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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