Seasonal Forecasts using Objectively Chosen Analog Years

Seasonal Forecastsusing

Objectively Chosen Analog Years

•The Technique

•2012-13 Verification

•Analogs for Upcoming Winter

•The Forecast

Analog Seasonal Forecasting

• Look at this year so far…• Look at this year so far…

• Look at this year so far…

• Look for past years that are similar to this year …

• Use what subsequently happened in those past years as a forecast for what will happen this year.

Climate IndicesClimate IndicesPNA (Pacific North American Index)

NAO (North Atlantic Oscillation)

Jones NAO

EPO (Eastern Pacific Oscillation)

NTA (North Tropical Atlantic Index)

CAR (Caribbean Index)

Nino 3

Nino 1+2

Nino 3+4

Nino 4

Pacific Warm Pool

Tropical Pacific SST EOF

WHWP WP (West Pacific Index)

QBO (Quasi-Biennial Oscillation)

PDO (Pacific Decadal Oscillation)

PMM (Pacific Meridional Mode)

NP (North Pacific Index)

PNA (Pacific North American Index)

NAO (North Atlantic Oscillation)

Jones NAO

EPO (Eastern Pacific Oscillation)

NTA (North Tropical Atlantic Index)

CAR (Caribbean Index)

Nino 3

Nino 1+2

Nino 3+4

Nino 4

Pacific Warm Pool

Tropical Pacific SST EOF

WHWP WP (West Pacific Index)

QBO (Quasi-Biennial Oscillation)

PDO (Pacific Decadal Oscillation)

PMM (Pacific Meridional Mode)

NP (North Pacific Index)

NOI (Northern Oscillation Index) AO (Arctic Oscillation) AAO TNI Atlantic Tripole SST EOF AMO AMM (Atlantic Meridional Mode) ACE (Atlantic Accumulated Cyclone

Intensities) Solar Cycle (Flux) Monthly Hurricane Total MDR Hurricanes SST Anomaly MDR - Tropics SST Anomaly Central India Monsoon Precipitation Sahel Rainfall Brazil Rainfall SW USA Monsoon Global Mean Temperature ESPI Globally integrated angular

momentum

NOI (Northern Oscillation Index) AO (Arctic Oscillation) AAO TNI Atlantic Tripole SST EOF AMO AMM (Atlantic Meridional Mode) ACE (Atlantic Accumulated Cyclone

Intensities) Solar Cycle (Flux) Monthly Hurricane Total MDR Hurricanes SST Anomaly MDR - Tropics SST Anomaly Central India Monsoon Precipitation Sahel Rainfall Brazil Rainfall SW USA Monsoon Global Mean Temperature ESPI Globally integrated angular

momentum

Not just the index…But sensible weather…IE Warm/Cool… Wet/Dry

Automate the ProcessAutomate the Process

• Compare each previous year to this year…

• Compute a “Goodness of Fit” number…

• Sort “Goodness of Fit”…

• Print/Save results…

• Do this for multiple indices…

• Find “Consensus” analog years

Last Year’s

2012/13 Forecast Summary2012/13 Forecast Summary

Forecast: Climate Division 2 – Willamette Valley

Dec Jan Feb Mar Apr May

Precip:

Near Near Above Near Near Near Near Near Above Near Near Near Below Above Below Near Above NearBelow Above Below Near Above Near

Precip:

Climate Division 2 – Willamette ValleyObserved:

Precip:

Near Below Near Above Near AboveNear Below Near Above Near AboveAbove Below Below Below Near Above Above Below Below Below Near Above

Precip:

Climate Division 2 – Willamette ValleyObserved:

Precip:

Near Below Near Above Near AboveNear Below Near Above Near AboveAbove Below Below Below Near Above Above Below Below Below Near Above

2012/13 Verification2012/13 Verification

• 3 “Hits”

• 6 One-category errors

• 3 Two-category errors

On to Next Winter…

Last Year’s IndicesLast Year’s Indices

CPC SOI, MEI, ONI, CPC SOI, MEI, ONI, BOM SOI, Nino 3.4 Anom, BOM SOI, Nino 3.4 Anom, Nino 3 Temps, Nino 4 Temps, Nino 3 Temps, Nino 4 Temps, PNA, PDO, NAO, AO, WP, PNA, PDO, NAO, AO, WP, and the QBO.and the QBO.

This Year’s IndicesThis Year’s Indices

CPC SOICPC SOIMEIMEIONI ONI PDOPDO

Choosing AnalogsArt or Science?

Steve Pierce: 1959/60 1962/63 1985/96 1990/91 2001/02 2008/09Steve Pierce: 1959/60 1962/63 1985/96 1990/91 2001/02 2008/09

Steve Pierce: 1959/60 1962/63 1985/96 1990/91 2001/02 2008/09