If you want realtime info, use Bramblemet.co.uk which gives up to date weather from the middle of Bramble bank.
If you want to forward plan then Wind Guru is a pretty accurate for a few days ahead. (remember to set the spot to Calshot)
There are loads of others like MagicSeaweed, Metcheck, Met Office and even the BBC site gives shipping info and decent tide tables.
Finally, it's not in the Solent but keep an eye on the Channel light ship - http://www.ndbc.noaa.gov/station_page.php?station=62103
This will give you the wave height and duration out in the Channel which can be an indication of things to come depending to the wind direction.