Climate variations in the Northwest, seasonal climate forecasting, and outlook for winter Philip W. Mote Climate Impacts Group University of Washington

A history of the PDO warm cool warm A history of ENSO

Effects of PDO and ENSO on Idaho temperature Warm ENSO, warm PDO Warm ENSO Cool ENSO Cool ENSO, cool PDO ½½ ENSO neutral, cool PDO Degrees F Years classified according to

Effects of PDO and ENSO on Idaho precipitation Warm ENSO, warm PDO Warm ENSO Cool ENSO Cool ENSO, cool PDO ENSO neutral, cool PDO Years classified according to

Summary ENSO, PDO play a modest role in winter and spring climate: zwarm ENSO, warm PDO tilt balance to above- average temperatures and below-average precipitation zcool ENSO, cool PDO tilt balance (less) toward cool wet zENSO and PDO can “cancel” each other zJan-Jun sensitive period for temp, Nov-Mar sensitive period for precipitation

Nov 2000-Feb mb height

Nov 2000-Feb 2001 temperature anomalies Degrees F

Nov 2000-Feb 2001 precipitation anomalies Standard deviations

Idaho temperature Warm ENSO, warm PDO Cool ENSO, cool PDO ½½ Degrees F Years classified according to

Idaho precipitation Warm ENSO, warm PDO Cool ENSO, cool PDO Years classified according to * 2001 water year

Monitoring El Niño ENSO Observing Network of 70 buoys

The European Center’s ENSO Forecast Forecast SSTs in the eastern equatorial Pacific, from the European Center for Medium Range Weather Forecasting (

ENSO outlook summary zENSO remains in a near-neutral state zLeading ENSO prediction models are calling for weak El Nino sometime zWe’ve heard this before…

The Pacific Decadal Oscillation

Global SST anomalies

Pacific Decadal Oscillation Update Since fall 1998, PDO index has consistently had negative values PDO Persistence has historically been a skillful forecast (correct ~75% of the time) odds favor “cool/negative PDO” for winter

NDJ FMA MJJ

The Pineapple Express and tropical rainfall: a potential NW link to the tropical Madden-Julian Oscillation

Conclusions zWeak El Niño possible early 2002? zCPC’s forecast (educated guesswork) for Idaho: normal winter, spring will be warmer zwhat about PDO? Cool/wet influence (ignored by CPC) zOcean situation similar to last year (but atmosphere ignored ocean last year)