NOUS41 KWBC 061115



Service Change Notice 17-26

National Weather Service Headquarters Silver Spring MD

715 AM EDT Mon Mar 6 2017


To:        Subscribers:

           - NOAA Weather Wire Service

           - Emergency Managers Weather Information Network

           - NOAAPORT

           Other NWS Partners and NWS Employees


From:      Dave Myrick

           NWS Office of Science and Technology Integration


Subject:   Probabilistic Tropical Cyclone Storm Surge (P-Surge)

           Model Upgrades Effective April 11, 2017


Effective on or about April 11, 2017, starting with the 1200

Coordinated Universal Time (UTC) cycle, the National Centers for

Environmental Prediction (NCEP) will upgrade the Probabilistic

Hurricane Storm Surge model (P-Surge) from version 2.5 to

version 2.6. 


P-Surge is run on demand when hurricane watches and/or warnings

are in effect for the Atlantic and Gulf Coasts of the

continental United States and on a case-by-case basis for

tropical storms. The model is based on an ensemble of Sea, Lake,

and Overland Surge from Hurricane (SLOSH) model runs. The

ensemble members are forced by storms derived from the National

Hurricane Center (NHC) official advisory along with historic

errors in its track, size and intensity. 


P-Surge version 2.6 includes the following updates:


- Extend the forecast hours from 78 to 102 hours on web services


- Allow the NHC to add new storm types: Sub-Tropical Storm, Sub-

Tropical Depression, Potential Tropical Cyclone and Post

Tropical Cyclone


- Update the South Florida basin area: Five historic operational

basins were replaced with a single South Florida basin with

higher resolution and the latest bathymetry/topography

information. Unfortunately, run-time issues required it to be

split into three parts. Future upgrades will address using the

single basin.


- Remove products on NCEP servers and add to National Digital

Guidance Database (NDGD).


Web Product Changes:


1. Extend forecasts hours to 102 on the NDGD Web service:


The following exceedance GRIB2 products (on a CONUS 625 m

resolution grid corresponding to the National Digital Forecast

Database CONUS 2.5 km resolution grid) defined as the surge +

tide height in feet that X% of storms exceed.


   * Exceedance above ground level (incremental grouping): 10,

20, 30, 40, 50% for 0-6, 6-12, 12-18... 84-90, 90-96, 96-102


     File: VD.agl/ds.psurgeexcdPPinc.bin


   * Exceedance above ground level (cumulative grouping): 10,

20, 30, 40, 50% for 0-6, 0-12, 0-18... 0-90, 0-96, 0-102 hours

     File: VD.agl/ds.psurgeexcdPPcum.bin


   * Exceedance above NAVD-88 (cumulative grouping): 10, 20, 30,

40, 50, 60, 70, 80, 90% for 0-80 and 0-102 hours

     File: ds.psurgeexcdPP.bin


   Where PP is the respective percentage of exceedance


The following probability GRIB2 products (on the same CONUS 

625 m resolution grid) defined as the probability that X feet of

surge + tide will be exceeded in a cell.


   * Probabilities of > 0, 1, 2,...  20 feet above ground level

(incremental grouping) for 0-6, 6-12, 12-18, ... 84-90, 90-96,

96-102 hours

     File: VD.agl/ds.psurgeabvPPinc.bin


   * Probabilities of > 0, 1, 2... 20 feet above ground level

(cumulative grouping) for 0-6, 0-12, 0-18... 0-90, 0-96, 0-102


     File: VD.agl/ds.psurgeabvPPcum.bin


   * Probabilities of > 2, 3, 4... 25 feet above NAVD-88

(cumulative grouping) for 0-80 hours and 0-102 hours

     File: ds.psurgeabvPP.bin


   Where PP is the respective probability


2. Add the 10, 20, 30, 40, 50% exceedance above NAVD-88 hourly

incremental groupings (e.g. 0-1, 1-2, 2-3 ... 99-100, 100-101,

101-102 hours) GRIB2 products (on the same CONUS 625 m

resolution grid) to the NDGD Web service     File:



   Where PP is the respective percentage of exceedance


3. Remove all P-Surge output from NCEP web services


Users can find all products for P-Surge under the NDGD web




   Where YYYYMMDD is Year, Month, and Day





There are no changes to any NOAAPORT/SBN products. For a

complete list of existing product WMO Headers please reference:


A sample set of parallel data is available on the NCEP server

via the following URLs:


Graphical versions as well as ESRI shape files of the products

will be posted online at:


NCEP urges all users to ensure their decoders can handle changes

in content order, changes in the scaling factor component within

the product definition section (PDS) of the GRIB files, and

volume changes. These elements may change with future NCEP model

implementations. NCEP will make every attempt to alert users to

these changes before implementation.


Any questions, comments or requests regarding this

implementation should be directed to the contacts below.  We

will review any feedback and decide whether to proceed.


For questions regarding this notice, please contact


      Arthur Taylor

      NWS Meteorological Development Laboratory

      Silver Spring, Maryland 20910

      Telephone: 301-427-9444



      Tatiana Gonzalez

      NWS Decision Support Branch

      Silver Spring Maryland 20910

      Telephone: 301-427-9500



National Service Change Notices are online at: