So up here in the Upper Klamath Basin we had a pretty large rain on snow event around valenties day with rain at very high elevations. Take a look at some of these SWE graphs
Crater Lake (annie springs) snowtel at 6600 ft. You can see the storm move in around the 13th and precip levels climb but snow depth doesnt. This is a rain event. You can see before and after that event the depth totals can increase alot but not necessarily the precip or the SWE, these are snow storms. So you can see that the SWE did increase during the rain storm. However during this storm Annie Creek (which drains the area below this snowtel) blew up and went to bankfull. The 35 inch snow pack was able to absorb the rain event and store that water. However the thinner snowpack at lower elevations could not deal with the rain and warm temps and much of that snow melted causing the high water.
This plot at the Fish Lake Snowtel, which is in the Cascades @ 4,660 ft shows what happened to thinner snowpacks at lower elevations. Around the 13th the precip began increasing as the rain fell but the snow depth and SWE both dropped. The thinner snowpack couldnt handle all of the rain and alot of it melted and the rain turned into run off. We saw pretty big peaks in most of the cascade streams coming into the Klamath Basin.
Last plot is from Taylor Butte which is east of the cascades in the high desert @ 5,030 ft. You can see that the rain even pretty much obliterated the shallow snowpack that we had there.
So the point is that (like others have stated) the condition of the snowpack has alot to do with the SWE response. But if you are looking at SWE to predict runnoff (especially in eastern oregon) you can get tricked. For example here in the upper klamath, that storm may have increased SWE at the high elevations (where most of the snowtel sites are) but it utterly wiped out most of the snow pack at the lower elevations. This is going to mean lower spring flows on our rivers out here because all of that low elevation snow that would normally come down in the spring is gone; and in our basin that is a much larger proportion of the area than the high peaks.
OK I have been rambling for a while. Hope that makes sense.
Pray for snow