Wasatch Weather Weenies

Photos courtesy Trevor Alcott and Jim Steenburgh If you are a regular reader of this blog or just an occasional visitor, I hope you have enjoyed our discussions of mountain weather and climate.  Perhaps you also peruse and take advantage of some of our weather forecasting products at weather.utah.edu or mesowest.utah.edu .   If you like the Wasatch Weather Weenies blog and are interesting in helping us transform weather and climate prediction in mountainous regions, especially in the Wasatch Mountains and northern Utah, click here and consider making a donation to our Mountain Meteorology Fund. Created by an anonymous donor in 2005, the  Mountain Meteorology Fund supports education and research in mountain weather and climate at the University of Utah .   Now is a great time to give as I will personally match the first $500 in contributions.  So, consider a donation (typically tax deductable) and help us address challenges ranging from powder pred...

Chapter 18 of Clouds in a Glass of Beer: Simple Experiments in Atmospheric Physics  by Craig Bohren One of the more important individuals in my academic development was Craig Bohren, a meteorology professor at Penn State University who was my undergraduate advisor and physical meteorology instructor.  Craig was a lunatic.  When they banned smoking on campus, Craig came into class smoking a cigarette and blowing smoke rings to teach us about vorticity.  When students asked him if they could bring a one page cheat sheet to the exam he responded, "you can bring whatever the hell you want, it won't help you one bit because I don't give those kind of tests."  His tests were indeed nasty.  If you got something like a 45 out of 100 on an exam, you were probably on track for an A. Craig was a lunatic, but he was brilliant and inspirational (it took a few years past graduation to realize this).  He always carried a camera.  Whatever he saw on his lon...

You decide.  

As can be seen in the loop below, your classic spring day is on tap today with showers and thunderstorms.  Put on some Clapton and enjoy, because July will be here soon.  

Rumors of up to 30" at Whiteface Mountain in NY.  Photos below from whiteface.com .

Looking for pow this Memorial Day?  The base is pathetic, but you can find freshies today in the Adirondacks of New York and the mountains of northern New England. Whiteface Memorial Highway 25 May 2013 Source: Whiteface Facebook Page Morgan Langey Meanwhile in Utah, the Wasatch snowpack is taking a beating with temperatures near 60 at 8000 feet.  I walked up to our observing site near Alta at about noon and was dismayed to find that a river runs through it! If only I knew this site turned into a stream bed during the runoff!  Special thanks to whoever hung our interval board and snow depth sensor on the ladder.  Of course, it could have provided reliable stream depth measurements instead (they can do that).  This is a prime example of how it can be difficult to get representative information about the snowpack based on an observation collected at a single point!    

If you haven't been to the Natural History Museum of Utah , you should go soon as it is one of the most spectacular Natural History museums in the U.S. if not the world.  In addition, if you are a Wasatch Weather Weenie, there is a really good reason to visit between now and December 8 as they are hosting the traveling display Nature Unleashed: Inside Natural Disasters , which opens for members today and the public on Saturday. I had the good fortune of attending the unveiling party last night.  There are displays on earthquakes, volcanoes, hurricanes, and tornadoes. The hurricane exhibit asks the question, why does a hurricane form? This is a great question because it actually remains inadequately answered by scientists today. Wasatch Weather Weenie, U atmospheric sciences graduate student, and certified "storm chaser" Peter Veals served as a subject matter expert last night.  In July, they are adding an exhibit on wildland fires, which should be qui...

Over the past few years, we have seen a number of wind-blown dust events, especially in the spring, which have turned our precious Greatest Snow on Earth into the Greatest Snirt on Earth (Snirt=part snow part dirt).  These dust events are typically "recorded" in the snowpack as dirty layers, which collect on the snow surface during the spring melt.  The intensity and frequency of dust events vary from year to year depending on meteorology and land surface conditions.  Below are examples of relatively clean and dirty spring snowpacks in the Wasatch Mountains. This year has been relatively dust free.  I haven't been up in the Cottonwoods for a while, but reports suggest that the snowpack is relatively clean and that was the case in April when I last made turns.  Yesterday, however, we saw some wind-blown dust over the Salt Lake Valley, with some obscuration of the visibility both in the pre- and post-frontal environment.   The lack of dust e...

