"Hotter than Hell"

I heard a Catholic priest say in downtown Salt Lake City this weekend that the weather is "Hotter than Hell."  Who am I to argue with a man of the cloth?

That said, let's take a quick look at the data and forecast as we approach the end of July.

The month actually started out with four days with minimum temperatures between 62 and 66 at the Salt Lake City International Airport.  And believe it or not on July 22nd, we actually had a maximum of only 87°F.  Other than thoat, it's been hot.  Since July 4th, every day but one has had a minimum temperature at or above 70°F and there have been nine days with a maximum temperature at or above 100°F, including the all-time record high of 109°F on July 12th.  

For the first 25 days of the month, the mean temperature at the Salt Lake City International Airport was 85.3°F.  This is not a record, but it is 4th all-time in the Salt Lake City area and 4.2°F higher than any equivalent period in the 20th century.  If you are wondering, the 20th century record is 81.1°F in 1985.  

The period also rates as the 4th warmest at the Bountiful Bench observing site with a mean temperature of 81.4°F, which is 3.1°F higher than any equivalent period in the 20th century.  There the 20th century record is 78.3°F in 1988.  

July is a month with less weather variability in Utah than we see in winter. On average, as shown in the mean 500-mb height analysis below, there is a mean 500-mb ridge to our east, with the axis centered over Colorado and Wyoming.  This results in the mid-latitude storm track being to our north.  Sometimes a midlatitude system can sneak in here, but it happens less frequently than in winter.  Instead, our weather is controlled more by variations in the strength and position of the ridge, which is a component of what is known as the North American Monsoon System. 

Source: https://psl.noaa.gov/cgi-bin/data/composites/printpage.pl

The forecast for the evolution of that ridge over the next several days does look hell like.  Below is the GFS forecast valid this afternoon [0000 UTC 28 January (1800 MST Tuesday)].  The 500-mb ridge (upper left panel) is centered to our east in northeast New Mexico.  Over northern Utah, the 700-mb temperatures (lower left panel), which are roughly at 10,000 feet or crest level, are around 18°C, which is quite high, but not record setting. 

That ridge though is expected to move slowly westward over the next few days and by 0000 UTC 2 August (1800 MDT Saturday) it is forecast to be parked over Utah.  The 500-mb heights are above 6000 meters, which is a value that typically draws the attention of meteorologists.  Forecast 700-mb temperature are exceptionally high and over 22°C in northern Utah.  In fact, at 6 PM on Saturday they are forecast to be 21.6°C, which would be more than 1°C higher than observed in the upper-air sounding record from the airport. 

The ridge in the ECMWF HRES is also parked over Utah, but not quite as strong.  That said, the 700-mb temperatures are also over 20°C in northern Utah and 22°C in portions of southern and central Utah. 

So, there is no rest for the wicked controlling the weather this week.  Lows at the airport will remain in the mid 70s or higher.  Maximum temperatures will be near or above 100.  If we're lucky, we'll get a thunderstorm, although the likelihood of that will be declining later in the week as the ridge moves overhead.  Temperatures will climb later in the week.  It's too soon to say if we might make a run for 105+, perhaps on Saturday, but it's in the cards. 

Hotter than Hell indeed.

Source: https://chatgpt.com/

Snow Storage at SoHo

I've been wondering for some time if snow storage will come to Utah, even posting on the possibility ten years ago (see Is Snow Storage Coming to Utah).  

It finally has come, but to a place I didn't expect, the Soldier Hollow Nordic Center (SoHo).

If you walk around the center, you might spy a whale of white a bit to the southwest of their day lodge.  As you approach, you'll see an insulated mat manufactured by a company called Snow Secure covering about 60,000 cubic meters of snow.  

Last February, Soldier Hollow put eight snowguns in this area and made snow whenever they could for a few weeks.   That snow was then piled high by snowcats.  Even now, in late July, the pile is perhaps as much as 15 feet high in the center.  

