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AIM

10/12/17

7−1−63

Meteorology

5. Wind. The wind is reported as a five digit

group (six digits if speed is over 99 knots). The first

three digits are the direction the wind is blowing

from, in tens of degrees referenced to true north, or

“VRB” if the direction is variable. The next two digits

is the wind speed in knots, or if over 99 knots, the next

three digits. If the wind is gusty, it is reported as a “G”

after the speed followed by the highest gust reported.

The abbreviation “KT” is appended to denote the use

of knots for wind speed.

EXAMPLE−

13008KT − wind from 130 degrees at 8 knots

08032G45KT − wind from 080 degrees at 32 knots with

gusts to 45 knots

VRB04KT − wind variable in direction at 4 knots

00000KT − wind calm

210103G130KT − wind from 210 degrees at 103 knots with

gusts to 130 knots

If the wind direction is variable by 60 degrees or more and

the speed is greater than 6 knots, a variable group

consisting of the extremes of the wind direction separated

by a “v” will follow the prevailing wind group.

32012G22KT 280V350

(a) Peak Wind. Whenever the peak wind

exceeds 25 knots “PK WND” will be included in

Remarks, e.g., PK WND 28045/1955 “Peak wind two

eight zero at four five occurred at one niner five five.”

If the hour can be inferred from the report time, only

the minutes will be appended, e.g., PK WND

34050/38 “Peak wind three four zero at five zero

occurred at three eight past the hour.”

(b) Wind shift. Whenever a wind shift

occurs, “WSHFT” will be included in remarks

followed by the time the wind shift began, e.g.,

WSHFT 30 FROPA “Wind shift at three zero due to

frontal passage.”

6. Visibility. Prevailing visibility is reported in

statute miles with “SM” appended to it.

EXAMPLE−

7SM − seven statute miles

15SM − fifteen statute miles

1

/

2

SM − one−half statute mile

(a) Tower/surface visibility. If either visi-

bility (tower or surface) is below four statute miles,

the lesser of the two will be reported in the body of the

report; the greater will be reported in remarks.

(b) Automated visibility. ASOS/AWSS

visibility stations will show visibility 10 or greater

than 10 miles as “10SM.” AWOS visibility stations

will show visibility less than 

1

/

4

 statute mile as

“M

1

/

4

SM” and visibility 10 or greater than 10 miles

as “10SM.”

NOTE−

Automated sites that are augmented by human observer to

meet service level requirements can report 0, 1/16 SM, and

1/8 SM visibility increments.

(c) Variable visibility. Variable visibility is

shown in remarks (when rapid increase or decrease

by 

1

/

2

 statute mile or more and the average prevailing

visibility is less than three miles) e.g., VIS 1V2

“visibility variable between one and two.”

(d) Sector visibility. Sector visibility is

shown in remarks when it differs from the prevailing

visibility, and either the prevailing or sector visibility

is less than three miles.

EXAMPLE−

VIS N2 − visibility north two

7. Runway Visual Range (When Reported).

“R” identifies the group followed by the runway

heading (and parallel runway designator, if needed)

“/” and the visual range in feet (meters in other

countries) followed with “FT” (feet is not spoken).

(a) Variability Values. When RVR varies

(by more than on reportable value), the lowest and

highest values are shown with “V” between them.

(b) Maximum/Minimum Range. “P” indi-

cates an observed RVR is above the maximum value

for this system (spoken as “more than”). “M”

indicates an observed RVR is below the minimum

value which can be determined by the system (spoken

as “less than”).

EXAMPLE−

R32L/1200FT − runway three two left R−V−R one thousand

two hundred.

R27R/M1000V4000FT − runway two seven right R−V−R

variable from less than one thousand to four thousand.