A Charmed Hike

We thought we’d gotten a bum deal when we went hiking on the Heliotrope Ridge Trail last Thursday. The end of October is generally not a good time to go hiking in the North Cascades but it looked like El Niño was on our side, providing fairly warm enough temperatures to keep the snow away. And the National Weather Service forecast called for a lull in the rain, although it did say that rain was more likely in the mountains than in the lowlands.

You can read all about the hike on D-Jan-ity but, to make a long story short, it was raining very lightly when we started and it stopped entirely after about a half an hour. There were even patches of blue sky urging us onward, but we were flummoxed when we got to the first of three creeks and couldn’t find a safe place to cross. It is pretty commonplace to turn back at the third one but this is the first time that we couldn’t even pass the first one. So we had to settle for a 3 mile hike, getting back to the cars at about noon.

It seems that I was too focused on snow and falling rain to take into account the rain that had already fallen and made its way into the creeks. In fact we are under the influence of something called an “atmospheric river” or “Pineapple Express”, wherein a plume a moist Pacific air from the tropics set its sights on the State of Washington and brings huge amounts (for us) of rain. You can read more about this on Cliff Mass’ Weather Blog.

Last evening my curiosity drove me to look at the data from a SNOTEL (a remote automated weather station) that is located across the road, a few miles from where we were hiking and at about the same elevation. It records the snow depth, temperature and accumulated rainfall at one hour intervals to the nearest one-tenth of an inch – that is pretty coarse, since 1/10 of an inch in an hour is pretty heavy rainfall. The sort of drizzle that fell on us early in the hike  wouldn’t even register on that scale. Anyways, here is a graph of the hourly rain accumulation for Thursday:

 

Notice that, except for the wee hours and the late evening, the only time when that graph isn’t streaking upward is the three hours that we were hiking. And look at the time just before 9AM – over an inch in about 5 hours! So no surprise that Kulshan Creek was raging and we were actually pretty lucky.

Last night in the wee hours we got almost an inch of rain here in town, so I went back to the SNOTEL and downloaded the hourly data from Thursday through 11AM today (Saturday). The arrow points at our hiking time.

That’s some serious rain!

By the way, that accumulation is from October 1, the start of what the weather folks call a “water year”. So the mountains have had considerably more rain in the last 2½ days than in the rest of October.