1. Warn on Forecast Workshop 8-9 February 2012 Warn on Forecast Case Studies: Progress Report February 2012 Contributors Dusty Wheatley (NSSL/CIMMS) Nusrat Yussouf (NSSL/CIMMS) Dan Dawson (NSSL/CIMMS) Ted Mansell (NSSL) Corey Potvin (NRC PostDoc) Robin Tanamachi (CAPS/OU) Thomas Jones (NSSL/CIMMS) Mike Coniglio (NSSL) Adam Clark (NSSL/CIMMS) James Corriea (SPC) Terra Thompson (NSSL/OU) Lou Wicker (NSSL)

2. Warn on Forecast Workshop 8-9 February 2012 Purpose To test storm-scale NWP in a variety of severe weather situations Two basic classes of events isolated cells mesoscale convective systems Basic questions to be answered: core sets of observations needed accuracy needed of background analysis for convective scale forecasts analysis versus prediction predictability (0-1, 0-3, 0-6 hours?)

3. Warn on Forecast Workshop 8-9 February 2012 Cases Isolated Cells Tornadic supercells 8 May 2003 OKC F4 tornado 4 May 2007 Greensburg KS EF5 tornado 27 April 2011 MS/AL/TN superoutbreak 10 May 2010 Central OK outbreak Downburst 14 June 2011 Norman macroburst Mesoscale convective systems 4 July 2004 IN/OH/KY derecho (BAMEX) 14 June 2010 W TX tornado / flash flood (VORTEX2)

4. Warn on Forecast Workshop 8-9 February 2012 May 8, 2003 Oklahoma City Tornadic Supercell Damage Path of OKC Tornado Hu and Xue (2007) HPC Synoptic Scale Surface Analyses at 18:00 UTC KOUN Radar Observations at 22:10 UTC Nusrat Yussouf

5. Warn on Forecast Workshop 8-9 February 2012 8 May 2003: Multiscale experiment EnKF used at multiple scales Mesoscale Ensemble 45 member WRF mesoscale ensemble at 18 km horizontal grid spacing over CONUS initialized from GFS 3 day cycling with assimilation of routinely available observations from metar, marine, radiosondes and ACARS using DART system Physics options used: MYJ, Thompson, Kain-Fritsch, Noah, Dudhia and RRTM Storm-scale Ensemble 45 member storm-scale ensemble nested down from the 45 member mesoscale ensemble data system 2-km horizontal grid spacing, 225 x 180 x 50 grid points Assimilates KTLX radar radial velocity and reflectivity observations every 3-min for a one-hour period T - 3 days 8 May Nusrat Yussouf

6. Warn on Forecast Workshop 8-9 February 2012 Reflectivity, Vorticity and Horizontal Winds at 1 km AGL KTLX Reflectivity at 22:01 UTC Final Analyses at 22:00 UTC 30 min Forecast at 22:30 UTC 15 min Forecast at 22:15 UTC Ensemble Member #9 Vorticity contours: 0.005 to 0.01 by 0.001 KTLX Reflectivity at 22:16 KTLX Reflectivity at 22:31 UTC Nusrat Yussouf mesocyclone

7. Warn on Forecast Workshop 8-9 February 2012 Probability of Vorticity During 45-min Forecast Period 22:00 – 22:45 UTC Observed damage track and times ~22:06 ~22:38 z ≥ 0.003 s -1 at 1 kmz ≥ 0.005 s -1 at 3 km Probability (%) ~22:38 Observed damage track and times ~22:06 ~22:38 Nusrat Yussouf

8. Warn on Forecast Workshop 8-9 February 2012 Greensburg KS (2007) EnKF analysis and prediction of the significant tornadic storm on 5 May 2007 storm near Greensburg, KS Single radar retrieval using DDC Vr & dBz Homogeneous initial environment Examined sensitivity to low-level wind profile and (to a lesser extent) microphysics Dan Dawson

9. Warn on Forecast Workshop 8-9 February 2012 Probabilistic Vorticity Forecast (All 9 experiments) Background VAD Profile (UTC) Used 013002000230 60 min forecasts 45 min forecasts Dan Dawson

10. Experiment 1: 1900-2000 UTC initialization Warn on Forecast Workshop 8-9 February 2012 27 April 2011 Tornado Outbreak: EnKF Radar DA and Ensemble Forecasts 45-member WRF-ARW ensembles (Δx=3 km) initialized from Rapid- Refresh model (Δx=13 km) at two times (1900 and 2100 UTC) Data from 4 radars assimilated every 3 min for 1 h KBMX, KDGX, KGWX, KHTX additive noise only source of ensemble spread Ensemble forecasts produced after radar DA 19Z 20Z 21Z 22Z 23Z 21Z 22Z 23Z Radar DA Experiment 2: 2100-2200 UTC initialization KDGX KGWX KHTX KBMX observed tornado tracks ensemble forecast ensemble forecast Radar DA David Dowell

