NOUS41 KWBC 271900
PNSWSH
Technical Implementation Notice 11-36
National
Weather Service Headquarters Washington DC
300 PM
EDT Wed Jul 27 2011
To: Subscribers:
-Family of Services
-NOAA Weather Wire Service
-Emergency Managers Weather
Information Network
-NOAAPORT
Other NWS Partners, Users and
Employees
From: Tim McClung
Chief, Science Plans Brach
Office of Science and Technology
Subject: Notice of Intent to Replace Rapid Update
Cycle (RUC)
Model: Effective Fall 2011
Sometime
after mid-October 2011, the National Centers for Environmental Prediction plans
to replace the current Rapid Update Cycle (RUC) modeling system with the Rapid
Refresh (RR) modeling system. More specifics, including an implementation date,
will be sent in the next two months.
Brief
Description of Changes:
-Change
of name of system from Rapid Update Cycle (RUC) to
Rapid Refresh (RR)
-Replace
RUC prediction model with WRF using ARW dynamic core
-Replace
RUC 3-D variational analysis (3DVAR) with the
Gridpoint
Statistical Interpolation (GSI)
-Expand
domain to cover Alaska and Caribbean basin
The
transition of the Rapid Update Cycle into use of the WRF model has been planned for more than 6 years. The Rapid Refresh configuration allows
the system to take advantage of the community development of the WRF model and
GSI data assimilation, used in other NCEP systems including NAM and GFS, while
maintaining many of the elements of the RUC crucial to aviation and severe
weather forecasting, such as the diabatic digital filter
initialization, the assimilation of radar reflectivity data, and the analysis
of cloud hydrometeors using METAR and
satellite data. The Rapid Refresh domain
extends hourly “rapid updating” to all of North America, including
A full
description of the changes can be found on the Earth Sciences Research Laboratory’s
web page for the Rapid Refresh:
Please
note that the experimental 3-km High-Resolution Rapid Refresh (HRRR) is not part of this
implementation.
Model
products:
Most
of the output currently available from the RUC will be available for the Rapid
Refresh to ensure a smooth transition to the new system. This output includes:
- 13,
20, and 40-km Lambert Conformal grid data covering the
CONUS
region with output on pressure levels
- 13,
20, and 40-km Lambert Conformal grid data covering the
CONUS
region with output on native levels
- BUFR
model station time series output (with an expanded list
of stations to accompany the larger domain)
New
data will include:
- Full-domain
output on a 32-km Lambert Conformal grid, the only
grid on which data covering the entire domain will be
generated)
- Alaska
data on an 11-km polar-stereographic grid
Data
that will no longer be available are 80-km Lambert Conformal grid data covering
the CONUS region
A
parallel version of the RR is being run at the Environmental Modeling Center
each hour with statistics being computed daily. Forecast graphics are available at
http://www.emc.ncep.noaa.gov/mmb/gmanikin/rap/para
Formal
evaluation will begin in the fall of 2011, with data files available from NCEP
Central Operations, which will be running the system in a real-time dedicated
parallel. The location of this parallel
test data will be sent in a follow-on notification. Users who wish to get a
head start on their evaluation of test files to prepare for the transition can
obtain them from the EMC parallel at:
ftp://ftp.emc.ncep.noaa.gov/mmb/mmbpll/rap
NCEP
would encourage users to ensure their decoders are flexible and are able to
adequately handle changes in content order, parameter fields changing order,
changes in the scaling factor component within the Product Definition Section
(PDS) of the GRIB files and also 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 implementation.
For
questions regarding these changes, please contact:
Geoffrey Manikin
NCEP/EMC Global Modeling Branch
301-763-8000 x7263
or
Stan Benjamin
NOAA/ESRL
303-497-6387
stan.benjamin@noaa.gov
NWS
National Technical Implementation Notices are online at:
http://www.nws.noaa.gov/os/notif.htm
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