[nws-changes] 20110930: Exp ice accumulation grids for NDFD

NOUS41 KWBC 301400


Public Information Statement

National Weather Service Headquarters Washington DC

953 AM EDT Fri Sep 30 2011


- Family of Services

- NOAA Weather Wire Service

- Emergency Managers Weather Information Network


Other NWS Partners and NWS Employees

From:Eli Jacks

Chief, Fire and Public Weather Services Branch

Subject:Experimental Ice Accumulation Grids to be Added

tothe National Digital Forecast Database (NDFD),

forCONUS Only Effective October 12, 2011

Effective Wednesday, October 12, 2011, at 1400 Coordinated Universal Time (UTC), Ice Accumulation grids will be added to NDFD on an experimental basis at a number of NWS Weather Forecast Offices (WFOs) over the Conterminous United States (CONUS) only. The WFOs issuing these grids are shown in the Product Description Document (PDD) available online at:


The experimental Ice Accumulation grids are the expected average ice thickness on all exposed surfaces (in hundredths of inches) during a 6 hour period. An Ice Accumulation grid will be specified whenever at least a trace of ice accumulation is forecast for any hour during a valid period. The Ice Accumulation grids will be added to the NDFD CONUS sector and to the 16 pre-defined NDFD CONUS subsectors for each6-hour period out to 48 hours from 00 UTC Day 1.

More details regarding these new elements are available in the PDD in the online catalog of experimental NWS products and services at:


With this implementation, these forecasts will be available from NDFD in the standard methods:

- GRIdded Binary version 2 (GRIB2) files via Hypertext Transfer

Protocol (HTTP) and File Transfer Protocol (FTP)

- eXtensible Markup Language (XML) via Simple Object Access

Protocol (SOAP) and Representational State Transfer (REST)

- Graphics via web browser

Users who pull NDFD elements in GRIB2 format, either via the Internet or via the Family of Services server access service may need to update their procedures and scripts to access these new elements.

For customers who key on the World Meteorological Organization super heading to access NDFD elements, the super headings for the experimental Ice Accumulation grids are:

Geographic AreaWMO Header


Central Great LakesYZFZ98 KWBN

Central Mississippi ValleyYZHZ98 KWBN

Central PlainsYZKZ98 KWBN

Central RockiesYZNZ98 KWBN


Eastern Great LakesYZEZ98 KWBN

Mid-AtlanticYZCZ98 KWBN

NortheastYZBZ98 KWBN

Northern PlainsYZJZ98 KWBN

Northern RockiesYZMZ98 KWBN

Pacific NorthwestYZPZ98 KWBN

Pacific SouthwestYZQZ98 KWBN

SoutheastYZDZ98 KWBN

Southern Mississippi ValleyYZIZ98 KWBN

Southern PlainsYZLZ98 KWBN

Southern RockiesYZOZ98 KWBN

Upper Mississippi ValleyYZGZ98 KWBN

Customers who use the NDFD in XML via Web service or the online graphical NDFD images can use the same methods they currently use to acquire these new experimental elements.The NDFD Ice Accumulation graphics will be labeled experimental.

General information on accessing and using NDFD elements is available online at:


If October 12, 2011 is declared a critical weather day, this implementation may be postponed.In that case, partners and users will be notified of that decision via an updated Public Information Statement as far in advance as possible.

Comments and feedback on the experimental NDFD Ice Accumulation grids will be accepted through May 1, 2012.Links to online surveys for NDFD customers are:

- GRIB2 users:

http://www.weather.gov/survey/nws-survey.php?code=ndfd-grids <http://www.weather.gov/survey/nws-survey.php?code=ndfd-grids>

- Users OF XML SOAP service:


- NDFD online graphics:


These new Ice Accumulation grids will remain experimental until all feedback is assessed and a technical analysis is completed.At that time, the NWS will determine whether to transition these experimental elements to operational status, discontinue them, or revise and retain them as experimental elements.

For general questions regarding NDFD data, please email:

NWS.NDFD@xxxxxxxx <mailto:NWS.NDFD@xxxxxxxx>

For technical questions regarding NDFD data, please contact:

David Ruth

Chief, Mesoscale Prediction Branch

NOAA/NWS Office of Science and Technology

Silver Spring, Maryland 20910

David.Ruth@xxxxxxxx <mailto:David.Ruth@xxxxxxxx>

For general questions regarding the Ice Accumulation grids or this PNS, please contact:

Andy Horvitz

Fire and Public Weather Services Branch

NOAA/NWS Office of Climate Water and Weather Services

Silver Spring, Maryland 20910

Andy.Horvitz@xxxxxxxx <mailto:Andy.Horvitz@xxxxxxxx>

National Public Information Notices are online at: