Wasatch Weather Weenies

There are dramatic differences in air pollution episodes over the Salt Lake Valley between winter and summer. During winter, when the sun angle is low, we frequently lack sufficient surface heating to warm the atmosphere and develop a deep layer in which turbulence can mix the near-surface air with the atmosphere aloft.  The layer in which that turbulence occurs, which is known as the boundary layer (or mixed layer) , can be very shallow.  As a result, emissions from our urban area are trapped in the valley, leading to elevated particular matter concentrations. An example is the inversion event of late December 2016.  As can be seen in the photo below, taken on the afternoon of 30 December, smog is confined primarily to the valley and the visibility improves dramatically with altitude.  Typically in these instances, one can find clean air simply by going to the mountains. A sounding taken that afternoon at the Salt Lake Airport is very typical of of winterti...

" The old records belong to a world that no longer exists " - Dr. Marty Hoerling, Research Meteorologist NOAA Earth Systems Research Laboratory It has been a remarkable summer across the Northern Hemisphere, with high-temperature records being set at locations in North America, Asia, Europe, and North Africa.  Now that we are well into the fire season, a pall of smoke generated by large wildfires hangs over much of the western United States, as evident in yesterday afternoon's GOES-16 satellite image.   Source: CIRA Will we ever return to normal? No. Although the climate, especially on regional scales, has always exhibited variability, we are now accelerating into a future in which the planet will be warming at a rate not seen since the emergence of human civilization.  Further, while this warming may occur in fits and starts rather than at a steady rate, the idea that what we are currently experiencing is "just a cycle" is pure fantasy...

Thermal anomalies (red) and smoke from the Carr Fire as seen from Aqua/MODIS 26 July 2018 A catostrophic situation is unfolding in northern California where the Carr Fire is threatening communities in and around Redding. The latest incident information from Cal Fire indicates that as of 9:17 AM this morning (27 July), the Carr Fire has burned 44, 450 acres, destroyed 65 structures, and damaged 55 structures.  Only 3% contained, the fire is currently threatening almost 5,000 structures, with numerous evacuations and road closures.  News reports indicate that the fire has now claimed the lives of two firefighters . News footage of the fire is simply unbelievable.  Below are a couple of perspectives on rotating updrafts associated with the fire. No, this is not a tornado. The Carr Fire in Shasta County created this rotation updraft. #CarrFire #California pic.twitter.com/CVvcafJBGK — ABC10 (@ABC10) July 27, 2018 Timelapse video shows the #CarrFire approa...

This morning dawned with smoky skies and a fairly orange sun that wasn't well captured by my cell phone camera while looking up City Creek Canyon from the Bonneville Shoreline Trail.  Although the perspective is a bit oblique, I love looking at the beautiful GOES-16 imagery from CIRA.  Smoke covers a large portion of central and northern California, northern Nevada, southern Oregon, and southern Idaho.  There's some that has snuck into northern Utah as well.  GOES-16 imagery from CIRA at 1507 UTC 26 July 2018 The purple air network shows moderate or worse air quality across much of that area (sadly with few observations in Nevada).  Source: PurpleAir, 9:35 AM MDT 26 July 2018 Those of us in northern Utah shouldn't complain.  The misery index in California is off the scale.  In addition to smoke and associated poor air quality, high temperatures in the Central Valley are expected to be anywhere from 106 to 112˚F.  Hideous.

Yesterday afternoon, a grass fire quickly burned 100 acres above Victory Lane just north of the Utah State Capitol, threatening homes in the area.  Source: Rich Bowmer | The Associated Press | The Salt Lake Tribune Smoke from the fire sent a chill up my spine as it emerged from Capitol Hill, illustrating that this was a very serious situation.  Kudos to the Salt Lake City Fire Department, which responded quickly and got the situation under control.  According to the Salt Lake Tribune , only one home was damaged.  Three firefighters were, however, hospitalized, two for heat exhaustion and smoke inhalation and one for a leg injury.  We wish them speedy and complete recoveries.  The origin of the fire remains unknown, but was almost surely human caused.  The threat of a similar fire remains, with caution, vigilance, and taking steps to protect your home the keys to reducing risk.  Below are recommendations of the National Fire Protection...

Take a gander at the GFS 10-day forecast below, especially the top frame, which illustrates the evolution of the winds on the dynamic tropopause (jet-stream level).  Note the slow westward movement, or retrogression , of a very strong upper-level ridge across the southwest US and northern Mexico during the period.  The intensity of this ridge over the southwest US and northern Mexico is quite unusual for this time of year.  For example, the NAEFS mean 500-mb height forecast for 1800 UTC today shows values that are outside climatological values for the 1979-2009 period.  In other words, we are dealing with unusually strong ridging at those latitudes for July. Source: NWS In general, people associate high pressure with fair weather, but the #1 weather-related killer nationally is heat and a strong ridge this time of year over the southwest makes for extreme heat.   As can be seen in the NWS forecast below, excessive heat warnings extend across much...

The climatologically hottest week of the year begins today. There is a 7-day stretch from 23-29 July during which each day the average temperature is 80˚F at the Salt Lake City airport, the warmest of the year. Call it hump week.  After this, we are on the downward slope to winter! It's worth a look back at the summer so far.  We've done this once or twice already, but let's dig a little deeper.  The period from 1 June - 22 July ranks as the 4th warmest on record based on average temperature .  Technically, we are tied for 4th with 2007. Source: NOAA Regional Climate Centers Curiously, this warmth has been achieved with only one day with a maximum temperature of 100˚F or greater (102˚F on 6 July).  Indeed, for average maximum temperature, the period only rates as the 15th on record with 90.6˚F, nearly 3˚F behind 1961 (93.5˚F). Source: NOAA Regional Climate Centers However, for minimum temperature the period is the 4th warmest on record behind...

