AIRMET TURB...HI
OVER AMD IMT S THRU W OF MTN.
TEMPO MOD TURB BLW 070.
COND CONT BEYOND 2200Z.
=HNLZ WA 241600
AIRMET ZULU UPDATE 2 FOR ICE AND FZLVL VALID UNTIL 242200
NO SIGNIFICANT ICE EXP

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 Notification Messages describe areas of expected severe
thunderstorms. (Severe thunderstorm criterire 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

7-1-20

Meteorology