Roger Edwards (SPC) and Greg Carbin (WPC) ESTIMATED CONVECTIVE WINDS: RELIABILITY and EFFECTS on SEVERE-STORM CLIMATOLOGY Roger Edwards (SPC) and Greg Carbin (WPC) Title

DATA BACKGROUND SPC FINAL SEVERE-STORM DATASET CONVECTIVE WIND-SPEED DATA (NOT DAMAGE) 15,145 “MEASURED” GUSTS (KT) 135,188 “ESTIMATED” GUSTS (KT) EXPLICIT TAGS: 2006–2015, 10 YEARS of DATA NO SYSTEMATIC INSTRUMENT-CALIBRATION INFO in STORM DATA, SOURCE SOMETIMES NOT SPECIFIED MISCLASSIFICATIONS UNKNOWN BUT POSSIBLE BASED on MILLER et al. (2016) NONCONVECTIVE-WIND STUDY 2010 POPULATION DATA for STATE BREAKDOWNS AGDAS et al. (2012) WIND-TUNNEL TESTS on HUMANS

DATA BACKGROUND Before 2006 2006-Present

TSTM-GUST DISTRIBUTION: LOG SCALE

TSTM-GUST DISTRIBUTION: LOG SCALE

TSTM-GUST DISTRIBUTION: LOG SCALE SVR criteria 1 mph above SVR criteria, 2 orders of magnitude fewer EGs CLIMATOLOGY INFLUENCES: Arbitrary thresholds Hidden errors Integers 0 and 5

MEASURED-GUST DISTRIBUTION: LINEAR SCALE ?

MEASURED-GUST GEOGRAPHY: 15,145

ESTD-GUST GEOGRAPHY: 135,188

COMBINED GEOGRAPHY

MEASURED-GUST GEOGRAPHY

MEASURED vs. ESTD: HUMAN FACTOR HOW GOOD ARE HUMAN WIND ESTIMATES? 54 mph OPERATIONAL, FIELD & RESEARCH EXPERIENCE WITH TSTM WIND ― AND THE DATA ― COMPEL US TO ASK: HOW GOOD ARE HUMAN WIND ESTIMATES?

MEASURED vs. ESTD: HUMAN FACTOR Doswell et al. (2005): “Human observers typically overestimate the wind speed, owing to a lack of experience with extreme winds.” Miller et al. (2016, in press): synoptic wind events, GHCN observed vs. mesoβ-proximal human estimates: ≈ 1.33 overestimation factor Agdas et al. 2012: 76 subjects in wind-tunnel 10–60 mph in random order. ≈ 1.25 perceived/ actual (P/A) ratio. Testing under truly convective conditions is practically impossible.

MEASURED vs. ESTD: HUMAN FACTOR Adapted from Agdas et al. (2012) Human Subjects ≈1.25 OVER Adapted from Agdas et al. (2012)

APPLYING 1.25 P/A RATIO to DATA Extrapolated A12 curve, still 1.25 P/A at higher speeds, apply to TSTM-wind data 1.25 P/A ratio may be conservative based on nonconvective study (Miller et al. 2016). Values <73 mph (126,474) drop out of “severe” database Only 7% of EG data would remain as severe Only a few 73–74-mph EGs, thus, effectively: EGs less than hurricane force are NON- SEVERE for bulk analysis.

ISSUES & IMPLICATIONS ARTIFACTS: Human estimators preferentially offer values at minimal severe thresholds or “0 and 5”. What do we do? Many implications for data mapping, weighting, research use, forecast verification, calibration of CAM-based guidance. Should bulk EG counts be reduced by factor of 10? How should verification metrics be weighted away from estimates (toward measured)? Should EG coverage be detrended by corresponding density of MGs in same regions or states, to normalize in verifying outlooks and watches? Should EGs be used at all—or be reduced by 1.25 in research and even in parallel, on report logs? Should EGs not hurricane-strength be discarded for verification and/or research use? Defining NSTC convective mode

Research Contact: Roger.Edwards@noaa.gov DATA: www.spc.noaa.gov/wcm DOCUMENTATION: www.spc.noaa.gov/publications Research Contact: Roger.Edwards@noaa.gov Where to get data and info