Escape from Hothouse Earth

After living through the hell of Seattle, I finally found pleasant weather yesterday in Ketchikan, Alaska, where we are visiting family.

The weather today was perfect.  High of 70ish with sunshine and a good breeze.  It's rare, but when the weather here is nice, its a great place to be.  

I have been reflecting on the heat of the past few weeks.  June in Salt Lake City was ridiculous.  7 days of triple digits and a mean temperature that will easily set a new record.  Through yesterday, the average temperature for the month was 80.1˚F.  The next highest is 77.5.  

Source: NOAA Regional Climate Centers

Then, how does one wrap their head around the Northwest US/Southwest Canada heat wave?  I can't.  I still can't fathom a high in Lytton, British Columbia of 121˚F.  Even in celsius it sounds awful.  49.6˚C.  Unfathomable.  Reports are this is the highest temperature ever recorded north of 45˚ north (and I suspect south of 45˚ south for that matter).  The town is now being evacuated due to wildfire.

BREAKING NEWS: The mayor of Lytton, B.C., said he has ordered the entire town to be evacuated after a fast-moving wildfire swept in on Wednesday evening. https://t.co/EK6Oz2wvse

— CBC British Columbia (@cbcnewsbc) July 1, 2021

The death toll from this heat probably won't be known for a few days if not weeks to properly account for changes in death rates.  BC's chief coroner said today at least 165 deaths can be attributed to the heat.  

If this was a glimpse of the future, it wasn't pretty.  I am reminded that we are on a path for the summer temperatures in Salt Lake City later this century to be similar to those of St. George in the 20th century.  Yeah, it's going to suck.  Anyone want to set the over under on the first year Salt Lake City observes 110?  How about 115?  Seem ridiculous?  

Not anymore.  

Greetings from the Apocalypse

Sunrise this morning over downtown Seattle

I lived in Seattle from 1989 to 1995.  It was a great time in my life and I thoroughly enjoyed the mild climate, especially the cool, dry summers.

In 1989, the all-time record maximum temperature at the Seattle-Tacoma International Airport, known as SeaTac, was 99˚F. and it was great to boast about the region's natural air conditioning.

In 1994, they reached 100˚F for the first time.  Then in 2009, 103˚F.  Still, those were the only two days in the triple digits since record keeping began at SeaTac in 1945.  

A few weeks ago, we committed to going up to Seattle for a few days to cool down, a prospect that seems laughable now.  We drove across the Cascades on Saturday and enjoyed a view of the great snow scoop in the sky, Mt. Rainier, from the top of Crystal Mountain.

It looks innocent enough in pictures, but temperatures that afternoon reached 102˚F at SeaTac as we pulled into town.  

The evening forecast on KOMO news seemed preposterous.  106 on Sunday.  113 on Monday!  Even for a meteorologist who was looking at remarkable warmth in our computer models, that was shoking.  

Yesterday SeaTac didn't quite get to 106˚F, but it did get to 104˚F, breaking their all-time record.  Insane, but we were able to spend the day on my brother-in-law's boat on Lake Washington, a luxury that we feel fortunate to have had.  

We'll see where things end up today.  At noon, it was 102˚F at SeaTac.  It's worth noting that the dewpoint is also 62˚F, not as high as one might find in a heat wave on the east coast, but still enough to add to the discomfort.  

There tend to be sharp contrasts in temperature between inland areas and coastal areas next to the Puget Sound in situations like this.  How high SeaTac will get today will strongly depend on the local flows.  I'm not sure they will make it to 110, but they might come close and some inland locations to the east probably will.  With temperatures in the 90s even in the mountain passes, we're essentially taking a down day and laying low. 

A Concerning Cool Down, Then More Pain and Agony

A weak short-wave trough and moisture surge moving into northern Utah later today will bring cooler temperatures and a threat of a few showers and thunderstorms tomorrow.  The likelihood increases through tomorrow with isolated T-storms later today, scattered tonight, and showers likely tomorrow.  

The NAM forecast valid at 1500 UTC (9 AM MDT) tomorrow morning shows the short wave trough and associated clouds and precipitation over central Utah.

This isn't a major monsoon surge, so it won't be a drought buster, event if you happen to get a good downpour wherever you are.  The concerning part of the cool down is that while we will get some precipitation, there will also be dry thunderstorms, which are thunderstorms that produce lightning, but little to no precipitation.  Enjoy the modest cool down, but hope that we don't see many if any fire starts.  

The extended model forecasts are putting an enormous ridge over the Pacific Northwest and southwest Canada.  Below is an example from the GFS valid 0000 UTC 28 June (6 PM MDT Sunday).  

This has the potential to bring historic heat for this time of year to portions of the Northwest.  It is likely that we will see a return to near or above 100˚F next week too.  

What can I say?  Despite short-term cooling, the long-term trend is not our friend.