The past few decades have been quite exciting for meteorologists as our field, like many others, has been transformed by massive technological change.  Today I took some time to go through my personal archives from graduate school and finally pitch some stuff that's been collecting dust for years.  It was a good reminder of just how far we've come in the past 25 to 30 years.  As an undergrad in the late 1980s, the Internet wasn't really yet a thing.  I don't recall using it and I certainly didn't have an e-mail account.  We did not look at weather observations, satellite imagery, radar imagery, or model forecasts online.  That information came via DIFAX charts and you were happy to get what you got.  If you wanted to forecast the weather, you had to go somewhere that had these charts, such as a University "map room", so named because the maps were simply hung on the wall.  Through the 1990s, DIFAX remained a thing and I spent a lot of time i...

This morning's 500-mb upper air pattern features an upper-level ridge, or anticyclone , centered off the southern California coast.  The anticyclone is zonally elongated , which means stretched in an east-west direction.  The flow at this level roughly parallels the 500-mb height contours, with lower heights on the left, which yields easterly flow to the south of the anticylcone over Mexico and the subtropical eastern Pacific Ocean, and westerly flow to the north over Canada and the Pacific Northwest.  Such a pattern is not unusual in July, although in this case, the anticyclone is centered west of its climatological mean position over southern New Mexico and the easterlies to the south are a bit stronger than average.  There are two important smaller-scale features at this level.  The first is a trough in the westerlies over the Pacific Northwest, indicated by a brown dashed line.  The second is a trough in the easterlies over northern Mexico, also ...

After an aborted attempt to ski Kings Peak in May (see Uinta Misadventures ), my son and I decided we needed to go back this summer and make the summit.  I have lived in Utah for 23 years and incredibly haven't done Kings Peak, so we left Friday afternoon to try and bag it Saturday (yesterday).  The hike in on Friday evening was as enjoyable as a long slog can be.  The meadows were pretty and the trail dry and fast.  We realized quickly what a folly it had been to try and ski Kings in May with patchy, unsupportable snow on AT gear.  Good golly, what a long approach for what would have been a minimal amount of turns! Friday night I awoke at 2 AM or so and peered out at wonderfully clear skies.  Sunrise Saturday morning was beautiful.  However, just visible in the pond reflection are some clouds that were floating about and gave me a little heartburn.  I was mainly concerned about afternoon thunderstorms.  I had anticipated a slight...

Nordic Valley is a small ski area near Eden in the Odgen Valley east of the northern Wasatch Mountains.  It has a base elevation of 5400 feet, the lowest in Utah, and a vertical drop of 1000 feet. The owners, however, have recently announced major expansion plans ( see this Salt Lake Tribune article published this morning  and this Ogden Standard-Examiner article published on June 25th ) that include the installation multiple lifts including a 4.3 mile long gondola from North Ogden and expansion onto 2800 acres of national forest.  The map below is from the Nordic Valley expansion plan web site ( https://nordicvalleyproject.com ), which unfortunately is oriented so that north is toward the bottom.  The summit elevation would be around 8100 feet, a tad higher than the base of Snowbird and a tad lower than the base of Alta. Source: https://nordicvalleyproject.com/ There are a host of concerns about the proposed project highlighted in the articles linked...

Olympic gold medalist Kikkan Randall announced yesterday that she was recently diagnosed with breast cancer.  Randall is a 5-time Olympian and 13-time World Cup race winner in cross country skiing.  She and Jessie Diggins provided one of the great moments during the 2018 Pyeongchang Winter Olympics when they won the women's team sprint and earned the first Olympic gold medals for a U.S. cross-country skiers.  Jessie Diggins and Kikkan Randall (right).  Photo: Sarah Brunson/U.S. Ski & Snowboard. Randall's diagnosis hits home for me as my wife is a two-time breast cancer survivor.   According to the Anchorage Daily News , Randall found two pea-sized lumps in her breast on Mother's Day and will begin chemotherapy this week.  Like many younger women affected by the disease, she is a mother, with a 2-year-old son.  There is a 1 in 8 chance of a woman in the United States developing breast cancer during her life time.  However, there ...

Human comfort is strongly influenced by a number of factors including temperature, humidity, cloud cover, and wind.  For the purposes of this post, I am going to focus on one that I consider to be especially relevant to human comfort in the Salt Lake Valley, the minimum temperature. In particular, I am going to declare 70ºF as a critical threshold in comfort, with minimum temperatures below that value generally yielding reasonable comfort, whereas minimum temperatures above that level generally yielding uncomfortable sleeping conditions.  Going a step further, I'll define the human misery index in Salt Lake City as being equal to the number of days with a minimum temperature at or above 70ºF.  Looking at historical data for the Salt Lake City Area stretching back to 1874, we see a rapid change in the July human misery index beginning around Y2K.  In particular, around that time a clear upward trend began and we have had five Julys since 2007 with 15 or more days...

Beating the heat, I did a quick climb of Mt. Baldy and Hidden Peak this morning, giving my knees a break with a descent via the Snowbird Tram.  Some observations. I was on the summit of Mt. Baldy at about 9:45 am.  The view to the east was a scene from the Great Smokies and a good example of how smoke can become trapped in valley cold pools that develop overnight.  We've been fortunate in the Salt Lake Valley to have not been in the smoke plume except for a brief period late Thursday night and Friday.  For snow lovers, I found the patch below at about 9400 feet in an area where contributions of artificial snow to the snowpack would probably be small to non-existent.  I'm guessing it is the lowest remaining snow in the Wasatch.  Prove me wrong... Finally, a little comparison of the snowpack on this date (8 July), compared photos I've taken in July the previous two years.  The situation this yea is pretty grim.  Just a few patches to...