ESRL – Some Recommendations for Mesoscale Ensemble Forecasts

• Consolidate all NCEP regional storm-scale model runs perhaps under HRRRE (or other) banner (including NAM-nest, Hi-Res Windows, SPC runs, Fire-Weather nests)

• David Dowell on CAMs– Weisman 1997 -Grid spacing should be ≤ 4km– Increased realism of convective structures from 4 to 3 to 2km (Weisman, Kain,

others)• Recommend – use 3km, better to add ensemble members and retain 3km

dx.– Another advantage for 3km (for now): much research experience now available

with 3km (NCAR, ESRL, WoF for outer next.)• Question – Use ARW and NMMB equally? (ESRL and EMC have assumed yes

for now for HRRRE).• No difference in ARW vs. NMMB run time at same res.

– Therefore run both at same resolution.

Mesoscale Ensembles Toward 2020 – Stan, David Dowell, Curtis, Steve Weygandt

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2019?High-Resolution Rapid Refresh

ENSEMBLE (HRRRE)• Each member of NARRE contains 3 km nests

– CONUS/Gulf/Carib, Alaska, Hawaii nests– The two control runs initialized with radar data & other hi-res obs

• This capability puts NWS/NCEP[+OAR/ESRL] in a position to – Provide NextGen Enroute AND Terminal guidance – Provide PROBABILITY guidance with full Probability Density

Function specified, hence uncertainty information as well– Provide a vehicle to improve assimilation capabilities using hybrid (4d-

ens-var) technique with current & future radar & satellite– Address Warn-on-Forecast as resolutions evolve towards ~1 km

• NAM nests are extensions of the 00z, 06z, 12z & 18Z runs.

• HRRRE requires an increase in HPCC funding over and above that required for the NARRE

From Geoff DiMego, Dec 2011, NCEP Model Review

DRAFT Storm Prediction Center Desired Numerical Guidance Attributes

2015 2017 2022•North America Short-Range Mesoscale Ensemble: 12-15 km ~30 member multi-model/multi-physics/multi-IC ensemble with EnKF/hybrid DA, run every 6 hrs with forecasts to 84 hrs

•North America Short-Range Mesoscale Ensemble: 12-15 km ~40 member multi-model/multi-physics/multi-IC ensemble with EnKF/hybrid or newer-state-of-the-art DA, run every 6 hrs with forecasts to Day 4*

•Global Mesoscale Ensemble Forecast System: 10-12 km global domain 40-50 member ensemble with advanced state-of-the-science DA, run every 6 hrs with forecasts to Day 7-10*

•CONUS Storm Scale Ensemble Forecast (SSEF): 4 km CONUS ~10 member multi-model/multi-physics/multi-IC storm scale ensemble with EnKF/hybrid DA, issued every 6-hrs with forecasts to 48-60 hrs*

•CONUS Storm Scale Ensemble Forecast (SSEF): 3 km CONUS ~15 member multi-model/multi-physics/multi-IC storm scale ensemble with EnKF/hybrid or newer state-of-the-art DA, issued every 6-hrs with forecasts to 48-60 hrs*

•CONUS SSEF: 2 km CONUS 30-50 member multi-model/multi-physics/multi-IC storm scale ensemble with advanced state-of-the-science DA, issued every 6-hrs with forecasts to 48-60 hrs*

•Movable domain update SSEF: 2-3 km movable regional domain ~7 member storm scale ensemble with EnKF/hybrid run every 2-4 hrs with forecasts to 15-18 hrs*, focused on “severe weather of the day” areas

•Movable domain update SSEF: 2 km movable regional domain 10-15 member storm scale ensemble with EnKF/hybrid or newer state-of-the-art DA ,run every 1-2 hrs with forecasts to 18-24 hrs*, focused on “severe weather of the day” areas

•Movable domain update SSEF: 1 km movable regional domain 20-30 member storm scale ensemble with advanced state-of-the-science DA run every 1 hr with forecasts to 18-24 hrs*, focused on “severe weather of the day” areas

•Stormscale 3D Analysis: 4 km EnKF/hybrid DA, CONUS storm scale analysis updated every 1-hr.

•Stormscale 3D Analysis: 2 km EnKF/hybrid or newer state-of-the-art DA, CONUS storm scale analysis updated every 15 min

•Stormscale 3D Analysis: 2 km EnKF/hybrid or newer state-of-the-art DA, CONUS storm scale analysis updated every 5 min

•Appropriate RAP (HRRR), Global deterministic / ensemble, and CFS capacities

•Appropriate RAP (HRRR), Global deterministic / ensemble, and CFS capacities

•Stretch Goal - Warn-on-Forecast Prototype Ensemble: Develop <1 km multi-WFO domain 10-20 member nested SSEF, advanced state-of-the science DA, run as needed every 5-10 min with forecasts to 1-2 hrs*

*Model and data assimilation (DA) complexity will be impacted strongly by High Performance Computing capabilities.

