NOUS41 KWBC 311510 AAA


Technical Implementation Notice 12-30, Amended

National Weather Service Headquarters Washington DC

1110 AM EDT Tue Jul 31 2012

To:†††††† Subscribers:

††††††††† -Family of Services

††††††††† -NOAA Weather Wire Service

††††††††† -Emergency Managers Weather Information Network

††††††††† -NOAAPORT

††††††††† Other NWS Partners, Users and Employees

From:†††† Timothy McClung

††††††††† Chief, Science Plans Branch

††††††††† Office of Science and Technology

Subject:Amended Date: Upgrade to Short Range Ensemble Forecast

††††††††† System Effective August 21, 2012

Amended to reschedule the implementation to Tuesday, August 21,

2012, to allow for additional testing.Corrected erroneous

quotation marks in filename for new NMMB output files.Also

added specifics about addition of 1-hourly output to the NWS FTP



On or about Tuesday, August 21, 2012, beginning with the

1500 Coordinated Universal Time (UTC) run, the National Centers

for Environmental Prediction (NCEP) will update its Short Range

Ensemble Forecast system (SREF).

SREF Modeling System Changes:

1.Remove two of the four models currently used in the SREF: the

Eta and the Regional Spectral Model (RSM). A new model will be

added: the Non-hydrostatic Multiscale Meteorological Model on the

B grid (NMMB).

2.Upgrade two Weather Research and Forecasting (WRF) model

cores in model version from WRF v2.2 to WRF v3.3: Non-hydrostatic

Multiscale Meteorological Model (NMM) and Advanced Research WRF


3.Increase the NMM and ARW horizontal resolution from 32/35km

to 16km. The NMMB will also have a 16km horizontal resolution.

4.Increase the number of WRF members for NMM and ARW from 5

to 7. There will be 7 members for the new NMMB model. The naming

convention of all the files will follow the pattern:

sref_MODEL.tCCz.pgrb???.PERT.fxx, where MODEL is nmm, em, nmb

for the NMM, ARW and NMMB, respectively, CC is the model cycle

(03, 09, 15, 21), ??? is the number of the grid the data are on,

PERT is the perturbation, represented by ctl, n1, p1, n2, p2, n3,

p3, and fxx is the forecast hour.

5.Increase diversity by selecting physics schemes used in

existing models: NAM, GFS, NCAR, HWRF and Rapid Refresh (RAP).

6.Increase Initial Condition (IC) diversity by:

††† -Using RAP analysis as a control analysis for the ARW, NAM

†††† analysis used for the NMMB, and GFS analysis used for

†††† the NMM.

††† -Mixing IC perturbation schemes by using a mix of the Global

†††† Ensemble Transform with Rescaling (ETR), regional Breeding

†††† and blending between the two.

††† -Increasing the Land Surface Initial States (LSIS)

†††† diversity by using the LSIS from the NAM, GFS, and RAP.

7.New capabilities will be added in post-processing SREF data:

††† -Bias correction (by frequency matching) of the

†††† precipitation forecasts for both individual members and the

†††† ensemble mean.

††† -Clustering with two methods, NCEP and University of

†††† Oklahoma, with output including a text table about each

†††† cluster's membership and size, a GRIB output of probability

†††† of each cluster, and a GRIB output of cluster products for

†††† the mean and spread of thirty-nine fields, as well as the

†††† probabilities for 2-meter temperature and 3hr-accumulated

†††† precipitation.

††† -Performance ranking of each ensemble member, providing

†††† different weights for different members in both text and

†††† GRIB format.

††† -Statistical surface down-scaling from 16km SREF to 5km NDGD

†††† grid using the 5km Real-Time Mesoscale Analysis (RTMA)

†††† fields.

8.Modified the snow liquid ratio from being fixed at 10:1 to a

surface temperature dependency method.

Change to Current Product Delivery Schedule:

Due to the current high resource usage on the supercomputers run

by NCEP, this updated SREF system can be run only in its defined

time window. In the event the NCEP production suite is delayed,

the SREF may not be run for a given cycle to preserve the

timeliness of other NCEP models. In this situation, no SREF

output products will be disseminated, and that cycle will not be

rerun later. NCEP does not anticipate this situation occurring

often, but wanted to alert customers of the slight possibility of

missing one cycle of SREF output.This SREF susceptibility to

cancellation will remain until NCEPís upgrade to new

supercomputers in late 2013. We apologize for any inconvenience

this causes our users.

Current Product Output Changes:

1.Change to product generating process ID in the GRIB encoding

of individual SREF members output products on the NCEP server.

Currently all SREF members are labeled with process ID 84. Now

the ID's will be:


††† -NMB 111

††† -NMM 112

††† -ARW 116


The generating process ID of the SREF ensemble products,

currently 113, will stay the same.

