# Presentation: 104850

## Decision Brief: Q1 FY2009 Upgrade to NAM/NDAS/DGEX

**where the nation’s climate and weather services begin**

- Mesoscale Modeling Branch
- 12 December 2008
- Geoff DiMego, Eric Rogers, Tom Black, Mike Ek, Brad Ferrier, George Gayno, Zavisa Janjic, Dennis Keyser, Ying Lin, Geoff Manikin, Matthew Pyle, Wan-Shu Wu, and Jacob Carley (summer visitor now at Purdue)
- http://www.weather.gov/os/notification/tin08-79aaa_nam_upgrade.txt

## Changes in NAM/NDAS/DGEX 1: Analysis / Assimilation Changes

- Partial cycling:
- Use GDAS forecast for atmospheric fields at start (tm12) of NDAS instead of previous NDAS forecast fields
- Continue to use fully-cycled land-states
- New observations:
- TAMDAR data
- Canadian AMDAR data
- METOP2 data
- Latest GSI analysis code with improved CRTM
- New hi-res AFWA snow depth analysis

## Changes in NAM/NDAS/DGEX 2: Model Changes

- Replace the cumbersome WRF-SI (Standard Initialization) with the new faster WRF-WPS (WRF Preprocessing System) and associated REAL codes of WRF version 2.2+
- Radiation: increased absorption for cloud ice and snow
- LSM: two changes related to snow & frozen conditions
- Mixing: vertically mix each hydrometeor species

## Changes in NAM/NDAS/DGEX 3: Output Changes

- Add expanded 32-km output grid #151 covering full computational domain containing same fields as grid #221 (req. by AWC/TPC)
- Add Ri-based PBL height, mixed layer depth, and transport u/v wind components to grid #221 (32 km N.America), grid #218 (12 km CONUS), and #242 (11.25 km Alaska)
- Change post to use 2-m temp instead of skin temperature in underground check for lowest freezing level height. (req. by AWC, provided by Hui-Ya Chuang of GWCMB)
- Add snow mixing ratio to 3 grids that had only output cloud ice so that total ice can be computed (for primarily internal use)

## Model changes I: Impact of cold-season LSM modifications

## Modified Run:

_**Modified Run:**_
**Limit the negative value of potential evaporation ETP  (frost fall) on cold snow covered ground:**
**ETP=Min[ETP*(1.-Rib),0]**

_**Operational NAM**_

_**Operational NAM**_

**2-m Dewpoint Temps too low in Calif. Sierra-Nevada mountain & Colorado Rocky mountains where Bulk Richardson # Rib is large (stable) over snow covered area.**

## Control Run

_**Operational NAM**_

**Too foggy (small 2-m T-TD) over daytime, because potential evaporation rises unrealistically as air temperature rises but melting snowpack remains at freezing point.**

## Model changes II: Impact of radiation modification

## Freezing Rain Case : Impact of Radiation Changes

- Observed Conditions at 00z Feb. 13th, 2008

## Part I: Freezing Rain Case and Radiation Adjustments

- 2m Temperature (°F): Black line is freezing line

- Significant Cold Air Damming

- RUC Analysis of 2mT at 00z Feb. 13th, 2008

- Control 12hr forecast of 2mT valid 00z Feb. 13th, 2008

- Control used as an analog for the NAM’s forecast.

- RUC ANALYSIS

- CTL

## 2m Temperature (°F): Black line is freezing line

- 2m Temperature (°F): Black line is freezing line

- Control 12hr forecast of 2mT valid 00z Feb. 13th, 2008

- Experiment 12hr forecast of 2mT valid 00z Feb. 13th, 2008

## AFWA Snow Change George Gayno

- We need to use 16th mesh data in OPS as
- (1) The 16th mesh (nominally ~23 km) data is better quality than the current 8th mesh (nominally ~45 km)
- (2) The 8th mesh data will eventually go away
- Data path is circuitous - NESDIS pulls from AFWA, then NCO pulls from NESDIS
- NESDIS has setup up the dataflow for the 16th  mesh AFWA data and NCO is pulling it to CCS in real-time

