Wasatch Weather Weenies

Friday was a remarkably active thunderstorm day in northern Utah, including a verified tornado in the Wasatch Mountains east of Fruit Heights.   Sadly, a 19 year old man was killed by lightning on the summit of Mt. Timpanogos Friday morning.  Media reports suggest the victim was taking shelter during the storm in the shack on the summit, with authorities called around 6 AM.  Lightningmaps.org provides access to strike data for 24-hour periods.  The map below is for 0600 UTC 18 September to 0600 UTC 19 September (Midnight to Midnight MDT Friday) showing the high density of strikes in the Mt. Timpanogos area and surrounding region.  The prevailing flow was such that the storms on Friday were moving from southwest to northeast and you can see a strong clustering extending from southwest of Utah Lake over Mt. Timpanogos.   Source: https://www.lightningmaps.org/ It's unclear precisely when the lightning strike occurred, but at the time of the rep...

In the wake of recent tragedies, it's worth a bit of review of flood and lightning safety.  In the case of floods, here's some data from the National Weather Service and their partners: More deaths occur due to flooding than any other thunderstorm hazard. Over half of all flood-related drownings occur when a vehicle is driven into flood waters. The next highest percentage of flood-related deaths is due to walking into or near flood waters. Source: National Weather Service A full run-down of National Weather Service flood products, including outlooks, watches, advisories, and warnings is available at  https://www.weather.gov/safety/flood-products .  In Utah, the National Weather Service also provides flash flood potential ratings for southern Utah and covering 12 recreation areas at  https://www.weather.gov/slc/flashflood .   As evident in near the Cottonwood Fire and Beaver, fire scars can be especially problematic for flash flooding and debris flows. ...

Tonight is the opener for the University of Utah football team.  Masks aren't required, but clear bags are.  Plan accordingly! Have you bought your clear bag yet? As a reminder, Rice Eccles Stadium only allows clear bags! Make sure you're ready for tomorrow's game with one of your own. Buy one here: https://t.co/iwvOOuwtuP pic.twitter.com/RV0XzSTrLi — Utah Red Zone (@UtahRedZone) September 1, 2021 The Storm Prediction Center has us in the marginal risk category, meaning that isolated severe thunderstorms are possible. Source: SPC If I were attending the game, I would keep this in mind.  Things could work out just fine, but if there is a thunderstorm in the vicinity, it is best to take appropriate measures, which likely means moving to a hard-topped vehicle such as your car.  Stadiums are generally not safe from lightning, even in covered open-air areas.  I always get a pit in my stomach when a thunderstorm is near Rice-Eccles stadium, most recently in Septembe...

Readers of this blog know that I frequently discuss issues with lightning safety at outdoor stadiums.  Prior to yesterday's game, I discussed the difficulties of the game-day forecast and the potential for thunderstorms during the game (see prior post Difficult Game Day Forecast ).  I did not catch the start of the game as we were out with friends, but when I turned on the game at some point into the first half, I heard some discussion about their camera people leaving for safety.  Nevertheless, the game was going on.  I thought this was quite odd.  They returned to the field at some point and the game went on, with the Utes achieving a convincing victory. This morning I decided to look into things.  Information on lightning strikes is available at lightningmaps.org.  According to their site, there was a lightning strike 4.3 km (2.7 miles) from Rice-Eccles stadium at 2:49 UTC/8:49 PM MDT during the game.  The NCAA Sports Medicine Handbook...

I had to spend a few hours in Utah County last night.  My skin began to crawl as I passed south across the county line and my stomach churned when I saw the white letter of the school down south on the hill.  There are places where one should not linger, and Utah County is one of them.  It is best to go down there, kick butt, shut people up, and get out, as the Utes will do tonight. The Holy War kickoff is scheduled for 8:15 PM MDT.  There is a chance of thunderstorms later this afternoon and evening.  These storms are expected to be scattered, so the pre-game festivities, game itself, post-event celebration by Ute fans, and whining by Cougar fans could go off without a hitch.  On the other hand, the potential for a thunderstorm and related impacts is there should they be in the wrong place at the wrong time.  Chances are you have noticed the increase in humidity since yesterday.  At the Salt Lake City Airport, dewpoints yesterday were in the ...

