1. 1 NMM, ARW in NCEP Operations Pre-WRF NMM at NCEP May 2000: nonhydrostatic option released in upgrade to NCEP’s workstation EtaNCEP’s workstation Eta May 2001: NMM model equations, solution techniques & test results published in Janjic, Gerrity, and Nickovic, 2001, Mon. Wea. Rev. also Janjic, 2003, Meteor. & Atmos. Phys.Janjic, Gerrity, and Nickovic Janjic February 2002: HiResWindow runs upgraded to use 8 km NMM replaces 10 km Eta (hydrostatic)HiResWindow February 2002: On-Call Emergency Response (OCER) capability begins using 4 km NMM to support HYSPLITOn-Call Emergency Response May 2003: Fire Weather / IMET Support runs implemented using 8 km NMMFire Weather / IMET Support WRF-ARW at NCEP September 2004: HiResWindow first WRF implementation of 10 km WRF- ARW v1.3HiResWindow June 2005: HiResWindow upgraded to use 5.8 km WRF-ARW with explicit convectionHiResWindow December 2005: Short Range Ensemble Forecasting system adds 3 members using 45 km WRF-ARW v2.0Short Range Ensemble Forecasting September 2007: HiResWindow expanded domain and upgraded to 5.1 km WRF-ARW v2.2.1HiResWindow October 2009: SREF WRF-ARW upgraded to v2.2.1, add 2 members and increase resolution to 35 km

2. 2 WRF-NMM in NCEP Operations April 2004 thru present: NSSL/SPC Spring Program, daily developmental run of 4.5 km WRF-NMM with explicit convection NSSL/SPC Spring Program September 2004: HiResWindow first WRF implementation of 8 km WRF-NMM v1.3 replaces pre-WRF NMM HiResWindow June 2005: HiResWindow upgraded to use 5.1 km WRF-NMM with explicit convectionHiResWindow December 2005: Short Range Ensemble Forecasting system adds 3 members using 40 km WRF-NMM v2.0Short Range Ensemble Forecasting June 2006: NAM runs use 12 km WRF-NMM v2.1 & WRF-GSI replacing Eta & Eta-3DVarNAM runs September 2007: HiResWindow expanded domain and upgraded to 4 km WRF-NMM v2.2.1 HiResWindow December 2008: final major NAM/NMM upgrade

3. Runtime & optimal node apportionment for NMMB nesting with a Fire Wx nest over CONUS (30 nodes): 12 hr fcst in 1619 s [Matt Pyle] 3 km Puerto Rico nest 1.5/30 or 5% 1.33 km CONUS FireWx nest 5/30 or 17% 4 km CONUS nest 17/30 or 57% 3 3 km Hawaii nest 1.5/30 or 5% 12 km parent 3/30 or 10% 6 km Alaska nest 2/30 or 7%

4. WRF-NMM takes 3.6 times longer to run comparable nesting with Fire Wx nest over CONUS (30 nodes): 12 hr fcst in 5857 s [Matt Pyle] 4 km* Puerto Rico nest 30/30 or 100% 1.33 km CONUS FireWx nest 30/30 or 100% 4 km CONUS nest 30/30 or 100% 4 4 km* Hawaii nest 30/30 or 100% 12 km parent 30/30 or 100% 4 km* Alaska nest 30/30 or 100%

5. 5 More Stats Showing Improved Computational Speed & Efficiency Runtime for NAM with 5 nests on 72 nodes: Current opnl code: > 4 hours New code: 70 minutes New NAM is doing 11 times more work than the current NAM, but uses only 7.7 times more compute resources! IBM estimates the NMMB will easily scale to at least 24,000 processors (if we could ever get them)

6. Why Does NMMB Run So Much Faster? NMMBNMM Runtimes1619 s5857 s3.6 x faster Contribution to speed up New Model Dynamics NMMBNMM~2% InfrastructureNEMSWRF~2% Nesting NMMB specific Outside of the NEMS infrastructure Processor apportionment 1-way nests solved simultaneously ~Core independent* Part of the WRF infrastructure No processor apportionment 1-way nests solved sequentially ~96% Horizontal resolution step- down ratio Any integer ratio, e.g. 2:1, 3:1, 4:1, … Only 3:1* 0% - this relates to flexibility, not speed 6

7. Hypothetical NMMB Simultaneous Run Global [with Igor & Julia] and NAM [with CONUS nest] 27 km Global NMMB 12 km NAM NMMB 4 km NAM-nest NMMB 9 km Igor NMMB 9 km Julia NMMB

8. Movable Storm Scale SPC’s 2022 Requirement –Inside every HRRRE member –Movable domain update SSEF: –1 km movable regional domain –20-30 member storm scale ensemble –advanced state-of-the-science DA –run every 1 hr with forecasts to 18-24 hr –focused on “severe weather of the day” areas In 2014, NAM upgrade could include –Movable FireWx nest tracking tropical storm –Movable FireWx nest with prescribed motion 8

9. Superstorm Sandy was ‘contained’ in fixed domain NAM 1.33 km nest from 18z 10/29/12 SLP, 1-h Accum Precip (in), 10-m wind (kt) 9

10. Superstorm Sandy was ‘contained’ in fixed domain NAM 1.33 km nest from 18z 10/29/12 1-h Maximum Wind Speed Gust (kt) 10

11. Hurricane Irene was not ‘contained’ in fixed domain NAM 1.33 km nest from 18z 10/29/12 SLP, 1-h Accum Precip (in), 10-m wind (kt)

12. 1.33 km Moving nest 12 Courtesy Brad Ferrier, Eric Aligo & Dusan Jovic

13. 1.33 km Moving nest 13 Courtesy Brad Ferrier, Eric Aligo & Dusan Jovic