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 stormís

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, MD20910

301-713-1677 x122

timothy.schott@noaa.gov

 

National Service Change Notices are online at:

 

http://www.nws.noaa.gov/om/notif.htm

 

$$