Brian, your conditions are often encountered during the winter in "my" mountains of TN and NC, and I have been thru countless storms in the same conditions or worse: A butt cold February or December rain which comes down in buckets and afterwards like clockwork the temps drop significantly.
I was on a 5,000 foot open bald in January and got hit with a "hurricane" rainstorm with 60mph winds and buckets and buckets of rain. Hiking and moving thru such crap is one thing, staying dry in a tent is another.
Dave and Roger are right---a double wall tent is designed for these conditions and performs better than a single wall. Whether it's spraying mist or dripping condensation or even splashing effluvia (well, depending on personal dexterity), a double wall tent performs so much better.
My Hillebergs have a silnylon fly (kerlon) and it's easy to remove the inner tent and sit under just the fly in such a storm and get a light mist and sometimes heavy condensation with an inside saturated fly---but the yellow canopy keeps this stuff out and off of me, critical in a trip lasting longer than a couple days.
The worst is staying in basecamp storm mode for 3 or 4 days in a long cold snowstorm with high humidity---then the inner canopy gets some serious condensation and/or ice buildup. (Hence the advantage of packing up the tent every day and moving---it "cleans" off the inner tent and removes the ice automatically and at your next camp you can set up and remove all the ice from the tent floor---there can be a liter of the stuff---or wipe up the floor water puddles from the saturated inner tent canopy).
Beyond all this, it also important as you know to wake up in the morning and if possible hang out the sleeping bag to dry or "sublimate" or whatever it's called---if only for an hour to help the shell dry. I pulled one 18 day trip in January 2012 and got 153 hours straight of cold rain and I thought I set a new record. Then dangit a year later in January 2013 I pulled another 18 day trip in the Big Frog/Cohuttas and got walloped with a 180 hour cold rainstorm with insignificant lulls and breaks in the clouds.
Point is---a long butt cold rain is inevitable and so the shelter must be able to handle it.