1 examples: predicting the extreme events. 2 recent forecast examples: extreme events west coast –...

1

Examples: Predicting the Extreme Events

2

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

3

Rapidly Developing Pacific Storm: Not Predicted

Reed and Albright, MWR, 1986

4

January 3-5, 2008 West Coast Rain/Snow Event

00Z 5 January, 2008

5

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.”

6

8-14 Day Outlook

HazardsAssessment

8

6-10 Day Outlook

9

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

11

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

12

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

13

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

14

HazardsAssessment

February 5-6, 2008 Tornado Outbreak

15

February 5-6, 2008Tornado Outbreak

Day 4-8

16

February 5-6, 2008 Tornado Outbreak

Day 3

Day 2

Categorical Probabilistic

Categorical Probabilistic

17

February 5-6, 2008 Tornado Outbreak

Day 1

Convective High Winds

Hail Tornado

18

19

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

21

Predicting the April 16, 2007 Nor’easter

22

Surface Analysis 48 hour precipitation

Valid 12Z April 16, 2007

23

Surface Analysis

Valid 12Z April 16, 2007

Seven day forecast

24

Surface Analysis

Valid 12Z April 16, 2007

Six day forecast

25

Surface Analysis

Valid 12Z April 16, 2007

Five day forecast

26

Surface Analysis

Valid 12Z April 16, 2007

Four day forecast

27

Surface Analysis

Valid 12Z April 16, 2007

Three day forecast

28

Surface Analysis

Valid 12Z April 16, 2007

Two day forecast

29

Surface Analysis

Valid 12Z April 16, 2007

One day forecast

30

Day 4-5 48 hr Quantitative Precipitation Forecast

48 hour observed precipitation

Valid 12Z April 16, 2007