1 examples: predicting the extreme events. 2 recent forecast examples: extreme events west coast –...
TRANSCRIPT
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Examples: Predicting the Extreme Events
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Recent Forecast Examples: Extreme Events
• West Coast – 13-14 November 1981 3-5 January 2008• Central U.S. – 3-4 April 1974 5-6 February 2008• East Coast – 18-19 February 1979 15-16 April 2007
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Rapidly Developing Pacific Storm: Not Predicted
Reed and Albright, MWR, 1986
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January 3-5, 2008 West Coast Rain/Snow Event
00Z 5 January, 2008
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Madden-Julian Oscillation (MJO) Update
• Issued each Monday by Climate Prediction Center– http://www.cpc.ncep.noaa.gov/products/precip/
CWlink/MJO/mjoupdate.pdf
MJO Update issued December 24, 2007:
• “Moderate MJO activity continues. After a short break, eastward propagation has resumed during the past week and the enhanced phase is currently centered in the western Maritime continent region…
• Some potential exists for a heavy precipitation event tied to tropical convection by week 3. Currently, however, details of this potential event are unclear but interests along the west coast of the US should monitor the status of the MJO during the next 1-2 weeks.”
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8-14 Day Outlook
HazardsAssessment
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6-10 Day Outlook
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HPC 48-h QPF ending 00Z 6 JanIssued 00Z 1 JanDay 4-5 Forecast
8.78x
4-5 Day Forecast Verifying Analysis
48-h QPE ending 00Z 6 Jan
10HPC 72-h QPF ending 00Z 7 Jan
Issued 00Z 4 JanDay 1-3 forecast
10.24x
72-h QPE ending 00Z 7 Jan
Verifying Analysis1-3 Day Forecast
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HPC 72-h PRISM adjusted snow accumulation forecast ending 00Z 7 Jan
Issued 00Z 4 Jan
HPC analysis of storm-total snowfall (in.) 3–7 Jan
3 Day Total Snowfall Forecast00Z Jan 4 – 00Z Jan 7
Verifying Analysis
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April 3-4, 1974 Super Outbreak
Tornado Tracks 12Z April 3 – 12Z April 4,
1974
• One of the deadliest tornado outbreaks in the 20th Century (330 fatalities)• Involved over one-quarter of the country
• 148 tornadoes in 13 states• Magnitude of event not realized until evening news – April 3
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Super Tuesday Tornado OutbreakFebruary 5-6, 2008
– 63 tornadoes, 57 fatalities– Deadliest event since ’85– Outlook issued 6 days prior– POD 100% for tornadoes occurring in SPC watches– Average warning lead time 17 min
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HazardsAssessment
February 5-6, 2008 Tornado Outbreak
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February 5-6, 2008Tornado Outbreak
Day 4-8
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February 5-6, 2008 Tornado Outbreak
Day 3
Day 2
Categorical Probabilistic
Categorical Probabilistic
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February 5-6, 2008 Tornado Outbreak
Day 1
Convective High Winds
Hail Tornado
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East Coast Storms
• 22 inches of snow buries Washington D.C. area• Rapid cyclogenesis off the coast• Not predicted even hours in advance
Presidents’ Day Storm 18-20 February, 1979
1830Z 19 Feb 1979
201 Km 10 Km 100 Km 1000 Km 10000 Km
6 hours
1 hour
1 day
2 days
4 days
6 days
12 hours
Thunderstorms
WindsHurricane-Force
HeavySnow
Gale-ForceWinds
Of Hurricanes
Distance
1970s: The Advance from Subjective to Model-Based Forecasts
1970s Limits of Predictability
Cressman, 1970
• The transition to model-based forecast was caught up in the inability to predict rapid cyclogenesis like the President’s Day 1979 storm
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Predicting the April 16, 2007 Nor’easter
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Surface Analysis 48 hour precipitation
Valid 12Z April 16, 2007
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Surface Analysis
Valid 12Z April 16, 2007
Seven day forecast
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Surface Analysis
Valid 12Z April 16, 2007
Six day forecast
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Surface Analysis
Valid 12Z April 16, 2007
Five day forecast
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Surface Analysis
Valid 12Z April 16, 2007
Four day forecast
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Surface Analysis
Valid 12Z April 16, 2007
Three day forecast
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Surface Analysis
Valid 12Z April 16, 2007
Two day forecast
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Surface Analysis
Valid 12Z April 16, 2007
One day forecast
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Day 4-5 48 hr Quantitative Precipitation Forecast
48 hour observed precipitation
Valid 12Z April 16, 2007