Tioga Pass and Glacier Point Roads Opening Dates 2014
Post date: Apr 05, 2014 2:2:46 AM
Another round of April 1 snow surveys is now complete and the numbers are not good. Estimates range from 29% in the northern Sierra to 39% in the central Sierra and 32% in the southern Sierra. See my original blog regarding my calculation methods. For the past two years the predictions have been pretty close (here's last year's blog). This year, I used some different stations because the most reliable (Tenaya Lake--TNY) stopped recording data sometime in February. However, I was able to find another station (Ostrander Lake--STR) and as it turns out this station predicts opening dates a little better than Tenaya Lake. I still looked at data from Virginia Lakes Ridge (VLks) and Dana Meadows (DAN--see the original blog) but also added Tuolumne Meadows (TUM) to the mix. The graph shows average and current (up to April 3) SWE values for the stations in Yosemite. Click the graph for a larger version.Yosemite announced that plowing would begin on Glacier Point Road on April 1 and on Tioga Pass Road on April 15. The April 15 date is pretty typical, so there shouldn't be any complications related to that or government sequestration this year. However, April 1 seems a little early to start plowing the Glacier Point Road. I'll take that into consideration in my estimate. So, let's get to it. With ~39% of average snowpack in the central Sierra (including Yosemite) as of April 1, this year is most similar to 2012 (43%) and 1990 (45%). Other similar years include 2007 (46%), 1994 (51%), 1988 (31%), and 1987 (51%). According to the station SWE values, this year is most similar to 1994 (DAN, VLks, and STR) and 2007 (VLks, TUM, and STR) as well as 1990 (DAN and VLks), 1988 (VLks and TUM), and 2012 (VLks and TUM). Below I've summarized the respective opening dates for the two roads (source):
Unfortunately, the opening dates for the Glacier Point Road only go back to 1995. Nonetheless, you can see that the opening for both roads is going to be fairly early and likely to be similar to 2012. Of the stations I'm looking at, STR (60% of variability) then TUM (59% of variability) are best for predicting the opening of Glacier Point Road. STR predicts an opening date of April 29 and TUM predicts May 3. Based on these April 1 numbers, when plowing begins, and looking at previous years, I estimate that the Glacier Point Road will open sometime between April 25 and May 3. STR (71% of variability) then VLks (62%) best predict the opening of Tioga Pass Road. STR predicts an opening date of May 9 and VLks predicts May 10. I estimate that the Tioga Pass Road will open sometime between May 5 and 13. I'm leaning toward making the Glacier Point Road range earlier, but I'll wait until the April 15 update to see what happens in the next couple of weeks.
Should these predictions prove accurate, it will be a third-straight early opening for both roads and the Yosemite waterfalls will again quickly dissipate. Plan on arriving almost a month earlier than an average year if you want to see the waterfalls during decent flows. The peak flow for the Merced River at the Pohono Bridge (which can serve as a proxy for the nearby creeks) on average occurs on May 27 (probably nearer to late-April or early-May for this year). Similar to the last two summers, don't expect Yosemite Creek to be running into August but the Glacier Point and Tioga Pass Roads should be open for longer than usual (unless winter arrives early). Check back in a couple of weeks when I update this post with April 15 numbers (more accurate than April 1 and Max SWE numbers).
UPDATE (4/16):
Well, the Glacier Point Road opened earlier than expected this past Monday (4/14). I guess I should have moved my predictions up two weeks because plowing began two weeks earlier than normal there. In all, it took less than two weeks to clear the Glacier Point Road and it probably won't take much longer than that to clear the Tioga Pass Road. STR best predicts the Tioga Pass Road opening date among the stations I'm looking at with Max SWE (71% of variability) and April 15 SWE (76% of variability) values. STR predicts an opening of May 5 and May 10 respectively. The next best predictor is VLks with Max SWE (65% of variability) and April 15 SWE (69% of variability) values. VLks predicts an opening of May 10 and May 9 respectively. I believe that these dates are on the later end of the probability range. If it takes the plow crews the same amount of time to clear the Tioga Pass Road as the Glacier Point Road, then the Tioga Pass Road will open on April 28. This would be the earliest opening date between 1980 and the present. Based on several of these factors, I am going to shift my prediction range a little earlier. I estimate that the Tioga Pass Road will open sometime between May 1 and 9. The flow in the Merced River in Yosemite Valley is slowing increasing near the average (see here) but will probably reach a peak within the next couple of weeks instead of toward the end of May. We're looking forward to a long season with the Tioga Pass Road open but will be planning for earlier wildflower blooms and crossing our fingers during the long fire season. Alpine hiking season is fast approaching!