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PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
308 PM EDT MON APR 20 2026
TO: SUBSCRIBERS:
-NOAA WEATHER WIRE SERVICE
-EMERGENCY MANAGERS WEATHER INFORMATION NETWORK
-NOAAPORT
OTHER NWS PARTNERS AND NWS EMPLOYEES
FROM: JAMIE RHOME, DEPUTY DIRECTOR
NATIONAL HURRICANE CENTER
SUBJECT: HURRICANE THREATS AND IMPACTS (HTI) MOSAIC TESTING ON
APRIL 21, 2026 (BACKUP DATE: APRIL 23, 2026)
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 TUESDAY, APRIL 21, 2026.
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 TEST NEEDS TO BE POSTPONED, DUE TO WEATHER
OR ANOTHER EVENT, THE TESTING WILL INSTEAD COMMENCE AT THE
AFFECTED OFFICES ON APRIL 23, 2026.
FOR THE TEST, HTI GRIDS WILL BE CREATED FOR TROPICAL 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
2026.
FOR MORE INFORMATION, PLEASE CONTACT:
ANDY NASH
METEOROLOGIST-IN-CHARGE
NATIONAL WEATHER SERVICE OFFICE
NORTON, MA 02766
ANDY.NASH@NOAA.GOV
NATIONAL PUBLIC INFORMATION STATEMENTS ARE ONLINE AT:
HTTPS://WWW.WEATHER.GOV/NOTIFICATION/
FOR THE LATEST UPDATES...PLEASE VISIT OUR WEBPAGE AT
WWW.WEATHER.GOV/BOSTON
YOU CAN FOLLOW US ON FACEBOOK AT
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.BOSTON.GOV
YOU CAN FOLLOW US ON TWITTER AT
@NWSBOSTON
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