## Snow Cover (Water Equivalent) at Initial Time (After 12 hr of NDAS)

## Operational NAM Lowest Freezing Level Height in hundreds of feet (eg 100 = 10,000’)

- Error of 8,000 to 11,000 feet in area

## NAM-PARA Lowest Freezing Level Height in hundreds of feet (eg 100 = 10,000’)

- No error in area.  Lowest freezing level height at KTXK agrees with point fcst sounding

## NAM Parallel PageExtensive Component Testing

_**NAM Parallel Page**_Extensive Component Testing

## Rogers – Early Test Result Pages

- 1) NAMY = full bundle, NAMX = full bundle minus radiation and LSM change _[http://www.emc.ncep.noaa.gov/mmb/mmbpll/pll12stats_namy_01aug08-31aug08_3mods/](http://www.emc.ncep.noaa.gov/mmb/mmbpll/pll12stats_namy_01aug08-31aug08_3mods/)_
- 2) _[http://www.emc.ncep.noaa.gov/mmb/mmbpll/pll12stats_namp_retro_26feb07-13mar08/](http://www.emc.ncep.noaa.gov/mmb/mmbpll/pll12stats_namp_retro_26feb07-13mar08/)_ (March 2007 retro test of bundle)
- 3) _[http://www.emc.ncep.noaa.gov/mmb/mmbpll/pll12stats.namexp_namy_18dec07-20mar08/](http://www.emc.ncep.noaa.gov/mmb/mmbpll/pll12stats.namexp_namy_18dec07-20mar08/)_ : Clean test of partial cycling is NAMEXP (current NAM, full cycling) vs NAMY (current NAM, partial cycling)
- 4) _[http://www.emc.ncep.noaa.gov/mmb/mmbpll/pll12stats.namy_01apr08-13jun08/](http://www.emc.ncep.noaa.gov/mmb/mmbpll/pll12stats.namy_01apr08-13jun08/)_ : NAMY=partial cycling, TAMDAR/AMDAR Other pages from 2 week test of physics prior to 31 July meeting: _[http://www.emc.ncep.noaa.gov/mmb/mmbpll/pll12stats.namx_18jul08-27jul08/](http://www.emc.ncep.noaa.gov/mmb/mmbpll/pll12stats.namx_18jul08-27jul08/)_ (ops NAM vs NAMX, test of LSM changes in NAMX) http://www.emc.ncep.noaa.gov/mmb/mmbpll/pll12stats_namexp_18jul08-27jul08_3mods/ : NAMEXP vs NAMY = test of new radiation (in NAMEXP)

## Ferrier Testing of New Shallow Convection Scheme

- Series of shallow convection changes, from which we settled on the "swapsoft22" (at http://www.emc.ncep.noaa.gov/mmb/bf/bmj/).  This page has a link to the description summarizing each of the cases (i.e., the "case descriptions" you noted below) are at http://www.emc.ncep.noaa.gov/mmb/bf/bmj/summary.html.
- The radiation change (increased cloud absorption) along with the shallow convection change (http://www.emc.ncep.noaa.gov/mmb/bf/rad/), with the control being the shallow convection change.
- The LSM changes were tested (http://www.emc.ncep.noaa.gov/mmb/bf/lsm/) with the shallow convection + radiation changes with the control being the previously listed item.  Further, it unfortunately included the now-absolete change relating the uptake of water from roots to root zone soil temperatures over deciduous broadleaf forest.
- All 4 of the previous items were compared against each other over Alaska (http://www.emc.ncep.noaa.gov/mmb/bf/alaska/).
- These pages are essentially *stained by the shallow convection change evaluation*, and to a lesser extent *the root zone changes to the LSM* *evaluation*.  Most of these were completed by mid July, except for the shallow convection evaluation that included soundings and forecast CAPE comparisons available to SPC through the "summary link" (2nd link in item #2), which was finished in early August.  That said, using some common sense and screening results to mostly cool season conditions and focusing on the Alaska statistics where shallow convection was not very active, one can conclude the following:
- The radiation change most dramatically improved surface temperature forecasts (00Z runs for T, 12Z runs for T, 00Z runs for Tdew, 12Z runs for Tdew) over CONUS.
- Over Alaska, the radiation change was colder than the other runs (00Z T, 12Z T, 00Z Tdew, 12Z Tdew).
- Despite the flaws and caveats, the results from these runs are consistent with what Eric showed today.  While the NAMY is cooler over Alaska now, there was hardly any change in the March 2007 retro (e.g., 00Z T over Alaska), as you keenly noted during the meeting.  I've attached the short presentation I gave at the July 31 meeting regarding the radiation change in case you need to refer to it, where slide7 shows no cool bias over SAK, NAK for cool season Launcher runs.
**We engaged SPC to assess impact of the shallow changes on CAPE.  They indicated the lower values of CAPE would cause them problems, so we withdrew the change from consideration.**

