Met Practical Flashcards
What is the criteria for an IFR outlook on a GFA?
Ceiling less then 1000agl and or vis less then 3sm
700-400hPa charts are for what alt?
100-FL240
When are SFF-400hPa N Atlantic charts issued?
Issued at approx 1410Z and 0235Z for valid times of 00Z and 12Z respectively
What does “OCNL EMBD TCU” mean on a SIG Wx PROG chart?
TCU with coverage of 50-75% embedded in area of significant cloud
The term “ISOL CB 240” represents?
Individual thunderstorms tops up to 240 with coverage less then 50% with scalloped border (ICAO), less then 25% on a GFA
Fronts and px centres depicted on P SIG WX charts are representative of:
Their surface positions at the chart valid period
The term “FRQ EMBD TCU” means?
Greater then 75% spatial coverage of TCU within other clouds
Freezing levels are drawn at what intervals on 700-400hPa charts?
Every 5,000ASL
WAFC SIG WX charts are issued when?
4 times a day, transmitted 16hrs before valid times of 00Z, 06Z, 12Z, 18Z
White boxes with FL’s inside represent what on a WAFC SIG WX chart?
Level of the Trop
Are “ISOL CBs” ever depicted on a WAFC SIG Wx 250-630 chart?
Yes, only when embedded in cloud within the standard scalloped border
FSS and FIC broadcast and provide upon request what reports to pilots while en route?
SIGMETs and urgent PIREPS
SIGMET rules for validity:
- Valid upon receipt until it is updated or cancelled
- Valid for 4 hrs and can be issued up to 4 hrs before valid time
- For volcanic ash or tropical storms they are valid for 6hrs and can be issued up to 12 hrs prior to valid time
GFA- time issued, valid times, applicable altitudes
- Approx 30 min prior to coverage period
- 00, 06, 12, 18Z. Valid until next GFA issued, can be amended by SIGMET, AIRMET
- Up to 24,000, convective above
TAF - time issued, valid times, applicable altitudes
- Approx 30 mins before beginning of coverage period
- Normally every 3-6hrs and valid for 12, 24, 30 hrs
- Surface
Surface Wx charts - time observed, time issued
- 00, 06, 12, 18Z
- 2 or 3 hrs after observation
Jet streams on upper level charts - speeds and labels
On chart if core above 80. If core is above 120, the label will show the core height, and also the lower and higher heights where the core is 80kts.
Severe squall lines are shown on upper level charts with what symbol?
V-V-V
On the WAFC, The symbol || when depicted on a jet stream means what?
An increase or decrease in wind velocity of 20kts
What measures ceiling in an AWOS observation?
A laser ceilometer at one point over the instrument
Difference between intermittent and continuous precipitation on a GFA
Intermittent is a dashed line with diagonal lines throughout
Continuous is a solid line around with dots in the middle
When are 700-400hPa charts issued?
They are prepared 4 times daily and issued approx 12hrs before the validity time displayed on the charts
Upper lvl chart - PROGs are prepared for flight levels 240, 340, 390, and 450. What are the issue and validity times for these charts?
Predictions software is run 4 times per day forecasting winds and temperatures for various altitudes at specific times in the future. The software run time and chart validity time are indicated in the head of the chart
A forecast area of turbulence implies a ___ probability of encountering turbulence somewhere within the depicted area.
50%
