Wasatch Weather Weenies

With one day left to go in the month, we are running 1.2ºF ahead of 2013 for the hottest July on record. Source: NOAA Regional Cliamte Centers Good work!  Your pain and suffering will pay off with a monthly record.  Congratulations! And, through July 30, we are in a tight battle with last year for the hottest summer on record.   Source: NOAA Regional Climate Centers Time will tell if more records will fall.

Comments made by Salt Lake City Mayor Jackie Biskupski yesterday illustrate some common misconceptions about recurrence intervals of precipitation events.  As reported by the Salt Lake Tribune, the Mayor said regarding this weeks floods that " It was not a failure of infrastructure at all.  The system was truly overwhelmed within one hour of time.  A storm like this hasn't happened in probably 200 years.  It's really an unprecedented event. " The term recurrence interval is one that perhaps needs to be put out to pasture.  I see it misinterpreted all the time.  An event with a 200 year recurrence interval doesn't mean the event happens at 200 year intervals.  It means that the odds of it happening at a given location  in any given year are 1 in 200.  It is possible to have another 200 year even this year or even next year.  The odds are low, but not zero. Estimates of recurrence intervals are also problematic.  We have a relati...

It was a great honor to work with Executive Director Connie Nelson, extremely creative designers from Unrivaled, and University of Utah graduate student Peter Veals to develop a new exhibit on snow and the Great Salt Lake Effect for the Alf Engen Ski Museum at the Utah Olympic Park.  Although the official grand opening won't be until fall, the exhibit is now up and running and is wonderful addition to the museum. I visited the museum briefly last night and was able to snap a few photos with my old cell phone (unlike the quality photo above, these are crooked and poorly lit).  The exhibit begins with a nice history of the Greatest Snow on Earth, which with help from Tom and Mike Korologos, was described in my book Secrets of the Greatest Snow on Earth . We set the record straight on what makes great powder skiing, with an interactive screen that allows visitors to examine how much water is in snow and what the average water content is in their state or region. On...

I've had an opportunity to dig in a little deeper to the deluge that hit the Sugarhouse area early Wednesday morning. Storm-total precipitation was greatest at a citizen weather station between Foothill Drive and Parley's Way near the mouth of Parley's Canyon.  Maximum precipitation rates at the site were 1.64 inches in 30 minutes, 2.28 inches in 60 minutes, 2.39 inches in 2 hours, and 2.41 inches in 3 hours.  If accurate, those all have recurrence intervals near 200 years, as also reported by Salt Lake City Public Utilities . Soundings collected at the Salt Lake City airport at about 6 AM either during or in the wake of the storm (depending on when the sounding was actually released) showed a precipitable water value of 1.41 inches.  Precipitable water is the depth of water that you would have if you condensed all of the water vapor out of an atmospheric column.  Such values are high, as one would expect in a flash-flood scenario, but not unprecedented, as il...

Thunderstorms with heavy precipitation moved into and intensified over the Salt Lake Valley last night, leading to some urban and small stream flooding.  The radar loop below runs from 0800–1300 UTC (0200–0700 MDT) and shows some especially strong storms in and around Sugarhouse and near and around Draper. Radar estimated precipitation amounts key in on both of those areas reaching over 1.5 inches in the Sugarhouse area and nearly 2 inches near Draper.   Gauge-measured rainfall amounts since midnight as reported to the National Weather Service include 2.38" at Sugarhouse near Parleys Way, 1.35" at our mountain meteorology lab on the University of Utah campus, and 1.20 inches in Draper.   Contrasts between radar estimated and gauge-measured precipitation are not uncommon and careful analysis will be needed to identify the magnitude of peak precipitation amounts.  Nevertheless, it is clear from both Sugarhouse and Draper received an impressive...

