Gday guys
Wondering if you can help me out on a couple of weather interpretations.
AF YBBN 242215Z 1300/1506 16015KT 9999 -RASH SCT025 SCT040
T17 18 19 19 Q1020 1018 1017 1017
METAR/TTF YBBN 0300Z 18020 9999 - RASH BKN020 18/16 Q1017
NOSIGConsider the meteorological messages above. The lowest cloud base forecast for an arrival at YBBN at 0700 is -
The answer is 2500AGL. Can you please inform me why it isn't 2000AGL with the BKN020 section?
Also
Your aircraft has a maximum take-off weight of 2100 kg.You plan a flight to TAREE (YTRE) with an ETA of 0040UTC. TAF YTRE extract reads:
TAF YTRE 011835Z 0520/0608 33015KT CAVOK
FM0601 18018KT 9999 FEW010 SCT012Nominate, with the appropriate reasons, whether or not an alternate must be provided --
The answer is an alternate must be provided because there is more than 4/8 cloud below the alternate minimum. However I read this as 0400UTC being before 0601 (date/time?) and therefore should be CAVOK?
Thanks for your help
Chris
Hi Chris,
In your first question, there is a TTF thrown in to confuse you. A TTF supercedes the TAF but only for 3 hours from the time of issue. That means the TTF runs out at 0600Z and you need to go back to using the TAF. So, for an arrival at 0700Z, you will have SCT025 AGL in the TAF as the lowest cloud base.
For your second question, the FM kicks in at 0100 on the 6th. Therefore, with an arrival time of 0400 UTC, you are well inside the FM period. You will need an alternate because FEW + SCT, both below 1500 ft is equivalent to more than 4/8ths below 1500 ft. Don't forget the cloud layers are cumulative.
Ain't Met fun 🙂
Cheers,
Rich
Once again, thank you.
TTF is a new one for me, I'll store that in the old memory bank.
As far as the second one, I was reading the time as 0040 (1040am) which makes no sense at all now that I "say it out loud"
Thanks for the info
Chris
Hi Chris,
Make sure you read up on TTF's - they come up regularly in the exam. In a nutshell, the TTF or Trend Type Forecast is a short 3-hour forecast which the met officer may append to a METAR or a SPECI report. The report follows the usual format but in the RMK section of the report, after the RF (rainfall) information, there will be additional information which outlines the expected conditions for the next 3 hours. Because the TTF is considered extremely accurate, it supercedes the TAF while it is valid. It's validity period starts from the time of issue of the report.
Cheers,
Rich
