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ARkStorm@Tahoe: Preparing for a major winter storm

From CNAP Researcher Dr. Michael Dettinger:
arkstorm_tahoe_coverFor the past year and a half, a series of modeling efforts and public meetings were conducted with literally (yeah, literally) hundreds of community members and agency representatives in the Tahoe-Reno-Carson City area to evaluate  and discuss the dangers and difficulties faced by emergency responders, utilities and resource managers, and environmental interests in the event of a major winter storm in the area. The strategy used in these meetings was a thorough evaluation with the community of the likely consequences and impacts of the USGS’s ARkStorm scenario (Poter et al., USGS OFR 2010-1312, 2011; Dettinger et al., Nat. Haz., 2012) as applies across this region. A new report describes findings from those conversations, and has just been released by the University of Nevada Cooperative Extension. The report can be referenced as:
  Albano, C., D.A. Cox, M.D. Dettinger, K. Schaller, T. Wellborn and M.I. McCarthy, 2014: ARkStorm@Tahoe — Stakeholder perspectives on vulnerabilities and preparedness for an extreme storm event in the greater Lake Tahoe, Reno and Carson City region. University of Nevada Cooperative Extension Special Publication-14-16, 48pp.
A pdf file of the report can be obtained at:
In the Tahoe-Reno-Carson City study area, modeling of ARkStorm by several different models yielded precipitation totals, and streamflow peaks and rates, roughly 1.5 to 3 times the size of those in the New Years 1997 storms and floods. Temperatures were comparable to that memorable storm, and the ARkStorm sequence yields cold very-snowy conditions for about a week followed by a week of warm rainy conditions, so that flooding was definitely the order of the day. Not surprisingly, the impacts of such an ARkStorm would be severe. Wide-ranging discussions with the community identified many specific consequences and details and interconnections among the impacts.  Serious discussions were begun about how to prepare for, preempt, and recover from the consequences. This report summarizes our
findings from those many discussions.

Runoff — filling our reservoirs — how much and when will it come ?

“… our ability to forecast seasonal water supplies derives from mixes of antecedent local hydroclimatic conditions and the distant echoes of El Nino. “

CNAP researcher Mike Dettinger provides an essay exploring runoff – the water we count on to fill our reservoirs here in the west.

Mike looks at forecast skill for runoff amount and timing. Three predictors are considered (and their associated colors): 1) water from the snowpack (current observations; blue); 2) runoff simulated just before the forecast period (green); and 3) El Nino status in the 3-month period leading up to the forecast (red). The triangles below show the darker the color the more skill the forecast has.


The sample map shown below illustrates where the skill is in a forecast of April-July total runoff using the observed December snowpack (SWE, snow water equivalent), the runoff simulated for the season just before the forecast period (October through March) and the El Nino status (for January through March). This map shows knowing how much snow is on the ground in December (blue colors) leads to skill in the Pacific northwest mountain ranges as well as the Rockies. There is an influence from El Nino in the the southwest (light pinks) and the mountains. The greens indicate where the simulated runoff leads to some forecast skill.


Click on the link to the essay above for more information and more graphics!

CNAP Researcher Dr. LeRoy Westerling guest on Mariposa “Old Town Show”


CNAP Researcher Dr. LeRoy Westerling discusses the increasing trend in large forest fires on Mariposa’s “Old Town Show” (shown Chuck Leonard, LeRoy and Bob Borchard; left to right)

October 1, 2014

CNAP researcher Dr. LeRoy Westerling recently discussed the growing trend in large forest fires on Mariposa’s “Old Town Show” (click here to see the full video on YouTube). Bob Borchard wrote in his summary of the show: “Dr. Leroy Westerling, Professor at the University of California-Merced, is a leading Climatologist and Forest Fire Science expert in the country. He was a guest on my Old Town Show, not only because he is a resident of Mariposa (he lives right up the street from the Gold Coin) but because much of his research is based in Yosemite National Park and the Sierra Mountains around our part of the west. Dr. Westerling explains the growing trend in large destructive forest fires, in the West, over the past thirty years and the relationship between this growth and severity to Climate Change phenomenon.” Great outreach LeRoy!

Coast Clouds: A photo/satellite project you can contribute to!

Do you live near the coast? Observe interesting clouds? Take photos? Then check out Coast Clouds!

Coast Clouds is a project developed by Rachel Schwartz, a NASA Earth and Space Science Fellow and a PhD student at Scripps Institution of Oceanography. This project allows you to post a photo you have taken of coastal clouds and a satellite image from the photo location will be posted with your photo. See clouds from below and above! Below is the photo and satellite image from the site for Friday, September 19, 2014. Interesting to see the clouds off shore in the photo and on the satellite image.


Rachel was able to discuss her project in a recent guest blog post at NASA’s Observe Your World blog site.

63 trillion gallons of water lost – new GPS study released

CNAP researcher Dan Cayan is co-author of a study just released by Science that examines the uplift of the earth’s surface in the west due to the extreme drought conditions. This innovative research uses GPS measurements to examine the uplift in the earth’s surface due to water loss. The amount of water loss is staggering at 63 trillion gallons which would be an approximate 10 cm layer of water over the entire region. This water loss is consistent with observed decreases in precipitation and streamflow. The figure below shows the detrended March 1, 2014, vertical displacement (mm).


Please click here for a personal-use pdf file of the article:
Borsa, A.A., D.C. Agnew and D.R. Cayan, 2014: Ongoing drought-induced uplift in the western United States. Science, published online 21 August 2014, DOI:10.1126/science.126079, 5 pages.

Nevada – could an El Nino be a drought buster ?



Can northwestern Nevada climb out of the drought with El Nino precipitation?

CNAP researcher Mike Dettinger has applied his analysis of the potential impact of an El Nino winter on making a dent in the 2-year drought situation to the climate divisions in the state of Nevada. The current chances of having an El Nino winter are about 65%. El Nino winters typically (but not always) spell wet conditions and the figure shown here illustrates the how precipitation from past El Nino winters would impact the current water deficit. The first dashed line (at about 10 inches) shows how much precipitation is needed to get to normal for water year 2013-14 (which ends September 30, 2014) – no prior El Nino winters would get us out of the current deficit. The higher dashed line (at about 20 inches) shows how much precipitation would be needed to get back to normal. 17% of the historical El Nino winters brought this area back to normal.

Please click here to see more of Mike’s analysis for Nevada.
Click here to see Mike’s analysis for California.

Water for the Seasons — new project funded for northern Nevada

Water for the Seasons


A new $3.8 million project to examine the region’s changing water supply will involve CNAP researcher Mike Dettinger and CNAP collaborating group the Desert Research Institute (DRI). The award has been granted to the University of Nevada, Reno and DRI in partnership with the U.S. Geological Survey. Engaging stakeholders through extensive community outreach the program will identify expected impacts of climate change and find solutions for protecting water resources throughout northern Nevada. The focus of the project will be the Truckee-Carson River System because that provides the model for snow-fed arid land. Please click here to read the full press release.