On Jul 28, 12:42*pm, " wrote:
On Jul 28, 8:34*am, GeoffSchultz
wrote:
...

I find exactly the opposite to be true. *The NOAA forecasts are much
more reliable off shore than they are on-shore where land effects can
significantly modify the wind patterns. *I believe that they even
state that the forecasts are for 12+ miles off-shore. ...

I don't know where you sail. *However, my guess is you are not using
the correct weather product. *In most places in the USA NOAA provides
marine forecasts in zones. *The zones tend to be along the lines of
near-shore, coastal and offshore with near-shore zones being the
smallest and having the highest detail the offshore the largest and
least detailed. *The near shore and coastal products do take land
effects into account. *For instance, there are nine zones for which
NOAA produces marine products in the bay and sea areas around San
Francisco. *That's pretty typical. *The reason they go to all that
trouble is that the wx is often quite different in each zone. *So, yes
it is likely they do provide a product that is only valid 12+ miles
off shore in your area. *But, if they do then they almost certainly
also have one for the near shore waters and the reason they have
another zone is that they expect the wx to be different nearer shore
and the near shore. *It shouldn't come as a surprise that the 12+ mile
out forecast does a poor job of predicting things closer in.

If you want to geek out on this then you will want to look into the
meso scale modeling. *You can get NAM and COAMPS grib data from NOAA
for the coastal waters of North America. *If you check it out I think
you'll see that the models do take local geographical features into
account. *Near shore your local wx dude has these high resolution
models, radar, reporting stations, and so on giving him the best
information to build his forecast from and a small area to
prognosticate over. *As the forecast area moves offshore and gets
larger he has less detailed information and has to average the
forecast over a larger area and, IME, the results are, as you would
expect less accurate. *YMMV.

-- Tom.

Most of my sailing is in the Caribbean with the majority of it being
in the NW Caribbean. I utilize GRIB files with GFS and/or NOGAPS
modules. There are no localized forcasts for on/off-shore.
Everything is off shore and on a macro scale. It's amazing how many
"small" scale systems move through that never make it onto any chart.
If you're coastal US, then I would believe that the localized coastal
forecasts should be fairly accurate.

-- Geoff