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NOUS44 KMRX 211205
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NCZ060-061-TNZ012>018-035>047-067>074-081>087-098>102-VAZ001-002-
005-006-008-220015-
PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE MORRISTOWN TN
805 AM EDT TUE APR 21 2026 /705 AM CDT TUE APR 21 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.
HTTPS://WWW.WEATHER.GOV/ERH/GHWO?WFO=MRX
HTTPS://WWW.WEATHER.GOV/PIMAR/CWABYWFO
HTTPS://WWW.WEATHER.GOV/SRH/TROPICAL?OFFICE=MRX#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:
DAVID HOTZ
SCIENCE AND OPERATIONS OFFICER
NATIONAL WEATHER SERVICE OFFICE
MORRISTOWN, TENNESSEE
DAVID.HOTZ@NOAA.GOV
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