NOUS41 KWBC 101555 AAA



Service Change Notice 17-26 Updated

National Weather Service Headquarters Silver Spring MD

1155 AM EDT Mon Apr 10 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: Update: Probabilistic Tropical Cyclone Storm Surge

         (P-Surge) Model Upgrades: Effective April 18, 2017


Updated the implementation date from April 11, 2017, to 

April 18, 2017


Effective on or about April 18, 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.


- Product removals on NCEP servers and additions to NDGD.



Web Product Changes:


1. Forecasts hours are being extended to 102 on the National

Digital Guidance Database (NDGD) Web service:


The following exceedance GRIB2 products (on a CONUS 625 m

resolution grid corresponding to the National Digital Forecast

Database’s 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 hours

     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. Addition of 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 instead find all products for P-Surge under the NDGD

web services.



   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

      National Weather Service

      Meteorological Development Laboratory

      1325 East West Highway

      Silver Spring, Maryland 20910

      Telephone: 301-427-9444



      Tatiana Gonzalez

      National Weather Service

      Decision Support Branch

      1325 East West Highway

      Silver Spring Maryland 20910

      Telephone: 301-427-9500



National Service Change Notices are online at: