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NOUS41 KWBC 301820 AAA

Service Change Notice 17-34 Updated
National Weather Service Headquarters Silver Spring, MD
220 PM EDT Thu Mar 30 2017

To:  Subscribers:
  -NOAA Weather Wire Service
  -Emergency Managers Weather Information Network
  Other NWS Partners and Employees

From:  Dave Myrick
  NWS Office of Science and Technology Integration

Subject:  Update: Extratropical Surge and Tide Operational
  Forecast System for the Atlantic and Gulf Coasts
  (ESTOFS Atlantic) Update: Effective April 25, 2017

Updated to include timeliness changes to NOAAPORT and Web

Effective April 25, 2017, beginning with 1200 Coordinated
Universal Time (UTC) run, the National Centers for Environmental
Prediction (NCEP) will upgrade the Extratropical Surge and Tide
Operational Forecast System (ESTOFS) as follows:

  - Increase grid resolution
  - Update open ocean boundary forcing
  - Change GFS components
  - Add Standard Hydrologic Exchange Format (SHEF) output
  - Make changes to directory on NCEP web services
  - Add timeliness delays for all output

1) Output changes

With this upgrade, the following changes will be noted on the
NCEP web services:

Directory Changes:
from - estofs/prod/estofs.YYYYMMDD
to   - estofs/prod/estofs_atl.YYYYMMDD
 Where YYYYMMDD is year, month and day.

Resolution changes:
The increased unstructured grid consists of 1.8 million nodes,
which increases coastal grid resolution from 3 km to 200 m and
extends inland to approximately the 10 m topographic contour
relative to the North American Vertical Datum of 1988 (NAVD88).
The increased resolution will impact the following file:

Addition of SHEF output:
Additional SHEF E format output at each CO-OPS observation
station will be made available. SHEF files contains 30-minute
combined water level (surges with tides), harmonic tidal
prediction (astronomical tides), and sub-tidal water levels (the
isolated surges). The files will be named:

Timeliness changes:
All netcdf files will be delayed up to 10 minutes from current
production output times. All GRIB2 files will be delayed up to
20 minutes from current production output times.

2) Update open ocean boundary forcing
Update open ocean boundary from TPXO7.2 to TPXO8-ATLAS. Harmonic
tidal constituents from the global tidal model TPXO8-ATLAS are
used to specify tidal water surface fluctuations at the open
ocean boundary, while tidal potential forcing is applied within
the interior of the domain. The performance of this grid for
astronomical tides was verified using published harmonic
constants from National Ocean Service/Center for Operational
Oceanographic Products and Services observation stations located
throughout the domain.

3) GFS grid resolution from 55 km to 13 km
With this upgrade the ESTOFS Atlantic will begin using the
increased Semi-Lagrangian T1534 (~13 km) GFS horizontal
resolution from Lat/Lon 0.5 deg (~55 km).

MDL will deliver output on the website at the observation
stations that provide ETSS predictions:

The Ocean Prediction Center of NWS will deliver graphics of the
model outputs on the following site:

There are no changes to any NOAAPORT/SBN products with this
upgrade. There are, however, timeliness changes up to 15 minutes
later to data distributed over NOAAPORT.

A consistent parallel feed of data is available on the NCEP HTTP
site at the following URL:

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.

For questions concerning science changes, please contact:

Dr. Edward P. Myers
Coastal Marine Modeling Branch
Coast Survey Development Laboratory
NOAA/NOS/Office of Coast Survey
Silver Spring, MD

For questions regarding the data aspects, please contact:

Carissa Klemmer
NCEP/NCO Dataflow Team Lead
College Park, MD

National Service Change Notices are online at: is the U.S. government's official web portal to all federal, state and local government web resources and services.