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000
NOUS41 KWBC 031550
PNSWSH

Service Change Notification 24-36
National Weather Service Headquarters Silver Spring MD
1150 AM EDT Wed Apr 3 2024

To:  Subscribers
  -NOAA Weather Wire Service
  -Emergency Managers Weather Information Network
  -NOAAPORT
  Other NWS Partners, Users and Employees

From:  Patrick T. Marsh
  Chief, Science and Support
  NWS/Storm Prediction Center

Subject:  Upgrade to SPC Post Processing for NCEP Models,
  Effective May 7, 2024

On or about May 7, 2024, beginning with the 1200 Universal
Coordinated
Time (UTC) model run, the National Centers for Environmental
Prediction
(NCEP) will upgrade SPC_POST, SPC’s postprocessing package for the
NCEP
model suite, to v2.0.

In the event that the implementation date is declared a Critical
Weather
Day (CWD), an Enhanced Caution Event (ECE), or other significant
weather
is occurring or is anticipated to occur, implementation of this
change
will take place at 1200 UTC on the next weekday not declared a CWD
and
when no significant weather is occurring.

In preparation for the retirement of the Short-Range Ensemble
Forecast
(SREF) system, HREF/GEFS calibrated severe guidance is generated
using
storm information from the High-Resolution Ensemble Forecast (HREF)
system
and environment information from the Global Ensemble Forecast System
(GEFS). HREF/GEFS provides hazard-specific calibrated severe guidance
for
4-hour periods through day 2 and for full periods for day 1 (both 00Z
and
12Z runs) and day 2 (12Z runs only). The file name convention for
these
files is

severe/spc_post.tCCz.href_cal_gefs_HAZ_ENV.ACChr.fFFF.grib2

where CC is the HREF cycle (00 or 12), HAZ is the hazard (either
“tor”,
“wind”, or “hail”), ENV is the initialization hour for the
GEFS run used
for the environment data (00, 06, 12, or 18), ACC is the accumulation
length (either 4 or 24) and FFF is the 3-digit forecast hour.

This version of SPC_POST continues the HREF Calibrated Thunder
(HREFCT)
and HREF/SREF products from the previous version of SPC_POST and adds
several capabilities. The only change to existing output of HREFCT is
to
the file names to follow established conventions. The file names on
the
NOAA Operational Model Archive and Distribution Service (NOMADS) and
FTPPRD (see below for the URLs) change as follows:

thunder/hrefct.tCCz.thunder_1hr.fFFF.grib2 =>
thunder/spc_post.tCCz.hrefct_1hr.fFFF.grib2
thunder/hrefct.tCCz.thunder_4hr.fFFF.grib2 =>
thunder/spc_post.tCCz.hrefct_4hr.fFFF.grib2
thunder/hrefct.tCCz.thunder_full.fFFF.grib2 =>
thunder/spc_post.tCCz.hrefct_full.fFFF.grib2


Finally, this upgrade also adds GEFS-MLP, machine-learning based
severe
weather guidance through day 8 based on the GEFS. The algorithm is a
random-forest method originally developed by researchers at Colorado
State
University. GEFS-MLP provides probabilistic individual hazard
guidance
through day 3 and probabilistic total severe guidance on days 3-8.
The
file naming convention is as follows:

gefs_mlp/spc_post.tCCz.gefsmlp_HAZ_SIG.fFFF.grib2

where CC is the cycle (00 or 12), HAZ is the hazard (either
“tor”, “wind”,
“hail”, or “severe”), SIG is either “std” for any severe
or “sig” for
significant severe, and FFF is the 3-digit forecast hour.


A consistent parallel feed of data will be available on the NCEP
parallel
NOMADS site beginning at least 30 days prior to implementation at the
following location:

https://nomads.ncep.noaa.gov/pub/data/nccf/com/spc_post/para/
https://www.ftp.ncep.noaa.gov/data/nccf/com/spc_post/para/
tp://ftp.ncep.noaa.gov/pub/data/nccf/com/spc_post/para/

New and existing data files for SPC_POST will remain at their current
location on the NOMADS/FTPPRD web services at:

https://nomads.ncep.noaa.gov/pub/data/nccf/com/spc_post/prod/
https://www.ftp.ncep.noaa.gov/data/nccf/com/spc_post/prod/
ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/spc_post/prod/

For questions regarding this change, please contact:

Tim Supinie
NWS/Storm Prediction Center, Norman, OK
tim.supinie@noaa.gov

For questions regarding the data flow, please contact:

Tony Salemi
NCEP/NCO Implementation and Data Services Branch
College Park, MD
301-683-0567
Email: ncep.pmb.dataflow@noaa.gov




National Service Change Notices are online at:

http://www.weather.gov/notification