Worm Flows, St. Helens - Conditions and Forecast (4/17)

Synopsis: I've got a trip up St. Helens on the Worms Flows route planned for this Sunday (4/17) and want to talk about weather/conditions. I'm curious how you all interpret the weather forecast, and determine whether or not conditions are suitable for climbing.

Background: We're a party of three, permits in hand, with varying skill levels and experience. I have admittedly little experience in snow travel, though I have taken a course on the fundamentals of snow safety (self arrest, ice axe techniques, etc.). My partner is less equipped with knowledge and hard skills, but possesses adequate fitness. The third in our group, The Ringer, is a family friend of my partner who has years of experience and has been up and down many mountains here in the PNW. Please understand that the conversation I'm hoping to have here will also be had within our group independently. 

What I know: We've recently entered a period of cold weather with substantial precip throughout the region. I'm out in the Portland Greater Metro area, and we've seen snow on the ground and I know that Hood had been blasted over the weekend. I see that Avalanche.org shows avalanche risk in the St. Helens area to be considerable, and will continue as such through at least Tuesday. Outside of what Avalanche.org tells me directly, I've only had free avalanche awareness training and don't possess the confidence to assess avalanche conditions in situ. Keep in mind we'll be leaning heavily on The Ringer in this department. 

Questions: Being less than a week out, I believe the weather forecast to be reliable enough to start to fine tune our plans. It looks like the temps are forecasted to increase and the precip to taper off throughout the week with potentially clear weather on the scheduled day of the climb. I'm unsure of what exactly these numbers mean in regards to conditions, whether it be climbing or avalanche. So here are the questions I'm hoping to chew through on here: 

• Equipped with forecasting knowledge and third party avalanche assessment, but without being on site, how do you determine feasibility of the climb? As a peripheral, how to determine how necessary flotation devices are, generally, as I understand this route is possible in just boots under certain conditions? (We're planning to bring snow shoes, and not skis.)
• How would you interpret the forecast as it relates to avalanche danger in this scenario? Based on current weather and information provided by Avalanche.org, I likely wouldn't attempt the climb today, but the weather is variable and expected to change. 
• Any other tidbits and advice as it pertains to these topics would be helpful while I/we gain the experience and develop the skills to confidently come to a conclusion on my/our own. 

Again, I feel like we have a reliable and knowledgeable climber in our party who will be invaluable during this phase of planning, but would like some input from other experienced members of the community if for nothing else than a learning opportunity. Many thanks in advance!

Disclaimer: I have never taken an AIARE course, nor any formal mountaineering/outdoor training. I have climbed Helens thrice, and skied it once. 

Last week, Helens was ,experiencing sunny temps in the 60's and 70's--which dropped significantly with the arrival of this storm. My guess is that this would lead to depth hoar (which one would expect as spring gets underway anyways). The arrival of this storm, and the fact that it will be snowing on and off all week (at near or sub freezing temps) leading up to your trip date of the 17th, would indicate the development of a storm slab over the aforementioned persistent weak layer (depth hoar, etc.). In addition to this, the prevailing wind (according to mountain forecast) will be generally from the South, which could indicate some wind loading. 

This being said, Worm Flows is, by design, a relatively low angle route. If I remember correctly, only a few portions of it are over 27 degrees in pitch (a quick check on caltopo has the average grade at 17 degrees)--this generally indicates low avalanche danger. 

But back to mountain forecast--on the 17th it will be snowing all day, and as low as 5 degrees with wind chill. Depending on the hour to hour precipitation, visibility could be quite low. Helens is an easy climb, but if I saw that forecast, I probably wouldn't do it. That being said, I am a complete amateur--I have never taken an AIARE course, nor any formal mountaineering/outdoor training. I trust that your ringer will also have a ton of thoughts about the weather on the 17th.