As far as I'm concerned there is no true way to change how abruptly the weather changes happen. I am pretty sure the default weather engine resets and replenishes the weather at every interval you have it set to do it. Changing the time for updates is one option, as maybe faster updates like you have it at could produce smaller changes in the long run, but almost definitively will have more changes through your flight. A slower update time would have less changes in the flight, but maybe more drastic changes. I don't think so though, as weather usually doesn't work that way. I have seen that maybe xEnviro would help, but I would be hesitant to go with this option as xEnviro could cause frame drops and even then the changes in weather would still be abrupt. Not to mention the $69.90 price tag.
A summary of what I said is that the weather will always defy basic laws of nature, and the only changes you can make are making that happen more or less often. Making it happen more often will give you more realistic weather to fly in or over, and making it happen less often will mean more stability with flight dynamics, but less up-to-date weather. Also keep in mind I do not work with Laminar, but this is the best answer I can give you based on what I have experienced and seen elsewhere.