Aided by a weak mid-latitude trough sitting along the coast of northern California, our first major monsoon surge of the season has finally brought relief to northern Utah this morning. It's worth taking a look at a 1-month meteogram for the Salt Lake City International airport to put the weather this morning into perspective.  Currently, the temperature is 69ºF, the lowest temperature observed since July 2nd, bringing our record run of consecutive 70+ days to an end at 22.  Good riddance! The dewpoint is currently 63ºF, and peaked at 65ºF around 2 am, which I suspect is the highest observed since at least last summer, although that needs to be confirmed.  While no good for swamp coolers, it's wonderful for the skin. Through 8 AM, the airport has only picked up .03" of precipitation.  That's not much, but it's the most rain we've had on a calendar day since June 13.  Again, relief!  Other locations have surely had more. Enjoy this weather while...

It's a holiday weekend in the Wasatch, which means it's best to start early to avoid the crowds.  I believe this weekend and the next are also considered the "Wasatch Wildflower Festival," although in my view the mountains need no promotion this time of year.   My hike this morning took me to the top of Mt. Baldy and Hidden Peak, enabling a quick assessment of ski conditions (sans skis).  Near as I could tell, Main Chute doesn't go any more, although there are some turns to be had a the top. Pipeline?  A careful look also shows it no longer goes and is bisected by a couple of snow free strips. TAYers will need to hit the Timp "glacier" or head to better options in the Cascades and Sierra.  I'll stick to the trails. In case you are wondering, the overnight minimum at the Salt Lake City airport was only 76ºF, making it virtually certain that this will be the 20th consecutive day with a minimum of 70 or higher (technically 71 since th...

I'm beating a dead horse, but here's an updated look at July now that we're 2/3 of the way through the month from hell. Perhaps most remarkably, every day this month has an above average minimum and maximum temperature (normal range in plot below indicated by green background). Source: NWS Making that even more remarkable is that the National Weather Service uses the 1981–2010 period for their average.  That's a period that is relatively warm compared to the rest of the 20th century. And the first 2/3 of July, not surprisingly, is the hottest on record, 2.3ºF warmer than 2007. Source: NOAA Regional Climate Centers I have been looking at the models the entire month and waiting for evidence of a bonafide monsoon surge into northern Utah.  We've been tickled by the monsoon moisture in places like Utah County and over the central Wasatch, but for the far north, we've mainly been on the edge of the action with just some light or trace accumulations. ...

At just before 1 AM MDT on 19 July, a weak thunderstorm moved over the Salt Lake City International Airport, producing .01" of rain.  The thunderstorm was isolated in nature, but was enough to produce measurable precipitation at the airport for the first time in 34 days. So that streak, although not even close to record breaking, is over.  If my notes are right, the record at the Salt Lake City airport for consecutive days without measurable precipitation is 63 days and there have been 9 instances of 40 or more.  Of course, .01" isn't really much in July when it evaporates off in a few minutes. Getting to record breaking streaks, our consecutive day streak with minimum temperatures above 70 continued through yesterday and now sits at 17.  The overnight low this morning was only 77 or 78 degrees, so that streak will go to 18 unless we can get some thunderstorm cooled air to drop things to below 70 this afternoon or evening. Speaking of thunderstorms, we noted...

Hopes were dashed at the Professor Powder abode last night as storms over the Salt Lake Valley left us high and dry. The storms moved over the Oquirrh Mountains around dinner time. And they brought measurable rain to many sites in the Salt Lake Valley, including a few that reached 0.15 inches.  Imagine that! However, we barely traced at my house and a scant trace was also all that was observed at the Salt Lake City International Airport. Thus, two ugly streaks continue at the airport.  The first is the number of consecutive days with a minimum temperature at or above 70ºF.  We are now at 15, which is an all-time record.  Last night's minimum was 74, so it is likely we'll stretch the record at least another day. The second ugly streak is consecutive days without measurable precipitation, which now sits at 34.  That's not a record, but it's still a long time without a decent shower. The models have been suggesting that we might have a modest mons...

