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10 Years of U.S. Hazards Assessments –Where do We Go from Here? Edward O’Lenic Climate Prediction Center-NCEP 32nd Climate Diagnostics and Prediction Workshop October 22-25, 2007 Tallahassee, Florida
“When you come to a fork in the road, take it.” - Yogi Berra
“When you come to a fork in the road, take it.” - Yogi Berra The tools and technology now exist to move the Hazards Assessment to a new level, one of probabilistic forecasts, which can eventually be used in objective decision-making.
Outline • Description & History • Criteria • An example • Frequency of Hazards • ROC diagram of Extreme Precipitation • Steps to the Future
U.S. Hazards Assessment Schedule, Leads The U.S. Hazards Assessment is intended to provide advance warning of extreme weather events to emergency managers, weather forecasters, planners and citizens at all levels of government, the private sector and the public. Issued each day from Monday through Friday and covers days 3-14. A preliminary version of the product is prepared and placed on a web site by 11:00 AM on Monday for examination by NCEP Centers, and NWS Field offices who provide input to the Hazards forecaster. Comments from NCEP service centers and output from dynamical models, including the GFS, ECMWF, Canadian model, NOGAPS, etc…, are the primary inputs to the product. Each Wednesday, CPC hosts a telephone conference call which is open to the public.
A Unique Product and Origin The U.S. Hazards Assessment is unique among NWS Official products, being a weather- oriented product, produced by a climate entity. Also it required, first NCEP, then NWS to officially acknowledge the importance of weather-climate (C-W) links. Ants Leetmaa conceived the idea of a C-W links-based NWS product early in 1997, when El Nino became a real possibility. He tirelessly, aggressively, and successfully sold the idea to NCEP and NWS HQ. I was the lucky person who got to develop the actual product, with input from a lot of people.
September, 1997: As CPC’s first real El Nino forecast gets National attention, NCEP embraces the idea of weather impacts linked to a climate event. A series of coordination meetings were held during September and late October, 1997. These secured buy-in from NWS and emergency management entities. Ron McPherson was heavily involved early-on. He emphasized the importance of gaining buy-in from the NWS Field, and from other outside entities. His support greatly facilitated NWS cooperation. Coordination meetings were held each week in October. The basic form of the product was agreed upon by late October.
One of the first “Threats Assessment” maps, October, 1997. The product also featured numerous links to forecast information and a weekly telephone conference call.The product became fully operational in September, 2001, at Jack Kelly’s urging.
Extreme precipitation hazards are verified using a 10x10 grid over the CONUS (881 points).
ROC for Extreme Precipitation Events 2003-2007 Extreme precipitation events were subjectively predicted with modest skill. Probability of detection, a/(a+c) fraction of observed events that was correctly forecast False Alarm Rate, b/(b+d) Fraction of all non-events that were incorrect
Probabilistic Hazards: Getting There from Here This will require: • Climatologies • Model forecasts • Real-time obs We have these for P, T, Heat, Drought, Thunderstorms Ken Pelman will report on his effort to do this for heavy precipitation using GFS ensemble members to create an automated probabilistic forecast tool. Results are promising.
Summary • The U.S. Hazards Assessment is a categorical forecast of extreme events for days 3-14. • It is intended to provide users forecasts based, in part, on climate-weather links and heavily on model forecasts. • First experimental versions were released in October, 1997. Operational in September, 2001. • Relative frequency of posted hazards has been stable, and is dominated by drought, rain, flood, thunderstorms, wildfire and wind, in that order. • ROC scores for extreme precipitation events indicate modest skill. • Simple, uncalibrated ensemble probability forecasts show promise for precipitation forecasts. • Other parameters, and automated forecast techniques will be explored using similar techniques.
Scores for Hazards Extreme Precipitation January 2004-October 2007 Threat Score=a/(a+b+c) Bias = (a+b)/(a+c) Probability of detection=a/(a+c) False Alarm Ratio=b/(a+b)
A 3-panel Decomposition was adopted in 1999.