During periods of weak large-scale forcing in the summer, the mountains play an important role in the initiation of convective clouds and thunderstorms.  Nowhere is this more apparent in our region than over the Uinta Mountains where a visit sometimes makes one feel like they've traveled to another planet. The photo below was taken from the Gobblers Knob summit at about 10 AM this morning looking east toward the Uintas.  As is often the case, one can see the first cumulus clouds of the day forming over the Uintas.  Often, these clouds grow in depth, producing showers or thunderstorms later in the day.  I don't know of a study that has specifically examined the influence of the Uintas on convective cloud initiation and evolution, as well as growth into thunderstorms, but I'll speculate here on one of the reasons why the Uintas are so active: their scale.  They are quite high and broad with large expanses of lower elevation terrain to the north and south of...

Yesterday afternoon, a series of convective storms formed over or near the central Wasatch and moved northwestward toward Bountiful and portions of the Salt Lake Valley. The first of these storms was near Parley's Canyon at 2059 UTC (1459 MDT) and organized in a line. It looked like a close call for the University of Utah to receive rain, as well as thunder and lightning. Over the next 13 minutes, the storm shifted northward and became more cellular in structure.  By that time, it was northeast of campus and we had missed out on any significant precipitation. However, it is important to realize that threats from lightning can often extend many miles from the rain shaft and indeed, that was the case yesterday.  I was taking the occasional glance at the wonderful lightning products at lightningmaps.org and noticed a strike not only on Little Black Mountain close to the storm, but also in the mouth of City Creek Canyon, not far from downtown. That strike illust...

I need to pick on myself today for poor lightning safety practices.  Much like avalanche accidents, human factors often come to play in lightning accidents. As I was heading out for a quick mountain bike, a cell was popping over the Oquirrhs.  It wasn't much to be concerned with at the time, but I made a mental note to keep an eye on it.  Plus, I needed to be somewhere later and had to get my ride in. The climb from the valley to the ridge was uneventful, other than running into this not-so-friendly fellow. I know little about snakes, but I come across one about once a month in the warm season.  Usually they are gopher snakes.  I'm not sure what this one was.  It was fairly non-aggressive and wasn't rattling, but a close look at the tail suggested it may have been a rattlesnake that had lost the rattle.  I watched him slither into the grass and kept my distance. Getting back to lightning safety, I didn't hear any thunder on the climb, but on...

Although the University of Utah general commencement was last night, most college convocations are today, ensuring that campus is bustling with activity.  The morning dawned, however, with thunderstorms and rain on campus, which surely sent a shiver down the spine of Deans, Administrators, and campus planners. Thunderstorm over the University of Utah campus around 7:05 AM MDT this morning. Radar imagery at 1333 UTC (7:33 AM MDT) showed stronger returns just west of the Wasatch spine east of campus, with two cells further west, including one over campus. These storms were moving northward and as I write this at 7:50 AM MDT, rain has stopped. Graduation day was always stressful for me back in the day.  We used to have our college reception outdoors, and the dean would always want to know if he needed a tent and would call me for a forecast starting days in advance. Today, we have a new building and enough room to hold the reception indoors, so I'm off the hook. ...

Given that this is lightning week, it seems quite appropriate that a paper examining the influence of topography on lightning strikes came out this week in Monthly Weather Review ( Vogt and Hodanish 2014 ; paywalled, but I'll hit the highlights). Specifically, they used data from the North American Lightning Detection Network (NLDN) operated by Vaisala to document the characteristics of 12.5 million cloud-to-ground lightning strikes over Colorado from 2003–12.  The topographic map below highlights some of the key topographic features that influence lightning strikes within the state. Source:  Vogt and Hodanish (2014) The map below shows the stroke density during the warm season (1 April to 31 October).  One can clearly see the influence of elevation, but also some important geographic effects.  Stroke densities are highest in the high terrain encompassing Pikes Peak, the southern Front Range, and along the Palmer Divide east of east of Pikes Peak.  High d...

