Local Temperature Monitoring in West-Central Idaho: RAWS

This post follows, in part, the theme of my previous post: US Forest Service avoidance of local data in project analyses. For example, the Final Environmental Impact Assessment (FEIS) for a recent project that I was involved with as Forest Fishery Biologist (available here) contained this statement:

Climate data for the last 55 years (1951–2006) (The Nature Conservancy 2011) reveal that on average, temperatures in Idaho have increased 0.031 °F per year (Figure 1-2), and precipitation has increased 0.085% per year (Figure 1-3). Consistent with findings by Diaz and Eischeid (2007), the temperature increases have been more severe at higher elevations.**

The overview of the "Affected Environment" in this document talked generally about temperature requirements for native fishes, but did not expand upon local temperature trends. At the time, the Forest maintained a large water temperature monitoring network, and I tried to remedy lack of local temperature data to some extent in the Biological Assessment (BA)* for that project by including analysis of water temperature monitoring data in the project area; unfortunately, the general public generally does not routinely get to see BAs. The BA contained this statement about project area stream temperatures:

Stream temperatures within the analysis area are generally functioning appropriately and appear to be declining (Figure 19 and Appendix F).

and contained this graphic***:

My previous post on local temperatures from the New Meadows, Idaho, USHCN station suggested that the FEIS statement above might not be true for local temperatures (or might be essentially true if data adjustments and estimates were appropriate). This post examines additional local temperature data so that the reader can come to his or her own conclusions about that, and focuses on what should be the agency's obligation to look at local data beyond such generalized statements.

There is a network of remote automated weather stations (RAWS) scattered around the United States, established principally as interagency resources related to wildland fire management. I have suggested that the Forest could also use these data in addition to USHCN data to assess local trends. They have not, to the best of my knowledge done so, even though it's local, agency, and readily available information. So I look at some here.

I downloaded data for four sites on or very near the Payette National Forest from the Western Regional Climate Center (WRCC): Weiser River, at 5500 ft elevation; Ski Hill, at 5500 ft elevation; Tea Pot at 5152 ft elevation; and Snake River at 4100 ft elevation. These stations are located as shown in this Google Earth image:

Only the Ski Hill RAWS station has a photo as part of its metadata, shown here:

If the others are similar, they're in quite undeveloped settings. While temperature records are incomplete prior to 2001 or 2002, they appear to be raw (unadjusted) data. The Ski Hill site had one missing monthly average (February), which I estimated by averaging the other 12 points in the 13 year record. I averaged all twelve months for each year to generate annual mean temperatures. Here are the results:

All but one linear fit to these points (Tea Pot) are weakly negative. While I would not assert that these demonstrate decreasing temperature generally in this part of Idaho, they certainly refute any contention that temperatures, even at high elevation, are rapidly increasing; the most reasonable conclusion is that temperatures have been moostly stable over the past several years (much like the contentious "hiatus").

Whatever one takes away from this review, I think it should be obvious that project analyses for the Payette National Forest should use local data in its project assessments. Even if the increasing trend such as those shown for Idaho as a whole are correct, a proposed project needs to be evaluated in it's geospatial context as well.

UPDATE (04-15-2019): There are two Weiser River RAWS station graphics in the post; one of them should have been this one from the Snake River station:

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* BAs are bureaucratic documents describing potential effects to species protected under the Endangered Species Act during consultation with federal regulatory agencies (US Fish and Wildlife Service in this case). The analysis is typically more rigorous than for NEPA.
** This information and a graph were obtained from the Nature Conservancy site at  http://www.climatewizard.org/ for Idaho using the graph for last 50 years option.
*** MWMT is Maximum Weekly Maximum Temperature, a 7-day moving average of daily maximum water temperature (see here).