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279
NOUS41 KWBC 041501
PNSWSH
Service Change Notice 13-28
National Weather Service Headquarters Washington DC
1100 AM EDT Thu Apr 4 2013
To: Subscribers:
-Family of Services
-NOAA Weather Wire Service
-Emergency Manager Weather Information Network
-NOAAPORT
Other NWS partners and NWS employees
From: Mark Tew
Chief, Marine and Coastal Weather Services Branch
Subject: Change in Tropical Cyclone Watch and Warning
Definitions to Include Post-Tropical Cyclones Effective
June 1, 2013
Post-Tropical Cyclone is a generic term to describe a cyclone
that no longer possesses sufficient tropical characteristics to
be considered a tropical cyclone. Former tropical cyclones that
have become fully extratropical, as well as remnant lows, are two
specific classes of post-tropical cyclones.
One of the challenges associated with Hurricane Sandy in 2012 was
the forecast transformation of the storm from a tropical cyclone
to a post-tropical cyclone prior to landfall. Although NWS
watches and warnings were issued well in advance of the storms
landfall, the NWS received some criticism from partners for
opting to not issue hurricane watches or warnings for New York
and New Jersey. The national tropical cyclone policy in place,
however, during 2012 required the discontinuation of any
hurricane watches or warnings at the time Sandy became post-
tropical. Discontinuing these warnings in the middle of the event
was not viewed as an acceptable option by the NWS.
After a careful assessment of recommendations from partners and
users, including feedback provided to the NWS Hurricane Sandy
Assessment Team, the NWS will officially modify its national
tropical cyclone policy for the 2013 hurricane season. The
following changes are effective on June 1, 2013:
1. The definitions of hurricane and tropical storm watches and
warnings will be broadened to allow these watches and warnings to
be issued or remain in effect after a tropical cyclone becomes
post-tropical.
2. The National Hurricane Center (NHC) and the Central Pacific
Hurricane Center (CPHC) will continue issuing advisory products
after a tropical cyclone becomes post-tropical in those cases
where the system continues to pose a significant threat to life
and property, and where the transfer of responsibility to another
office would result in an unacceptable discontinuity of service.
Similarly, WFO Guam will continue issuing advisory products after
a tropical cyclone becomes post-tropical in those cases where the
system continues to pose a significant threat to life and
property.
Specifically, NHC/CPHC text advisory products, including the
Tropical Cyclone Public Advisory (TCP) and the Tropical Cyclone
Watch/Warning (TCV) products, would continue to be issued under
the POST-TROPICAL CYCLONE XXXXXX header (where XXXXXX is the name
of the storm) and be accompanied by the full suite of standard
tropical cyclone graphical products. In addition, local NWS
Weather Forecast Offices (WFOs) would continue to issue Hurricane
Local Statements as appropriate under the POST-TROPICAL CYCLONE
XXXXXX header until NHC/CPHC discontinues advisories. WFO Guam
would continue to issue its Hurricane Local Statements under the
POST-TROPICAL CYCLONE XXXXXX header using their TCP product.
The updated watch and warning definitions will be used by the
National Hurricane Center, Central Pacific Hurricane Center, WFO
Guam, and local WFOs. The updated definitions and an example of
an NHC-issued Public Advisory (TCP) for a post-tropical cyclone
is posted online at:
http://www.nhc.noaa.gov/news/20130404_hsu_postTropicalChanges.php
In summary, for Sandy-like storms in the future, this policy
update will enable the NWS to issue tropical watches/warnings at the outset, allow them to stay in place into the post-tropical phase, permit the NHC and CPHC to retain the lead in issuing advisories for the post-tropical phase, and permit WFO Guam to issue advisories for the post-tropical phase. For questions regarding this policy change, please contact: Timothy Schott National Weather Service Headquarters Marine and Coastal Services Branch, W/OS21 Silver Spring, MD 20910 301-713-1677 x122 timothy.schott@xxxxxxxx National Service Change Notices are online at: http://www.nws.noaa.gov/om/notif.htm $$
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