NOUS41 KWBC 021445



Public Information Statement 17-04

National Weather Service Headquarters Silver Spring MD

1045 AM EST Thu Feb 2 2017


To:      Subscribers:

        -NOAA Weather Wire Service

        -Emergency Managers Weather Information Network


        Other NWS Partners and NWS Employees


From:    Allison Allen

         Chief, Marine, Tropical and Tsunami Services Branch


Subject: Soliciting comments through March 4, 2017, on changing

         criteria for issuing tropical cyclone watches and   

         warnings to include certain land-threatening  

         disturbances that are not yet tropical cyclones


Effective immediately and continuing through March 4, 2017,

NWS is seeking user feedback on the proposed option to issue

watches, warnings and graphical and textual advisory products

for disturbances not yet tropical cyclones but which pose the

threat of bringing tropical storm or hurricane conditions to

land areas within 48 hours. 


Under previous long-standing NWS policy, the NWS has not been

permitted to issue a hurricane or tropical storm watch or

warning until after a tropical cyclone had formed.  Advances in

forecasting over the past decade now allow the confident

prediction of tropical cyclone impacts while these systems are

still in the developmental stage.  For these land-threatening

"potential tropical cyclones," the NWS proposes to issue the

full suite of products that previously have only been issued for

ongoing tropical, subtropical or post-tropical cyclones. 


Potential tropical cyclones would share the naming conventions

currently in place for tropical and subtropical depressions,

with depressions and potential tropical cyclones being numbered

from a single list (e.g., One, Two, Three, ..., Twenty-Three,

etc.). The assigned number would always match the total number

of systems (tropical cyclones, subtropical cyclones, or

potential tropical cyclones) that have occurred within that

basin during the season. 


For example, if three systems requiring advisories have already

formed within a basin in a given year, the next land-threatening

disturbance would be designated Potential Tropical Cyclone

Four.  If a potential tropical cyclone becomes a tropical

depression, its numerical designation remains the same (i.e.,

Potential Tropical Cyclone Four becomes Tropical Depression Four).


The issuance times for potential tropical cyclone products would

be identical to the standard tropical cyclone product issuance

times.  No changes would be necessitated to the format of NWS

text products.  These products would add the term "potential

tropical cyclone" to describe the system responsible for the

watch or warning conditions in the MND header and the body of

the product as appropriate. 


NWS products for potential tropical cyclones would be issued

until watches or warnings are discontinued or until the threats

for land areas sufficiently diminishes, at which point

advisories would be discontinued. If, however, it seems likely

new watches or warnings would be necessary within a short period

of time (say 6-12 hours), then advisories could briefly continue

in the interest of service continuity. Once a system becomes a

tropical cyclone, the normal rules for discontinuing advisories

would apply. Potential tropical cyclone advisories would not be

issued for systems that pose a threat only to marine areas.


Because NHC and the Central Pacific Hurricane Center would be

issuing their normal graphical products depicting the 5-day

forecast track and uncertainty cone for potential tropical

cyclones, the Graphical Tropical Weather Outlook would no longer

display a formation area for these systems to avoid confusion.


If comments are favorable, the NWS will offer the option

beginning at or around the start of the 2017 hurricane season to

issue tropical cyclone watches and warnings for land-threatening

"potential tropical cyclones." An SCN will be issued prior to

implementing this change.


Comments may be submitted via the survey link below:


Or send comments or requests for more information to:


Jessica Schauer

NWS Marine, Tropical and Tsunami Services Branch

National Hurricane Center

Miami, FL 33165

Telephone: 305-229-4476



Wayne Presnell

NWS Marine, Tropical and Tsunami Services Branch

Silver Spring, MD  20910

Telephone: 301-427-9390



National Service Change Notices are online at: