snow tires necessary for 2014 prius or not?

Do you mean General rather than Continental? A quick search on tire rack came up with General making the Altimax Arctic. Rated 1 of 4 in studdable snow tires.

General Altimax Arctic

 

You can look up reviews on TireRack.

 

There is a full test on the link I provided of three studdable snow tires including these generals as studded and not studded

 

Couple of TireRack links:

General Altimax Arctic

Consumer Survey Results By Category

Pretty positive comments in owners reviews, too (in first link).

 

We drive on General Altimax tires on our vehicles [Prius Prime, Prius 3, Honda Odyssey].

 

In my town we have to use studs. Otherwise people end up sliding into snow banks fairly often, and you would have to avoid driving across ice.

Winter tire treads are designed and rated for their ability to handle driving through standing water, which is good when temps are above freezing. So you may need that depending on where you are driving. Winter tires [without studs] are much better when driving through water than all-season tires would be.

Studs provide grip when driving on ice. Once the ground freezes hard, we do not anticipate driving on bare pavement again until next Spring. Only in the higher taxed cities do they use salt to clear the pavement of ice.

I live out in a low tax rural area. Our roads do no get salted, and we may tend to drive across frozen bodies of water to shorten daily commutes. Studs make a big difference in the tire's ability to grip on ice.

 

Studded tyres are great if you often drive on ice, but can be a bit noisy, and some states (e.g. NH) only allow studs to be used between November and April, since they tend to chew up the road surface. I was thinking of using studs after the awful winter we had two years ago, but after looking at the reviews, ended up with Bridgestone Blizzak WS80s on a set of 15" steel rims - and so far (on their second winter) they're brilliant (and pretty good in the wet also) - at the end of April I will put the OEM 16" alloy wheels shod with summer tyres back on for the warm season. Having a spare set of rims for the winters is easier on the tyres since each removal/fitting can compromise the sealing bead, particularly if the work is being done by a ham-fisted teenager. (see other threads for the complete story…)

Edit: I was wrong!

Studded Tires - AAA Digest of Motor Laws