Climatologically, the highest frequency of significant (F2 or greater) tornadoes in the world occurs the southern Great Plains during the spring.  That's why the region is appropriately referred to as  Tornado Alley and why Norman, Oklahoma has become the nexus for severe weather research, forecasting, and education in the United States (with a tip of the hat to many talented people who helped to make it so).   Source: Storm Prediction Center We don't usually think of Tornadoes as a mountain meteorology problem, but it turns out that the severe storm environment of the Great Plains is partly a consequence of topography and land-sea contrasts.  During the spring, the confluence of dry, downsloped air from the deserts and high terrain of the southwest US and northern Mexico (airstream SP below) with cooler, moister air originating over the Gulf of Mexico (airstream M) frequently leads to the development of the dryline .  The dry, downsloped air often conti...

Radar reflectivity loop of the Moore Tornado of 20 May, 2013.  Moore area indicated by red box.   When I heard yesterday afternoon that a tornado struck Moore, OK, I got a pit in my stomach.  Moore was devastated by powerful tornado that rated as high as F5, the highest rating for tornado intensity on the Fujita Scale, in May of 1999.  Sadly, tragedy had struck again. Jeff Masters provides a far better summary of this event than I could on his WunderBlog site.  Click here to see his discussion of the historical context of the tornado and the storm structure.  I thought I would take a few moments to put this storm into context for those of us who live along the Wasatch Front. Many of you will recall the tornado that hit Salt Lake City on August 11, 1999.  It was a day I will never forget as I watched the tornado move directly through the Avenues, very near my home.  It was the first tornado that I had ever seen, and, being a meteorologist...

For lovers of clouds, you don't get many days better than today.  Some probably like big cumulonimbus clouds, but I prefer a mixture and today we have just about everything from the cumulus humilis (a.k.a. cumulus patheticus) over extreme northwest Utah and northeast Nevada to cumulus congesus over northeast Utah.  There's also evidence of cloud bands downstream of the Great Salt Lake. Watching this look you can learn a lot about the wind structure today.  Track the clouds to ascertain the wind direction.  You can find easterlies near the Uinta Mountains and North–Northeasterlies over and south of the Great Salt Lake.  You can also infer a lot about the temperature of the lakes of northern Utah.  The Great Salt Lake appears to be contributing to the initiation of cloud bands, whereas there is a clear cloud hole over and downstream of Bear Lake for much of this loop.  Presumably the Great Salt Lake is warm enough to destabilize the atmosphere, wher...

Der Bau der Arche Noah by Franzosischer Meister Source: Wikipedia The rains continue this morning and I'm wondering if it is time to start building an ark.  Here are a few of the bigger 48-hour precipitation totals over the northern Wasatch Front for the period ending at 7 PM last night as reported to the National Weather Service.  This is before the overnight deluge. Logan Airport: 1.18 inches Brigham City (4400 ft): 1.88 inches Ogden Airport: 1.26 inches Bountiful (4760 ft): 1.51 inches For the 72-hour period ending this morning at 7 am, the Salt Lake Airport has received 0.52 inches.  That's not all that impressive, but it appears to be one of the drier areas in the Salt Lake Valley (as it often is).  A few sites along the upper east bench were near a full inch before the rains last night.   For you gardeners out there, the next few days will offer up the best weeding and tilling conditions of the year.  

Nearly everyone along the Wasatch Front from Draper north is getting a good soaking this morning and for that we can all be thankful.  A dump like this will really increase the soil moisture and help with the gardens and the lawns. Plus, it is snowing again in the mountains. Source: Snowbird Many of the observing sites at the resorts have been shut down for the summer, but our site near the base of Alta shows a temperature of 32.5ºF with about 0.32 inches of snow-water equivalent since midnight and 0.56 inches in the past 24-hours.  It's probably cream on crust at upper elevations, but one shouldn't complain in May.

Regular readers will recall the overhyped and inaccurate predictions of record snowfall (218 inches in four days) on Mount Shasta last winter which we discussed in two posts ( Is a US Snowfall Record in Jeopardy and Mt. Shasta Update ).  The storm that still holds the record for single-storm accumulation occurred on Mt. Shasta from 13–19 February 1959 (more below).   An article examining this storm  (Hansen et al. 2013) is included in the inaugural edition of the Journal of Operational Meteorology, a publication of the National Weather Association. Unfortunately, the article is payrolled except for National Weather Association members, but if you aren't a member, you can have a looksee at the abstract above and get the gist. There does, however, seem to be some confusion concerning the record status of the February 1959 Mount Shasta storm.  Hansen et al. (2013) suggest that the 4.8 m (189 inches) of snow that fell on Mt. Shasta was unmatched and unbroken unti...

