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Wind forecasts for P/Philip Bay - inaccuracy of

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Created by downunderdom > 9 months ago, 2 Mar 2016
downunderdom
VIC, 14 posts
2 Mar 2016 1:22PM
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Anyone else finding the wind forecasts for Port Philip Bay this year in particular have been maddeningly inaccurate?

Of course it's always going to be an inexact science, but this year they seem to have been a LONG way off (not just by a few knots). I've lost count of the number of days when there was unforecasted wind and I've missed out, and the number of days I've fronted up only to find nothing at all or it being 180 degrees out from what was forecasted. The latter is particularly vexing, since the missus regards an afternoon beach visit as a windsurfing day irrespective of whether I got out or not...

It's just about reached the point where I need to keep the gear in the car 24/7 just in case.


jermaldan
VIC, 1572 posts
3 Mar 2016 8:06AM
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I think that its been pretty spot on, keeping in mind that they don't forecast seabreezes but rather frontal winds.

Yesterday was a great example. It was hot and there was light southerly winds. Then the seabreeze kicked in at 3.

Todays forcast is similar. Light 10-15 knot southerly. Its warm and its quite likely there will be a 20knot seabreeze after 3pm too.

Faff
VIC, 648 posts
3 Mar 2016 8:11AM
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If MetEye shows 14-15 knots in Elwood at 5 pm, then I turn up.

jakranz
VIC, 125 posts
3 Mar 2016 11:10AM
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Except for a few times when I got skunked I reckon forecast was not too bad. I usually take the general BOM forecasts (Bay and Melbourne), then Meteye to confirm times and finally I find that Windyty Streamlines has some additional info. Yesterday was much stronger than expected, would have been some fronts adding to the Seabreeze effect.
All graphs including Point Wilson and South Channel showed high winds in the arvo, the latter are normally less affected by the Seabreeze which is more prominent in the north.
Was good sailing though

jermaldan
VIC, 1572 posts
3 Mar 2016 12:36PM
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There will be another today I recon... watch the arrows at 3-4pm. St kilda is already hovering around 15 knots.

windaddict
VIC, 1099 posts
3 Mar 2016 2:38PM
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jermaldan said..
There will be another today I recon... watch the arrows at 3-4pm. St kilda is already hovering around 15 knots.


Not looking likely now...unless it comes in really late....

jermaldan
VIC, 1572 posts
3 Mar 2016 3:37PM
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Yeah probably not warm enough early on to heat up the land. Only just hit 26 an hour ago. Probably be later than yesterday.

BTW Mordialloc Sailing Club is showing 20 knots and 22 knot gusts.

Relapse
VIC, 284 posts
3 Mar 2016 3:50PM
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downunderdom said..
Anyone else finding the wind forecasts for Port Philip Bay this year in particular have been maddeningly inaccurate?

Of course it's always going to be an inexact science, but this year they seem to have been a LONG way off (not just by a few knots). I've lost count of the number of days when there was unforecasted wind and I've missed out, and the number of days I've fronted up only to find nothing at all or it being 180 degrees out from what was forecasted. The latter is particularly vexing, since the missus regards an afternoon beach visit as a windsurfing day irrespective of whether I got out or not...

It's just about reached the point where I need to keep the gear in the car 24/7 just in case.




You are not the only who noticed downunderdom a couple of us weather junkies were discussing the same yesterday. Forecast evaluations are always a tricky thing and very subjective. For some if a 15 knot forecast gets them 17 knots actual then the world is a beautiful place but for the +20 knot junkies its a world of hurt.

Even worse if that 17 knot forecast ends up at 24 knots average like yesterday and you have made other plans because for the last couple of week 15 knots meant 15 knots.... Forecast bias is manageable if its consistent, i.e. always add 5 knots but if it bounces around like I have found it to do this season then its a headache.






JonE
VIC, 53 posts
6 Mar 2016 8:57PM
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I do wonder what the guys who spent years getting their maths PhDs and spend their days trying to squeeze every percentage point of accuracy out of their models think when they read what amounts to "this free service is crap"....

Read the news (not the herald sun) - new hot/dry records set all the time - reckon it might be getting harder every year.....?



Relapse
VIC, 284 posts
11 Mar 2016 3:38PM
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Salvation is at hand according to the BOM, as of the 16 March we will be able to set our windsurfing calenders 72 hours out in advance!!! Wonder if their verification metrics include wind speed..... Fingers crossed.

Summary: The APS2 version of the Bureau of Meteorology’s global numerical weather prediction model ACCESS-G will be commissioned on 16 March 2016.

Some highlights:

Horizontal resolution increase from ~40km to ~25 km, vertical resolution of 70 levels stays the same.
Assimilation of additional new observation types such as Cris, ATMS, Clear Sky Radiance satellite products and use of additional local wind profilers; these new observations make the model less sensitive to outages compared to legacy and current data sources.

An overall forecast skill increase compared with APS1 as measured by standard verification metrics. For example the skill of APS2 over the Australian verification region at +72 hours is approximately equivalent to the +64 hour forecast of the current operational system.

ginger pom
VIC, 1735 posts
12 Mar 2016 12:10PM
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Relapse said..

An overall forecast skill increase compared with APS1 as measured by standard verification metrics. For example the skill of APS2 over the Australian verification region at +72 hours is approximately equivalent to the +64 hour forecast of the current operational system.


Wow! Those of us who need 68 hours to plan a sail are in luck!!

windaddict
VIC, 1099 posts
12 Mar 2016 5:47PM
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Select to expand quote
ginger pom said..

Relapse said..

An overall forecast skill increase compared with APS1 as measured by standard verification metrics. For example the skill of APS2 over the Australian verification region at +72 hours is approximately equivalent to the +64 hour forecast of the current operational system.



Wow! Those of us who need 68 hours to plan a sail are in luck!!


You only sail about two or three times a year now anyway ginger so it shouldn't make much of a diff to you

ginger pom
VIC, 1735 posts
15 Mar 2016 9:30PM
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windaddict said...
ginger pom said..

Relapse said..

An overall forecast skill increase compared with APS1 as measured by standard verification metrics. For example the skill of APS2 over the Australian verification region at +72 hours is approximately equivalent to the +64 hour forecast of the current operational system.



Wow! Those of us who need 68 hours to plan a sail are in luck!!


You only sail about two or three times a year now anyway ginger so it shouldn't make much of a diff to you


Exactly.... The 68 hour lead time makes it pretty difficult to hit!



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