Alberta Broadcasters Public Alerting Recognition Symposium

Meteorological Decision Making

Image Courtesy Steve Ricketts

Outline• Alberta Summer Weather

• Weather Centre Operations

• Severe Weather Meteorologist

• Convective warnings

• Decision Making Process

Photo Courtesy Justin Hobson

Elie Manitoba June 22, 2007

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April May June July August Sept

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Alberta Convective Climate

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Time (UTC)

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Annual Alberta Svr Weather EventsYear Hail Wind Tornado Rain Total

2000 56 9 15 1 81

2001 44 7 6 3 60

2002 12 4 3 1 20

2003 70 19 14 1 104

2004 52 17 15 6 90

2005 68 6 9 4 87

2006 83 14 5 4 106

2007 89 37 12 8 146Average 48 12 11 8 79

Weather Centre OperationsPASPC

• Responsible for Public and Marine Forecasts & Warnings

• Edmonton & Winnipeg split the Responsibility

• Each office 2.4 people shifts, 24hrs per day, 365 days per year

• Automation leveraged• Co located with Aviation

forecast centre – CMAC in Edmonton

PSPCOSPC

PASPCPASPC ASPC

SPC Areas of Responsibility

Graphic Courtesy McCarthy 2007

Equivalent Areas of ResponsibilityS ize of the PA SP C ’s area of respons ibility

if it w ere in Europe

L a superfi c ie de la region de responsabilite du CP T PA vis -a-vis l’Europe

S ize of the PA SP C’s area of respons ibilityif it w ere in the U nited S tates

(equal to approx . 65-70 U .S . Weather offi c es)

L a superfic ie de la region de responsabilite du CP T PA vis -a-vis les E tats -U nis

(l’equivalent d’environ 65-70 bureaux meteorologiques americ ains)

Graphics Courtesy McCarthy

Means for Dissemination

• Weatheroffice web site. Most popular Web site in gc.ca domain…

• Specialized media site• WeatherRadio• ATADs• Media Partners• EPWS• Warning Lead time for

supercells/tornados is critical

Weather Radio Network in Alberta

Severe Weather Meteorologist• Supervisor on shift • Analysis/Diagnosis/

Prognosis• Highly trained• Convective weather • Radar interpretation• Decision making

Phases of shift• Workup-anticipation• Weather watch• Heat of battle

Bulletins• Thunderstorm

Watches/warnings• Tornado

Watches/warnings

Radar

• Critical and sophisticated tool• Spirit River, Jimmy Lake

Carvel, Strathmore, Schuler• Measures hydrometeor

intensity and radial motions• Detects rotating storms

(Supercells) but not tornadoes

• Ground reports critical for tornadoes

• Doppler coverage of southern and central Alberta is not continuous

Decision MakingInformation• Analysis of temp, wind

and moisture• NWP guidance• Radar and satellite

– Monitor boundaries• Lightning detection• Soundings including

aircraft• Weather watchers

Thunderstorm Options

• Watches - When to issue? Where? Type to issue?

• Thunderstorm Warnings – When? Where?

• Difference between a Watch and a Warning?

• Tornado warnings• On busy days numerous

bulletins can be in effect

Photo copyright Neil Taylor

Decision Making EPWS

• Always Issue for Dangerous Supercells

• Tornado warnings require SPC to trigger EPWS

• Most effective way to deliver message

• Nerve racking task• Practice is key

Info includes storm/tornado location and motion

Preset Forms• Unusually strong

Supercell• Possible tornado

(rotation detected within doppler range)

• Tornado on ground

Conclusion

• Weather Radio fills an important gap in our dissemination process because said radios can sleep until a programmed watch or warning id is received

• EPWS decisions add to the work load of the forecast team

• However, within Environment Canada’s dissemination network there is no better means to quickly disseminate life threatening severe weather situations than the EPWS

Copyrighted and courtesy of Brad McLeod

Why do we activate EPWS?