I thought I'd take a moment to report three items of interest making news this past week.   1. Quantum Leap .  First, as discussed at the Capital Weather Gang , a major infusion of computer power is in the works for the National Centers for Environmental Prediction (NCEP), which is receiving support from the Disaster Relief Appropriations Act of 2013 (a.k.a., the Sandy Supplemental) to increase their computer capacity from 213 teraflops to 2,600 teraflops by the 2015 fiscal year.  The Capital Weather Gang called it a game changer, so I'll call it a quantum leap.  No matter what it is called, it is a badly needed infusion of computer power that will hopefully be leveraged to produce a significant advance in weather prediction capabilities for the nature.  Source: allposters.com 2. Strategic Planning .  Curiously, as NCEP gets this infusion of computer power, this week also saw the release of  Forecast for the Future: Assuring the Capacity...

There was a great rainbow display this evening in the Avenues with very distinct primary and secondary bows.  The primary is the brighter, inside bow, but unfortunately, the pot of gold was located just a bit east of campus.  That's a pity as we're always looking for more funding. To compensate for my poor photographic skills and the fact that it was nearly impossible to take a picture given that wind was coming from the rainbow's direction and driving rain into the lens, I've doctored the photo below just a bit to help with contrast. There was some evidence of supernumerary bows on the inside of the primary bow.  I tried to get a good photo, but alas, it was beyond my skills. For you weather and optics geeks, Les Cowley's Atmospheric Optics site is the cat's meow.  He has a great page on rainbows .  I just learned that the dark area between the primary and secondary rainbow is known as Alexander's dark band  and is named for Alexander of Aph...

If you think it has been hot in Salt Lake with maximum temperatures of 93ºF and 89ºF the past two days, it could be worse.  Temperatures in parts of Kansas, Nebraska, Iowa, and Minnesota reached or eclipsed 100ºF yesterday. The ramp up to the 106ºF in Sioux City, Iowa is most impressive.  The call letters for this station are KSUX, and I think it is safe to say that the weather there SUX at present. It was less than two weeks ago that it was snowing in Iowa (see  From snow to 100 degrees, this is Iowa | Weather - KCCI Home ). Ah, the joys of spring!

Yesterday's high of 93ºF broke the previous record for the date of 92ºF set in 1996.  The relative humidity dipped to as low as 11%.  We need rain. There's a slight chance of thunderstorms the next couple of days, but then a bonafide trough coming in for Friday and Saturday (timing TBD). Keep your fingers crossed.  We could use the rain.

There is considerable media coverage this week discussing how CO2 concentrations at Mauna Loa observatory have eclipsed 400 parts per million for the first time since measurements began in 1958.  This somewhat ill defined but all important milestone is discussed in a press release issued by NOAA yesterday . Charles David Keeling of the Scripps Institute of Oceanography began collecting CO2 measurements on Mauna Loa in 1958 and the graph illustrating the subsequent increase in CO2 to the present is often referred to as the Keeling Curve .  The graph usually is based on monthly average CO2 concentrations and thus shows both the long term increase in CO2, but also the decline of CO2 in the Northern Hemisphere spring and summer due to plant growth and a rise in the fall due to plant decay. Source: http://keelingcurve.ucsd.edu/ It is a bit hard to see, but the annual rate of rise has increased from about 0.7 parts per million per year in the late 1950s to about 2.1 parts per...

If you like it hot, get ready because your day is coming.  A high amplitude ridge will be building in over the Intermountain West this weekend and we will see temperatures climbing a bit more each day until we reach a blistering climax on Monday when 700-mb (mountain top) temperatures are forecast to be near 13ºC. That translates to a maximum temperature at the Salt Lake airport approaching 90ºF.  Sounds like a good reason to get the swamp cooler or A/C tuned up, although the models suggest this will only be a brief flirtation with the big 90. With such high temperatures, we probably will see the most intense runoff so far this spring on Monday afternoon and evening along the snow-fed streams of northern Utah.  Snowpack snow-water equivalent (SWE) peaked at Snowbird in late April and has been dropping steadily the past week, indicating that the snowpack is fully ripened and that any excess energy from the sun or atmosphere will be going directly into melting snow. ...

