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AIM

10/12/17

7

−1−15

Meteorology

EXAMPLE

See FIG 7

−1−6 for an example of the G−AIRMET

graphical product.

g. Watch Notification Messages

The Storm Prediction Center (SPC) in Norman, OK,
issues Watch Notification Messages to provide an
area threat alert for forecast organized severe
thunderstorms that may produce tornadoes, large
hail, and/or convective damaging winds within the
CONUS. SPC issues three types of watch notification
messages: Aviation Watch Notification Messages,
Public Severe Thunderstorm Watch Notification
Messages, and Public Tornado Watch Notification
Messages.

It is important to note the difference between a Severe
Thunderstorm (or Tornado) Watch and a Severe
Thunderstorm (or Tornado) Warning. A watch means
severe weather is possible during the next few hours,
while a warning means that severe weather has been
observed, or is expected within the hour. Only the
SPC issues Severe Thunderstorm and Tornado
Watches, while only NWS Weather Forecasts Offices
issue Severe Thunderstorm and Tornado Warnings.

1.

The Aviation Watch Notification Message.

The Aviation Watch Notification Message product is
an approximation of the area of the Public Severe
Thunderstorm Watch or Public Tornado Watch. The
area may be defined as a rectangle or parallelogram
using VOR navigational aides as coordinates.

The Aviation Watch Notification Message was
formerly known as the Alert Severe Weather Watch
Bulletin (AWW). The NWS no longer uses that title
or acronym for this product. The NWS uses the
acronym SAW for the Aviation Watch Notification
Message, but retains AWW in the product header for
processing by weather data systems.

EXAMPLE

Example of an Aviation Watch Notification Message:
WWUS30 KWNS 271559
SAW2
SPC AWW 271559
WW 568 TORNADO AR LA MS 271605Z - 280000Z
AXIS..65 STATUTE MILES EAST AND WEST OF LINE..
45ESE HEZ/NATCHEZ MS/ - 50N TUP/TUPELO MS/
..AVIATION COORDS.. 55NM E/W /18WNW MCB - 60E
MEM/
HAIL SURFACE AND ALOFT..3 INCHES. WIND
GUSTS..70 KNOTS. MAX TOPS TO 550. MEAN STORM
MOTION VECTOR 26030. 
LAT...LON 31369169 34998991 34998762 31368948 

THIS IS AN APPROXIMATION TO THE WATCH AREA.
FOR A COMPLETE DEPICTION OF THE WATCH SEE
WOUS64 KWNS FOR WOU2.

2.

Public Severe Thunderstorm Watch Notifica-

tion Messages describe areas of expected severe
thunderstorms. (Severe thunderstorm criteria are
1-inch hail or larger and/or wind gusts of 50 knots [58
mph] or greater). A Public Severe Thunderstorm
Watch Notification Message contains the area
description and axis, the watch expiration time, a
description of hail size and thunderstorm wind gusts
expected, the definition of the watch, a call to action
statement, a list of other valid watches, a brief
discussion of meteorological reasoning and technical
information for the aviation community.

3.

Public Tornado Watch Notification Messages

describe areas where the threat of tornadoes exists. A
Public Tornado Watch Notification Message contains
the area description and axis, watch expiration time,
the term “damaging tornadoes,” a description of the
largest hail size and strongest thunderstorm wind
gusts expected, the definition of the watch, a call to
action statement, a list of other valid watches, a brief
discussion of meteorological reasoning and technical
information for the aviation community. SPC may
enhance a Public Tornado Watch Notification
Message by using the words “THIS IS A
PARTICULARLY DANGEROUS SITUATION”
when there is a likelihood of multiple strong (damage
of EF2 or EF3) or violent (damage of EF4 or EF5)
tornadoes.

4.

Public severe thunderstorm and tornado

watch notification messages were formerly known as
the Severe Weather Watch Bulletins (WW). The
NWS no longer uses that title or acronym for this
product but retains WW in the product header for
processing by weather data systems.

EXAMPLE

Example of a Public Tornado Watch Notification 
Message:
WWUS20 KWNS 050550
SEL2
SPC WW 051750
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 243
NWS STORM PREDICTION CENTER NORMAN OK
1250 AM CDT MON MAY 5 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED
A
*TORNADO WATCH FOR PORTIONS OF
WESTERN AND CENTRAL ARKANSAS