11. Warn on Forecast Workshop 8-9 February 2012 Two Ensemble Forecasts: initialized at different times, valid at same time Ensemble-Based Probabilities of Rotating Updrafts 2200-2300 UTC 27 April 2011 2-3 h forecast initialized at 2000 UTC 0-1 h forecast initialized at 2200 UTC northern swath of high probability changed relatively little southern swath moved significantly based on recent radar data and/or RR mesoscale analysis David Dowell

12. Warn on Forecast Workshop 8-9 February 2012 0-1 h Forecast Ensemble Member 1 2-5 km AGL Max Updraft Helicity 2200-2300 UTC observed composite reflectivity NSSL/Q2 Mosaic3D 2200 UTC observed tornado tracks model maintains long-lived storms initialized in Tuscaloosa County and Cullman/Blount County David Dowell

13. Warn on Forecast Workshop 8-9 February 2012 Measured wind gusts > 36 m/s (130 km/hr) Wind-driven golf ball or larger hail 33,000 residents without power for over a day Residential damage took > 4 months to repair http://www.srh.noaa.gov/oun/?n=events-20110614 dBZ 0030 UTC Downburst June 14 Macroburst Lou Wicker

14. Warn on Forecast Workshop 8-9 February 2012 2245 Vis Mesoscale Environment Weak elevated convection ongoing for hours Cold Front CAPE~200 CAPE~2200 LCL~730 mb deep convection initiates ~ 2330 UTC CAPE~3200 LCL~730 mb Lou Wicker Moderate shear

15. Warn on Forecast Workshop 8-9 February 2012 Model Analysis vs Radar Obs at 0010 UTC 35 min of radar DA 8 radar volumes KOUN Location Lou Wicker

16. Warn on Forecast Workshop 8-9 February 2012 20 minute Ensemble Forecasts of Svr Wind (0030 UTC) Verification Wind Plot Vectors: Wind speed > 10 m/s Color: 20 m/s < wind speed < 40 m/s Ensemble Prediction for SVR SFC WINDS Ensemble Forecast Output of Severe Wind Probability Vectors Wind speed > 20 m/s Color at least 33% of members have 25 m/s < wind speed < 40 m/s Lou Wicker 3DVAR SFC WIND FIELD

17. Warn on Forecast Workshop 8-9 February 2012 The 4-5 July 2003 MCS event 2130 UTC 0200 UTC0030 UTC 2300 UTC - Observed during BAMEX - Produced 100+ wind reports across Indiana and Ohio - Contributed to record flooding across north-central Indiana - Not captured in NWP models of the day (including the WRF model) Dusty Wheatley

18. Warn on Forecast Workshop 8-9 February 2012 From Davis et al. 2005 Satellite imagery from 4 July 2003 Outflow boundary Gravity wave 4 July 2003 MCS Sensitivity to previous convection Depicts movement of two earlier systems Dusty Wheatley

19. Warn on Forecast Workshop 8-9 February 2012 EnKF analyses at 2300 UTC OBS 1.5-km AGL simulated reflectivity 2-m temperature (deg C) 10-m winds (full barb = 10 ms-1) Radar DA only Sub-hourly surface data Better cold pool analysis Radar + Sfc DA Surface data DA needed on storm-scale grid Dusty Wheatley

20. Warn on Forecast Workshop 8-9 February 2012 Dusty Wheatley Simulated reflectivity from sample members at 0030 UTC 5 July

21. Warn on Forecast Workshop 8-9 February 2012 EnKF analyses of 2-m temperature With the assimilation of sub-hourly surface data, the mesoscale cold pool is better developed at the last analysis time (2300 UTC) and subsequent forecast times. 2300 UTC 4 Jul30 min fcst60 min fcst90 min fcst Radar DA only Inc. sub-hourly surface DA Dusty Wheatley

22. Warn on Forecast Workshop 8-9 February 2012 June 14, 2010 west-TX VORTEX2 event 6-h QPEs ending 00Z 15 June 2010 NSSL Q2 Stage IV x LBB 2. Flash flood: -HP supercell with weakly tornadic mesocyclone along gust front/pre-existing boundary intersection -Severe wind gusts (34 – 37 m s -1 measured by VORTEX2) and strong cold pool (ΔT 15 - 18 K) 1. Severe weather: x LBB 6”+ max 3”+ max 100 km 1937 UTC Focus area Mike Coniglio

23. Warn on Forecast Workshop 8-9 February 2012 Initial mesoscale assimilation tests: Final analysis valid 18 UTC EnKF mean RUC analysis RMSD = 1.90 ME = 0.19 RMSD = 2.35 ME = 0.47 2-m T 2-m Td RMSD = 1.70 ME = 0.51 RMSD = 2.10 ME = 0.54 EnKF mean reduces analysis errors vs. RUC But moist bias remains (MYJ PBL scheme) Mike Coniglio

