Creating TAFs...
Thread Starter
Joined: Nov 2004
Posts: 30
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From: UK
Creating TAFs...
Best place I can find here for this. Calling all Met trained folks.
How can you tell and what tools do you use to differentiate between the following? What is it that allows you to be this sure, whether it happens or not?
SCT025 - SCT035 - what is it that causes the 1000' difference?
SCT030 - BKN030 - what is it that makes sct 'sct' and not 'bkn'?
RA +RA - presumably much easier here?
SHRA - RA - patchy/less water suspended equals only showers?
BCFG - 150mFG
FG - BR etc etc…
GS - GR - what conditions form the difference between the two? GR is constantly forming in layers below the freezing point so is much harder and more dangerous, whereas GS are just quick-forming non-laminar pellets?
Isobars to wind strength and direction understood but where cloud/precipitation are concerned - specifically to do with the amount of moisture present and the T/DP relationship or is it more than that?
TVM!
How can you tell and what tools do you use to differentiate between the following? What is it that allows you to be this sure, whether it happens or not?
SCT025 - SCT035 - what is it that causes the 1000' difference?
SCT030 - BKN030 - what is it that makes sct 'sct' and not 'bkn'?
RA +RA - presumably much easier here?
SHRA - RA - patchy/less water suspended equals only showers?
BCFG - 150mFG
FG - BR etc etc…
GS - GR - what conditions form the difference between the two? GR is constantly forming in layers below the freezing point so is much harder and more dangerous, whereas GS are just quick-forming non-laminar pellets?
Isobars to wind strength and direction understood but where cloud/precipitation are concerned - specifically to do with the amount of moisture present and the T/DP relationship or is it more than that?
TVM!
Joined: Apr 2012
Posts: 683
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From: In Space
SCT025 - SCT035 - what is it that causes the 1000' difference?
There is a layer of cloud its that simple.
SCT030 - BKN030 - what is it that makes sct 'sct' and not 'bkn'?
Sky coverage based on Oktas .
SKC = Sky Clear = 0/8
Few = 1/8 to 2/8
Scattered = 3/8 to 4/8
Broken = 5/8 to 7/8
OVC = Overcast = 8/8
There is a layer of cloud its that simple.
SCT030 - BKN030 - what is it that makes sct 'sct' and not 'bkn'?
Sky coverage based on Oktas .
SKC = Sky Clear = 0/8
Few = 1/8 to 2/8
Scattered = 3/8 to 4/8
Broken = 5/8 to 7/8
OVC = Overcast = 8/8
Joined: Nov 2007
Aviation Qualifications: ATPL
Posts: 1,954
Likes: 30
From: Texas
I believe the OP was asking how forecasters know which to forecast.
That's a good starting point. Cloud base can be determined by the difference in surface temperature and dew point, they have different lapse rates. Coverage will be a function of instability and dew point. The amount and intensity of rain fall depends on the available precipitable water and the type of clouds expected to develop. After that I don't know.
specifically to do with the amount of moisture present and the T/DP relationship or is it more than that?
Joined: Nov 2005
Aviation Qualifications: PPL
Posts: 12,446
Likes: 367
From: Wildest Surrey
I believe the OP was asking how forecasters know which to forecast.
That's a good starting point. Cloud base can be determined by the difference in surface temperature and dew point, they have different lapse rates. Coverage will be a function of instability and dew point. The amount and intensity of rain fall depends on the available precipitable water and the type of clouds expected to develop. After that I don't know.
That's a good starting point. Cloud base can be determined by the difference in surface temperature and dew point, they have different lapse rates. Coverage will be a function of instability and dew point. The amount and intensity of rain fall depends on the available precipitable water and the type of clouds expected to develop. After that I don't know.
Joined: Jun 2001
Posts: 3,991
Likes: 8
From: UK
In the UK, forecasters no longer prepare TAFs, they're all computer generated.
I did hundreds of 'em. Over 30 years later, I still have dreams about having forgotten to do the 04-13 and getting in a panic, ha! ha!
Joined: Jun 2001
Posts: 3,991
Likes: 8
From: UK
In the early 1980s we checked into Met at Manchester for briefing for a night Ibiza. I asked why Palma was forecasting fog but Ibiza wasn't. Without batting an eyelid the forecaster replied "Katabatic drainage off the high ground on the north side of Majorca" - EGQL1964 you guys did a fantastic job for us!