SoHo is hoping that 80% of the snow they put under the mat will still be around by mid November for them to spread out on about a kilometer cross country trail, enabling them to open early and focus snowmaking efforts elsewhere to get a jump start on opening more terrain.  

Snow Secure's insulating mat does two critical things to limit snowmelt during the Utah summer.  First, it is white and highly reflective of the sun's rays.  Most of the energy to melt snow in Utah comes from the sun.  At solar noon in summer, direct sunlight onto a flat surface provides about 1000 watts of energy per square meter.  The idea is to reflect as much of that as possible, limiting the amount of solar energy input into the snow pile.  

You can actually see the importance of reflecting sun if you look carefully at the pile. It's a little bit lower where there are straps that aren't as white and higher in between.  I suspect those straps are absorbing more sunlight and the underlying snow is densifying and shallowing more rapidly underneath them.  

The folks at SoHo told us that someone climbed up the pile and left some chocolate cake on the top and that led to a dimple in the snow.  More evidence of how darker surfaces absorb more sunlight.  Lol.      

Second, the mat is insulated, limiting the transfer of heat from the outer surface of the mat into the underlying snow.  The mat also protects the snow from other weather elements, like rain and wind.  

We will see how things look in November, but after visiting yesterday, I'm optimistic they will preserve a significant fraction of snow until the start of the next ski season.  That's remarkable because SoHo is probably the most challenging ski area and outdoor Olympic venue for snow storage.  It has a low elevation (the pile is at about 5600 feet), is hot and sunny in the summer, and sees very little shading from the surrounding topography.  Additionally, they receive limited natural snowfall and have a relatively short snow-cover season.  As a result, they had to make snow for the pile rather than collecting snow from around the resort when they close for the season.  

A resort that has snow after they close for the season could potentially use that snow for storage rather than making it.  This would make storing snow less energy and water intensive.  Additionally, saving snow from the prior season would allow a resort to open in the late fall or early winter even if the weather is not favorable for snowmaking.  

A look at Snow Secure's web site shows a remarkably large number of resorts in North America and Europe are now storing snow.  I suspect we will see this list expanding in the future. 

Thunderstorm Safety

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.  

National Weather Service lightning safety tips and resources are available at https://www.weather.gov/safety/lightning.  Lightning kills about 20 people a year nationwide, most commonly in summer, but deaths have occurred in all seasons (and in fact lightning is a threat for skiers in Utah which has a relatively high rate of thundersnow).  If you can hear thunder and are outdoors, you should move indoors or into a hard-topped car if you can.  If you are car camping and are in a tent of soft-sided trailer, move into a vehicle.  If you are at an outdoor sporting event, move indoors or into your car.  

Source: https://www.weather.gov/media/owlie/backcountry_lightning.pdf

In the backcountry, more than 30 minutes from an enclosed modern building or vehicle, lightning safety is about minimizing risk.  The most important thing is to monitor forecasts and time your visit to high-risk areas such as mountain peaks, ridgelines, and open water areas accordingly.  Think of it as being the equivalent of selecting the proper terrain for a given avalanche hazard.  Next is to move to safer terrain, as quickly as safely possible, if you hear thunder or believe the thunderstorm hazard is increasing.  This will not eliminate risk, but strikes are more random in lower elevation areas.  Avoid high trees, open areas, and if you can find a dry, lower elevation area, move there.  Pick tent sites to minimize risk too, but be careful when looking at ravines and other gullies if there is a possibility of flash flood.  

Below is more detailed information from a brochure put together by the National Weather Service and NOLS.  Note that getting into the lightning position is a last resort.  If you can move to a safer location focus on that.  For example, if I was on a ridge, I would move down in elevation as fast as I safely could rather than stay there in the lightning position.  

Source: https://www.weather.gov/media/owlie/backcountry_lightning.pdf

Many of the "FACETS" heuristic traps in avalanche accidents also apply to lightning safety.  