24. Warn on Forecast Workshop 8-9 February 2012 1 Hour Radar Assimilation Experiments: Final analysis valid 19Z Mike Coniglio

25. Warn on Forecast Workshop 8-9 February 2012 Total 3-h accumulated precipitation 19-22 UTC NMQ QPE (color shading) and ensemble raw probabilities > 10 mm (contours) 1-radar 4-radars More backbuilding, slower eastward movement, but still too far east overall Little to no backbuilding, convection moves too fast to east Accumulation too low in most runs Mike Coniglio

26. Warn on Forecast Workshop 8-9 February 2012 GOES Cloud Property Assimilation using WRF-DART Initial Implementation: convert NASA Langley retrieval algorithm cloud properties into proxy WRF state variables Use Cloud Top Pressure (CTP) and Cloud Base Pressure (CBP) to determine 3-D location of cloud Create QCLOUD, QICE, QGRAUPEL, QRAIN, Relative Humidity Proxy columns on GOES horizontal grid with ~50 hPA vertical resolution Thomas Jones

27. Warn on Forecast Workshop 8-9 February 2012 GOES Visible & CTP/CBP 2045 UTC Convection initiating ahead of dryline in OK Low-level clouds present in eastern OK Cirrus Outflow Low-level clouds CTP ~200 hPa CTP ~800 hPa Developing Convection Thomas Jones

28. Warn on Forecast Workshop 8-9 February 2012 WRF-DART Characteristics WRF-DART WRF-DART – ARW, version 3.2.1 – EnKF assimilation using 36 members – Use 15 km CONUS and 3 km one-way nested grid domains – Mesoscale assimilation window from 1200 UTC – 2100 UTC 10 May 1 hour intervals – Nested grid assimilation 1800 – 2100 UTC 15 minute intervals Create 2 runs: – One assimilating derived cloud and humidity variables (CLD) – One with variables set to evaluate-mode only (NOCLD) 15 km Domain 3 km Domain Thomas Jones

29. Warn on Forecast Workshop 8-9 February 2012 QCLOUD Differences 2045 UTC RED = CLD Greater BLUE – NOCLD Greater Large areas of differences at 900 and 850 hPa Magnitude ~ 0.1 g kg -1 Greatest differences near developing cumulus and in low-level clouds fields further east Interesting wave-like pattern in QCLOUD differences at 850 hPa Differences at 700 hPa and above have limited coverage Only significant differences occur along dryline Also see differences in model IWP (black shading) Hard to ascertain physical significance of these differences Thomas Jones

30. Warn on Forecast Workshop 8-9 February 2012 1 hour reflectivity forecast Probability of simulated reflectivity > 25 dBZ changes between NOCLD and CLD ensembles Neither shows much skill relative to the other Thomas Jones

31. Warn on Forecast Workshop 8-9 February 2012 Summary Two supercell cases: SS-NWP can predict the track of the strongest rotation with some accuracy in 0-1 hour time frame. Using tornado proxy for track - less skill with genesis/decay Microphysical parameterization strongly impacts the forecast at these scales. Need to test cases from environments with more marginal tornado parameters Initial macroburst forecast is promising

32. Warn on Forecast Workshop 8-9 February 2012 Summary Mesoscale convective systems –accurate depiction of mesoscale environment critical –Multi-radar improved QPF predictions Satellite case – Takes 2 hours of assimilation of cloud properties to start making a difference – GOES-R should reduce this time by providing 5 – 10 minute resolution data. – Results likely very sensitive to microphysics

33. Warn on Forecast Workshop 8-9 February 2012 Take Aways.. Prediction of isolated severe convection shows promise –MCS’s appears to have more challenges Everything matters? –success with isolated cells: getting the (enough) details right over a small area? –MCS problem may require getting the details right over a much larger area... Its the boundary layer.... –much of forecast error can be traced (we think) to errors in boundary layer structure of humidity and temperature –all phases of convective evolution (initiation, intensification, decay) are impacted by these errors (even tornadogenesis?)

