Training Guide in Surface Weather Observations - Multiple Choices
Training Guide in Surface Weather Observations - Multiple Choices
Training Guide in Surface Weather Observations - Multiple Choices
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2.1 W<strong>in</strong>d Group - dddff(f)Gfmf m(f m)KT<br />
CHAPTER 2<br />
WIND<br />
The w<strong>in</strong>d group is the first weather element reported <strong>in</strong> a METAR/SPECI and immediately follows the<br />
Date/Time group <strong>in</strong> the transmitted coded report.<br />
Observ<strong>in</strong>g and report<strong>in</strong>g w<strong>in</strong>d speed and direction are relatively easy.<br />
2.1.1 W<strong>in</strong>d Direction - ddd<br />
The direction is reported us<strong>in</strong>g three characters. When us<strong>in</strong>g direct read<strong>in</strong>g dials, you determ<strong>in</strong>e the<br />
w<strong>in</strong>d direction by averag<strong>in</strong>g the direction over a 2-m<strong>in</strong>ute period. The true w<strong>in</strong>d direction is reported<br />
<strong>in</strong> tens of degrees us<strong>in</strong>g three digits. The third character will always be a zero. See Table 2-1, W<strong>in</strong>d<br />
Direction <strong>in</strong> Tens of Degrees.<br />
2.1.2 W<strong>in</strong>d Speed - ff(f)<br />
W<strong>in</strong>d speed is reported us<strong>in</strong>g two digits or three when necessary. If the direction was determ<strong>in</strong>ed to be<br />
variable (VRB) and the w<strong>in</strong>d speed is 6 knots or less, the speed is appended to the VRB, e.g., VRB05.<br />
However, w<strong>in</strong>d directions should be reported whenever they can be determ<strong>in</strong>ed even when the w<strong>in</strong>d<br />
speed is 6 knots or less, e.g., 14004. A calm w<strong>in</strong>d (less than 1 knot) is coded with five zeros, e.g.,<br />
00000. The transmitted coded group ends with the letters “KT” to <strong>in</strong>dicate the unit of measurement is<br />
<strong>in</strong> knots; however, it is not recorded on MF1M-10.<br />
Examples of Transmitted/Coded Data: 31015KT VRB04KT 040112KT<br />
2.1.3 W<strong>in</strong>d Gusts - Gfmf m(f m)<br />
14004KT 00000KT<br />
Report<strong>in</strong>g gusts is a bit more difficult. The w<strong>in</strong>d gust is coded <strong>in</strong> two or three digits immediately<br />
follow<strong>in</strong>g the w<strong>in</strong>d speed. The w<strong>in</strong>d data for the most recent 10 m<strong>in</strong>utes are evaluated. Gusts are<br />
<strong>in</strong>dicated by rapid fluctuations <strong>in</strong> w<strong>in</strong>d speed with a variation of 10 knots or more between peaks and<br />
lulls. The speed of the gust shall be the maximum <strong>in</strong>stantaneous w<strong>in</strong>d speed. The letter “G” is placed<br />
right before the w<strong>in</strong>d gust speed <strong>in</strong> the transmitted coded report; however, it is not recorded <strong>in</strong> column<br />
5 of MF1M-10.<br />
Examples of Transmitted/Coded Data: 31015G25KT 090115G125KT<br />
Squalls are reported <strong>in</strong> Present <strong>Weather</strong> and are also part of what makes up the w<strong>in</strong>d character. A Squall<br />
is a sudden <strong>in</strong>crease <strong>in</strong> average w<strong>in</strong>d speed of at least 16 knots and susta<strong>in</strong>ed at 22 knots or more and<br />
last<strong>in</strong>g for at least 1 m<strong>in</strong>ute. The difference between Gust and Squall is duration and <strong>in</strong>tensity of the<br />
<strong>in</strong>crease.<br />
2-1