How to forecast seeing?

[cookie8]

How can I predict/forecast seeing from suburban Sydney?

[BalderAsir]

a good way to do it is go to the BOM website and access the aviation weather service, login (it gives you the details) and select
1st a Terminal Aerodrome Forecast
click on sydney (or near abouts) on the map that comes up

you'll get a hell of alot of paragaphs under the page titled Area 20 Aerodrome Weather.

here's an example

DUBBO YSDU
11:00 UTC, 27/08/2008
TAF YSDU 271100Z 271206
17008KT CAVOK
FM13 10010KT 9999 FEW025
RMK
T 07 06 04 04 Q 1025 1025 1025 1026


Now highlighted in bold is the cloud coverage for the area near dubbo airfield. Cloud is represented in portions of 8 OKTAS

SKC (Sky Clear) = No Cloud
FEW (Few) = 1-2 OKTAS
SCT (Scattered) = 3-4 OKTAS
BKN (Broken) = 5-7 OKTAS
OVC (Overcast) = 8 OKTAS

Important to note, underlined is a change in the weather. it means that FROM 1300 UTC the weather will be wind 100deg 10 kts 9999(this is visability means greather than 10km, somtimes shown as CAVOK) with FEW025

FEW025 means 1-2 OKTAS of cloud at 2500ft

Another important fact is the TIME this is valid. at the top of the forecast we have TAF YSDU 271100Z 271206, this means it valid on the 27th at 1100UTC till the 27th 1206 UTC (Everything is UTC)

Now, this is only for the local area around Dubbo. to get a wider view of the weather we look for an Area Forecast.

Click your back button twice from the Terminal Aerodrome Forecasts

Click Area Forecast (ARFOR)

Click Sydney or Area 20 (In your case)

here's and example again

CLOUD:
ISOL CB 3500/25000 AS PER TS IN OVERVIEW.
BKN ST IN PRECIPITATION, 1000/3000 SEA/COAST, 3000/4000 RANGES.
BKN ST 3000/4000 RANGES E OF MVI/YTFD.
SCT CU/SC 3500/8000 SEA/COAST, 4000/8000 RANGES/W SLOPES NE OF
YNBR/YSTW/MVI, LOCALLY BKN IN SH.
SCT AC/AS 8000/14000 SEA N OF YCFS, CONTRACTING NE OF AREA BY 17Z.In bold is what your mainly looking for, this will give the type of cloud, their base (where it starts) and their tops. eg SCT CU 2500/3000

ST = stratus
CU= Cumulus


Do a google search for decoding TAF and Area Forecasts they will explain how to read the whole thing. but for cloud thats probably all you'll need.

Remember this is taylored to pilots, so alot of it horizontal visability.

If this confuses the hell out of you (its second nature for me) let me know, and i'll write up a proper how-to


Nick

[okiscopey]

Check the jetstream conditions as well.

http://www.wunderground.com/global/Region/AU/JetStream.html

Short arrows = good. Long arrows = do something else.