First Results of Thunderstorm Forecast Verification in Terminal Aerodrome Forecasts in Croatia Jadran Jurković and Igor Kos Croatia control Ltd, MET Division Croatian-USA Workshop on Mesometeorology June 2012 Croatia Control Ltd.

2 Introduction Part of Quality management system (ICAO Annex 3) Forecasts Improvement Understand correct, miss, false alarm events Verification of special problems Convection (TS) Fog (reduced visibility) Wind (especially bora events) Thunderstorm (TS) Mesoscale phenomenon (deep and moist convection) Month with max. frequency of days with TS has 12-25% Impact on aviation First Results of Thunderstorms Forecast Verification in TAF in Croatia Croatian-USA Workshop on Mesometeorology June 2012 Croatia Control Ltd. 1/15/2015

o METAR Surface wind Direction Speed Gusts Visibility Runway visual range (RVR) Present weather Cloud Amount Height of cloud base [TCU/CB] T i T d Atmospheric pressure Recent weather Wind shear State of the runway Trend forecast o METAR ( ∀ 30min) Surface wind Direction Speed Gusts Visibility Runway visual range (RVR) Present weather Cloud Amount Height of cloud base [TCU/CB] T i T d Atmospheric pressure Recent weather Wind shear State of the runway Trend forecast o TAF (T=9/24 ∀ 3/6h) Surface wind Direction Speed Gusts Visibility Present weather Cloud Amount Height of cloud base [TCU/CB] Change groups -BECMG -FROM -TEMPO -PROBABILITY 30/40 o TAF Surface wind Direction Speed Gusts Visibility Present weather Cloud Amount Height of cloud base [TCU/CB] Change groups -BECMG -FROM -TEMPO -PROBABILITY 30/40 1/15/2015 First Results of Thunderstorms Forecast Verification in TAF in Croatia Croatian-USA Workshop on Mesometeorology June Verification- a larger view Input Forecaster skill, experience, education Available tools and materials Models quality, interpretation, availability Observation system Climatology Technical details Criteria for weather elements, format System supervision Education system Customer requirements FORECASTER’S PICTURE WEATHER FORECAST OBSERVED WEATHER REAL STATE OF ATMOSPHERE VERIFICATION = ≠ Croatia Control Ltd.

1/15/ Approach Method similar to Austrocrontrol’s Mahringer (2008) TAF, two basic principles forecast for time periods contains a range of forecast conditions Each hour Example for TS TAF LDSP Z 2306/ KT 9999 FEW050 TEMPO 2308/2320 RA PROB30 TEMPO 2310/2406 TSRA FEW030CB BKN040 BECMG 2311/ KT BECMG 2316/2318 VRB02KT= First Results of Thunderstorms Forecast Verification in TAF in Croatia Croatian-USA Workshop on Mesometeorology June 2012 Croatia Control Ltd.

1/15/ Data Forecasts for 6 airport in Croatia Inland: Zagreb (LDZA), Osijek (LDOS) Onshore: Pula (LDPL), Zadar (LDZD), Split (LDSP), Dubrovnik (LDDU) Period ~500,000 forecasted hours Contingency tables for each airport First Results of Thunderstorms Forecast Verification in TAF in Croatia Croatian-USA Workshop on Mesometeorology June 2012 Croatia Control Ltd.

1/15/ Results Proportion correct (PC) First Results of Thunderstorms Forecast Verification in TAF in Croatia Croatian-USA Workshop on Mesometeorology June 2012 Bias Croatia Control Ltd.

First Results of Thunderstorms Forecast Verification in TAF in Croatia Croatian-USA Workshop on Mesometeorology June /15/ Results PC - better for inland airports and LDPL Climatology Bias similar results LDPL smallest bias-local characteristics Croatia Control Ltd.

1/15/ Conclusions Verification has been initiated Frequency of hours with TS ~1-1.5% Better scores when forecast TS period is shorter Less bias at inland airports due to pronounced daily and yearly maxima Local features Future work (in progress): Details for every miss and false alarm event Synoptic situations Lead time and duration Croatia Control Ltd. THANK YOU First Results of Thunderstorms Forecast Verification in TAF in Croatia Croatian-USA Workshop on Mesometeorology June 2012 Acknowledgement to Ms. Laurette Rako for helping with translation