P-ETSS v1.5 proposal adds blended GFS/GEFS surge guidance and more GRIB2 delivery

NOAA/NWS issued PNS 26-32 on April 17, 2026, soliciting comments through May 17, 2026 on proposed P-ETSS v1.5 changes for the 2026-2027 winter season.

P-ETSS is the Probabilistic Extra-Tropical Storm Surge model. The proposal is relevant to GribStream because it uses GFS and GEFS as part of the proposed forcing blend, and because NOAA explicitly discusses GRIB2 dissemination for Puerto Rico and the U.S. Virgin Islands.

Main proposed changes

The proposal includes several domain and method changes:

• replace five south Florida computational domains with two higher-resolution domains from Cape Canaveral to Fort Myers
• upgrade the Puerto Rico domain from roughly 1.5 km near San Juan to about 650 m
• expand the station uncertainty range by adjusting the 10% and 90% exceedance levels using recent anomaly information
• add an initial blended storm-surge capability
• add SHEF output above Mean Higher High Water (MHHW) in addition to current Mean Lower Low Water (MLLW) output
• discontinue the 2.5 km CONUS gridded output because NOAA says the same data are available on higher-resolution 625 m CONUS grids

The proposed blended surge method averages hydrodynamic-model results forced by:

• GFS
• the GEFS control member
• the Canadian GEPS control member

That is the key model-input change.

GRIB2 and station-output changes

NOAA says it already generates Puerto Rico and U.S. Virgin Islands GRIB2 products, but those products are currently available only through NOMADS. P-ETSS v1.5 would also disseminate the Puerto Rico/USVI gridded GRIB2 products over the Satellite Broadcast Network (SBN), along with station products in SHEF format.

The proposal also adds or updates station support:

• one new station for Puerto Rico/USVI
• one new station for Alaska
• SHEF support for additional Puerto Rico/USVI and Alaska stations
• improved tidal constituents for 14 stations
• datum updates for 10 stations
• additional observation stations along the East Coast, with the final number still in flux

NOAA also proposes discontinuing older model-specific GFS-forced ETSS station text files. Those storm-surge-only station files are superseded by SHEF files and CSV files on NOMADS.

What this means for GribStream users

GribStream supports GFS and GEFS Atmosphere. P-ETSS is not currently a GribStream dataset, but this proposal matters because its new blended surge guidance depends partly on those model families.

It also fits the future NOMADS-GRIB direction: Puerto Rico/USVI P-ETSS gridded output is explicitly described as GRIB2, currently available via NOMADS. There is no GribStream support date to announce, but P-ETSS is the kind of NOMADS GRIB product family worth tracking for coastal-risk workflows.

If NOAA proceeds, a final Service Change Notice should be issued at least 30 days before implementation.

Sources

• NWS PNS 26-32, "Proposed Changes to the Probabilistic Extra-Tropical Storm Surge (P-ETSS) Model" (Apr 17, 2026): https://www.weather.gov/media/notification/pdf_2026/pns26-32_P-ETSS_v1.5.pdf
• NWS notification index: https://www.weather.gov/notification/