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Public Information Statement
National Weather Service Morristown TN
1244 PM EDT Wed Apr 23 2025 /1144 AM CDT 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

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:

David Hotz
Science and Operations Officer
National Weather Service Office
Morristown TN
david.hotz@noaa.gov

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

NNNN

$$