Winter 2014/15 – Another Harsh One?
October 18, 2014
Joe D’Aleo

Looking Back on the Historic
Winter of 2013/14
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US Climate Prediction Center
Dec/Jan/Feb Jan/Feb/Mar Feb/Mar/Apr
NWS CPS July 2013 forecast for winter 2013/14 and early spring 2014

WeatherBell Saw It Coming
US Temperature Anomaly - Issued July 2013 Actual Temperature Anomaly
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Last Winter the Driver Was the Pacific
Warm pool caused the
Polar Vortex like it did in 1917/18

1917/18 Sea Surface Temperature Anomalies

1917/18 Winter Anomalies

WeatherBell Winter Forecast

2013/14 Winter Anomalies
2013/14 Winter Coldest Ranking
Ironwood, Michigan 1 st
Marquette, Michigan 1 st
Eau Claire, Wisconsin 1 st
Rhinelander, Wisconsin 1 st
Oshkosh, Wisconsin 1 st
Sturgeon Bay, Wisconsin 1 st
Munising, Michigan 2 nd
Green Bay, Wisconsin 2 nd
Wausau, Wisconsin 2 nd
Alpena, Michigan 2 nd
Houghton Lake, Michigan 2 nd
Duluth, Minnesota 2 nd
International Falls, Minnesota 2 nd
Chicago, Illinois 3 rd
Rockford, Illinois 3 rd
Mason City, Iowa 3 rd
Wheaton, Minnesota 3 rd
St. Cloud, Minnesota 4 th
Waterloo, Iowa 4 th
Flint Michigan 5 th
Chicago had its coldest
December to March on record - since 1872,
Detroit its snowiest – since 1880

Forecast Verifications
December 2013 Forecast
Issued 11/26/13
December 2013 Result

Forecast Verifications
January 2014 Forecast
Issued 12/24/13
January 2014 Result

Forecast Verifications
February 2014 Forecast
Issued 01/28/14
February 2014 Result

Forecast Verifications
March 2014 Forecast
Issued 02/25/14
March 2014 Result

Winter 2014/15 Forecast
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WeatherBell
Analog
Forecast for
Winter 2014/15

September NWS
CPC Forecast for
Winter 2014/15

October NWS
CPC Forecast for
Winter 2014/15
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Seasonal Forecasts
Dynamical Models – coupled numerical ocean and atmosphere climate models that project future mean
(temperatures, rainfall) based on interaction with ocean warm and cold pools which often anchor jet stream and associated anomalies
Statistical Models – empirical approaches that relate seasonal weather temperature and precipitation anomalies with persistent large-scale modes within the atmospheric/ oceanic system, and on the sun

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(Ropelewski etal 1986 1987)

Teleconnections
 El Nino Southern Oscillation (ENSO)
 Pacific Decadal Oscillation (PDO)
 Pacific North American (PNA)
 Tropical Northern Hemisphere (TNH)
 Quasi-Biennial Oscillation (QBO)
 East Pacific Oscillation (EPO)
 Indian Ocean Dipole (IOD)
 North Atlantic Oscillation (NAO)
 Arctic Oscillation (AO)
 West Pacific Oscillation (WPO)
 Atlantic Multidecadal Oscillation (AMO)
 Scandinavia (SCAND)
 Solar flux and geomagnetic (Ap)

Winter 2014/15

Weak El Nino Modoki – cold central/east

Warm pool in the North Pacific - blocking

Confused PDO

Warm AMO - favors blocking

Strong east QBO – broad cold and blocking

Moderate and declining solar

Ap Index has been low --- but

Volcanism not playing a major role
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December to March
Cold El Ninos
Next winter
Warm El Ninos

Different Flavors of El Nino
Favored
In +PDO
Favored
In -PDO
Called
Modoki
El Ninos

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Pacific Decadal Oscillation (PDO)
When El Ninos occur briefer, weaker and cool
La Ninas dominate
La Ninas dominate
El Ninos dominate
And tend to be warm
El Ninos dominate

Pacific Decadal Oscillation (PDO)
(Mantua 1999)

Atlantic Multidecadal Oscillation (AMO)

Atlantic Multidecadal Oscillation

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Coldest
Winters
Negative
NAO

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Quasi-Biennial Oscillation-QBO
 The QBO is the slowly oscillating wind at 10-12 miles over the Tropical Pacific, which alternates between west and east about every 13 months
QUASI-BIENNIAL OSCILLATION 50MB
2
1.5
1
0.5
0
-0.5
-1
-1.5
-2
-2.5
1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001
Year
 Barnston, Livezey, and Halpert (CPC) found some significant differences in
ENSO and solar related anomalies between east and west QBO years during the winter season (JClimate)

Winter Temperatures
West QBO East QBO

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AMO & PDO Affect Annual Temperatures

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Solar Cycles
High Solar Activity
Contracted polar vortex winter
More zonal flow
Low Solar Activity
Expanded polar vortex winter
More amplified meridional flow
Less blocking except west QBO More blocking especially east QBO
Stratospheric warmings west QBO Stratospheric warming east QBO
More variability
Less snow most winters
More persistence
More snow most winters

Winter Temperatures
High Solar Low Solar

Sun’s Scary Slumber

Lower geomagnetic means -NAO/AO
Increased cosmic rays mean more low clouds (higher albedo)
Lower solar flux means lower UV (6-
8%) which means expanded polar vortex
More amplified patterns and higher persistence

Winter
1999-2000
Winter
2000-2001
Winter
2001-2002

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106, 212 Year Cycles Combine
Clilverd 2006
Cycle 5
Cycle 24

Niagara Falls 1911 and 2014

Paralleling Cycle 5 (1798)

Dalton Minimum
Early 1800s 2008/09/10/11/12/13

3
2
1
0
Sun and Ocean Cycles Versus Temperatures
US
Annual
Temps
Ocean
PDO+AMO
-1
-2 Solar
TSI
Both sun and oceans suggest cooling
-3
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
1368
1367.5
1367
1366.5
1366
1365.5
1365
1364.5
1364

Still Colder Winters Ahead?




Cold PDO favors more La Ninas (hold temperatures at bay)
Warm AMO favors blocking which make winter cold in Eurasia, North America. When the AMO turns cold
(2020?), it will favor more general cold like the
1960s/1970s.
The solar entering the a ‘Dalton like’ Minimum would accelerate cooling
High latitude (2007-2010) volcanoes enhance high latitude blocking (Oman 2004)

Trend = -2.26 F/20 years or -1.13F/decade

Winters the last 20 years 70

Joseph D’Aleo
CCM, AMS Fellow daleo@weatherbell.com