Some of you have asked me why the overnight minimum temperatures have been so high in Salt Lake City this summer.  In particular, it seems like the minimum temperatures are more above normal than the maximum temperatures. To answer this question, let's take a look at the long-term trends in mean maximum and mean minimum temperature in Salt Lake City during the first half of July since 1874. As can be seen from the chart below, both exhibit a long term warming trend.  If you look carefully, however, you can see a surge in minimum temperature during the early 1900s, and abrupt drop in minimum temperature in 1928, and then another rapid increase in minimum temperature, at a rate faster than the increase in maximum temperature, beginning in the 1970s. These changes are better illustrated if we plot the mean difference between the maximum and minimum temperature, which meteorologists call the diurnal temperature range (DTR).  Prior to 1928, you can see a gradual decline...

The first 15 days of July are in the bag and it has been ridiculously hot in Salt Lake City.  The average temperature for those 15 days was a whopping 86.6ºF, 2.3ºF warmer than the first half of July 2002. Source: NOAA Regional Climate Centers Such a temperature, if it were to hold throughout July, would also easily set the all-time monthly record. Brutal.

As many of you already know, the Uinta Mountains are often another world weather wise compared to the Wasatch Front. Indeed that was the case today as our hike turned into a quagmire thanks to thunderstorms that fired up near the Uinta crest. I knew there was a chance we'd get caught out, so our plan for the day was to hike the Highline Trail to either Rocky Sea Pass or Naturalist Basin, hopefully being down in the trees if anything sparked.    Ideally, we would have had a crack of dawn start, but it's hard to get the teenager out of bed, so we hit the trail mid morning. After a quick approach, we approachedNaturalist Basin, but heard a few rumbles to the east.  Not a good sign. Eventually it was clear the time had come to turn around, so we headed back down.  That's when things really fell apart.  First heavy rain turned the trail into a quagmire. And then the pea size hail started.  Although not large, the some of the larger stones stun...

If you haven't seen Thank You for Smoking , watch it some day as it is a great satirical comedy.  The main character, Nick Naylor, is a lobbyist for Big Tobacco who does a hell of a job spreading disinformation about the linkages between smoking and lung cancer.  The sad thing of course is that this really did happen, delaying improvements in public and individual health for Americans. Fast forward to 2017.  Nick Naylor is now Scott Pruitt, Administrator of the Environmental Protection Agency.  Pruitt wants scientists to debate climate on TV, and "red team, blue team" exercises to evaluate climate science. These proposed debates and exercises have nothing to do with science.  They have one objective, and that is to create doubt in the minds of Americans about the quality of climate science and the threat posed by global warming.  Doubt is his product, just as doubt was the product for the cigarette industry. I have been around long enough to rememb...

Chances are you thought that yesterday afternoon was comparatively pleasant compared to the previous several afternoons.  However, was yesterday really cooler than the previous several days? Well, it depends.  If we're talking maximum temperature, it was cooler.  Yesterday's maximum temperature was 96ºF, the lowest maximum temperature since July 1st when we reached only 94ºF.  However, if we're talking minimum temperature, it was warmer.  Yesterday's minimum temperature was 79ºF, the highest minimum of the past 10 days. Source: NOAA Regional Climate Centers With a low of 79ºF and a high of 96ºF, yesterday's mean temperature was 87.5ºF, rating as the fourth highest of the month behind the 5th (90.5ºF), 8th (90.5ºF), and the 9th (88.5ºF).  So, from this perspective too, yesterday was pretty warm.   You can blame all of this on the cloud cover, which acts to reduce the diurnal range of temperature, or the difference between the minimum and maxi...

The loop below shows very nicely the evolution of the western "Death Ridge" from 1200 UTC (0600 MDT) Saturday 8 July through 1200 UTC (0600 MDT) Saturday 15 July.  The evolution is subtle, but there is some weakening early this week (hence the slight drop in maximum temperatures), followed by a Lazarus like return to dominate the circulation over the western US by next weekend. At this point, I rate the odds that this July will go down as the hottest on record in Salt Lake as better than 50/50.  That is admittedly a risky forecast to make with three weeks left in the month, but we are off to a hell of a start.  Through the first 9 days of July, the average temperature for the month was 86.5ºF.  If that were to hold for the entire month, we would beat 2014 by a full 2.4ºF. Source: NOAA Regional Climate Centers At this point, I hope that either the models are wrong or we break the record.  If we must suffer, we may as well get bragging rights.