920
NOUS41 KWBC 171500
PNSWSH
PUBLIC INFORMATION STATEMENT 26-32
NATIONAL WEATHER SERVICE HEADQUARTERS SILVER SPRING MD
1100 AM EDT FRI APR 17 2026
TO: SUBSCRIBERS:
-NOAA WEATHER WIRE SERVICE
-EMERGENCY MANAGERS WEATHER INFORMATION NETWORK
-NOAAPORT
OTHER NWS PARTNERS, USERS AND EMPLOYEES
FROM: MARK WILLIS
CHIEF, WEATHER INFORMATION APPLICATIONS DIVISION
METEOROLOGICAL DEVELOPMENT LABORATORY
NWS OFFICE OF SCIENCE AND TECHNOLOGY INTEGRATION
SUBJECT: SOLICITING COMMENTS ON PROPOSED CHANGES TO THE
PROBABILISTIC EXTRA-TROPICAL STORM SURGE (P-ETSS) MODEL THROUGH
MAY 17, 2026
THE NWS METEOROLOGICAL DEVELOPMENT LABORATORY (MDL) IS PROPOSING
TO UPGRADE THE PROBABILISTIC EXTRA-TROPICAL STORM SURGE (P-ETSS)
MODEL FOR THE 2026-2027 WINTER SEASON.NWS IS SEEKING COMMENTS
ON THE PROPOSED CHANGES THROUGH MAY 17, 2026. IF APPROVED, A
SERVICE CHANGE NOTICE (SCN) WILL BE ISSUED AT LEAST 30 DAYS
PRIOR TO THE IMPLEMENTATION OF THESE CHANGES WITH MORE DETAILED
INFORMATION.
THE PROPOSED CHANGES TO P-ETSS INCLUDE:
A. REPLACE FIVE (5) COMPUTATIONAL DOMAINS FOR SOUTH FL
COVERING FROM CAPE CANAVERAL TO FORT MYERS WITH TWO (2) HIGHER
RESOLUTION COMPUTATIONAL DOMAINS. THIS WILL IMPROVE THE SPATIAL
RESOLUTION, IMPROVE THE TIMELINESS OF THE UNDERLYING BATHYMETRY
AND TOPOGRAPHY, AND BE CONSISTENT WITH THE BASINS USED WITHIN
THE PROBABILISTIC TROPICAL STORM SURGE (P-SURGE) MODEL.
B. UPGRADE THE COMPUTATIONAL DOMAIN USED FOR PUERTO RICO.
THE CURRENT DOMAIN, BUILT IN 2010, HAS A SPATIAL RESOLUTION OF
APPROXIMATELY 1.5 KM NEAR THE COASTLINE OF SAN JUAN. THE NEWER
DOMAIN, BUILT IN 2025, HAS A SPATIAL RESOLUTION OF ABOUT 650 M
NEAR THE COASTLINE OF SAN JUAN.
C. ENHANCE THE P-ETSS METHODOLOGY USED TO ESTIMATE THE SPREAD
OF THE 10 TO 90% UNCERTAINTY RANGE AT STATIONS. THIS WILL BE
DONE BY ADDING THE ABSOLUTE VALUE OF THE TWO (2) DAY AVERAGE
ANOMALY (OBSERVATION - SURGE - TIDE) TO THE 10% EXCEEDANCE LEVEL
WHILE ALSO SUBTRACTING IT FROM THE 90% EXCEEDANCE LEVEL. THE
INTENT IS TO EXPAND THE RANGE SO IT BETTER REPRESENTS THE
UNCERTAINTY.
D. DEVELOP AN INITIAL BLENDED STORM SURGE CAPABILITY. THE
METHOD USED FOR V1.5 WILL BE TO AVERAGE MODEL RESULTS DERIVED
FROM USING (A) THE GLOBAL FORECAST SYSTEM (GFS), (B) THE CONTROL
MEMBER OF THE GLOBAL ENSEMBLE FORECAST SYSTEM (GEFS), AND (C)
THE CONTROL MEMBER OF CANADA'S GLOBAL ENSEMBLE PREDICTION SYSTEM
(GEPS) AS FORCING FOR THE P-ETSS HYDRODYNAMIC MODEL.
E. PROVIDE STANDARD HYDROMETEOROLOGICAL EXCHANGE FORMAT
(SHEF) OUTPUT ABOVE MEAN HIGHER HIGH WATER (MHHW) IN ADDITION TO
THE CURRENT SHEF DATA IN MEAN LOWER LOW WATER (MLLW). AMONGST
OTHER BENEFITS, THIS WILL SUPPORT THE ALASKA REGION WITH THEIR
MESSAGING EFFORTS.
F. DISCONTINUE P-ETSS GRIDDED OUTPUT ON 2.5 KM CONTIGUOUS
UNITED STATES (CONUS) GRIDS, SINCE THE SAME DATA IS PROVIDED ON
HIGHER RESOLUTION 625 M CONUS GRIDS.
