NOUS41 KWBC 201925



Service Change Notice 16-42

National Weather Service Headquarters Washington DC

925 AM EDT Tue Sep 20 2016


To:      Subscribers:

         -NOAA Weather Wire Service

         -Emergency Managers Weather Information Network


         Other NWS partners and employees


From:    Mary Mullusky

         Chief, Water Resources Services Branch


Subject: Upgrade to the Automated Flood Warning System (AFWS)

         Website on or after October 12, 2016


The AFWS website currently enables users east of the Mississippi

River to view point precipitation as a percent of county-based

flash flood guidance (FFG). The AFWS website, at


color codes the precipitation as a percentage of FFG as follows:


-Less than 70% of FFG: green

-Greater than or equal to 70% but less than 90% of FFG: yellow

-Greater than or equal to 90% of FFG: red 


Effective on or after Wednesday, October 12, 2016, AFWS website

users will be able to view point precipitation as a percent of

Gridded FFG. Gridded FFG provides analysis information at

approximately a 4km x 4km scale, which is more consistent with

flash floods. Transitioning from county-based FFG to gridded FFG

provides more specific information at these precipitation points.


For more information, please contact:

Daniel Roman

1325 East-West Highway

Silver Spring, MD  20910



National Service Change Notices are online at: