Impacts of La Niña (and NAO) on Washington DC Winters Winter Media Workshop 12/9/2011 Jared Klein LWX Climate Program Leader

NOAA/CPC Winter Outlook (Updated outlook- mid November) Temperatures Precipitation The seasonal outlooks combine the effects of long-term trends, soil moisture, and, when appropriate, ENSO.

Current State of ENSO

Current State of ENSO (cont.)

The majority of ENSO models predict the continuation of a weak to moderate La Niña at least through the Northern Hemisphere winter. ENSO Forecast International Research Institute (IRI) for Climate and Society

products/analysis_monitoring/ensoc ycle/nawinter.shtml El Niño pattern that dominated the winter La Niña pattern that dominated last winter and so far this fall

products/analysis_monitoring/ensoc ycle/nawinter.shtml El Niño pattern that dominated the winter La Niña pattern that dominated last winter and so far this fall

La Niña Winters and Temperature

Normal DJF Temp- 38.2°F La Niña Averages La Niña Time Series

La Niña Winters and Precipitation

Normal DJF Precip- 8.48" Normal DJF Precipitation (8.48”) La Niña Averages La Niña Time Series

La Niña Winters and Snowfall

La Niña Averages La Niña Time Series Normal Seasonal Snowfall " Seasonal Snowfall (15.5”)

” (09-10) ” (95-96) ” (57-58) ” (02-03) ” (60-61) ” (78-79) ” (66-67) ” (63-64) ” (86-67) ” (65-66) ” (82-83) ” (87-88) ” (59-60) ” (77-78) ” (81-82) ” (62-63) ” (67-68) ” (79-80) ” (53-54) ” (64-65) ” (71-72) ” (73-74) Years with Above Normal Snowfall at DCA (>15.5”) since SD +2 SD +1 SD

Assessment on the Winter NOAA Attribution Team (Hoerling et al. 2010) 500 mb height anomalies from the 30 snowiest months at Washington DC -NAO

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