34. Warn on Forecast Workshop 8-9 February 2012 Thanks Questions?

35. Warn on Forecast Workshop 8-9 February 2012 Verification

36. Timing Verification with Tornado reports Model proxy Tornado Members shifted and focused more north than observed with minimal members co-located with TOR Obs cell density axes (30 min) Spatial location UH CA # members # storms - # storms verified Establishing metrics of success

37. Which DA verifies best? Percent severe Percent model severe 25 50 75 100% Being storm specific next hour A.No threat now B.Tornado threat in 30 min C.Decaying threat (storm ongoing) Explicit forecast of which storms will be severe and which won ’ t A C B StormSevere Storm

38. Warn on Forecast Workshop 8-9 February 2012

40. Microphysical Parameterization Development (T. Mansell, D. Dawson, Y. Jung, M. Xue) Development of 3-moment microphysical scheme suitable for deep convection Testing of 3-moment scheme within EnKF framework Verification of microphysical parameterizations –using dual-polarization radar data –forward operator from Y. Jung and M. Xue –collaboration with CAPS

41. Warn on Forecast Workshop 8-9 February 2012 Observations 8 May 2003 22:10 (tornadogenesis) 22 minute ensemble mean forecast with multi-moment microphysics valid 22:10 22 minute ensemble mean forecast with single-moment microphysics valid 22:10 Microphysical Sensitivity

42. Warn on Forecast Workshop 8-9 February 2012 Microphysical Sensitivity Greensburg KS Forecasts Single vs. Two Moment Microphysics SingleTwo

43. Warn on Forecast Workshop 8-9 February 2012

44. GOES Cloud Property Assimilation GOAL: Provide model analysis information on the location and vertical distribution of clouds Need high spatial and temporal resolution data 1 km, 30 minute cloud property retrievals available from GOES-13 data – Uses NASA Langley retrieval algorithm – Products include: Cloud top pressure(CTP) Cloud base pressure(CBP) Cloud liquid water path(CLWP) Cloud ice water path(CIWP) Cloud phase These variables are not suitable for direct assimilation into WRF-DART – Must convert to something it understands

45. Warn on Forecast Workshop 8-9 February 2012 Observation Diagnostics QCLOUD – No difference in bias or RMSE between 18-2000 UTC – Some reduction in bias and RMSE after 2000 UTC Reduction increases with time Max reduction ~0.05 g kg -1 RH Differences small at all times Posterior bias and RMSE at 2100 are smaller by ~0.5% Sample size ~800 Q* data points assimilated at each time interval Total possible: ~1300 ~300 for RH Saw-tooth pattern a result lower sample size at interpolated times (00, 30)

46. Warn on Forecast Workshop 8-9 February 2012 QCloud and RH Data at 2045 UTC Where low clouds exist, RH=100% assimilated Above 850 hPa, few clouds resulting in QCLOUD = 0 being assimilated VARIABLEN TOTAL N ASSIM % ASSIM QCLOUD20548218704291.0 QICE20548219079692.8 QRAIN20548219038092.6 QGRAUP20548219639292.6 RH371892235760.1 TOTAL85911778096790.9 1800 – 2100 UTC Sample size 5050 QCloud data RH data Thomas Jones

47. Warn on Forecast Workshop 8-9 February 2012 Cross Sections Small differences in location of QCLOUD peaks – 5-10 km offset Magnitude of IWP also differs QCLOUD IWP

48. Warn on Forecast Workshop 8-9 February 2012 Issues/Challenges to Explore Case-specific challenges/questions: –Event has multiple convective modes and a strong cold pool. Can Δ=3 km simulations produce a strong cold pool while still restraining its eastward propagation, as was observed? 2011 CAPS 4-km runs TTU SND 1732 Currently trying experiment with MYNN Bnd LYR scheme Environment from MYNN (MYJ) run from 2011 CAPS ensemble one of the best (worst) fits to observed soundings (see poster for more info). Low-level moist bias in the warm sector- will multiple PBL/land-surface schemes help? Only using MYJ currently. EnKF mean T, Td 1800 Mike Coniglio

49. Warn on Forecast Workshop 8-9 February 2012 10 minute Ensemble Forecasts of Svr Wind (0020 UTC) Lou Wicker Verification Wind Plot Vectors: Wind speed > 10 m/s Color: 20 m/s < wind speed < 40 m/s Ensemble Prediction for SVR SFC WINDS Ensemble Forecast Output of Severe Wind Probability Vectors Wind speed > 20 m/s Color at least 33% of members have 25 m/s < wind speed < 40 m/s 3DVAR SFC WIND FIELD

50. Warn on Forecast Workshop 8-9 February 2012 15 minute Ensemble Forecasts of Svr Wind (0025 UTC) Lou Wicker Verification Wind Plot Vectors: Wind speed > 10 m/s Color: 20 m/s < wind speed < 40 m/s Ensemble Prediction for SVR SFC WINDS Ensemble Forecast Output of Severe Wind Probability Vectors Wind speed > 20 m/s Color at least 33% of members have 25 m/s < wind speed < 40 m/s 3DVAR SFC WIND FIELD

51. Warn on Forecast Workshop 8-9 February 2012 Verification: Surface Winds Derived from 3DVAR Analysis Three-radar wind synthesis KTLX, KOUN, TDWR 0010 UTC Poor retrieval of winds near southern boundary Gust Front from Downburst 0020 UTC 0030 UTC Lou Wicker