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Table 3-2.—Icing Type (Ic) | Up
Aerographers Mate, Module 02-Miscellaneous Observations and Codes | Next
Table 3-5.—Minimum Amendment Criteria |
Table 3-3.—Thickness of Icing and Turbulence Layers (tL)
Code Figure
Thickness
1
1,000 feet
2
2,000 feet
3
3,000 feet
4
4,000 feet
5
5,000 feet
6
6,000 feet
7
7,000 feet
8
8,000 feet
9
9,000 feet
Table 3-4.—Turbulence Type and Intensity (B)
B = Turbulence
Code
Figure
0
None
1
Light Turbulence
2
Moderate Turbulence in clear air, occasional
3
Moderate Turbulence in clear air, frequent
4
Moderate Turbulence in cloud, occasional
5
Moderate Turbulence in cloud, frequent
6
Severe Turbulence in clear air, occasional
7
Severe Turbulence in clear air, frequent
8
Severe Turbulence in cloud, occasional
9
Severe Turbulence in cloud, frequent
X
Extreme Turbulence
8. Element QNHPIPIPIPIINS is the lowest
altimeter setting in inches expected during the forecast
period.
9 . T h e e l e m e n t s TTTTT GGGe Ge o r
TTGGGG are change groups used to indicate changes
in some or all of the elements forecast to occur at some
intermediate time during the 24-hour forecast period.
Several change groups may be used to properly identify
forecasted conditions as explained below.
The contraction “FMGGGG” indicates the
beginning of a change period in the forecast. All
forecast conditions preceding this group are superseded
by the conditions forecast in this group. For example, if
the TAF period is 1515 and a change is forecast at 1930
UTC, the entry "FM1930" is encoded. The elements
entered following this contraction are in effect from
1930 UTC until the end of the forecast period, 1500
UTC.
The contraction "BECMG" is used to indicate a
change to forecast conditions ‘expected to occur at
regular or irregular periods at an unspecified time
within the time period identified. The duration of the
change should not normally exceed 4 hours.
The contraction “TEMPO” is used to indicate
frequent or infrequent temporary fluctuations to the
forecasted meteorological conditions that are expected
to last less than 1 hour in each instance, and an aggregate
total of less than half the time of the forecast period
indicated.
10. Element TTFTF/GFGFZ is the temperature
group. This is an optional group. The letter "T" is the
temperature indicator and TFTF is the forecast
maximum or minimum temperature in whole degrees
Celsius, depending on the time of day. The GFGF is the
time at which the maximum or minimum temperature is
expected to occur.
TAF AMENDMENTS
Occasionally a TAF will need to be amended.
Established amendment criteria are based on ceiling
and visibility requirements outlined in OPNAVINST
3710.7, NATOPS General Flight and Operating
Instructions, and other safety of flight considerations.
Part of your job as an observer is to keep the forecaster
aware of any changes to the meteorological situation
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