Winter 2016 and Spring 2017 Flood Summary

This past winter and spring had its share of flooding across southeast Oregon and southwest Idaho.  Not only did spring runoff bring flooding to rivers and streams, but ice jams and snow melt caused flooding during the winter as well.  The stage was being set for an active spring flood season as far back as October 2016, when 150 to 400 percent of normal precipitation occurred across much of the region which moistened the soil profile.  The winter storm track brought well above average snowfall to most of southeast Oregon and southwest Idaho, with extreme snowfall across lower valleys.  A relatively cool and wet early spring was the final piece of the puzzle to ensure abundant spring runoff.  An indicator of how wet this past winter and spring have been, water supply forecasts for the April through September period rank in the top 10 for most of southeast Oregon and southwest Idaho, dating back to 1970.  Additionally, all major reservoir systems either have filled or are expected to fill.  Record high precipitation was seen across many areas from December 2016 through June 2017, shown in the figures below.

pnw_cl (3) pnw_cl (4)

The map below shows March 1 snow pack along with areas where flooding had a significant impact.


Although the threat of snow melt flooding has diminished, summertime thunderstorms can pose a serious flood risk.  Areas of steep terrain and areas burned by wildfire are at particular risk for flash flooding due to thunderstorms.  For flood safety information, visit  For the latest river conditions, see

Idaho Spring Flood and Water Resources Outlook – Mar 1, 2017

The potential for spring flooding due to snowmelt in 2017 is well above average across most of southern Idaho. Meanwhile, the spring flood potential is about average for northern Idaho. One thing to remember is that swe31mountain snowpack in Idaho generally peaks in early April, leaving several weeks to add to our snowpack and the flood potential.

The storm track through the winter has been very favorable for southern Idaho, resulting in an exceptional snowpack across the southern half of the state. Relatively warm weather accompanied by rain in February caused much of the snow in the lower valleys of southern Idaho to melt. However, substantial low elevation snow remains across portions of south-central and eastern Idaho. Additionally, well above average mid and high elevation snow exists across southern Idaho with a number of SNOTEL sites measuring record or near record snowpack. Across the northern half of Idaho, snowpack is near average.

The primary factors in the development of spring flooding are the occurrence of persistent above normal temperatures, and rain on snow precipitation events. Even for areas that have low snowpack, spring flooding is possible under the right scenario. Additionally, burn scars can have a significant impact on local flood potential during spring snowmelt.

Precipitation and Temperature

Water Year to date precipitation was above normal for almost all of Idaho. Percentages were highest in the Panhandle, Central Mountains, south-central and southeast regions, where 150 to 300 percent of average precipitation occurred. Lowest percentages in the state were across west-central and southwest Idaho at 100 to 130 percent of normal. Average temperatures have been average to below average across northern, and most of central and southwest Idaho. Across southeast Idaho, the average temperatures have generally been a little above average for the Water Year.

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As of March 1, snowpack was above median across southern Idaho with record or near record snowpack across much of south-central and extreme southeast Idaho. Percentages ranged from 157 to 192 percent of median in the Wood and Lost River Basins, Snake Basin above Palisades, Bear River, Raft River, Blackfoot, Willow, and Portneuf Basins. Elsewhere south of the Salmon River, basin percentages were generally 110 to 140 percent of median. Across the Clearwater, Spokane, and Panhandle Regions, snowpack ranged from 87 to 99 percent of median. Mountain snowpack in Idaho typically builds through March, and early April snow conditions will be pivotal to water supply conditions through the summer.

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Basin-wide reservoir summaries as of March 1 indicate average to above average storage across most regions of Idaho. Large inflows on the Owyhee System in February boosted reservoir levels to 100,000 acre-feet above average. This was a welcome site after multiple years of drought and below average reservoir levels on the Owyhee System. Weather patterns and irrigation demand will drive reservoir operations over the next several months. With the exceptionally large snowpack across much of the south, above average reservoir outflows and high river levels are a good bet on rivers of southern Idaho this spring.


Abundant autumn rain and a good winter precipitation have erased drought conditions across the state according to the latest U.S. Drought Monitor. Weather and precipitation through this spring will determine whether or not conditions continue to improve before heading into the warm and dry season. The U.S. Seasonal Drought Outlook suggests that drought conditions are not likely to return to Idaho through the spring.


Long Range Outlook

The outlook for March, April and May indicates equal chances of above normal, normal, or below normal temperatures across Idaho.  Probabilities slightly favor above normal precipitation during the period.



Water Supply Forecasts


National Weather Service April through September water supply volume forecasts vary from 115 to 225 percent of normal for the southern half of Idaho. Across the northern half of Idaho, percentages are generally 100 to 115 percent of average for the April through September period. These forecasts may change considerably over the next couple of months due to seasonal snow accumulation and rainfall that occur in March and April.


Water Supply Volume Forecasts…

National Weather Service-Northwest River Forecast Center
National Weather Service-Colorado Basin River Forecast Center
USDA-Natural Resources Conservation Service

Snowpack Information…

National Weather Service-Northwest River Forecast Center
National Weather Service-National Operational Hydrologic Remote Sensing Center
USDA-Natural Resources Conservation Service

Reservoir Storage…

Bureau of Reclamation Reservoir Storage
USDA-Natural Resources Conservation Service

Drought Information…

U.S. Drought Portal
U.S. Drought Monitor
National Drought Mitigation Center

Peak Flow Forecasts…

Northwest River Forecast Center
Colorado Basin River Forecast Center

Temperature and Precipitation Outlook…

Climate Prediction Center

Wildfire Burn Scars are a Flood Risk Infographic

Wildfire Burn Scars are a Flood Risk

Heavy rain can produce flash floods, mudslides & debris flows over burned areas from wildfires.  Water repellent soils are formed when organic material such as trees, scrubs, plants and litter burn at high intensity (high temperatures), causing water repellent compounds to become vaporized which then condense on cooler soil layers below the surface, which prevents the soil from absorbing water after a fire. During heavy rains, water cannot penetrate water repellent soil layers, so it runs off like pavement which causes dangerous flash flooding, debris flows and mudslides.

Drought Level since 2000 across Idaho and Oregon

Drought levels across Idaho and Oregon have improved since the recent drought from 2014-2015.  Here a look at the amount of area affected by drought in Idaho and Oregon. The graphs depict the state percentage of area affected by drought. Data is courtesy of the United States Drought Monitor.


Balloon Sighting over Boise

Did you notice a weird object in the sky during the evening?  It resembled a star in the early evening when stars aren’t usually present.  It was a balloon at 61,000 feet! These balloons belong to the Google Project Loon.  These balloons are visible on with the HBAL callsign.

Balloon Tracking - Courtesy of

Balloon Tracking – Courtesy of

Meet and Greet: Idaho Transportation Department Avalanche Center

Avalanche in March 2014 which took 10 days to clean up.

Avalanche in March 2014 which took 10 days to clean up.

At some point or another, we’ve all had our travel plans affected by road closures due to avalanche concerns.  Within the Boise forecast area, those slated with making these decisions work for the Idaho Department of Transportation (ITD) Avalanche Center in Lowman, Idaho. The National Weather Service works closely with this office, providing up to date weather conditions for three locations highly susceptible to large natural avalanches (versus human-triggered avalanches).  We thought it would be fun to meet and greet the two permanent Avalanche Center employees, Bill Nicholson and Chantel Astorga, for some hands-on training in how their operations are conducted.

NWS forecasters Jay Breidenbach (green), Elizabeth Padian (red), Korri Anderson (grey), and Aviva Braun (green) gather for a photo with ITD Avalanche employees Bill Nicholson (Blue) and Chantel Astorga (Pink). Excitement was high after digging a snow pit on February 26th as part of the monthly snowpack evaluation process.

NWS: Good morning! Could you introduce your office to our readers?

Avalanche: Good morning! Well, our program began about 8 years ago after realizing the need for avalanche forecasters for Highway 21, in the Boise forecast area, and Highway 12, in the Missoula forecast area. These roads had been hit by avalanches before and had put many, including the ITD maintenance staff, in danger. We now provide avalanche susceptibility ratings to the ITD staff and close down roads when avalanche dangers are high. Both of us come from ski patrol backgrounds and have a lot of experience with avalanches and understand their dynamics greatly.

NWS: How do you maintain situational awareness of current avalanche conditions?

Avalanche: We go out into the mountains (on our skis!) to evaluate the strength of the snowpack every day! We are skiers at heart for sure.  Because we are out there every day, we have an idea of how much stress the snowpack can take.  We always go in pairs for safety’s sake. When conditions become critical, we go out in our trucks. Those are the days we are on the phone with your office the most!

NWS: What weather phenomena have the greatest impacts on avalanche conditions?

Avalanche: The biggest impacts to avalanche conditions are heat – the first warm day after we’ve been having precipitation is a really big stress, the first prolonged thaw– beginning at the start of that melting period until the water has made it all the way down to the bottom of the snowpack, and finally, during big precipitation events. In very general terms, big precipitation events are when we have more than an inch of water weight (as snow) – that’s when we have to do something. An inch of water weight as rain is a really big problem! But that’s rare here, luckily. The days we call your office frequently are when the rain-snow line is at a level that we’re not quite comfortable with. If the snow level stays at 5500 feet, we’re okay, but if it goes to 5800 feet that would really cause some issues.  Another factor that can greatly influence avalanche danger is wind, but in this area, we rarely get wind-driven avalanches. Every canyon has its own personality; we have gotten to know and understand this canyon pretty well, therefore, we can predict how it’ll behave with each incoming storm.

NWS: How many avalanches do we average per year here on Highway 21?

Avalanche: We average 30 to 40 avalanches per year, and these are the large, destructive kinds. We’ll have days where just everything goes. On those days, the highway is closed.

NWS: How does the NWS help your office achieve its goals?

Avalanche: In 2000, one of the foremost scientists based out of the avalanche center in Calgary, Canada, estimated that with an aggressive avalanche program, the number of road closures could be limited to 30 days per year.  Our current average is 15 days!  Every day, NWS provides forecasts for us so that we can be up to date and ready for incoming changes to the weather – whether it is warmth, rain, or snow.  Without your forecasts, the roads would be closed all of the time!  When we do decide to close the road, we try to give people at least 8 hours warning.  You guys make that possible because we’ll see the next system coming in your forecasts.  However, there are outliers to the 15-day road closure average.  For example, two years ago in March 2014, we had that massive avalanche cycle that took 10 days to clean up!

NWS:  How does your team conduct its monthly snowpack stress tests?

Avalanche:  Once a month, we do an evaluation of the snowpack within the same location at Banner Summit (7200 feet). We do this to see where the snowpack layers are located. As you know, without layers, there would be no avalanche danger. We dig a (new) pit in the snow each month with a smooth wall in which we can pick out the layers. When we think the snowpack is weak, we dig many pits to evaluate the spatial variability. Within the pit, we take the temperature every 10 cm to see if there is a gradient since that gradient drives changes in the snow.  A temperature gradient increases the snowpack weakness; without a temperature gradient, the snowpack is stronger. Another test we do is a hand hardness test which relates directly to strength. However, we try to evaluate the snowpack in a general sense and not get too caught up in the specifics of each layer because sometimes the specifics can just be distractions. The end goal is to evaluate whether the snowpack can handle 1 or 2 inches of water – what will its breaking point be?. The weight of precipitation is what stresses the foundation of the whole snowpack.  During a big event, snow density can change rapidly. Snowpacks are a super dynamic system and change constantly, much like weather! The thing is, we begin keeping track of weather conditions in detail November 1st, so if we are doing our job correctly, we aren’t going into the pit to discover the snowpack details – we are going into the snow pit to verify what we already know.

NWS: This has been super enlightening! Thank you for speaking with us.

Avalanche: Our pleasure.


Snow Profile

Snow Profile showing the snow layers and temperature versus snow depth.


Monthly Snow Pit Profile showing snow showing snow crystals by depth and stability of snow by layer.




Fully staffed at National Weather Service Boise

Meet the Staff at National Weather Service Boise!

RDRobert Diaz—Meteorologist in Charge:  Bob grew up in Northern Idaho and attended Boise State University where he completed his BS in Math.  He then attended the University of Wisconsin for Meteorology and was hired some 30 years ago by the National Weather Service, where he began his career in Redwood City, California.  He has been in ten different positions within the NWS.  He is a huge Boise State Football fan and loves to golf and travel.

TBTim Barker—Science and Operations Officer: Tim is originally from Phoenix, Arizona. He came here via Salt Lake City, Utah and Missoula, Montana.   In his spare time he likes to hike, geocache, and do landscaping.

TLTroy Lindquist—Senior Service Hydrologist: Troy is originally from Nebraska and attended the University of Nebraska in Lincoln to study meteorology. He has worked at NWS offices in California, Colorado, Kentucky, Maryland, Indiana and Idaho. Outside of work, he enjoys spending time with his family, a variety of recreational sports, gardening and other projects around the home.

JBJason Baker—Information Technology Officer:  Jason grew up in Las Vegas, NV.  He has been the NWS Information Technology Officer in Boise for almost 15 years.  In his free time he likes camping, ATVing and fishing with his wife.

DDDavid Decker—Observing Program Leader: Dave is originally from Terre Haute, Indiana, and has lived in various places across the country and world, while in the U.S. Air Force. He has over 25 years of experience as a weather forecaster and program manager. In his spare time he enjoys golf and tennis.


JB1Jay Briedenbach—Warning Coordination Meteorologist: Jay is originally from Florida and attended Florida State University for his BS and MS degrees in Meteorology.  For fun, he enjoys hiking in the summer and skiing in the winter.  He loves living in Idaho!

TMTravis Mayer—Electronic Systems Analyst: Travis has enjoyed working on computers and electronics since he was in the Marine Corps. He is always amazed at how electronics are integrating with each other. There are many different types of electronics that keep our weather office running so each day is an adventure for the electronics shop. He has lived in Boise almost his entire life. He enjoys camping, fishing and ATVing with his family. Featherville and Island Park are his two favorite recreation destinations but he continues to explore new areas of the state. Travis just went over the 10 year mark of federal service, with six of those years working for the Boise weather office.

KJKelly Jardine—Administrative Support:  Kelly has lived in Idaho since her senior year of high school and has enjoyed life in Idaho with her kids, family and friends! NWS is the fourth federal agency she has worked for during her career, having also worked for the VA, BLM and the Forest Service. In her free time, she likes to ski, hike, garden and travel.

WHWasyl Hewko—Hydrometeorological Technician: Wasyl hales from western Pennsylvania, from a humble upbringing in one of America’s well known steel towns. He attended Penn State University for three years, joined the military, where he acquired 27 years of weather experience, after which he received a BS degree in IT from Capella University in 2007. He signed on with the NWS in 2009, starting with an interesting tour on Saint Paul Island, Alaska. Wasyl’s hobbies include sports and fitness training of all types, playing the guitar, and periodically studying math and statistics.

Senior Meteorologists

LCLes Colin: Les was born in New York City and arrived at Boise via New Jersey, Minnesota, and California. He has a BA in Math from the University of Minnesota and an MS in Meteorology from San Jose State University.  His hobbies include blitz chess, travel, and hitting baseballs.

VMValerie Mills:  Valerie is “from all over” having grown up in an Air Force family.  She holds a Master’s Degree in Meteorology from the University of Maryland, College Park. For summer 2015 fun she took a locomotive driving lesson and swam the McCall Parks & Recreation one mile open water swim.

BWBill Wojcik: Bill was born and raised in Buffalo, NY – renowned for prolific lake-effect snow storms. His passion for meteorology was developed at a young age due in part to the wild snow storms. He studied meteorology at Oswego State University and SDSM&T. His career with the NWS began in Phoenix, followed by Pocatello and Boise. He enjoys the outdoors and spending time with his family.

DGDave Groenert: Dave is a Navy child, so he has moved around quite a bit, but eventually settled in the Washington DC area. He has been a forecaster at NWS Boise for 12 years. In his free time he enjoys getting outdoors.

SPStephen Parker: Stephen is originally from a small town in Virginia, and came here by way of Oklahoma, Texas, Nebraska, and Tennessee. He enjoys spending time with family and friends, learning how to increase the amount of love and peace in his life, staying healthy, and following the SF Giants and 49ers, the Virginia Tech Hokies, and of course, the BSU Broncos!


JAJeanne Allen:  Jeanne earned her Meteorology degree at SUNY Oswego, NY.  Her first weather job was a summer job while still attending college and worked on the Fire Weather Program at the Fairbanks, AK NWS office.  After college Jeanne spent a few years as a civilian weather observer for the Air Force in Niagara Falls, NY.  Jeanne then joined the National Weather Service and spent a year in Glasgow, MT before being transferred to Boise, ID.  Jeanne has been at the Boise National Weather Service office for almost 25 years.  In her spare time Jeanne likes to go hiking and doing photography, but really enjoys spending time with her dogs and doing dog agility.

EPElizabeth Padian: Elizabeth has been with the NWS for 4.5 years.  She grew up in Phoenix and has worked at the Phoenix and Pocatello NWS offices. Her and her husband arrived in Boise for her promotion to forecaster in October of 2014. In her spare time she fosters animals and enjoys the art and culture of Boise.

KAKorri Anderson:  Korri was born in Seattle and raised in eastern Washington. He became fascinated in meteorology at a young age while experiencing the erratic weather of the Palouse, and watching his mother take weather observations for Horizon Air.  Korri completed his meteorology degree at MSU of Denver and his MS Civil Engineering at Boise State.  He has worked at the Anchorage, Alaska and Boise NWS forecast offices as a student. He enjoys photography, skiing, hiking, traveling, cooking and staying active.

JSJosh Smith: Josh is from Vermont and received his degrees in Meteorology and Computer Science from Lyndon State College. He has worked in the Burlington, Vermont and Grand Forks, North Dakota NWS offices before moving to the Boise office as a forecaster in 2005. He enjoys getting outside.

JTJoel Tannenholz: Joel is originally from Battle Creek, Michigan, where he developed an interest in weather at an early age. He and his family have lived in Boise since 1983. He is a University of Utah graduate in Meteorology. His many interests include hiking, Celtic music, and art, mainly watercolor painting.

 Fire Weather Meteorologists

CRChuck Redman: Chuck  was born and raised in Albuquerque, New Mexico.  He earned his BS in Meteorology from San Jose State University in 1935. (And doesn’t he look great for 102!?) Chuck’s been the Fire Weather Program Lead here at Boise WFO since 2001. Chuck’s hobbies include swinging golf clubs, mowing the lawn, and discussing the advantages and disadvantages of various protein bars.(But in all seriousness, Chuck was busy forecasting on a wildfire near Omak, Washington and I took some liberties here. – Megan) MTMegan Thimmesch: A born and raised Minnesotan, Megan prides herself on her cold-weather resilience and pronunciation of the word ‘about’. Her love of weather was spurred early on when she discovered the power of the winter storm, i.e. snow days! Megan attended the aptly named St. Cloud State University in St. Cloud, Minnesota; earning her BS in Meteorology in 2004. Her career path with the National Weather Service has included a summer internship in Juneau, Alaska and three different forecasting positions at NWS Boise. Fire weather is now her primary focus.


 Entry-Level Meteorologists

ABAviva Braun:  Aviva is originally from Maryland. After earning a BS in Earth Systems from UMA, Amherst, and her MS in Meteorology from Penn State U., she served in Senegal as a Peace Corps agriculture volunteer. She has now returned to her love for meteorology, and is having a blast living in Boise! In her spare time, she loves hiking, backpacking, camping, whitewater rafting, and general outdoor adventuring! JCJessica Caubre:  Jessica grew up in Belfair, Washington.  She joined the Air Force as a Weather Technician after high school and always dreamed of getting out and working with the NWS.  After the Air Force, she attended the University of Washington where she received a BS in Atmospheric Science while working at KOMO News 4 with Steve Poole, before being hired on in lovely Boise, ID.

Electronic Technicians

GBGeorge Buckwold: George grew up in Southern California before he joined the U. S. Air Force. George served all across the country and in Vietnam as a radar technician.  After retiring from the Air Force, George moved to Boise were he has been maintaining our electronic systems since 1995. George is an avid archery hunter.


EJEric Johnson: Eric’s career in electronics started in 1990 in the U. S. Air Force as an Avionics Technician on C-130E aircraft.  After his enlistment, he attended Boise State University while also enlisting into the Idaho Air National Guard as an avionics technician.  Eric graduated from BSU with an AS  in Electronics Technology and a BS in Communication and Management.  He holds a master certificate in spark adaptive theory for spark plug gap maintenance.   He has worked at the National Interagency Fire Center for 13 years;  10 years for the BLM working in Remote Weather in wildland fire and the remaining three for the NWS.  He is still in the Air National Guard and is a maintenance officer for the 124FW’s A-10C maintenance group.  In his spare time, he likes to camp and ATV in the mountains; he really likes the outdoors!   He enjoys the customer service part of the NWS, and looks forward to implementing new technology to help in the protection of life and property.