Terms in this set (77)

a. TYPE OF REPORTS - the METAR, and the SPECI (aviation special weather report)

b. ICAO station identifier - 4-letter station identifiers; in the contiguous US, the 3-letter identifier is prefixed with K.

c. DATE AND TIME OF REPORT - a 6-digit date/time gropu appended with Z (UTC). First two digits are the date, then two for the hour, and two for minutes.

d. MODIFIER (as required) - if used, the modifier AUTO identifies the report as an automated weather report with no human intervention. If AUTO is shown in the body of the report, AO1 or AO2 will be encoded in the remarks section to indicate the type of precipitation sensor used at the station.

e. WIND - 5-digit group (6 digits if speed is over 99 KTS); first three digits = wind direction, in tens of degrees referenced to true north. Directions less than 100 degrees are preceded with a zero; next two digits are the average speed in knots, measured or estimated (or, if over 99 KTS, the next three digits).

f. VISIBILITY - surface visibility in statute miles, space, fractions of statute miles (as needed), and the letters SM.

g. RUNWAY VISUAL RANGE (RVR), as required

h. WEATHER PHENOMENA - broken into two categories: qualifiers and weather phenomena.

i. SKY CONDITION - amount/height/type (as required) or indefinite ceiling/height (vertical visibility). Heights are recorded in feet AGL.

j. TEMPERATURE/DEW POINT GROUP - 2 digit format in whole degrees Celsius, separated by a solidus (/). Temperatures below zero are prefixed with M.

k. ALTIMETER - 4-digit format representing tens, units, tenths, and hundredths of inches of mercury prefixed with A. The decimal point is not reported or stated.

l. REMARKS (RMK), as required - operational significant weather phenomena, location of phenomena, beginning and ending times, direction of movement.
Winds and temperature aloft forecasts are computer prepared forecasts of wind direction, wind speed, and temperature at specified times, altitudes, and locations. They are produced 4 times daily for specified locations in the continental US, Hawaii, Alaska, and coastal waters,and the western Pacific Ocean. Amendments are not issued to the forecasts. Wind forecasts are not issued for altitudes within 1,500' of a location's elevation.

Some of the features of FBs are:

a. Product header includes date and time observations collected, forecast valid date and time, and the time period during which the forecast is to be used.

b. Altitudes up to 15,000' referenced to MSL; altitudes at or above 18,000' are references to flight levels (FL).

c. Temperature indicated in degrees Celsius (two digits) for the levels from 6,000'-24,000'. Above 24,000', minus sign is omitted since temperatures are always negative at those altitudes. Temperature forecasts are not issued for altitudes within 2,500' of a location's elevation. Forecasts for intermediate levels are determined by interpolation.

d. Wind direction indicated in tens of degrees (two digits) with reference to true north and wind speed is given in knots (two digits). Light and variable wind or wind speeds of less than 5 knots are expressed by 9900. Forecaste wind speeds of 100-199 KTS are indicated by subtracting 100 from the speed and adding 50 to the coded direction. For example a forecast of 250 degrees, 145 knots, is encoded as 7545. Forecast wind speeds of 200 KTSor greater are indicated as a forecast speed of 199 KTS. For example, 779 is decoded as 270 degrees at 199 KTS or greater.
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