NOUS41 KWBC 051145



Technical Implementation Notice 16-21

National Weather Service Headquarters Washington DC

745 AM EDT Mon Jul 5 2016


To:        Subscribers:

           -NOAA Weather Wire Service

           -Emergency Managers Weather Information Network


           Other NWS Partners, Users and Employees


From:      Paul Iwugo

           Chief, Software Development Branch

           NCEP Central Operations


Subject:   Model Analysis and Guidance Website imagery product

           URL path change on or about August 6, 2016


In an effort to improve performance of the Model Analysis and

Guidance (MAG) website during periods of high end-user demand,

the National Centers for Environmental Prediction (NCEP) will be

updating the Uniform Resource Locator (URL) of certain graphic



On or about August 6, 2016, the Global Forecast System (GFS)

model directory for each cycle will be subdivided into multiple

directory levels. This change affects our customers who access

graphic products by using a direct URL address and not those

using the MAG website user interface. Two additional directory

levels have been added for area and parameter name.


Currently, the URL for a GFS image file is:<cycle>/<filename>


After August 6, 2016, the new GFS URL will be:<cycle>/<area>/<parameter>



where cycle=00,06,12,18


The area and parameter name fields are the choices made through

the MAG web interface to navigate to and display the image and

are also used in the filename of the product. The GFS filenames

follow this pattern:


gfs_<area>_<forecast hour>_<parameter>[<size>].gif


where the optional size = _l or _s, and indicates a large or

small image, if available.


This URL change also applies to images accessed using the date

in the URL path. Currently, a URL that includes the date

directory level for a GFS image file is:<date>/<cycle>/<filename>


After August 6, 2016, the new GFS URL will be:<date>/<cycle>/<area>/<par



where cycle=00,06,12,18 and date=yyyymmdd



For questions regarding these changes, please contact:


    Tiros Lee

    NCEP/NCO Software Development Branch

    College Park, Maryland


NWS National Technical Implementation Notices are online at: