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Public Information Statement
National Weather Service Mobile AL
849 AM CDT Thu Apr 24 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:

Jessica Chace
Warning Coordination Meteorologist
National Weather Service Office Mobile, AL
jessica.chace@noaa.gov

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

$$