NOUS41 KWBC 191629



Technical Implementation Notice 14-27

NOAA’s National Ocean Service Headquarters Washington DC

Relayed by National Weather Service Washington DC

1230 AM EDT Thu Jun 19 2014


To:       Subscribers:

          -Family of Services

          -NOAA Weather Wire Service

          -Emergency Managers Weather Information Network


          Other NWS and NOS partners and employees


From:     Frank Aikman

          Chief, Marine Modeling and Analysis Programs

          NOS Office of Coast Survey     


Subject:  Implementation of New Extratropical Surge and

          Tide Operational Forecast System for the Pacific

          (ESTOFS Pacific) for the West Coast, Gulf of Alaska,

          and Hawaii, Effective June 24, 2014


Effective June 24, 2014, beginning at 1200Z Coordinated Universal

Time (UTC), 800 AM EDT, the Extratropical Surge and Tide

Operational Forecast System for the Pacific (ESTOFS Pacific) will

be implemented on the NOAA Weather and Climate Operational

Supercomputing System (WCOSS) operated by NCEP Central Operations

(NCO). ESTOFS Pacific will provide users with nowcasts (analyses

of near present conditions) and forecast guidance of water level

conditions for the West Coast, Gulf of Alaska, and Hawaii. The

forecast outputs will include water levels caused by the combined

effects of storm surge and tides, by astronomical tides alone,

and by sub-tidal water levels (isolated storm surge) out to 180



The hydrodynamic model employed by ESTOFS is the ADvanced

CIRCulation (ADCIRC) finite element model. ADCIRC was developed

to perform high resolution simulations of time-dependent, free

surface circulation and transport problems in two and three

dimensions. ESTOFS uses the Two-Dimensional Depth Integrated

(2DDI) version of ADCIRC, which computes the water surface

elevation and barotropic depth-averaged currents. ADCIRC uses the

finite element method in space, taking advantage of highly

flexible, irregularly spaced grids.


The unstructured grid used by ESTOFS Pacific consists of 132,630

nodes and 256,314 triangular elements. Coastal resolution

generally ranges between 1 and 3 km. 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 tidal elevation data from observation stations

located throughout the domain.


ESTOFS Pacific is designed to provide water surface elevations

caused by storm surge and astronomical tide to the NCEP WAVEWATCH

III (WW3) wave model for coupling wave and water level

predictions. Therefore, the ESTOFS set-up is designed to mimic

WW3: it uses the same Global Forecast System (GFS) atmospheric

forcing (ESTOFS applies 10 m wind speeds and sea level pressure

from GFS), has the same forecast cycle (4 times per day

concurrent with GFS), length (6 hour nowcast followed by a 180

hour forecast), and will run concurrently on the WCOSS.


ESTOFS output files are provided in two formats: structured GRIB2

files for the contiguous United States (2.5 km resolution) and

for Alaska (6 km resolution) and Hawaii (2.5 km resolution), and

unstructured NetCDF files on the native ESTOFS finite element

grid. NetCDF output is also provided at station locations. GRIB2

files are created for each hourly prediction during a forecast

cycle, consisting of records of combined water level (surge with

tide), harmonic tidal prediction (astronomical tides), and sub-

tidal water levels (the isolated surge). NetCDF files contain an

entire nowcast/forecast cycle, and consist of the hourly combined

water level over the native ESTOFS grid, or 6-minute combined

water level records at station locations.


Beginning June 24 at 1200Z UTC, operational forecast guidance

from ESTOFS Pacific will be available in the netCDF and GRIB2

files described above via the NCEP server at:


Operational ESTOFS GRIB2 output will also be disseminated via

NCEP’s NOAA Operational Model Archive and Distribution System

(NOMADS) server at


ESTOFS is monitored 24 x 7 by NCO. ESTOFS Pacific output is not

currently available via SBN or within AWIPS at this time.


For questions concerning these changes, please contact:


Dr. Jesse Feyen

Marine Modeling and Analysis Programs

Coast Survey Development Laboratory

NOAA/NOS/Office of Coast Survey

Silver Spring, MD


For questions regarding the dataflow aspects with respect to the

NCEP server at the WOC, please contact:


Rebecca Cosgrove

NCEP/NCO Dataflow Team

College Park, MD


National Technical Implementation Notices are online at: