New Developments in Aviation Forecast Guidance from the RUC (Rapid Update Cycle) Stan Benjamin NOAA / Forecast Systems Lab Stan.Benjamin@noaa.gov 303-497-6387 http://ruc.fsl.noaa.gov NY Courtesy: ADDS/AWC/NOAA

3-d RUC weather data updated hourly 301 x 225 x 50 vertical levels x 14 vars  47,000,000 data pts for each analysis or fcst time Turbulence Convection - 2-12h forecast Ceiling/visibility Icing Terminal / surface Better weather products require improved high-frequency high-resolution models with high-refresh data to feed them

RUC vector (kts) forecast error – 1200 UTC 8 Feb 2001 – FL350 (250 mb) 12h init 12z 9h init 03z Purpose of RUC – Improved forecast guidance using high-frequency updates initialized with recent observations 6h init 06z 3h init 09z 0 10 20 30 40 kts

RUC20 Wind forecast Accuracy Sept-Dec 2002 1 6 9 3 12 Analysis ~ ‘truth’ 6 8 10 12 (kts) Verification against rawinsonde data over RUC domain RMS vector difference (forecast vs. obs) RUC is able to use recent obs to improve forecast skill down to 1-h projection for winds

Verify RUC sfc fcsts against all U.S. sfc obs 10-m wind speed 0-h 1-h 3-h 6-h 9-h 12-h Fcst Length 10-m wind speed Persist SUM (Apr–Sep) WIN (Oct–Dec) 0-h 1-h 3-h 6-h 9-h 2-m temperature Persist RUC improves surface wind, temp skill down to 1-h fcst Much better than 1-h, 3-h persistence forecasts 12-h Fcst Length

RUC Convective Forecast 20km convective Precipitation (mm) (1 mm = 0.04”) Probability of 0.08” within 60 km A preliminary RUC Convective Forecast Product guidance tool 5h forecasts valid 19z 4 Aug 2003 50% prob of 0.08” within 60 km

Calibrating the preliminary RUC convective forecast product RUC-CFP Version 1 (preferred) CCFP – 4h forecast valid 19z Obs – 19z - NCWD 50% prob of 0.08” within 60 km POD=0.40 Bias = 1.1 CSI = 0.23 RUC-CFP Version 2 POD=0.32 Bias = 0.95 CSI = 0.20 25% prob of 0.04” within 40 km POD=0.68 Bias = 2.6 CSI = 0.23 Calibrating the preliminary RUC convective forecast product guidance 5h forecasts valid 19z 4 Aug 2003

Sample RTVS verification CSI for RUC Guidance and CCFP 12z (13z) fcst Valid 19z August 2003 RUC CCFP

Summary on RUC convective product (RUC-CFP) guidance Preliminary RUC-based convective probability product – compares favorably w/ CCFP skill in cases examined - work just started in 2003 - research with NCAR, MIT/LL Needs RTVS evaluation (underway) Quality expected to improve with use of Multiple model runs valid at same time Model-internal convective probability data Assimilation of radar reflectivity data Calibrating RUC-CFP requires interaction w/ ATM (and other) user communities

RUC – in testing – Assimilation of radar reflectivity RUC first guess Radar adjusted 1200 UTC 3 May 2002 RUC max Refl. (dBZ) RUC – in testing – Assimilation of radar reflectivity RUC 3-h fcst no radar data RUC 3-h fcst with radar data 1500 UTC 3 May 2002 RUC 3-h precip. (in)

RUC Upgrades 20 km/50 level 1 hr version – implemented May 2002 40km RUC topography 20km RUC topography RUC Upgrades 20 km/50 level 1 hr version – implemented May 2002 Replaced previous 40km / 40 level version Main operational implementation in 2003 Improved analysis (3-d variational) technique to improve initial conditions for RUC model (27 May 2003) Next -13km RUC topography WRF model in RUC - 2006

Backbone of improved aviation forecast products for winds, icing, turbulence, convection, TAFs = weather model forecasts updated at high frequency (1 h) with latest observations Keys to improvement of model aviation forecasts in RUC20 and future versions: Higher spatial resolution – better capture fine-scale weather hazards Use new observations to initialize model – force more realism in model initial conditions Improved realism of physical processes in model – clouds, turbulence, land-surface