NOUS41 KWBC 311720

PNSWSH

 

Service Change Notice 18-58

National Weather Service Headquarters Silver Spring MD

120 PM EDT Thu May 31 2018

 

To:        Subscribers:

           -NOAA Weather Wire Service

           -Emergency Managers Weather Information Network

           -NOAAPort

           Other NWS Partners, Users and Employees

 

From:       Dave Myrick

            NWS Office of Science and Technology Integration

 

Subject:   Upgrade to the RAP and HRRR Analysis and Forecast

           System: Effective July 11, 2018

 

Effective on or about Wednesday, July 11, 2018, beginning with

the 1200 Coordinated Universal Time (UTC) run, the National

Centers for Environmental Prediction (NCEP) will implement

Version 4 of the Rapid Refresh (RAP) and Version 3 of the 

High-Resolution Rapid Refresh (HRRR) systems.

 

Major changes will include:

- New HRRR Alaska system

- HRRR forecast extensions for specific cycles

- RAP forecast extensions for specific cycles

- Numerous data assimilation changes

 

Analysis Changes:

 

- The RAP and HRRR will both use an updated version of the

Gridpoint Statistical Interpolation (GSI) analysis code.

- The weighting of the ensemble-based component in the hybrid

data assimilation will increase from 0.75 to 0.85 for the RAP

and HRRR.

- The assimilation of velocity Azimuth Display (VAD) wind

retrievals, Atmospheric Motion Vectors (AMV) over land, and

Tropospheric Airborne Meteorological Data Report (TAMDAR) will

be added to the RAP and HRRR.

- The assimilation of Infrared Atmospheric Sounding

Interferometer (IASI), Cross-Track Infrared Sounder (CrIS), and

Spinning Enhanced Visible and InfraRed Imager (SEVIRI) radiances

will be added to the RAP including direct readouts.

- The assimilation of radar radial velocity and lightning data

will be added to the HRRR.

- Planetary boundary layer (PBL) pseudo observations will be

refined to reduce a relative humidity bias.

- Meteorological Terminal Aviation Routine Weather Report

(METAR)/Geostationary Operational Environmental Satellite (GOES)

cloud building is made consistent below 1200 m AGL (above ground

level).

- During cloud building, cloud number concentrations will be

more physically consistent with cloud mixing ratios to support

more retention of clouds/ceilings through the first few forecast

hours.

- Latent heating in the radar reflectivity assimilation is

reduced in the RAP to improve precipitation and reflectivity

biases in both the RAP and HRRR.

- The assimilation of the Global Positioning System (GPS)-

Integrated Precipitable Water will begin again. This data was

turned off in the RAP and HRRR in April 2017 due to corrupted

data.

 

Changes to Model:

 

- The RAP and HRRR will both begin using Weather Research and

Forecasting (WRF) version 3.8.1; both will continue to use the

Advanced Research WRF (ARW_ core).

- The RAP and HRRR will switch to using a hybrid vertical

coordinate system, which improves the depiction of the mesoscale

environment.

- The representation of terrain will be improved, leading to

better wind and turbulence forecasts.

- The RAP and HRRR will begin to use full geometric diffusion,

which improves wind and temperature forecasts over terrain.

- The Mellor Yamada Nakanishi Niino (MYNN) planetary boundary

layer scheme is being updated to improve the depiction of

subgrid-scale clouds and the mesoscale environment including

eddy diffusivity mass flux (EDMF).

- The 9-level Rapid Update Cycle (RUC) land-surface model is

being updated to include 15" Moderate Resolution Imaging

Spectroradiometer (MODIS) data to improve the lower boundary,

and roughness lengths have been refined over various land use

types.

- The Thompson microphysics scheme is being updated to improve

the depiction of upper-level clouds.

- The RAP and HRRR will begin to use real-time greenness

vegetative fraction from the Visible Infrared Imaging Radiometer

Suite (VIIRS).

- The RAP and HRRR have refined diagnostics of 2 m temperature

(removed grid-point speckling over snowpack at night), 10 m wind

(more physically consistent), 10 m wind gust (removed a low

bias) and visibility (removed a low bias).

 

Many of these changes to the data assimilation, land-surface

model, boundary layer scheme, and microphysics scheme are

designed to improve the depiction of cloud fields and to

mitigate a high precipitation and reflectivity bias in the RAP

and HRRR that is most notable during the first several forecast

hours. Significant reduction of these biases has been evident

during the extensive testing period.

