How much does the rest of the world's climate matter? Given a generally earth-like situation, arakish's (amazing!) work could be a fair representation of 'plausible fiction'. But if you dial the axial tilt, distance from sun, cloud cover, amount of icecaps & continental glaciation up and down, you could probably get any small area *exactly* how you like. The rest of the planet might shift uncomfortably toward frozen, or desert, or what-have-you.

Arakish, the way those currents swirl seems reasonable. Especially since the continent blocks global flow, those three small seas to the east of the desired Europe-like area probably are very warm, self-circulating hot-tubs. Overall though, there could be some circulation that gets the Europe Analogue Isthmus some cooling, some rain without being a jungle, etc. Prevailing surface winds drive a lot of the surface currents, along with coriolis forces and the fact that these inconvenient continents generally get in the way :-). Maybe a judicious application of the pseudoscience of the wind tutorial I've started could "justify" appropriate climate.

Another consideration is just how stable do you want Nuelan's climate to be, over time? If it wobbles a bit on its axis, or if its sun is a little variable, you could pick your desired point on a cycle of cooling... glaciation... warming... desertification... repeat.