El Niño and the Winter Weather Outlook

Transcription

1 El Niño and the Winter Weather Outlook 2015 NASEO Annual Meeting NWS Boston February 10, 2015 Jimmy Taeger Meteorologist National Weather Service San Diego September 15, 2015

2 Outline What is El Niño? El Niño Forecast How might El Niño affect the CONUS? Tropical Cyclones in the Atlantic Temperature and Precipitation Winter Weather Outlook 2

3 What is El Niño? Chris Farley on SNL Godzilla Youtube.com 3

4 What is El Niño? Easterly trade winds near the equator weaken, and allow sea surface temperatures (SSTs) in the eastern equatorial Pacific to warm due to less upwelling El Niño is a phenomenon in the equatorial Pacific Ocean defined by a five consecutive 3-month running mean of SST anomalies in the Niño 3.4 region that is above the threshold of +0.5 C. Niño Regions 4

5 What is El Niño? ( C) C. America Very Warm Australia 5

6 El Niño Forecast Strong El Niño conditions are currently present There is a >90% chance that El Niño will continue through Northern Hemisphere winter , and around an 85% chance it will last into early spring Strong Moderate Weak Yellow Line is the Average Forecast Official forecast peaks near 2.5ºC 3-Month Running Means 6

7 What is El Niño? SST anomalies from 1950-present in the Nino 3.4 region Circled years were strong (>1.5ºC) El Niño years in the winter Strong Years 7

8 How Might El Niño Affect the CONUS? TROPICAL CYCLONES IN THE ATLANTIC El Niño increases shear and enhances sinking air over portions of the Atlantic Updated 2015 Atlantic Hurricane Season Outlook (Issued August 6 th ) Named Storms: 6-10 Hurricanes: 1-4 Major Hurricanes: 0-1 NOAA Season Type Average Number of Tropical Storms Average Number of Hurricanes Average Number of Major* Hurricanes Above-Normal Near-Normal Below-Normal *Major hurricanes have sustained winds of 111 mph or greater (Category 3,4 or 5) 8

9 How Might El Niño Affect the CONUS? TROPICAL CYCLONES IN THE ATLANTIC Tropical cyclone activity usually peaks around September 10 th NOTE: Disastrous hurricanes can still impact the U.S. during El Niño years 9

10 How Might El Niño Affect the CONUS? TEMPERATURE AND PRECIPITATION January through March Warmer in the Pacific Northwest and the northern Rockies Cool from New Mexico to South Carolina Wet over the extreme southern half of the CONUS 10

11 How Might El Niño Affect the CONUS? TEMPERATURE AND PRECIPITATION Winter (DJF) Climate Normals Temperature (ºF) Precipitation (in) 11

12 How Might El Niño Affect the CONUS? TEMPERATURE AND PRECIPITATION DJF Climate Anomalies for Strong (>1.5ºC) El Niño Years - Warmer northern CONUS - Cooler southern CONUS - Wetter coasts and southern CONUS - Below norm. OH Valley, and near norm. elsewhere 12

13 How Might El Niño Affect the CONUS? TEMPERATURE AND PRECIPITATION DJF Climate Anomalies for Strong (>2ºC) El Niño Years - Warmer Northeast and Midwest - Cooler southcentral and southwest CONUS - Wetter coasts, southern CONUS and Midwest - Below norm. OH Valley, and near norm. elsewhere 13

14 How Might El Niño Affect the CONUS? TEMPERATURE AND PRECIPITATION DJF Climate Anomalies for the Strongest El Niño (2.3ºC) on record - Warmer, except extreme S. and SW CONUS - Cooler S. California, Arizona and New Mexico - Wetter coasts and southern CONUS - Below norm. OH Valley, and near norm. elsewhere 14

15 Winter Weather Outlook Climate Prediction Center Winter Probability Outlook Temperature Precipitation A A B B B B A A Greater chances and higher confidence of - Colder and wetter than normal winter in southern portions of the CONUS - Warmer and Drier than normal winter in northern portions of the CONUS 15

16 Summary Strong El Niño forecast to continue through this winter SST anomalies in the Nino 3.4 region could rise to a new record high value Strong El Niño years in the winter tend to correlate to Warmer than normal in the northern CONUS Cooler than normal in the southern CONUS Wetter than normal in the southern CONUS and along the coasts, with below normal in the OH Valley, and near normal precipitation elsewhere CPC winter forecast similar to previous strong El Niño years, except for greater chances of below normal precipitation near the Northern Rockies and Great Lakes region 16

17 Thank You! Questions? Contact: Weather forecasts: weather.gov Useful Links El Niño and long-range forecasts: cpc.ncep.noaa.gov Climate anomaly maps: esrl.noaa.gov/psd/data/usclimdivs/ Tropical cyclone forecasts: hurricanes.gov 17