 

Output Changes:

 

- The RAP and HRRR will be extending the forecast hours 4 times

a day. The RAP will be extended out to 39 hours for cycles 03,

09, 15 and 21 UTC. The HRRR will be extended out to 36 hours for

cycles 00, 06, 12 and 18 UTC. The HRRR sub-hourly output,

however, will not cover the forecast extensions; it will

continue to be available only through hour 18 for all cycles.

These forecast extensions will facilitate future NCEP plans for

the High-Resolution Ensemble Forecast (HREF) system.

 

- A new HRRR Alaska system will be introduced with this upgrade.

HRRR Alaska will run every third hour, with forecasts out to 

18 hours for cycles 03, 09, 15 and 21 UTC and out to 36 hours

for cycles 00, 06, 12 and 18 UTC. HRRR Alaska will provide

additional high-resolution guidance over the state of Alaska

with more frequent cadence.

  

 - The HRRR directory structure will be modified to include

conus and alaska subdirectories on the NCEP Web Services:

  http://nomads.ncep.noaa.gov

  ftp://ftp.ncep.noaa.gov

  http://www.ftp.ncep.noaa.gov

 

    OLD directory: hrrr/prod/hrrr.YYYYMMDD

    NEW directory: hrrr/prod/hrrr.YYYYMMDD/conus

    NEW directory: hrrr/prod/hrrr.YYYYMMDD/alaska

  Where YYYYMMDD is Year, Month and Day

 

- The forecast lengths of both the RAP and the HRRR will be

extended on the NCEP servers NOMADS Grib Filter and OpenDAP

Services for the specific cycles:

  http://nomads.ncep.noaa.gov/cgi-bin/filter_rap.pl

  http://nomads.ncep.noaa.gov/cgi-bin/filter_rap32.pl

  http://nomads.ncep.noaa.gov/cgi-bin/filter_hrrr_2d.pl

  http://nomads.ncep.noaa.gov:9090/dods/hrrr

  http://nomads.ncep.noaa.gov:9090/dods/rap

 

The new Alaska grid will also be made available through NOMADS

 

- The new HRRR Alaska domain output will be added to the NCEP

Web Services with the following files under the alaska

subdirectory:

  hrrr.tCCz.wrfprsfHH.ak.grib2

  hrrr.tCCz.wrfnatfHH.ak.grib2

  hrrr.tCCz.wrfsfcfHH.ak.grib2

  hrrr.tCCz.wrfsubhfYY.ak.grib2

  hrrr.tCCz.class1.bufr.ak.tm00

  hrrr.tCCz.bufrsnd.tar.ak.gz

Where CC is the cycle (00,03,06,09,12,15,18,21) and HH is the

forecast hour (00-36), and YY is the forecast hour (00-18)

 

- RAP Precipitation Field Changes

The RAP currently generates convective, non-convective and total

precipitation. In the previous upgrade total precipitation was

added to the output as part of the RAPv3 upgrade. This was so

users no longer needed to sum the convective and non-convective

amounts. To become consistent with other NCEP models that

generate only total and convective precipitation, the run total

and 1-hour accumulation non-convective precipitation fields

(NCPCP) will be eliminated in this upgrade.

 

- RAP Cloud Ice

The full vertical profile of cloud ice parameter (kg/m^2) is

replaced by full vertical profile of the cloud ice mixing ratio

(kg/kg) on all grids which contain a cloud ice profile (13 km

native and pressure level, 32 km full domain, 16 km Alaska, 13

km CONUS native level, and 20 km CONUS).

 

- Total Accumulated Snowfall

  The labeling for total accumulated snowfall is modified at

forecast hour 00 (f00) for the RAP and HRRR to include a 0-0 day

acc fcst label.  This change makes accumulated snowfall

consistent with the other accumulation fields at f00.

 

- Added and Removed Parameters from the RAP output on NCEP Web:

  * Cloud ceiling height is added to the Alaska grid.

  * Surface roughness length is added to the full domain 13 km

native level grid.

  * Instantaneous upwelling shortwave radiation at the top of

the atmosphere is added to the full and CONUS 13 km native level

grids.

  * Run total accumulated freezing rain is added to the 13 km

full domain pressure level grid, the 13 km CONUS pressure level

grid, and the Alaska grid.

