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KMD 250 Pilot's Guide
Section 2
FIS Operation
Basic Service Weather Products
Rev 4 Aug/2007
thunderstorms, or thunderstorms producing heavy precipitation affecting
an area 40 percent or more of an area at least 3,000 square miles.
Convective SIGMETs are issued hourly with a maximum forecast period
of 2 hours. A Convective SIGMET will contain elements in the following
order:
1. Region Identifier and issue date and time
2. Report designator
3. Validity period
4. Area of coverage
5. Location details
6. Weather phenomena details
NOTE: Convective SIGMETs older than the forecast period are dis-
carded. Amended or corrected Convective SIGMETs generated within
the issuance period are provided as soon as they are available, and the
previous outdated Convective SIGMET is no longer transmitted.
See the section on Understanding Textual Aviation Weather Reports, for
instructions on decoding textual Convective SIGMETs.
ALERT WEATHER WATCHES (VDL ONLY)
Alert Weather Watches (AWW) are Alert Severe Weather Watch
Bulletins that describe areas of possible severe thunderstorm or tornado
development. These are watches, not warnings; and are issued as
needed. Severe weather may not actually develop. An Alert Weather
Watch will contain elements in the following order:
1. Report designation and date and time of issuance
2. Watch number, reason for issuance, area of coverage and validity
period.
3. Watch coordinates
4. Forecast
NOTE: Alert Weather Watches older than the forecast period are dis-
carded.
See the section on Understanding Textual Aviation Weather Reports, for
instructions on decoding textual Alert Weather Watches.
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