1 What is the “NAM”? David Novak Science and Operations Officer NOAA/NCEP/ Hydrometeorological Prediction Center

2 Motivation How to make sense of a blizzard of acronyms referring to: 1)Native model differences 2)Display resolution differences 3)NMAP naming conventions

3 The NAM NAM = North American Mesoscale Model EMC/NCO consider it the name of a computing slot on the supercomputer. The core model can change, the model physics can change, the resolution can change, and it will still be called the “NAM” The core model recently changed from the WRF- NMM to the NMMB in October, 2011.

4 Native Model Differences “Parent” domain -12 km native resolution -Large North American domain -Uses full convective parameterization -Boundary conditions from GFS Fixed Nests -High Resolution -6 km Alaska -4 km CONUS -2.5 km OCONUS domains -Boundary conditions from parent NAM domain **Limited or no convective parameterization 12 km 6 km 4 km 1.3 km 2.5 km Fire Weather Nest -Moveable 1.33 km nest -Boundary Condtions from fixed nest Alaska CONUS Hawaii PeurtoRico

5 NMAP Names “Parent” domain nam12 CONUS Nest nam_conest 12 km 6 km 4 km 1.3 km 2.5 km Fire Weather Nest nam_firewx Alaska CONUS Hawaii PeurtoRico Puerto Rico Nest nam_prnest

nam12 30 h forecast 6-h accumulated precipitation valid 18 UTC 29 October 2011

nam_conest 30 h forecast 6-h accumulated precipitation valid 18 UTC 29 October 2011 More detail Differences in intense precipitation areas

nam_firewx 30 h forecast 6-h accumulated precipitation valid 18 UTC 29 October 2011 Downscaling of the nest

RFC Stage IV QPE 6-h accumulated precipitation ending 18 UTC 29 October 2011

10 nam12 24 h forecast 24-h accumulated precipitation valid 12 UTC 9 Nov 2011

11 Nam_conest 24 h forecast 24-h accumulated precipitation valid 12 UTC 9 Nov 2011

12 RFC Stage IV QPE 24-h accumulated precipitation ending 12 UTC 9 November 2011

13 Native Model Differences Summary nam12 and nam_conest can be quite different for precipitation -Likely mostly due to the limited use of convective parameterization on the 4 km nest and the higher resolution. Smaller differences in mass fields (heights, temps, etc) FireWx Nest is mostly a downscaling of the 4 km CONUS Nest

14 Display Resolution Differences NCO provides NAM data with variety of domains/resolutions. ModelDisplay ResolutionNMAP name 12 km Parent Domain 80 kmnam 12 km Parent Domain 40 kmnam40 12 km Parent Domain 20 kmnam12_20 12 km Parent Domain 12 kmnam12 4 km CONUS Nest4 kmnam_conest

15 80 km

16 40 km

17 12 km

18 4 km CONUS Nest

19 NSSL QPE

20 Can we Simplify this? NCO / OPC/ HPC in discussions ModelDisplay ResolutionNMAP name 12 km Parent Domain 80 kmnam 12 km Parent Domain ~ 40 km nam40 12 km Parent Domain 20 kmnam12_20 12 km Parent Domain 12 kmnam12 4 km CONUS Nest4 kmnam_conest

18Z 06Z 00Z 12Z 00Z, 12Z 06Z, 18Z HiResWindow Runs ≠ CONUS Nest Different model cores (WRF-NMM/ WRF-ARW vs. NMMB) Smaller domains Arrive later in the cycle Forecasts only to 48 h Can be preempted by hurricane runs

22 Summary Know what you are looking at Native model differences Display resolution differences NMAP naming conventions Are your spf’s updated? -Take advantage of new data Questions, feedback, & ideas welcome!