G. DISSEMINATE PUERTO RICO AND U.S. VIRGIN ISLANDS GRIDDED
(VIA GRIDDED BINARY - GRIB2) AND STATION (VIA SHEF) PRODUCTS
OVER THE SATELLITE BROADCAST NETWORK (SBN). WE CURRENTLY
GENERATE GRIB2 PRODUCTS FOR THAT REGION, BUT THEY ARE ONLY
AVAILABLE VIA NOAA'S OPERATIONAL MODEL ARCHIVE AND DISTRIBUTION
SYSTEM (NOMADS).
H. VARIOUS STATION CHANGES WHICH AT THE TIME OF THIS PNS
INCLUDE:
(A) ADDING ONE (1) STATION FOR PUERTO RICO AND THE U.S. VIRGIN
ISLANDS AND ONE (1) STATION FOR ALASKA, (B) ADDING SHEF SUPPORT
FOR FIFTEEN (15) STATIONS FOR PUERTO RICO AND THE U.S. VIRGIN
ISLANDS AND NINE (9) STATIONS FOR ALASKA, (C) IMPROVING THE
TIDAL CONSTITUENTS FOR FOURTEEN (14) STATIONS, AND (D) UPDATING
THE DATUM INFORMATION FOR TEN (10) STATIONS. ADDITIONALLY A
NUMBER OF STATIONS WITH OBSERVATIONS ARE BEING ADDED ALONG THE
EAST COAST, WITH THE EXACT NUMBER IN FLUX.
I. DISCONTINUE P-ETSS' GFS FORCED STORM SURGE MODEL (AKA
EXTRA-TROPICAL STORM SURGE (ETSS)) RESULTS AT STATIONS PROVIDED
IN A MODEL-SPECIFIC TEXT FORMAT. THOSE FILES, CONTAINING STORM
SURGE ONLY GUIDANCE, HAVE BEEN SUPERSEDED BY SHEF FORMATTED
FILES WHICH CONTAIN EITHER STORM SURGE + TIDE + ANOMALY (I.E.,
BIAS ADJUSTMENT) GUIDANCE WHEN OBSERVATIONS ARE AVAILABLE, OR
STORM SURGE + TIDE GUIDANCE. STORM SURGE ONLY GUIDANCE IS
AVAILABLE WITHIN THE COMMA-SEPARATED VALUE (CSV) FILES WHICH ARE
POSTED TO NOMADS.
THE EXPECTED BENEFITS OF THIS UPGRADE INCLUDE:
A. IMPROVED MODEL GUIDANCE IN SOUTH FL AND PUERTO RICO,
B. IMPROVED UNCERTAINTY COVERAGE AT STATIONS,
C. EXPERIMENTAL BEST GUESS GUIDANCE,
D. SHEF ENCODED STATION GUIDANCE ABOVE MHHW,
E. SUPPORT FOR PUERTO RICO AND THE US VIRGIN ISLANDS GUIDANCE
OVER THE SBN, AND
F. IMPROVED MODEL GUIDANCE AT VARIOUS STATIONS.
FOR ADDITIONAL DETAILS ON THE EXPECTED BENEFITS OF THIS UPGRADE,
PLEASE SEE THE USER EVALUATION SLIDES HERE:
HTTPS://VLAB.NOAA.GOV/DOCUMENTS/6609493/7858383/P-
ETSS_V1_5_DRAFTSCIENCEBRIEFING.PDF/1F35D712-D931-A0C2-D344-
DFE4A314BD50?T=1776352583095
FOR VISUALIZATION OF THE UPGRADED GUIDANCE, SEE:
P-ETSS (NAEFS): HTTPS://SLOSH.NWS.NOAA.GOV/PARA/PETSS/
P-ETSS (GEFS): HTTPS://SLOSH.NWS.NOAA.GOV/PARA/PETSS_GEFS/
P-ETSS (GFS): HTTPS://SLOSH.NWS.NOAA.GOV/PARA/ETSS/
FOR PROVIDING COMMENTS ON THE PROPOSAL, PLEASE USE THE FEEDBACK
FORM WHICH CAN BE ACCESSED VIA THIS LINK:
HTTPS://FORMS.GLE/MY3EFPMVDVSSMQZY8
ALTERNATIVELY, YOU CAN PROVIDE QUESTIONS, COMMENTS, OR REQUESTS
BY SENDING AN EMAIL BEFORE MAY 17, 2026 WITH A SUBJECT OF "P-
ETSS V1.5 FEEDBACK" TO:
ARTHUR TAYLOR
METEOROLOGICAL DEVELOPMENT LABORATORY
E-MAIL: ARTHUR.TAYLOR@NOAA.GOV
HUIQING LIU
METEOROLOGICAL DEVELOPMENT LABORATORY
E-MAIL: HUIQING.LIU@NOAA.GOV
MARK WILLIS
METEOROLOGICAL DEVELOPMENT LABORATORY
E-MAIL: MARK.WILLIS@NOAA.GOV
NATIONAL PUBLIC INFORMATION STATEMENTS ARE ONLINE AT:
HTTPS://WWW.WEATHER.GOV/NOTIFICATION/
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page