 

 - Added Parameters for the HRRR (files wrfprs and wrfsfc)

output on NCEP Web:

  *  Accumulated Freezing Rain

  * Instantaneous Upwelling Shortwave Radiation at Top of

Atmosphere

  * Max Reflectivity at -10C over the previous hour

  * Hourly Maximum 10-m U wind component

  * Hourly Maximum 10-m V wind component

  * Hourly Minimum Updraft Helicity in 2-5 km layer

  * Hourly Minimum Updraft Helicity in 0-3 km layer

  * Hourly Maximum Updraft Helicity in 0-3 km layer

  * Hourly Minimum Updraft Helicity in 0-2 km layer

  * Hourly Maximum Updraft Helicity in 0-2 km layer

  * Hourly Maximum Relative Vertical Vorticity in 0-2 km layer

  * Hourly Maximum Relative Vertical Vorticity in 0-1 km layer

  * Hourly Maximum Estimate of Maximum Hail/Graupel Size in

Model Column

  * Hourly Maximum Estimate of Maximum Hail/Graupel Size at

Lowest Model Level

 

 - Added Parameters for the HRRR (files wrfsfc) output on NCEP

Web:

  * 300-mb U wind component

  * 300-mb V wind component

 

 - Added Parameters for the HRRR (files wrfsubh) output on NCEP

Web:

  * Surface Height

  * Upward Shortwave Radiative Flux

 

 - Added Parameters for the HRRR (files wrfnat) output on NCEP

Web:

  * Volumetric Soil Moisture Content (Fraction) at surface

(labeled as 0 meters below ground)

  * Volumetric Soil Moisture Content (Fraction) at 0.1 meters

below ground

 

 - The following changes are made to existing parameters in the

wrfprs, wrfsfc, and wrfnat files on NCEP Web:

  The hourly maximum updraft and downdraft speeds, currently

labeled as parameters computed over a depth between 400 and 1000

mb are now labeled as parameters computed over a depth between

100 and 1000 mb to reflect a change to the computations.

 

 

 - BUFR Output

  A few current stations are being modified, and new stations

are being added to the station time series BUFR data for the RAP

and HRRR.  The update to the station list for the RAP and HRRR

will be done in conjunction with the updates to the stations

lists for the NAM, GFS, SREF, and Hi-Res Windows.  Please

reference the concurrent SCN for more information,

 

http://www.nws.noaa.gov/os/notification/scn18-57bufr_updates.htm

 

 - Product Delivery Time Changes

  The RAP and HRRR station time series BUFR data will arrive

later for the extended cycle. The 03, 09, 15, and 21 UTC RAP

BUFR data will arrive 10 minutes later than the files for the

other cycles, and the 00, 06, 12, and 18 UTC HRRR BUFR data will

arrive 30 minutes later than the files for the other cycles.

 

 - There will be no changes to data on NOAAPORT/SBN

 

Parallel Data Available:

  A consistent parallel feed of data is available on the NCEP

server via the following URLs:

http://para.nomads.ncep.noaa.gov/pub/data/nccf/com/hrrr/para

http://para.nomads.ncep.noaa.gov/pub/data/nccf/com/rap/para

 

For more general information about the RAP and HRRR, please see:

http://rapidrefresh.noaa.gov

 

NCEP urges all users to ensure their decoders can handle changes

in content order, changes in the scaling factor component within

the product definition section (PDS) of the GRIB files, and

volume changes. These elements may change with future NCEP model

implementations. NCEP will make every attempt to alert users to

these changes before implementation.

 

NCEP will evaluate all comments to determine whether to proceed

with this upgrade.

 

For questions regarding this implementation, please contact:

 

  Geoff Manikin

  NCEP/EMC/VPPG Branch

  College Park, MD

  301-683-3695

  geoffrey.manikin@noaa.gov

or

  Curtis Alexander

  ESRL / Global Systems Division

  Boulder, Colorado

  303-497-4725

  curtis.alexander@noaa.gov

 

For questions regarding the data flow aspects of these data

sets, please contact:

 

  Carissa Klemmer

  NCEP/NCO Dataflow Team Lead

  College Park, Maryland

  301-683-0567

  ncep.list.pmb-dataflow@noaa.gov

 

NWS National Service Change Notices are online at:

 

   http://www.nws.noaa.gov/os/notif.htm

 

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