Arc'teryx Nuclei FL Jacket

The new and improved Nuclei FL jacket is positioned as a climbing jacket or for, more specifically, "alpine travel’s static phases"—in other words, when you are standing or sitting still. I've had the Nuclei for the late fall and winter seasons. Because it weighs in at 325g only, it gets chucked in my pack for lunch breaks, long and cold transitions or if the shit should hit the proverbial fan. It accompanies the Arc'teryx Proton LT as a mid/uptrack layer and the Arc'teryx Rush LT jacket and Pants on the outside. This works for me really well here in the Kootenays as a complete, all-conditions ski touring system.

This is a size large and, though I often go for the medium, this works well as a layer to put over all the others you might have on. I am about 6'2" and weigh 178lbs, FYI. To keep the weight down on the Nuclei, there are few bells and whistles. See for yourself with the front and back photos below. 

The hood is helmet compatible but not super big and floppy like it can get on some hardshells. It's elasticized around your face and features a single drawcord at the back to cinch up if you need to. Note the seams in the bottom photo here—three of them perfectly placed to cradle your noggin. It's very comfortable if you are running a ball cap or toque. 

Here, in the open kimono shot, you can see the simplicity of the Nuclei FL at work. No little zip-up pocket for your iPhone; just two giant dump pockets suitable for gloves, skins or what-have-you. I am constantly rotating gloves/mitts and keep the ones I am not using next to my body to get warm and dry. The Nuclei FL inside pockets are perfect for this. 

Simple, elasticized piping around sleeves. It's the same material as what is used around the hood opening. Not too much, not too little.

Simple hem adjuster that tucks up under the jacket's hem when not in use. Note the zip-up hand warmer pockets (one to port and one to starboard). Like the internal dump pockets, these are voluminous, and they zip up to protect your valuables. 

The Arato 10D nylon ripstop face fabric is entirely windproof and remarkably low weight. In the right light, you can see the Coreloft fabric (Arc'teryx's own) underneath. I really like this fabric. Lightweight, cozy, and still warm when wet. 

Curious about Coreloft? — let the guy whose name I can't make-out tell you all about it. 

• Adjustable StormHood™ with soft brim gives added protection when needed
• Two hand pockets with zippers
• Two internal dump pockets
• Coreloft™ synthetic insulation provides warmth with minimal weight and bulk
• Articulated patterning for unrestricted mobility
• Gusseted underarms for mobility and comfort
• Adjustable harness compatible hem

The Nuclei FL has been my trusted companion on several overnight backpacking trips, many many day-long ski tours and two hut trips. I like it. I like it a lot. I have a down jacket but that seems like overkill here in the Kootenays because our winters are comparatively mild. One day that it was particularly cold, I tried the Nuclei FL as a mid layer on the uptrack and it got too hot—no surprise there. I don't run particularly hot and I always warm up when ascending.

This jacket works as advertised. It's best when you are at rest (or on your way to the brew pub). It has held up very well for the few months I've had it. As I posit in the CONS below, it might tear if you catch a branch. I haven't tried this experiment and the same goes for any light-weight jacket: down, synthetic or whatever.

The other advantage of the Nuclei is the warm-when-wet characteristic of Arc'teryx's proprietary Coreloft fabric. On wet days, I have tested this claim and can verify its validity. I haven't been in a total wet-out situation (largely because I pair the Nuclei FL with a GoreTex overlayer) but it's good to know. Like many bits of gear, the "there-when-you-need-it" aspect brings a lot of comfort to my adventures.