Weather Flashcards
How often is a Routine METAR transmitted?
At intervals of 1 hour or, if so determined by regional air navigation agreement, at intervals of one half-hour.
How often is a SPECI METAR transmitted?
Shall be issued as necessary.
METAR winds are reported using what direction?
Measured in degrees in relation to True North
Visibility on a METAR is reported in what unit?
Statute
If TCU or CB are reported on the METAR, what other information is given?
Amount: ISOL (Isolated), OCNL (Occasional), FRQ (Frequent), EMBD (Embedded). Heights.
If a TAF is valid for less than 12 hours how often is it issued?
Every 3 hours.
If a TAF is valid 12 to 30 hours how often is it issued?
Every 6 hours.
What does FM on a TAF indicate?
weather expected to change more or less completely to a different set of conditions. Quicker change over an hour.
What does BECMG on a TAF indicate?
Used where changes are expected to reach or pass through specified values at a regular or irregular rate. Over the course of two hours. A very slow change.
What does TEMPO on a TAF indicate?
Temporary fluctuations of less than one hour and in aggregate less than half the period indicated by the observation forecast period.
How long is a SIGMET valid for?
4 hours. 6 hours for volcanic ash clouds and tropical cyclones.
Define wind shear
A sudden, drastic change in wind speed and/or direction over a very small area. Can occur at any altitude. Associated with passing frontal systems, thunderstorms, temperature inversions, and strong upper level winds (greater than 25 knots).
What is the typical lifespan of a microburst?
5-15 minutes
How strong can the downdrafts be in a microburst?
up to 6,000 fpm
What are the criteria for the issuance of CAVOK?
Ceiling And Visibility OK.
- ) Visibility is 10km or more
- ) No cumulonimbus, towering cumulus and no other cloud below 1500m (5000ft) or below the highest minimum sector altitude, whichever is greater.
- ) No significant present weather
What is the meaning of “no clouds of operational significance?”
below 1500m (5000ft) or below highest minimum sector altitude, whichever is greater, and CB, TCU.)
What does NSC mean on a METAR?
Nil Significant Cloud
How is wind greater than 100 knots indicated on a METAR?
P199KMH, P99KT, or P49MPS
What unit is used to issue cloud coverage on a METAR/TAF?
Feet AGL
How many 8th’s of the sky are covered when the cloud coverage is indicated as CLR?
0-1 oktas
How many 8th’s of the sky are covered when the cloud coverage is indicated as FEW?
1-2 oktas
How many 8th’s of the sky are covered when the cloud coverage is indicated as SCT?
3-4 oktas
How many 8th’s of the sky are covered when the cloud coverage is indicated as BKN?
5-7 oktas
How many 8th’s of the sky are covered when the cloud coverage is indicated as OVC?
8 oktas
