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KMD 250 Pilot's Guide
Section 2
FIS Operation
Basic Service Weather Products
Rev 4 Aug/2007
SPECI
A SPECI (Aviation Selected Special Weather Report) is related to the
METAR. SPECIs are issued when certain specific conditions or events
have been observed at a particular location, usually an airport. A SPECI
will contain the same elements as a METAR and will generally be issued
for the following reasons:
1. Sudden, extreme changes in wind speed and/or direction.
2. Changes in surface visibility, especially those that change the flying
category at the reporting site.
3. Changes in runway visibility above or below 2,400 feet.
4. Appearance or termination of significant weather or natural atmos-
pheric events such as tornados, waterspouts, funnel clouds, thun-
derstorms, squalls and volcanic eruptions.
5. Changes in precipitation intensity or form.
6. Changes to ceilings when previously reported ceilings were at or
below 3,000 feet, or the formation of a ceiling below 3,000 feet.
Also, new formation of cloud layers or other obscuring phenomenon
that occur below 1,000 feet.
7. Aircraft mishaps.
8. Other meteorological conditions that the agency or the observer
determine as critical.
Refer to the section on METARs for an explanation of the elements.
The element sequence and content will be the same as those in a
METAR report with the exception of the first element denoting report
type. “SPECI” will be seen in place of “METAR”.
NOTE: When a specific element of SPECI data is not available, it is
omitted from the report. The user must know the sequence of data to
recognize omissions. SPECI observations older than 120 minutes will
be discarded.
Basic service SPECIs are offered in the encoded textual format.
See the section on Understanding Textual Aviation Weather Reports, for
instructions on decoding textual METAR/SPECIs.
TAF
A TAF (Terminal Area Forecast) is a statement of expected meteorolog-
ical conditions at an airport during a specified period of time. Many
aspects of the TAF are the same as a METAR. Abbreviations are the
same as in a METAR with addition of a few more discussed later. Many
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