With temperatures in the 60s, dewpoints near 60, and rain falling steadily from the sky, I slept like a baby last night.  I can't even remember the last time we had a long period of steady rain like this and it seems like a gift from heaven, although yesterday's stronger downpours unfortunately caused some flooding and debris-flow problems in wildfire-scared areas such as near Alpine .  Further, the delay of the Texas–BYU football game is a prime example of why major stadiums need to prepare and have a plan for participant and spectator safety during severe weather (as does the Broncos–Ravens game on Thursday night).  Even if the U is prepared, the BYU experience provides a learning opportunity to see what worked effectively and what didn't.  U officials should also have a look at Gratz and Noble (2006) , who provide a summary of lightning safety guidelines for large groups.  It's not a matter of if but when there is a thunderstorm, possibly severe, that impa...

I don't know about you, but I thoroughly enjoyed last night's thunderstorms.  We had a BBQ in the evening and followed by the thunderstorms as they moved across the Oquirrh Mountains and towards Salt Lake City.   A crowded porch examines the approaching thunderstorms. Photo: Trevor Alcott Wasatch Weather Weenies BBQs never disappoint in August.  We're always able to conjure up some action.  Our resident photographer snapped this photo.  Fantastic! Photo: Trevor Alcott Classes start here at the University of Utah on Monday.  Readers of this blog who are U of U students might want to consider taking Atmos 1010: Severe and Unusual Weather and learn about storms like the one above.  

In Colorado, where thunderstorms are pretty much a daily occurrence during the summer, the rule of thumb is to be back down to timberline by 1 PM.  Here in northern Utah, thunderstorms are not always a daily occurrence, but that rule of thumb turned out to be quite useful today. Given the forecast, I opted for a mid-morning hike up Patsey Marley.  I awoke to just a few shallow cumulus clouds over the mountains, and kept an eye on things during the ascent, which proved uneventful.  On top at about 11:45, the sky was filled with cumulus, which were growing in depth, but hadn't yet become deep enough to glaciate (i.e., develop ice crystals), which is essential for the electrification.  Rather than push it, I enjoyed lunch on top and decided to head down. Subsequently, surface heating continued to destabilize the atmosphere, resulting in increasingly deep convective clouds and eventually the development of thunderstorms over the Oquirrh Mountains and portions of t...

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...

A man from Hamm, Germany was tragically killed by a lightning strike while hiking the Rim Trail near Sunset Point at Bryce Canyon Thursday afternoon.   We have discussed lightning safety in a previous post , but we didn't discuss a human element that sometimes plays a role at National Parks and other outdoor areas where there are larger concentrations of people.  In particular, we all have a false sense of security when others are around and tend to go with the crowd when it comes to decision making.  Don't let a crowd opting to stay outside dissuade you from taking safety measures if you hear thunder or lightning is nearby.  

Photo: John R. Southern/Wikipedia Commons As reported in today's Salt Lake Tribune , there have been two tragic lightning deaths in Utah this week .  On Monday, a man was struck and killed near the Wedge Overlook in the San Rafael Swell, and yesterday a Boy Scout was killed while camping at Scofield Reservoir.  Apparently, the Boy Scout was moving to shelter when he was struck.  What a tragedy. Perhaps today is a good day to discuss lightning safety and what you can do to minimize lightning hazard.  The NWS has a brochure on lightning safety available here .  The bottom line is that there is no outdoor place that is safe during a thunderstorm.  Head indoors or get in your car.  When car camping, move from your tent into your car. Many readers of this blog spend considerable time in the backcountry where one can take steps to minimize (but not eliminate) lightning hazard.  Plan ahead.  Know the forecast.  The rule of thumb to be of...