NOUS41 KWBC 091340



Technical Implementation Notice 15-52

National Weather Service Headquarters Washington DC

940 AM EDT Mon Nov 9 2015


To:       Subscribers:

          -Family of Services

          -NOAA Weather Wire Service

          -Emergency Managers Weather Information Network


          -Other NWS Partners, Users and Employees


From:     Tim McClung

          Portfolio Manager

          Office of Science and Technology Integration


Subject:  Changes to 2.5-km GFS-based Gridded MOS guidance for

          the CONUS effective December 15, 2015


On or about Tuesday, December 15, 2015, beginning with the 1200

Coordinated Universal Time (UTC) model run, the NWS

Meteorological Development Laboratory (MDL) will implement a

minor change to the 2.5-km Global Forecast System (GFS)-based

Gridded MOS guidance over the continental U.S. During a previous

MOS upgrade in January 2015, a bug was introduced which caused

all mesonet stations to drop out of the analysis for temperature

and wind elements. This bug resulted in a noticeable degradation

of the Gridded MOS guidance especially in areas of terrain over

the western U.S. 


This update will reincorporate between 450-600 mesonet stations

(depending on season) into the Gridded MOS analysis dropped in

the January upgrade, resulting in improved terrain detail and

overall improved quality of the guidance. Additional mesonet

stations will be introduced into the analysis in a future

upgrade after retuning efforts are completed.   


Beginning approximately 1 month prior to the implementation

date, users may find parallel data for download on NOAA's

Parallel Operational Model Archive and Distribution System

(NOMADS) at the following link:


For questions regarding the changes to GFS-based Gridded MOS

guidance for the CONUS please contact:


  Phil Shafer

  MDL/Silver Spring, Maryland



  Matthew Peroutka

  MDL/Silver Spring, Maryland



For questions regarding the data flow, please contact:


  Carissa Klemmer

  NCEP Central Operations



A Web page outlining the gridded MOS guidance can be found at:


Links to MOS products and descriptions are online at:


NWS national Technical Implementation Notices are online at: