NOUS41 KWBC 181150



Service Change Notice 17-94

National Weather Service Headquarters Silver Spring, MD

750 AM EDT Fri Aug 18 2017


To:        Subscribers:

           -NOAA Weather Wire Service

           -Emergency Managers Weather Information Network


           Other NWS Partners, Users and Employees


From:      Dave Myrick

           NWS Office of Science and Technology Integration


Subject:   Update NWM Processing of Streamflow Observations

           Effective August 22, 2017


Effective on or about August 22, 2017, beginning with the 1300

Coordinated Universal Time (UTC), the National Centers for

Environmental Prediction (NCEP) will update the National Water

Model (NWM) data pre-processing scripts to address an issue

impacting the model's use of USGS streamflow observations. 


Currently, the NWM system only searches in the current day's

directory for streamflow observations to assimilate. With this

change, the model will now ingest observations up to 3 hours

into the previous day (as originally intended).  The change will

increase the accuracy of NWM analysis cycle streamflow near

observation locations, especially within the 00 UTC cycle.


Users will see the output changes in the following files on the

NCEP Web services:


Where YYYYMMDD is year, month and day


The change only impacts the following channel-type output files

(other file types remaining unchanged):






Questions, comments or requests regarding this change should be

directed to the contacts below.  We will review any feedback and

decide whether to proceed.


For questions regarding these changes, please contact:


     Brian Cosgrove

     OWP/Analysis and Prediction Division

     Silver Spring, MD


     Carissa Klemmer

     NWS/NCEP Central Operations

     Dataflow Team Lead

     College Park, MD


NWS Service Change Notices are online at: