Tropical Cyclone Public Advisory  (Source: NHC web site)

World Meteorological Organization (WMO) and AWIPS (in parenthesis) headers:
WTNT31-35 KNHC (MIATCPAT1-5) - Atlantic
WTPZ31-35 KNHC (MIATCPEP1-5) - E. Pacific

The Tropical Cyclone Public Advisory contains a list of all current watches
and warnings on a tropical or subtropical cyclone. It also gives the cyclone
position in terms of latitude and longitude coordinates and distance from a
selected land point or island, as well as the current motion. The advisory
includes the maximum sustained winds in miles per hour and the estimated or
measured minimum central pressure in millibars and inches. The advisory may
also include information on potential storm tides, rainfall or tornadoes
associated with the cyclone, as well as any pertinent weather observations.

Public advisories are issued for all Atlantic and eastern Pacific tropical or
subtropical cyclones. Prior to 2008, public advisories for eastern Pacific
tropical or subtropical cyclones were issued only when the cyclones threatened
land. 

Public advisories for Atlantic tropical cyclones are normally issued every six
hours at 5:00 AM EDT, 11:00 AM EDT, 5:00 PM EDT, and 11:00 PM EDT (or 4:00 AM
EST, 10:00 AM EST, 4:00 PM EST, and 10:00 PM EST). 

Public advisories for Eastern Pacific tropical cyclones are normally issued
every six hours at 2:00 AM PDT, 8:00 AM PDT, 2:00 PM PDT, and 8:00 PM PDT (or
1:00 AM PST, 7:00 AM PST, 1:00 PM PST, and 7:00 PM PST). 

Intermediate public advisories may be issued every 3 hours when coastal
watches or warnings are in effect, and every 2 hours when coastal watches or
warnings are in effect and land-based radars have identified a reliable storm
center. Additionally, special public advisories may be issued at any time due
to significant changes in warnings or in the cyclone.

The numbers 1-5 in the headers are assigned on a rotating basis by cyclone
number, i.e., advisories on the first, sixth, or eleventh cyclones of the
Atlantic season would be sent under the WMO header WTNT31 KNHC; advisories
on the second, seventh, or twelfth cyclones of the Atlantic season would be
sent under the WMO header WTNT32 KNHC, and so on.