Desired Attributes of NOAA Operational Numerical Guidance System

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DRAFT Storm Prediction Center Desired Numerical Guidance Attributes

2015 2017 2022•North America Short-Range Mesoscale Ensemble: 12-15 km ~30 member multi-model/multi-physics/multi-IC ensemble with EnKF/hybrid DA, run every 6 hrs with forecasts to 84 hrs

•North America Short-Range Mesoscale Ensemble: 12-15 km ~40 member multi-model/multi-physics/multi-IC ensemble with EnKF/hybrid or newer-state-of-the-art DA, run every 6 hrs with forecasts to Day 4*

•Global Mesoscale Ensemble Forecast System: 10-12 km global domain 40-50 member ensemble with advanced state-of-the-science DA, run every 6 hrs with forecasts to Day 7-10*

•CONUS Storm Scale Ensemble Forecast (SSEF): 4 km CONUS ~10 member multi-model/multi-physics/multi-IC storm scale ensemble with EnKF/hybrid DA, issued every 6-hrs with forecasts to 48-60 hrs*

•CONUS Storm Scale Ensemble Forecast (SSEF): 3 km CONUS ~15 member multi-model/multi-physics/multi-IC storm scale ensemble with EnKF/hybrid or newer state-of-the-art DA, issued every 6-hrs with forecasts to 48-60 hrs*

•CONUS SSEF: 2 km CONUS 30-50 member multi-model/multi-physics/multi-IC storm scale ensemble with advanced state-of-the-science DA, issued every 6-hrs with forecasts to 48-60 hrs*

•Movable domain update SSEF: 2-3 km movable regional domain ~7 member storm scale ensemble with EnKF/hybrid run every 2-4 hrs with forecasts to 15-18 hrs*, focused on “severe weather of the day” areas

•Movable domain update SSEF: 2 km movable regional domain 10-15 member storm scale ensemble with EnKF/hybrid or newer state-of-the-art DA ,run every 1-2 hrs with forecasts to 18-24 hrs*, focused on “severe weather of the day” areas

•Movable domain update SSEF: 1 km movable regional domain 20-30 member storm scale ensemble with advanced state-of-the-science DA run every 1 hr with forecasts to 18-24 hrs*, focused on “severe weather of the day” areas

•Stormscale 3D Analysis: 4 km EnKF/hybrid DA, CONUS storm scale analysis updated every 1-hr.

•Stormscale 3D Analysis: 2 km EnKF/hybrid or newer state-of-the-art DA, CONUS storm scale analysis updated every 15 min

•Stormscale 3D Analysis: 2 km EnKF/hybrid or newer state-of-the-art DA, CONUS storm scale analysis updated every 5 min

•Appropriate RAP (HRRR), Global deterministic / ensemble, and CFS capacities

•Appropriate RAP (HRRR), Global deterministic / ensemble, and CFS capacities

•Stretch Goal - Warn-on-Forecast Prototype Ensemble: Develop <1 km multi-WFO domain 10-20 member nested SSEF, advanced state-of-the science DA, run as needed every 5-10 min with forecasts to 1-2 hrs*

*Model and data assimilation (DA) complexity will be impacted strongly by High Performance Computing capabilities.

Desired Attributes of NOAA Operational Numerical Guidance System

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Possible alternative NWP 2-member suite - 2022

Global ensemble – as shown by EMC

• 10-12km global 40-50 member ensemble• runs to Day 14 twice daily (to 7d at 06z, 18z)• hourly assimilation cycle with 24h runs init hourly

Single regional model/assimilation ensemble - SSEF• SSEF (equivalent to HRRRe) – 2-3km• Initialize hourly (or subhourly), run to 24h• Every 6h, run out to 48-60h• 2-3km EnKF/hybrid/other DA• Multi-species microphysics with at least 2-moment rain• Include aerosols/fire/smoke for all runs with aerosol-

aware microphysics• No separate HWRF or fire-weather runs or AQ/dust run• 0.5-1.0km multi-WFO nest where needed (WoF)• SSEF analysis = RUA, no separate products

From HRRR/HRRRe to WoF• Radar-DFI-LH effective start at 13km/3km• Mesoscale environment via GSI enhancements for RAPv2+ critical

for HRRR• 3km/80-member hourly updated GSI-hybrid data assimilation over

HRRR-CONUS domain plausible– Estimated needed 10,000 cores (Jeff W. / Stan)

• Model design for HRRR – most accurate numerics possible necessary for identification of storm structure (line vs. supercells vs. cell vs. MCS variations)– ARW, less 6th order diffusion, 5th-order vertical advection

• WoF options – discussion with NSSL, ESRL, EMC, U.OK, SPC partners, NCEP/PSR participants– direct nest inside HRRR/HRRRe within same executable– Separate system using HRRR/HRRRe lateral BCs/background 5Mesoscale Ensembles Toward 2020 – Stan, David Dowell, Curtis, Steve Weygandt