AIM 

4/20/23 

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

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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 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 

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Meteorology