F=Familiarity.  Something that feels familiar feels safer, but just because you've survived lightning storms at high elevations in the past doesn't mean you will today.  

A=Acceptance.  You want to fit in or impress your friends by climbing a line or bagging a peak, which might increase your tendency to push it as weather hazard increases.   

C=Commitment.  You don't want to turn around from the summit when you have invested time and effort and are more likely to to push it as weather hazard increases.

E=Expert Halo.  There's a tendency to defer decisionmaking to others with more experience.  Don't assume your friend with years of mountaineering experience is going to make the right weather-related decisions.

T=Tracks/Scarcity.  This one might be more seasonal, but since there is lightning risk in winter, don't ignore it because you want to get first tracks of the top of Mt. Superior. 

S=Social Facilitation.  This one is actually very valid to lightning safety.  It is much harder to move to a building or car, turn around from high elevations, or get off the lake when noone else is doing it.  However, just because nobody else is doing it doesn't mean you shouldn't be doing something to reduce risk.  

All of that said, I've been there.  In fact, the event that I often think of as pushing me into meteorology happened when I was a teenager backpacking with my Dad and we had to run very rapidly from and Adirondack peak to a lower-elevation pass as a thunderstorm moved in.  I've been pelted by hail and graupel during thunderstorms in the Uintas, keeping to the lowest terrain without flood potential possible.  And I've spent time in the lightning position on backpack trips.  On Saturday, we hiked in the morning because of the increasing thunderstorm hazard during the day, yet were just getting to our car when the thunder started at 11:30.  

Use the tips above to adventure at the safest times and to know what to do to minimize risk when you are caught out.  

A Tragic Friday and Saturday

Sadly there were six weather-related fatalities in Utah on Friday and Saturday.  A man was killed after being stuck by lighnting on the American Fork Twin Peaks at around 12:20 PM.  

We hiked up Snowbird that morning, reaching the summit around 11 AM.  There were a few sprinkles around at that time.  When we reached our vehicle at around 11:30 we heard the first rumble of thunder.  The strongest radar reflectivity in the Snowbird/American Fork Twins area was observed at 12:02 PM.  It was a fairly small scale cell.  

Source: https://weather.ral.ucar.edu/

Three lightning strikes were observed on the Alpine ridge yesterday (orange dots below).  One was just south of the American Fork Twin.  

Source: lightningmaps.org

Given uncertainties in strike geolocation, that may have been the one.  

On the prior day in southern Utah, a family of five were killed in a flash flood at a campground near Bicknell.  

These are sad reminders of the hazards of monsoon convection.  Let's hope we see beneficial rains in the coming days, but it's likely that flash-flood and lightning hazards will remain a concern.  

Update on the Great Salt Lake

Mid July is here and it's worth a look at the Great Salt Lake.  Satellite imagery from July 11, when northern Utah was cloud free, showed considerable lake bed exposed in the Bear River and Farmington Bays.  

Source: https://worldview.earthdata.nasa.gov/

Elevation data shows that both the north and south arms had early and broad peaks in April and began to decline in earnest around mid May.  The north arm currently sits at an elevation fo 4190.5 feet and the south arm at 4190.9 feet.  Each of these above their respective record minimums in 2002, which were a bit below 4189 feet.  It's unlikely we will get down that low this year, but getting below 4190 seems to be in play.  

Source: https://greatsaltlake.utah.gov/current-conditions

Next winter will be critical for whether or not we end up flirting with a record minimum again.  There are good reasons to root for a good snow year besides skiing. 

A New All-Time High

The Salt Lake City International Airport reached 109°F today (Sunday, July 12), setting a new all-time record for the site.  

If you are wondering, 20.4°C was observed at 700-mb in the 0000 UTC (1800 MDT) sounding, which is also the highest observed in the sounding records (the old record was 20.2°C).  

It really was a dry heat.  At the time of the 109°F, the dew point was 26°F, resulting in a dewpoint depression of a remarkable 83°F and a relative humidity of 6%.

Stay hydrated my friends.