GFA Flashcards
What does the GFA depict?
The most probable weather conditions that will occur at or below 24000ftASL (400hPa)
When are GFAs issued?
4x a day, 30 min before the beginning of the forcasted period.
This means that the GFA charts are issued every 6 hours.
Each of the two sets of maps (wx and icing) are published 4 times a day, and each set has three time stamps released with it.
Posting times are approximately 2330, 0530, 1130, 1730
Validity times therefore are 0000, 0600, 1200, 1800.
How many charts are in each pubished issue (4/ every six hours) of the GFA?
6 charts. Three for wx and three for icing.
For each two sets of three charts there is a current forcast, a 6 hours out forcast, and a 12 hours out forcast
The GFA publishes six charts (3 for wx and 3 for icing) four times a day. What time frame do those forcasts include?
Current forcast, 6 hours out forcast, 12 hours out forcast
What is on the 12 hours out wx forcast on of the GFA for IFR pilots?
An IFR outlook for an additional 12 hour period.
This means that each published GFA (with their six charts) contains a forcast for the next 24 hours for those who fly IFR
What are the cloud heights in the GFA given in?
ASL unless otherwise stated
For how long is an IFR Outlook valid?
24 hours
Ceilings less than 1000AGL and/or visibility less than 3SM equals…
IFR Conditions
What is Marginal VFR (MVFR)?
Ceilings between 1000 - 3000AGL and/or 3 - 5SM Visibility
What do ISOL, OCNL, and FRQ mean?
- Isolated: 25% or less
- Occasional: 26% - 50%
- Frequent: Over 50%
What do LCA, PTCHY, and XTNSV mean?
Local: 25% or less
Patchy: 26%-50%
Extensive: More than 50%
When multiple cloud layers are forcast, the amount of cloud at each layer is based on….
The amount of cloud at that level. It is not based on the sum of all the amounts of layer below it.
Where is the IFR Outlook located?
on the 12 hour clouds and wx chart comments box
The motion of synoptic features on the GFA will be indicated when movement is expected to be ____ or greater
5KTS
An area of fog is marked on the GFA as
dashed orange lines