## Ferrier - Assess Impact of Radiation Change on 2-m Temp over Alaska with Launcher runs

- Negative: Cooler surface temperatures during warm season when NAM is already too cool
- Positive: Warmer surface temperatures during cold season when NAM is also too cool

## Testing Supporting Final Physics Decision

- Real-time parallel NAMX (partial cycling only) & NAMY (everything)
- Cold Season retro parallel with NAMY setup: http://www.emc.ncep.noaa.gov/mmb/mmbpll/pll12stats_namp_retro_26feb07-13mar08/
- Final Decision Made 2 September based on real-time and cold-season retro results: use NAMY setup
- Final Bundle Frozen: shallow changes out and radiation change in

## Precip - Retro

## Final NAM Parallel testing

- 1 August 2008 – present : EMC Real-time
- 26 Feb 2007 – 31 Mar 2007 : Retrospective
-  5 Aug 2008 – 28 Sept 2008 : Retrospective
-  28 Oct 2008 – present : NCO Real-time providing gridded product for subjective evaluation

## Equitable Threat (top) and Bias (bottom) QPF Scores: Left=March 2007; Right=Aug-Sept 2008. Red=Ops NAM, Blue=Pll NAM

**March 2007**

**Aug-Sept 2008**

## 24/48/72-h CONUS RMS Height Error : Left=March 2007; Right=Aug-Sept 2008. Solid=Ops NAM, Dashed=Parallel NAM

**Aug-Sept 2008**

**March 2007**

## 24/48/72-h Alaska RMS Height Error : Left=March 2007; Right=Aug-Sept 2008. Solid=Ops NAM, Dashed=Parallel NAM

**March 2007**

**Aug-Sept 2008**

## 00z cycle 2-m Temp : Aug-Sept 08

- East CONUS

- West CONUS

- Alaska

## 00z cycle 2-m Temp : March 2007

- East CONUS

- West CONUS

- Alaska

## Real-Time QPF Stats for Nov. CONUS

## Real-Time Stats for Nov. CONUS

_**Real-Time Stats for Nov. CONUS**_

**HEIGHT**

**Temperature**

**Rel. Humidity**

**WIND**

## Real-Time Stats for Nov. Alaska

_**Real-Time Stats for Nov. Alaska**_

**HEIGHT**

**Temperature**

**Rel. Humidity**

**WIND**

## Results Summary

- Upper air stats are significantly better in both warm and cool seasons
- QPF impact is neutral (warm season) to slightly positive (cool season) with somewhat lower biases in both seasons (helps if NAM bias is high and hurts if it is low – regime dependent)
- Surface stats generally better (see previous slide for Alaska) with daytime warm bias reduced in Eastern CONUS and nightime cool bias reduced slightly in Western CONUS.

## E X A M P L E S

## Slide 36

## Slide 37

## Slide 38

## Slide 39

## Slide 40

## Slide 41

## Slide 42

## Slide 43

## Bottom line: parallel NAM tends to look more like the GFS at days 2-3.  However, while this is a good thing almost all the time, it is a bad thing if the GFS is experiencing a ‘dropout’.