2.Additions to several probability to the ensemble products:


††† -Probability of CAPE > 250

††† -Probability of visibility < 9654ft

††† -Probability of ceiling < 1830ft

††† -Probability of lower-level wind shear > 20kt/2000ft

††† -Probability of light fog

††† -Probability of moderate fog

††† -Probability of dense fog

3.Addition of 600hPa U, V, ABSV, HGT, T and RH to the ensemble

mean and spread.

4.Addition of bias corrected precipitation fields to

individual members and the ensemble mean.

New Product Outputs:

1.The temporal resolution for the CONUS (grid 212) domain will

increase from 3-hourly to hourly for forecast hours 0-39. Due to

the new 1-hourly temporal resolution files, all ensemble output

products will be renamed to reflect that they are 3-hourly.

-NCEP server:





-NWS server:

Current filenames in -


xxx_pt.*_gr.212 contain 3-hourly forecast hours.


With this implementation

fh.3hrly_pt.*_gr.212-- new name for 3-hourly forecast hours

fh.1hrly_pt.*_gr.212-- new 1-hourly forecast hours

2.Probability products from the Storm Prediction Center (SPC)

for severe thunderstorm, lightning, dry lightning and fire

weather parameters.


-NCEP server:



3.Forecast uncertainty/confidence information for forty fields

for all grids:


-max, min, mode, 10-25-50-75-90% (ZZZ in filename below)


-NCEP server:




4.Ensemble mean Binary Universal Form for the Representation of

meteorological data (BUFR) sounding products


-NCEP server:



5.NMB ctl, n1, n2, n3, p1, p2, p3 members will be added


-NCEP server:





6.Addition of a 16km North American domain (grid 132). Due to

the increased resources required to generate them, the ensemble

files will be outputted approximately 1 hour later than the

current SREF output.


-NCEP server:




7.Addition of a NDFD 5km CONUS domain (grid 197).


-NCEP server:


Current Product Output Removals:

1.All Eta and RSM members will be removed.

††† -NCEP server:

†† ††pgrb/sref_eta.tCCz.prgb???.???.fxx.grib2

†††† pgrb/sref_eta.tCCz.prgb???.???.grib2

†††† pgrb/sref_rsm.tCCz.prgb???.???.fxx.grib2

†††† pgrb/sref_rsm.tCCz.prgb???.???.grib2

†††† pgrb_biasc/sref_eta.tCCz.prgb212.???.grib2

†††† pgrb_biasc/sref_rsm.tCCz.prgb212.???.grib2

†††† bufr/eta_???.tCCz.bufrsnd.tar.gz

†††† bufr/eta_???.tCCz.class1.bufr.tm00

†††† bufr/rsm_???.tCCz.bufrsnd.tar.gz

†††† bufr/rsm_???.tCCz.class1.bufr.tm00

2.As part of this implementation, the NWS will remove the SREF

GEMPAK data sets from the NCEP server.


-NCEP servers:*


There will be a few changes in the SREF product data files. With

the addition of new levels/parameters, the order of placement

within each GRIB file may change. The products delivered over

NOAAPORT will not change in format or content. The products

disseminated via the NWS and NCEP servers will have some changes

in content with no expected delay of delivery time. Due to the

expected temporal changes, there will be a significant increase

in data volume. A slight increase in file size should be noted

for the bias corrected members and mean product.

These products are available at the following locations:


The following domains will be disseminated: CONUS grid 212,

Alaska grid 216 and Eastern North Pacific grid 243

NCEP server:

The following domains will be disseminated: CONUS grid 212,

Alaska grid 216, Eastern North Pacific grid 243, High Resolution

North America grid 221, North American grid 132 and NDFD CONUS

grid 197




NWS server:

The following domains will be disseminated: CONUS grid 212


where YYYYMMDD is the date and CC is the model cycle (03, 09,

15, 21)

Please reference NCEP's products information page for more detail

on current file outputs and format:


For more information on the generating process ID see:


A consistent parallel feed of data is currently available on the

NCEP ftp server which can be accessed via the following URLs:



The Environmental Modeling Center (EMC) Mesoscale Modeling Branch

(MMB) has a publicly available web site which can provide users

more information concerning the SREF modeling system as well as

other NCEP regional modeling systems:


All users should ensure their decoders are flexible and are able

to adequately handle changes in content, parameter fields

changing order, changes in the scaling factor component within

the Product Definition Section of the GRIB files and any volume

changes which may be forthcoming. These elements may change with

future NCEP model implementations. NCEP will make every attempt

to alert users to these changes prior to any implementations.

For questions regarding the scientific content of the modeling

system please contact:


†††† Geoff Dimego


†††† Camp Springs, Maryland 20746

†††† Phone: 301-763-8000 x 7221

†††† Email:


†††† Jun Du


†††† Camp Springs, Maryland 20746

†††† Phone: 301-763-8000 x 7593

†††† Email:



For questions regarding the dataflow aspects of these data sets

please contact:

†††† NCEP/NCO Dataflow Team

†††† Camp Springs, Maryland 20746

†††† Phone: 301-763-8000 x 7198

††† Email:



National NWS technical implementation notices are online at: