Wasatch Weather Weenies

The Caldor Fire continues its relentless march eastward and northeastward.  The latest on #Firemappers shows the fire has crossed route 89 and is now pushing into the Carson Range.  Many homes and cabins are threatened and there was a mass exodus from South Lake Tahoe yesterday when evacuation orders were issued.  You can add Heavenly to the list of ski areas threatened.   Source: Firemappers, 8 am MDT 31 Aug 2021 To the south, Kirkwood is now under direct threat.   Source: Firemappers, 8 am MDT 31 Aug 2021 My son and I ski toured a closed Kirkwood with a dwindling snowpack on May 9th.  It's a beautiful area and we were very impressed by the trees.  Enough so to take the photo below. I have no strong connection to the area other than that day, which was the first time I had been through Carson Pass.  I am hoping for a miracle for everyone and the forests effected.   Meanwhile to the north, the monstrous Dixie Fire has now surpa...

Tomorrow (Tuesday) is the last day of meteorological summer.  September is almost here!  Celebrate with Earth, Wind, and Fire. On the other hand, there's not much to celebrate this morning as summer is ending with hazards aplenty. Ida The children's song goes "What does Idaho, she hoes her Maryland," but yesterday, Ida raked Louisiana, coming ashore after rapidly intensifying into a ferocious category 4 hurricane.   Ida at Landfall.  Source: NCAR/RAL. The track and intensity forecasts for Ida were quite good, as pointed out by Sam Lillo below.   Every NHC forecast for Ida. One might say they're pretty good at their jobs. pic.twitter.com/aHhVvw2lHr — Sam Lillo (@splillo) August 29, 2021 Still, it is a devastating event and one with compound hazards from wind, storm surge, precipitation-related flooding, and COVID-19.  The phrase "it's over" doesn't really apply today in southeast Louisiana. Caldor Fire Fires continue to rage in California, with t...

Changes in the statistics of climate and climate variables is sometimes referred to as climate nonstationarity.  It makes climate "normals" and other statistics based on past data increasingly irrelevant as the climate changes.  A good example is provided by the mean summer (June, July, August) temperatures in Salt Lake City. The graph below shows the mean summer temperatures in the Salt Lake City area from 1875-2021 (blue;the latter year included with a few days missing), the 30-year running mean temperature (red), and the 1991-2020 average temperature (orange).   Data source: http://xmacis.rcc-acis.org/ Prior to approximately 1965, temperatures in the Salt Lake City area fluctuated without a major trend, but after that time, temperatures began to climb.  The average summer temperature for the 30-year period from 1936-1965 was 72.9˚F, but for the 30-year period from 1991-2020 it was 76.4˚F, an increase of 3.5˚F.   The 30-year averages are sometim...

My University of Utah Atmospheric Sciences colleague Dr. Timothy Garrett and his team are embarking on a citizen science project to classify snowflakes and train computer algorithms to improve snowfall prediction.  Tim provides a summary of this effort, including how you can participate, below. Snowflake ID A British expression for a phony excuse is “the wrong kind of snow”, a phrase originally coined by British Railways to justify winter train delays. For residents of Utah, such dry humor might be lost — snowflake type affects our enjoyment of wintertime sports. The key distinction that is usually made is between fluffy “aggregates”, or assemblages of pristine six-sided snow crystals, and denser “graupel”, small hail-like pellets that grow when a single snowflake collides with millions of tiny cloud droplets as it falls, and these freeze on its surface. Studies have shown that determining which type of snow forms in clouds is crucial for accurate weather and climate prediction. Be...

 

It's a little known fact that the U.S. Bureau of Labor Statistics projects an above average job outlook for the atmospheric sciences from 2019-2029.   The field is small, but growing with broadening career opportunities.  When most people think about meteorologists, they think of television or National Weather Service meteorologists, but the reality is that most of our students work in other areas.   As examples of emerging opportunities, Amazon currently has 5 weather-related openings to expand their group of weather professionals.  These openings are: Principal HPC Solutions Architect for Weather Modeling , AWS: Craft cloud-based weather and climate modeling solutions for AWS customers. Weather Research Scientist , Modeling and Optimization: Model weather’s impact on various aspects of Amazon's business, supply chain, and transportation network. Software Development Engineer , Modeling and Optimization: Build software systems that can help Amazon pre...

What a deluge.  Impressive totals around northern Utah and it's still raining hard this morning in some areas, including the University of Utah. Below are estimated rain totals for the 24-hour period ending at 1200 UTC (0600 MDT) this morning from the National Weather Service.  Nearly all of Utah saw measurable precipitation, with a large coverage of > 0.5 inches.   Source: NWS That analysis probably has some uncertainty in it due to spatial resolution and the datasets and algorithms used.  Below are some station reports for the 24-hour period ending around 1500 UTC (0900 MDT).  There are a few sites in the Salt Lake Valley with > 2" and in the Uinta Mountains reaching 2.7".   Source: MesoWest/Synoptic Data Some of that precipitation in the Uintas certainly fell as snow, although I suspect accumulations are limited due to the mild air and ground temperatures.  The soil temperature measured by the SNOTEL site at Chepeta (12,120 ft) in th...

After a summer of heat, enjoy the weather this week.  We are in a magical place meteorologically with a deep midlatitude trough at upper levels and monsoon moisture at low levels.  Overnight (0900 UTC; 3 AM MDT) GFS forecasts show the upper-level trough centered just west of Boise (black contours) with monsoon moisture, indicated by the color precipitable water contours, streaming northward at low levels through Utah.   This gives us instability, but also wind shear and large-scale forcing to help with precipitation generation and convective storm development.   Additionally, there's also a surface front somewhere out there, although there's so much convection and precipitation out there, it's pretty chewed up and not easy to precisely locate.   As I write this, the 1410 UTC (0810 MDT) radar shows a broad area of precipitation over Salt Lake, Summit, and Wasatch Counties, with scattered showers and thunderstorms elsewhere.   You don't se...

I've been out of town for the past week and it sounds like it has been an eventful one in Salt Lake City. Yesterday marked the 21st day with a maximum temperature of 100˚F or higher, tying the all-time record.  There was also that incredible fire in Parley's Canyon, which due to heroics by fire crews and a remarkable aerial assault, may have been tamed.  I hope that is the case. I've been visiting family and spending some time enjoying the Adirondack Mountains.  It has been a fun return to the homeland, although it has been quite humid, making for some sweaty hikes.   Any trip to these parts is a walk down memory lane for me.  I last hiked Cascade Mountain, one of the Adirondack "High Peaks" with my father in 1979 in an October snowstorm.  Forty-two years later, Andrea and I ascended the trail, which other than being snow-free this time, was still rocky and rugged. IThe weather on top was better this time and we could linger and enjoy the view.  B...

If you have some anxiety about the start of classes at the University of Utah on August 23rd, you are not alone.  I have been working on campus since sometime in April.  It's been pretty quiet, everyone I interact with is vaccinated, and until a few week ago, case counts were quite low.  In May and even June I wasn't very concerned about requirements imposed on us by the State Legislature to teach 75% in person, not require vaccinations, and not mandate masks.  I was hopeful for a return to something close to normal, if we weren't thrown a curve ball. However, that curve ball has come in the form of a significant population that has elected not to get vaccinated and the more contagious delta variant.  Earlier this week, Dr. Micheal Good, CEO of University of Utah Health and acting President of the University of Utah, provided the update below, illustrating some of the trends in COVID-19 cases, hospitalizations, and deaths.  I have been developing some class...

Smoke has returned to northern Utah and with it degraded air quality and reddish sunrises and sunsets.  Below is last night's sunset showing a deep orange sun and the reddish hue of the smoke.   Many people believe that the sun is yellow, but in reality, the sun is white.  It emits all visible wavelengths of light at sufficient intensities that the sun in space appears white.   NASA photo of the sun and International Space Station in May 2011 So, it is a myth that Superman's powers derive from the yellow sun.  It's a good story, but the sun really isn't yellow. On the other hand, to those of us on the Earth's surface, it certainly appears yellow or, in some instances, orange or red.  This is because of the selective scattering of light by the Earth's atmosphere and constituents, especially aerosols.  Molecules in the Earth's atmosphere scatter shorter wavelength light, such as blues and violets, more readily than longer wavelength light like ...

Thunderstorms with heavy rain, frequent lightning, and nearly continuous thunder move north-northwestward into the Salt Lake Valley from the Wasatch Mountains, resulting in a number of issues related to flash flooding. Portions of the northern Wasatch Front were also affected.   The system that affected the northeastern Salt Lake Valley, including Mill Creek, Sugarhouse, St. Mary's, the University of Utah, Downtown, and the Avenues began to develope over the Wasatch Mountains just before 0000 UTC (6 PM) yesterday evening.  At 2352 UTC (5:52 PM MDT), the first strong cell appeared over Big Cottonwood Canyon. This cell exploded in intensity and coverage over the next 20 minutes.  Anyone recreating in Big Cottonwood or Mill Creek Canyon would have been quickly overwhelmed by heavy rainfall, and possibly small hail.  A second cell began to develop at this time on the Alpine Ridge south of Little Cottonwood.  At this point, all hell began to break loose as more ...