CPC s Week-2 probabilistic forecasts of hazards and extremes

Transcription

1 CPC s Week-2 probabilistic forecasts of hazards and extremes Melissa Ou, Matt Rosencrans, Mike Charles, Jon Gottschalck Acknowledgements: Stephen Baxter, Dave Unger, and Dan Collins

2 Outline Background Forecast Strategy Show current and proposed forecasts for feedback CPC issued forecasts Future public tools Get feedback for strategy and forecast of wind extremes/hazards

3 Impacts of extremes Extremes are the most impactful climate/weather events Studies and projections have suggested that climate change may lead to amplification and increased frequency of weather and climate extremes (Easterling, 2000, O Neil 2009) Societal infrastructure is becoming more sensitive to extremes, which would be exacerbated by climate change (Easterling, 2000) Extremes can have damaging effects on human health, infrastructure ecosystems, economics, air quality

4 Goal / Mission Produce/issue probabilistic forecasts of extremes and hazards at the week-2 lead time (moving away from categorical forecasts) Support DSS by providing valuable information regarding increased chances for potentially hazardous weather/climate conditions across the U.S. FY 16-17: DOC Agency Priority Goal Improve Forecasting Accuracy and Lead Times for High-Impact and Extreme Weather By September 30, 2017, the Department of Commerce will improve the useful lead time of its weather forecast model guidance to 9.5 days which will enable more accurate, consistent, forecasts and warnings for high-impact and extreme weather events. More lead time for the prediction of weather events allows people and businesses to make informed choices and enables better protection of life, property and enhancement of the National economy.

5 Forecast Strategy Main guidance tool is real-time ensemble model forecasts statistically adjusted using past forecasts and observations CPC currently issues probabilistic hazards forecast of extreme min/max temperature CPC planning to issue probabilistic hazards forecasts of precipitation within the next year CPC in planning phase to develop probabilistic hazards forecasts of winds

6 Feedback - CPC Issued Hazards Temperature outlook Typically based on Tmax > 85th ptile and > deg F Tmin < 15th ptile and < deg F Look and feel (contours, colors, text)? Ability to understand forecast? Usefulness of forecast for decision making? Improvements?

7 Feedback - Proposed CPC Issued Hazards Precipitation Typically based on 3-day accumulated liquid equivalent > 85th ptile, > 1 total in 3-days Look and feel? Ability to understand forecast? Usefulness of forecast for decision making? Improvements?

8 Feedback - Proposed CPC Issued Hazards Aggregate Map Summary map geared towards DSS Contains moderate risk contours and frozen precipitation hazards Usefulness of having frozen precip and aggregate map? Look and feel? Ability to understand? Usefulness for decision making? Improvements?

9 Feedback - Extremes Tmin Tool (Percentiles) Thresholds Percentiles: < 1, 2, 5, 10, 15, 20, 50 % Values: < 40, 32, 28, 20, -40 F, > 80, 85 F Most important thresholds? Look and feel? Ability to understand? Usefulness for decision making? Improvements?

10 Thresholds Percentiles: > 50, 80, 85, 90, 95, 98, 99% Values: > 85, 90, 95, 100, 105, 110 F, < 40, 32, 28, 20, 0 (useful?) Most important thresholds? Look and feel? Ability to understand? Usefulness for decision making? Improvements? Feedback - Extremes Tmax Tool (Percentiles)

11 Feedback - Extremes Precipitation Tool (Percentiles) Thresholds Percentiles: > 67, 85, 90, 95, 98, 99 % Values: > 1, 1.5, 2, 4 Most important thresholds? Look and feel? Ability to understand? Usefulness for decision making? Improvements?

12 Feedback - Extremes Winds Tool Proposed strategy Statistically adjusted model forecasts of mean daily 10m wind speeds for days 8 to 14 Forecast in probabilities of exceeding percentile and wind speed thresholds Averaging all 4 model cycles may wash out high winds Average only 2 update cycles, e.g. 18Z and 0Z most likely U.S. peak wind speeds. Con: May miss overnight MCS (difficult for models to capture anyway). Another option is calculating a proxy for wind energy as a proxy, similar to ACE index (wind speed squared possibly useful for DSS?) Suggestions for this potential issue? Potentially plot most likely wind direction vectors

13 Feedback - Extremes Winds Tool Proposed thresholds In the week two time range, probabilities may be small. Therefore may need lower thresholds (have seen this with precip). Note: Currently typically use 30 kts evaluating all model cycles separately OPC suggest Force 6 winds, kts CPC proposes evaluating probabilities for 30 and 20 kts Suggested thresholds for various DSS needs? Wind speeds >= 85th percentile compared to climatology

14 Feedback - Extremes Winds Display Proposed look and feel Tool Display would look similar to temp and precip tools Issued Forecast Display would look similar to CPC issued temp and precip forecasts with slight, moderate, high risk areas highlighted. Any suggestions regarding look and feel of winds tool or issued forecast?

15 Thank you! Please send any suggestions/comments to Melissa Ou Or come find me! CPC Hazards Forecasts threats/threats.php

16 Feedback - Extremes Tmin Tool (Temperatures) Thresholds: Values: < 40, 32, 28, 20, -40 F, > 80, 85 F Most important thresholds? Look and feel? Ability to understand forecast? Usefulness of forecast for decision making? Suggestions for improvements? Heat guidance

17 Feedback - Extremes Tmax Tool (Temperatures) Thresholds: Values: < 40, 32, 28, 20, 0 F, > 85, 90, 95, 100, 105, 110 F Most important thresholds? Look and feel? Ability to understand forecast? Usefulness of forecast for decision making? Suggestions for improvements?

18 Feedback - Extremes Precipitation Tool (Liquid Equivalent) Thresholds: accumulated amounts > 1, 1.5, 2, 4 Most important thresholds? Look and feel? Ability to understand forecast? Usefulness of forecast for decision making? Suggestions for improvements?

19 Impacts of extremes As of April 2017, 5 weather and climate disaster events led to losses exceeding $1 billion each across the U.S. and 37 deaths annual average is 5.5 events Annual average for the most recent 5 years ( ) is 10.6 events 2016 had the 2nd highest total number of >$1 billion loss events since 1980 (2011 had 16) In events with > $1 billion losses

20 Winds Suggestions OPC Gale - FORCE 8, knots Storm - FORCE 10, knots Hurricane Force - FORCE knots and greater In the week two time range, probabilities may be small. Suggest using FORCE knots Near Gale - Force knots.