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Public Information Statement
National Weather Service San Diego CA
900 AM PDT Wed Apr 23 2025

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

From:      Greg Schoor, Chief
           Marine, Tropical and Tsunami Services Branch

Subject:   Hurricane Threats and Impacts (HTI) Mosaic Testing on
April 24, 2025 (backup date: April 29, 2025)

The National Weather Service (NWS) Weather Forecast Offices
(WFOs) in Honolulu, Hawaii, San Juan, Puerto Rico, and all WFOs
in the contiguous United States that can issue tropical storm
and hurricane hazards will commence with Hurricane Threats and
Impacts (HTI) threat grid mosaic testing on Thursday, April 24,
2025. Testing will begin at approximately 1500 UTC. Test activities
will take approximately 1 hour. However, NWS dissemination systems
may take up to an hour and a half to purge all test data. All test
data is expected to be cleared by 1730 UTC.

In the event that the commencement date is declared a Critical
Weather Day (CWD), an Enhanced Caution Event, or other event is
occurring or is anticipated to occur, the testing will commence
at the affected offices on April 29, 2025.

For the test, HTI grids will be created for hurricane Wind
Threat, Flooding Rain Threat, Tornado Threat, and Storm Surge
Threat (where applicable) at each participating WFO. Those grids
are stitched together into storm-scale HTI graphics. The HTI
Mosaic graphics are available in Keyhole Markup Language (KML)
format on the following webpage:
https://www.weather.gov/hti

The mosaics are also available through the National Digital
Forecast Database and on web pages hosted by the Weather
Forecast Offices (WFOs) affected by tropical cyclones.
webpages include WFO Tropical Webpages and Graphical Hazardous
Weather Outlook (GHWO) Webpages.

GHWO Webpages use the following URL format, where XXX should
be replaced with the 3-letter identifier for the WFO of interest
(note that WFO Honolulu does not have a GHWO webpage):
https://www.weather.gov/erh/ghwo?wfo=XXX

WFO 3-letter identifiers and the respective NWS Region that each
WFO belongs to is listed at the following page:
https://www.weather.gov/pimar/CWAbyWFO

NWS Eastern, Southern, and Western Region WFO Tropical Webpages
use the following URL format, where XXX should be replaced
with the 3 letter identifier for the WFO of interest:

NWS Eastern Region WFOs:
https://www.weather.gov/XXX/tropical#hti

NWS Southern Region and Western Region WFOs:
https://www.weather.gov/srh/tropical?office=XXX#hti

The Tropical Webpage for WFO Honolulu can be found at:
https://www.weather.gov/hfo/hti

User information about HTI can be found here:
https://www.weather.gov/media/srh/tropical/HTI_Explanation.pdf

More specific details on HTI can be found in the Product
Description Document:
https://www.weather.gov/media/srh/tropical/PDD_HTI.pdf

Periodic software and hardware testing in preparation for
tropical cyclone events will continue during the remainder of
2025.

For more information, please contact:

Jonathan Suk
Meteorologist In Charge
National Weather Service Office
San Diego CA
jonathan.suk@noaa.gov
National Public Information Statements are online at:
https://www.weather.gov/notification/

$$