1. science
2. weather

ALASKA REGION
CLIMATE FORECAST BRIEFING
April 17, 2015
Rick Thoman
National Weather Service Alaska Region
Today
•  Climate Forecast Basics
•  Feature of the month: Climate divisions based anomalies
•  Review of recent climate forecasts and conditions
•  CPC Forecasts and observations for most recent month and season
•  Current Atmosphere and Ice
•  Climate Drivers: SSTs, PDO, ENSO
•  Climate Forecast Guidance
•  ENSO
•  Statistical
•  Dynamic--NMME
•  Climate Prediction Center Last Month
•  CPC Outlooks
•  Next month
•  Next season
Climate Forecast Basics
Climate Prediction Center: primary
NOAA/NWS forecast responsibility
•  Climate Forecasts
•  Relation to some long term
normal (1981-2010)
•  Categorical (often three)
•  Probabilistic
•  Traditional Elements
•  Temperature: centered around
average
•  Precipitation: centered around
median (can significantly differ
from the “normal”, which by
convention is the mean)
Alaska Climate Divisions
•  Developed by Peter
Bieniek at UAF
•  Implemented by NCEI*
March 2015
•  Grid based
•  Broader scale but less
sensitive to variations in
individual station availability
and quality
•  Five category POR rankingsbased anomalies
*Formerly known as NCDC
March 2015 Temperatures
Preliminary data subject to revision
March 2015 Precipitation
Preliminary data subject to revision
March 2015 Precipitation Anomalies
Skill Score=+0.15
Above Normal
Near Normal
Below Normal
Preliminary data subject to revision
March 2015 Temperature Anomalies
Skill Score=+0.70
Above Normal
Near Normal
Below Normal
Preliminary data subject to revision
Jan-Feb-Mar 2015 Precipitation Anomalies
Skill Score=-0.30
Above Normal
Near Normal
Below Normal
Preliminary data subject to revision
Jan-Feb-Mar 2015 Temperature Anomalies
Skill Score=+0.90
Above Normal
Near Normal
Below Normal
Preliminary data subject to revision
Mid-April Sea Ice Comparison
15 Apr 2015
16 Apr 2014
2015: more Bering Sea ice compared to 2014
Arctic-Wide Sea Ice: Extent
Past three years
Remember: Difference is the marginal ice zones
Arctic-Wide Sea Ice: Volume
Significantly more volume than past four years
Alaska Near-Shore SSTs
Global SST Anomalies
Positive PDO Pattern
Pacific Decadal Oscillation
Longest stretch ≥ +2
since 1997
Tropical Pacific SSTs and Winds
Equatorial Upper Ocean Heat Anomaly
Guidance
•  ENSO
•  Models
•  Expert Evaluation
•  Comparison to Last Year
•  Statistical
•  Trends in the Past 10/15 Years
•  SST Anomalies
•  Oceanic Correlation (PDO and ENSO)
•  Dynamic
•  SST Anomalies
•  Global Temp and Pcpn Anomalies
CPC Niño 3.4 Forecasts
Bottom Line: increasing support for a warm Niño 3.4
region…but we “learned” this past winter that does
not necessarily translate to action
CPC Niño 3.4 Forecast
El Niño Advisory:
Issued when El Niño
conditions are observed
and expected to continue.
“But you said last Spring…”
May: Temp & Pcpn Trends
Temps: 10 years
Pcpn: 15 years
Sig Above Normal
Sig Below Normal
Sig Above Normal
Sig Below Normal
May-June-July: Temp & Pcpn Trends
Temps: 10 years
Pcpn: 15 years
Upper Temp Tercile
Lower Temp Tercile
Upper Pcpn Tercile
Lower Pcpn Tercile
Constructed Analogs based on SSTs
PDO: Then and now during MJJ
1948-88
↓
1989-2013
←Temps→
←Precip→
↓
ENSO Regions since 1980: MJJ
Temp
↓
← Niño 4 →
← Niño 3.4 →
Precip
↓
Dynamic Forecasts
•  Extratropical SSTs
•  Arctic Sea Ice
•  Temp and Pcpn Anomalies
NMME Forecast SST Anomalies
Moderately Positive
PDO pattern
CFS Sea Ice Forecast
May Mean Coverage
July Mean Coverage
May 2015 Temp Anomaly Forecasts
May 2015 Pcpn Anomaly Forecasts
Probability Forecasts for May 2015
Fcst from February
Fcst from March
Fcst from April
May-June-July 2015 Temp Anomaly Forecasts
May-June-July 2015 Pcpn Anomaly Forecasts
Probability Forecasts for May-Jun-Jul 2015
Fcst from February
Fcst from March
Fcst from April
NMME Skill for May and MJJ
Temp
Pcpn
CPC March Forecast for May-June-July
And the Answer Is…
CPC May 2015 Outlook
37%
55%
33%
37%
12%
33%
33%
30%
33%
34%
33%
30%
45%
65%
30%
05%
33%
45%
22%
33%
22%
Above%
Normal%
Below%
CPC May-Jun-Jul 2015 Outlook
65%
30%
05%
45%
33%
22%
33%
Above%
34%
Normal%
33%
Below%
55%
45%
33%
33%
12%
75%
37%
22%
33%
02%
30%
22%
33%
34%
33%
Climate Forecast Links
•  CPC Monthly
•  http://www.cpc.ncep.noaa.gov/products/predictions/30day/
•  CPC Seasonal
•  http://www.cpc.ncep.noaa.gov/products/predictions/90day/
•  NMME
•  http://www.cpc.ncep.noaa.gov/products/NMME/
•  ENSO at CPC (including weekly briefing)
•  http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/
enso.shtml
•  ENSO at IRI
•  http://iri.columbia.edu/our-expertise/climate/forecasts/enso/