## Slide 45

## Slide 46

## Slide 47

## Improved Real-Time Parallel (NAMX) Case  8-9 Dec. 2008 Brad Ferrier

## 250 mb Comparison

## 500 mb Comparison

## Precipitable Water Comparison

## 36-60 hr QPF Comparison

## 48-72 hr QPF Comparison

## OPC Real-Time Evaluation & RecommendationJoe Sienkiewicz and Jim Clark

- They do not see significant differences between fields through 60 hours
- For OPC purposes, there did not appear to be improvement or degradation with coastal / offshore winds
- OPC agrees with implementation on 12/16/08

## HPC Real-Time Evaluation & Recommendation 1. Mike Bodner

- Our forecasters made frequent use of the NAMP and provided mostly positive feedback.
- The only negative feedback was that the NAMP did not improve on the NAM on a few occasions.
- There were no occasions where the NAMP performed worse than the operational NAM.
- On two specific events over the central plains, I received extensive feedback (see next slide).
- In both cases, the NAMP influenced forecaster reasoning on shift.
- Therefore, the HPC gives a "thumbs up" in moving forward with new NAM implementation.

## HPC Real-Time Evaluation & Recommendation 2. Mike Bodner

- 1st Case: October 21, 2008 at the 12Z cycle
- The NAMP was further north than the operational NAM with a deep closed low over the central plains.
- This positioning clustered well with the 12Z CMC GEM and the NCEP GFS as well as the 00Z ECMWF.
- The NAMP performed well in both positioning and precipitation type of the comma-head banding over central and western Nebraska.
- 2nd Case: November 9, 2008 at the 00Z cycle
- The NAMP trended faster then the operational NAM in moving a 500 hPa low across the central plains after 60 hours.
- Once again the NAMP moved into closer clustering with the 00Z ECMWF and CMC.

## AWC Evaluation of Dec 2008 NAM Parallel 5 Dec 2008 Dr. Steverino Silberberg, Andy Fischer and Bruce Entwistle 

- NAM-Parallel basic meteorological fields equivalent to NAM-Operational, some parallel fields slightly better than operational
- New post-process lowest freezing level height algorithm is a _significant_ improvement over operational algorithm
- Using 2 m temperature instead of surface temperature
- Thank you Hui-ya Chuang and Eric Rogers!

## AWC Recommendation & Suggestion

- AWC recommends operational implementation of NAM-Parallel
- Thank you to:
- EMC for development
- and NCO for dataflow
- Suggestion: Please notify AWC _3_ weeks before parallel dataflow begins because AWC requires:
- Configuration Control Board Approval for DBNet and NAWIPS configuration changes to acquire, configure, compute, and render AWC-specific diagnostics
- Implementation of AWC-specific model evaluation procedure

## SPC NAM Evaluation:  December 3, 2008 Steven Weiss 

- SPC Evaluation Procedures
- SPC examined several real-time parallel NAM runs during the 30 day evaluation period when there were enhanced severe storm threats
- Comparisons were made between operational (NAM) and parallel (NAMp) versions for synoptic pattern evolution and several parameters used for severe thunderstorm forecasting
- RUC 00-hr grids for fields aloft and SPC Mesoscale Analysis fields for surface parameters were used as “truth”
- Unfortunately, severe weather days have been infrequent during the evaluation period.  November 5 and November 14 severe weather cases were examined in more detail
- Examples / case study slides are provided in full in the Backup Section

## SPC Recommendation

**Parallel NAM provided guidance for severe convective weather forecasting that is as good or better than operational NAM**
- Based primarily on close examination of two November severe weather cases
- SPC was also involved in aspects of a late summer “pre-evaluation”, and discussions at that time clearly showed parallel NAM performance was considerably improved based on nearly all statistical measures
- Improved physics/dynamics
- Partial cycling and use of WPS
- GSI upgrade
**Summary - SPC gives a “thumbs up” for implementation**