of the National Climatic Data Center (NCDC)

January 2011 ( Forecast Issued October 16, 2010) Forecast Temperatures Actual Temperatures Data courtesy of the National Climatic Data Center (NCDC)

February 2011 ( Forecast Issued October 16, 2010) Forecast Precipitation Actual Precipitation Data courtesy of the National Climatic Data Center (NCDC)

February 2011 ( Forecast Issued October 16, 2010) Forecast Temperatures Actual Temperatures Data courtesy of the National Climatic Data Center (NCDC)

November – January ( Forecast Issued October 16, 2010) Forecast Precipitation Actual Precipitation Data courtesy of the National Climatic Data Center (NCDC)

November – January ( Forecast Issued October 16, 2010) Forecast Temperatures Actual Temperatures Data courtesy of the National Climatic Data Center (NCDC)

December – February ( Forecast Issued October 16, 2010) Forecast Precipitation Actual Precipitation Data courtesy of the National Climatic Data Center (NCDC)

December – February ( Forecast Issued October 16, 2010) Forecast Temperatures Actual Temperatures Data courtesy of the National Climatic Data Center (NCDC)

Winter Forecast Well above normal precipitation. Well above normal precipitation. Near normal temperatures. Near normal temperatures. Above average mountain snow. Above average mountain snow. One or more of the following in December and/or January: coastal windstorm(s); Arctic outbreak; valley snow/ice; flooding. One or more of the following in December and/or January: coastal windstorm(s); Arctic outbreak; valley snow/ice; flooding.

Typical ENSO Patterns

WarmEvent ColdEvent

PWODT Seasonal Climate Forecasting Method Use the SOI and ONI to Identify Past Years With Similar Tropical Pacific Ocean Sea-Surface Temperatures. Use the SOI and ONI to Identify Past Years With Similar Tropical Pacific Ocean Sea-Surface Temperatures. Use Historical Data From Those Years to Make General Seasonal Predictions. Use Historical Data From Those Years to Make General Seasonal Predictions. No Corrections are Made for Changes in Global Climate…Creating Error. No Corrections are Made for Changes in Global Climate…Creating Error.

SOI Based On Pressure Anomalies of Two Sites Tahiti Darwin

La Niña Events El Niño Events

RepeatingPattern?

( ; ; ; ; ) 1st Year2nd Year

ONI Based on SST Departures in Niño 3.4

La Niña Events El Niño Events

ONI Based on SST Departures in Niño 3.4 RepeatingPattern?

1st Year2nd Year ( ; ; ; ; )

El Niño Modoki Feb. 2010

La Niña Feb. 2011

ENSO-Neutral July 2011

August - October, 2011

La Niña Oct. 2011

ENSO-Neutral Oct. 2008

La Niña Returned? Dec. 2008

La Niña Oct. 2011

Winter Forecast

November 2011 Forecast PrecipitationTemperatures

November 2011 Forecast (Based on 1971, 1974, 1989, 1999, & 2008) Above to well above average temperatures. Above to well above average temperatures. Precipitation will most likely be near or slightly below normal statewide. Precipitation will most likely be near or slightly below normal statewide. Expect minimal mountain snow before the final week of the month. Expect minimal mountain snow before the final week of the month.

December 2011 Forecast PrecipitationTemperatures

December 2011 Forecast (Based on 1971, 1974, 1989, 1999, & 2008) Confidence in the December forecast is below average, due to large variations in weather conditions during the analog years. Confidence in the December forecast is below average, due to large variations in weather conditions during the analog years. Extreme weather conditions are possible. Extreme weather conditions are possible. The average of the analog years would suggest slightly above average temperatures and slightly below average precipitation. The average of the analog years would suggest slightly above average temperatures and slightly below average precipitation.

January 2012 Forecast PrecipitationTemperatures

January 2012 Forecast (Based on 1972, 1975, 1990, 2000, & 2009) The analog years are consistent in showing a switch to above normal precipitation. The analog years are consistent in showing a switch to above normal precipitation. Analog years do not yield a consistent temperature forecast...a blend would suggest near to slightly below normal temperatures west and above normal east. Analog years do not yield a consistent temperature forecast...a blend would suggest near to slightly below normal temperatures west and above normal east. Significant mountain snow likely with a good chance of a late-month Arctic event. Significant mountain snow likely with a good chance of a late-month Arctic event.

February 2012 Forecast PrecipitationTemperatures

February 2012 Forecast (Based on 1972, 1975, 1990, 2000, & 2009) Near to above normal precipitation. Near to above normal precipitation. Below normal temperatures. Below normal temperatures. Significant mountain snow likely with an above average snowpack for most areas. Significant mountain snow likely with an above average snowpack for most areas. Good chance that the month will begin with a cold outbreak along with some valley snow or freezing rain. Good chance that the month will begin with a cold outbreak along with some valley snow or freezing rain.

November - January Forecast PrecipitationTemperatures

PrecipitationTemperatures

December - February Forecast PrecipitationTemperatures

PrecipitationTemperatures

Winter Forecast Above average temperatures early. Bonus if ski areas can open by Thanksgiving. Above average temperatures early. Bonus if ski areas can open by Thanksgiving. Turning stormy in December and January with another cold February. Turning stormy in December and January with another cold February. Cold periods will have a better chance of being accompanied by snow this winter. Cold periods will have a better chance of being accompanied by snow this winter. Most mountain snowpacks should be above normal by late January - February. Most mountain snowpacks should be above normal by late January - February.

Winter Snowlights Average Portland snowfall 4.5” Average Portland snowfall 4.5” Analog average snowfall 7.5” Analog average snowfall 7.5” Above average snowfall likely for the Willamette Valley. Above average snowfall likely for the Willamette Valley. Watch out for freezing rain. Watch out for freezing rain.

Winter’s Big Question? Could We See a Repeat of ? Or Worse…?

Winter Forecast October 29, 2011 Pete Parsons, ODF Meteorologist Pete Parsons, ODF Meteorologist oregon.gov/oda/nrd/weather.shtml#weather_forecastsoregon.gov/oda/nrd/weather.shtml#weather_forecasts PWODT/OMSI Exclusive Presentation! Exclusive Presentation! PWODT/OMSI Exclusive Presentation!