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Public Information Statement
National Weather Service Melbourne FL
1230 PM EDT 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. These 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:

Matthew Volkmer
Science and Operations Officer
National Weather Service Office
Melbourne, FL
matthew.volkmer@noaa.gov

National Public Information Statements are online at:
https://www.weather.gov/notification/

$$