NOUS41 KWBC 092012



Technical Implementation Notice 15-53

National Weather Service Headquarters Washington DC

412 PM EST Mon Nov 9 2015


To:      Subscribers:

         -Family of Services

         -NOAA Weather Wire Service

         -Emergency Managers Weather Information Network


         Other NWS Partners and Employees


From:    Tim McClung

         Portfolio Manager

         Office of Science and Technology Integration


Subject: RTMA and URMA Upgrade: Effective December 15, 2015


Effective on or about December 15, 2015, beginning with the 1300

Universal Coordinated Time (UTC) cycle, the National Centers for

Environmental Prediction (NCEP) will upgrade the Real-Time

Mesoscale Analysis (RTMA) and the Unrestricted Mesoscale

Analysis (URMA) to:


- Change model components

- Add new product fields

- Change product output


1) Model Component Changes


-Add a variational quality control for the observations to RTMA-


-Add an observation buddy-check for temperature to RTMA-Alaska -

-Relax the observation quality control for coastal mass

observations in RTMA-Hawaii

-Add a 3.0 km resolution URMA-Alaska system


The analysis runs hourly for 00z, 01Z, 02Z ... to 23Z. Compared

with the corresponding RTMA-Alaska, the analysis is initiated

with a 6-hour delay so that late arriving observations can also

be assimilated. For example, the 02Z URMA-Alaska analysis is

initiated at approximately 0835Z.


The new variational quality control helps reduce the intensity

of the bulls eyes that might occur in the analysis due the

assimilation of bad observations. Because of its relaxed

observation cutoff time, the new URMA-Alaska uses more

observations than the existing RTMA-Alaska, thus providing users

with a superior analysis for verification purposes.


- For hourly precipitation RTMA: uses Stage IV hourly as primary

source of precipitation RTMA, supplemented by Stage II hourly

when Stage IV is not available at the time precipitation RTMA is

made. At present, only Stage II hourly is used for the RTMA.

NCEP now receives hourly QPEs from some RFCs before the RTMA

cutoff time (33 minutes past the top of the hour), using these

QPEs will allow RTMA to benefit from local expertise as well as

at least some human oversight at RFCs.   


- For 6-hourly precipitation URMA: coverage inside of an RFC’s

domain proper will only come from that RFC (at present, if an

RFC’s input is late or missing, coverage from neighboring RFCs

is used). The WGRFC domain will be expanded to cover its area of

responsibility in Mexico. Areas outside of the RFC domains

(except for Gulf of Mexico and the Atlantic) will be set to no

data/missing. Coverage for the Great Lakes will come from

specific RFCs assigned to each Lake (at present the average of

all available coverage from nearby RFCs is used for the Great

Lakes). By only using data from specific RFCs responsible for

each given grid point in the mosaic, NCEP can ensure data

contributing to the mosaic are properly quality-controlled. The

only exception is for areas in the Gulf of Mexico and off the

Atlantic Coast, which are filled in with data from the

neighboring RFCs as before; these data are provided mainly for

visual interest (e.g., when there is a tropical cyclone passing

through), even though the coverage would not be of the same

quality as the areas that are within RFCs’ domains of



2) Addition of Variables


Files will be available on the NCEP ftp, http and NOMADS servers

via the following URLs (YYYYMMDD is the year, month, day):





- Daytime maximum temperature (TMAX) analysis, and overnight

minimum temperature (TMIN) analysis, along with the

corresponding fields of the analysis uncertainty to the URMA-

CONUS GRIB2. The new fields have a nominal spatial resolution of

2.5 km and are produced once a day. The current day 8Z analysis

creates the TMAX analysis for the previous day, while the

current day 20Z analysis creates the TMIN analysis for the

current day.


- Maximum Temperature (TMAX) analysis will be added to:




- Maximum Temperature (TMAX) analysis uncertainty will be added





- Minimum Temperature (TMIN) analysis will be added to:




- Minimum Temperature (TMIN) analysis uncertainty will be added






NCEP is adding the following 3.0 km resolution analysis fields

and corresponding analysis uncertainty fields from the new URMA-

Alaska system:


- 2-m temperature,

- 2-m specific humidity

- 2-m dew point

- 10-m wind speed

- 10-m wind direction

- 10-m wind gust

- surface pressure

- surface visibility

- maximum temperature (TMAX)

- minimum temperature (TMIN)


These fields are produced hourly for 00z, 01Z, 02Z, ... , and

23Z,  except for TMAX and TMIN, which are produced once a day

each. The current day 8Z analysis creates the TMAX analysis for

the previous day, while the current day 20Z analysis creates the

TMIN analysis for the current day.


The URMA-Alaska GRIB2 files containing these fields will be

available on the NCEP ftp, http and NOMADS servers as follows:


akurma.tCCz.2dvaranl_ndfd_3p0.grb2  (for analysis)

akurma.tCCz.2dvarerr_ndfd_3p0.grb2  (for analysis uncertainty)


3) Product output changes


The radius of the Earth used for the GRIB2 encoding of the

RTMA and URMA output files is changing from 6,371,229.0 m to

6.371,200.0 m, which is the value used by the National Digital

Forecast Database and AWIPS. 


4) Additional airport temperature data


RTMA temperature data will be interpolated at an additional 

141 airports (all in Alaska) to serve as a real-time observation

where an observation is unavailable. This action will change the

order of text. Use of the RTMA is expected to help mitigate the

problem of flight delays, diversions, and cancellations caused

by the lack of a temperature report. Interpolated temperature

data at airports across CONUS, Hawaii, Puerto Rico and Guam will

continue to be available. Users can download the hourly text

product, alphabetized by the airport 3 or 4 character code, on

the NCEP server at:


5) Sample Parallel Data will be available on the NCEP HTTP

server in early-November. The parallel data will be available

via the following URLs:


Information about the precipitation RTMA/URMA, with links to

parallel run data directories if available at:


For questions regarding these changes, please contact:


Geoff DiMego

NCEP/EMC Mesoscale Modeling Branch

College Park, Maryland



For questions regarding the data flow aspects of these data

sets, please contact:


Carissa Klemmer

NCEP/NCO Dataflow Team

College Park, Maryland



NWS National Technical Implementation Notices are online at: