11/21/2006

Is our Weather More Extreme?

Anne-Marie PalfreemanEnvironment Canada

11/21/2006

Is our weather more extreme?

• Review of recent “extreme” weather • Was it “extreme”? • Influences on our weather perceptions• Climate Change or variable weather?

11/21/2006

Extreme Weather…

2004–– Very cold JanuaryVery cold January–– Greatest oneGreatest one--day March rainfallday March rainfall–– Greatest oneGreatest one--day May snowfallday May snowfall–– Coldest summer on recordColdest summer on record–– Record earliest Record earliest ““FallFall”” frostfrost

11/21/2006

Extreme Weather…

2005–– Two heavy snowfalls in three days Two heavy snowfalls in three days

Dec 30Dec 30--Jan 1 Jan 1 –– Heavy rains in spring and summerHeavy rains in spring and summer–– Record severe weather seasonRecord severe weather season

11/21/2006

Extreme Weather…

2006–– The warmest January ever in most The warmest January ever in most

locations in Southern and Central locations in Southern and Central ManitobaManitoba

–– Record warm AprilRecord warm April–– Very dry summer in Southern MBVery dry summer in Southern MB–– Active severe weather SeasonActive severe weather Season

11/21/2006

Is this Extreme?

11/21/2006

January Mean Temperature - Winnipeg Warmest 2006 (-7.4) Coldest 1875 (-27.0)

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TemperatureNormal

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Thompson - Annual precipitation 1968-2005

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Record Dry in 2003 (367.9 mm) - Record Wet in 2005 (894.2 mm)

Annual precipNormal

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Marquette - Annual Precipitation 1970-2005

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Record Dry in 1976 (359.1 mm) - Record Wet in 2005 (789.6 mm)

Annual PrecipNormal

11/21/2006

Summer (June-Aug) Precipitation at Portage la Prairie

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Driest 2006 (85 mm) - Second Driest 1961 (92.7 mm) Wettest 1944 (456.4 mm) - Second wettest 2005 (386.6 mm)

Summer precipNormal

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Severe weather events in Manitoba 1984-2006

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Quietest year 1985 (21 events) - Busiest year 2005 (99 events)

TornadoesHailTotal Annual EventsAverage Annual Events

11/21/2006

Influences on Our Weather Perceptions

Media: 1. Weather events on all scales are more

often reported and repeated, and with a greater sense of them being “abnormal”.

2. Commentary from non-weather people relating future global warming to an increase in severe weather events

11/21/2006

Influences on Our Weather Perceptions

Modern Lifestyle and Economy: 1. Weather events tend to have a larger

impact on our daily activities…tight time scheduling

2. Weather events have larger economic impacts… agriculture, transportation, damage to property/vehicles, infrastructure, etc.

3. Losing our “memory” for past weather events due to information overload

11/21/2006

Is it Climate Change?

11/21/2006

What We Know • Temperature Changes - increasing more

over Prairies and the Arctic than the rest of Canada

• Precipitation Changes - increasing in Canada but little change over the Prairies

• Summer Severe Weather – no significant increasing or decreasing trend

• Winter Weather – fewer blizzards and cold spells

11/21/2006

Temperature ChangesChanges in temperature are unevenly distributed

Degrees C

Trends for 1950-98

11/21/2006

Insert figure

Precipitation ChangesPrecipitation Changes

11/21/2006

What We Might Know • Temperature Changes - current winter and

spring trends will continue, and we may see hotter summer weather

• Precipitation Changes – current trends will continue, and we may have an increase in heavy precipitation events

• Winter Weather – current trends will continue, and we might see more precipitation events

• El Nino/La Nina – maybe more frequent

11/21/2006

Future TemperaturesTemperature patterns will change substantiallyby 2050

11/21/2006

Future PrecipitationChanges in precipitation patterns by 2050 areuncertain, but will be complex

11/21/2006

What We Don’t Know • Summer Severe Weather – far too complex to

make reasonable predictions • Other Seasonal Storms – some thought that

there might be an increase in heavy precipitation events, but maybe more in coastal areas than over the prairies

• Seasonal Distribution of Precipitation Events– even though yearly precipitation may not change, seasonal trends are difficult to forecast

11/21/2006

What is the Bottom Line?