Investigating the Tradeoff Between Spatial and Temporal Resolution of Radar Data in EnSRF data Assimilations and Forecasts

Tim Supinie, Youngsun Jung, Ming XueWarn-on-Forecast Workshop2 April 2014Preliminary Results from EnSRF data Assimilations and Forecasts of the 24 May 2011 EventARPS30030051 3 km grid spacingNAM IC/BCMilbrandt-Yau 2-moment MP3D Ensemble Square-Root Filter40-member ensemble6 km localization radius5 dBZ, 3 m s-1 obs. errorsMultiplicative (1.2) and RTPS (0.9) covariance inflation

Experiment ConfigurationDomain OutlineMethods and Knob Settings

Terrain Height (m)

Surface data: ASOS (1-minute), AWOS (20-minute), OK Mesonet (5-minute)Sounding data: ARM (3-hourly)WSR-88D: 17 Radars, including KTLX, KFDR, and KVNXExperiment timeline and data1 km AGL Reflectivity (Analyses)

Reflectivity (dBZ)1 km AGL Reflectivity (2100 UTC Forecast)Reflectivity (dBZ)

Updraft Helicity (1930-2030 UTC Forecast)

2020 UTC2031 UTC2047 UTCP(UH > 50 m2 s-2)

Updraft Helicity (2000-2100 UTC Forecast)2020 UTC2031 UTC2047 UTC2046 UTC2050 UTCP(UH > 50 m2 s-2)

Updraft Helicity (2100-2200 UTC Forecast)2050 UTC2235 UTC2206 UTC2226 UTCP(UH > 50 m2 s-2)Equitable Threat Score (ETS)

2100 UTC FCST 1930 UTC FCST 2000 UTC FCST P(Z > 40 dBZ) > 0.5 from ensembleZ > 40 dBZ from WSR-88DsFull volume scans (9-14 tilts)Contingency Table Visualization

(Preliminary) ConclusionsNEP Updraft Helicity swaths line up with observed tornadoesReasonably Well: Canton Lake TornadoOkay: El Reno EF5 (UH swath deviates left)Poorly: Goldsby Tornado (1 hour too early)ETS drops off quickly after initializationModel wants to move storms too quickly (closer to LCL-EL mean wind)Unresolved supercell dynamic pressure perturbations?

Future Work4D EnSRF (Wang et al. 2013)500 m simulationsImproved track forecasts?Sounding data partitioningSources of vertical vorticity for the forecastsQuestions?Integrated from 0-3 kmNeighborhood Ensemble Probability7.5 km neighborhood

Updraft Helicity TracksSchwartz et al. (2010), Fig. 82100 UTC hodographs

Observed Storm MotionEnsemble Mean Storm Motion1-10 km MSL Mean Wind (Advective)