Doug Wewer sent me some remarkable photos of mammatus clouds that he took at about 1 PM yesterday (May 8) on highway 191 just north of Rock Springs, WY. Photos courtesy Doug Wewer The name for mammatus or mammary clouds derives from the breast like lobes at the cloud base.     Schultz et al. (2006) called mammatus clouds an "enigma of atmospheric fluid dynamics and cloud physics" as they have rarely been the subject of detailed scientific investigation and remain poorly explained.  Since their article, there have been several papers on the subject, but a so called "unified theory" has yet to emerge.  Most mammatus events in the Intermountain West feature a dry, well mixed layer beneath cloud base and cooling produced by the mixing of moist and dry at cloud base and the sublimation (i.e., evaporation) of ice crystals falling out of the cloud may be important contributors in generating the convection that produces the lobes ( Kanak et al. 2008 ; Kudo ...

For the second day in a row we are being treated to flashes of lightning and rumblings of thunder on the University of Utah campus.  In both instances, the thunder and lightning are being produced by storms that moved in from the east or southeast.  Here's the latest showing the thunderstorms that are moving across the Wasatch and towards campus at about 2:15 PM today. The culprit in driving these storms westward is of course the huge split flow that is present over North America along with an embedded upper-level trough that is stretched out like a rubber band from southern California to Colorado and driving easterly flow across northern Utah at 700 mb. Given all these thunderstorms, now is a good time to remind everyone that when thunder roars, head indoors .   As discussed in today's Salt Lake Tribune , lightning yesterday damaged an Air National Guard plane and struck a house in West Jordan.  Take a few minutes to read our post Lightning Safety and take...

Yesterday we discussed the anomalous split flow pattern that is dominating the weather of North America .  The pattern is producing some weird weather, as illustrated by the maximum temperature analysis for yesterday. In particular, note how upside down the temperatures are in the west.  Maximum temperatures in the Pacific Northwest reached 87ºF in Seattle and 91ºF at The Dalles along the Columbia River.  Compare these to the 87ºF and 85ºF in Phoenix and Tucson, respectively.  Climatologically, the average Maximum temperature is 66ºF in Seattle and 73.5ºF at The Dalles, compared with 93.7ºF in Phoenix and 90.5ºF in Tucson. If you look up into western Canada, you can find a few sites in the high 80s and even a 92ºF at what appears to be Lytton, BC, which is located at 751 ft MSL in the Fraser River Valley. Similarly, the things are topsy turvy in the east.  Maximum temperatures in northern New England and southern Quebec at or above 80ºF, including an 86...

" When you come to a fork in the road, take it " - Yogi Berra Strong split flow presently persists over North America, with a strong polar jet over Canada and a strong subtropical jet over Mexico and the Gulf of Mexico.  I've crudely identified these jets on the dynamic tropopause (jet level) wind speed analysis below.  This strikes me as an unusually strong example of split flow in May, but some digging is needed to ascertain how unusual. This split flow extends further downstream across the North Atlantic and into Europe and Africa, making this a hemispheric-scale event.  This is a good time to be flying westward across the North Atlantic or continental US as you aren't fighting the westerly flow that is commonly found at mid latitudes. One nice aspect of this pattern is that it doesn't favor strong Intermountain cyclogenesis and associated southwesterly flow.  This has contributed to the dearth of dust storms this spring.

There are times when I get a pit in my stomach as I come to the realization that something is happening that wasn't well forecast.  I had such a feeling when I got home last night around 10:30 and felt an east wind blowing at my house in the Avenues.  We have had a good run of forecasts pertaining to downslope winds over the past year or two, but the event last night was poorly forecast and illustrates that we have some work to do. Here are a few time series from overnight.  They illustrate easterly downslope winds reaching 60 mph at Farmington, 55 mph at Logan, and 51 mph at the University of Utah.      We really whiffed on these forecasts.  Here are the NWS forecasts issued 3:39 PM yesterday afternoon.  The zone forecast for the Salt Lake Valley has no mention of downslope winds: TONIGHT...PARTLY CLOUDY. ISOLATED SHOWERS AND THUNDERSTORMS IN THE EVENING. LOWS IN THE UPPER 40S. CHANCE OF PRECIPITATION 20 PERCENT. And, for...