Yes, Its Not Cooling Off as Much at Night

A lot of people have commented lately that it hasn't been cooling off at night.  Indeed, minimum temperatures have been rising in Salt Lake City and in many other regions.  

Let's have a look at Salt Lake City.  National Weather Service observations of the average June minimum temperature since 1874 (2021 includes only the first 20 days) shows significant variability from year to year, which is a reflection of weather variability.  

Source: http://xmacis.rcc-acis.org/

There is an abrupt drop that occurs, however, in 1928, after which the average temperature seems to be much lower than it was previously.  This drop is almost certainly due to the moving of the observing site from downtown Salt Lake City to the Salt Lake City Airport, which is not only lower and prone to colder overnight temperatures, but back in 1928 would have been in a highly undeveloped area.  

After 1928, average minimum temperatures seemed to fluctuate around with little long-term trend for a couple of decades before they began to rise over the last 50 or 60 years.  

And minimum temperatures are increasing faster than maximum temperatures.  The average minimum June temperature from 1951-1980 was 53.2˚F.  From 1991-2020 it was 57.4˚F, an increase of 4.4˚F.  For the same periods, the average maximum June temperatures were 82.9˚F and 83.9˚F, an increase of 1˚F.  As a result, the average size of the daily temperature range has decreased from 29.7˚F to 26.5˚F.  This decrease in the daily temperature range has important implications for human health and energy consumption as the lack of cooling at night increases stress on individuals without access to adequate air conditioning during heat waves and energy consumption for the air conditioning of homes, buildings, etc. 

The rise in temperature and the decline in daily temperature range are consistent with expectations from urbanization and global warming.  However, I do not know know the size of the contribution of each of these in Salt Lake City and they may not add up in a way that is linear.  In other words, there could be some feedbacks between the two of them that amplify the warming (or reduce it) compared to what you would expect if you could just add the net warming from each effect together.  

Regardless, these effects are making Salt Lake less comfortable during summer, especially during heat waves.  

Addendum

I should have added that although this June has featured a couple of very warm nights, the average diurnal temperature range is 28.9˚F, which is actually larger than the 1991-2020 average (but a bit smaller than the 1951-1980 good old days).  I suspect this is in part due to the dry conditions (low humidity and low soil moisture) and less cloud cover than we would see in a typical June.  

If June Is the New July, What Will July Be?

 

This blog post is brought to you by Panda Express, which along with the adjoining but depleted Union food court, appears to be the only place to eat on the University of Utah campus and provided me with the fortune above yesterday.  

Forget that.  

This June has been awful.  How awful?  Some statistics:

• Although we just went through the climatologically coolest first half of June, if the month ended today, it would still rate as the warmest on record at the Salt Lake City International Airport (KSLC) by 1.4˚F.  
• Likewise for Tooele.  So far 1.1˚F hotter than the hottest June on record (records back to 1896).
• The average temperature at KSLC for June 1-16, 78.9˚F would rank in the top 25% hottest Julys.  More on July in a minute.
• KSLC has had no measurable rain so far this month (they recorded a trace on June 5).

But what about the future? 

As it says at the gates of hell, Abandon Hope All Ye Who Enter Here.  

The GFS forecast through June 27 below is very much July-like. The storm track remains to our north.  Weak troughing at times near the west coast.  Maybe a brush-by slight cool down.  

This isn't a recipe for another 107˚F day, but it also isn't a recipe for a return to near average temperatures.  Temperature forecasts from the National Weather Service's National Blend of Models show we will likely see high temperatures near or above 90 for the period.  The best odds for below 90˚F are on Sunday and Monday when we may feel the effects of the bush by.  Still the majority of NBM members call for highs at or above 90˚F those days.  

Source: NWS

I'm not a fan of looking farther out, but I'll give you what you want.  The Climate Prediction Center 8-14 day outlook, covering the last week of June, shoes the odds stacked for above average temperatures.  

Source: CPC

Essentially, this June is the new July, with a large-scale pattern, temperatures, and precipitation characteristics more reminiscent of that typically hot, dry month than June.  

But what will July bring?

Really, I have no idea.  However, we can look at past Julys and think about what the climatological likelihoods are, doing some tweaking and educated guesses since our climate is changing. 

July is on average our hottest month, but it also exhibits the least amount of variability from year to year.  The coldest July on record occurred in 1993.  That was a black swan July with an average temperature of 69.9˚F, considerably cooler than we've had so far this June.  

Source: http://xmacis.rcc-acis.org/

However, July 1993 had two things going for it that we don't have today.  First, the planet was cooler in general.  Second, Mount Pinatubo, a volcano in the Philippines, erupted in June 1991, spewing particulates into the stratosphere and temporarily cooling the planet about 0.5˚C through 1993.  A repeat of July 1993 is highly unlikely.  

Perhaps a reasonable request would be something like July 2015, which was the coldest July in the past 20 years.  The average temperature was 77.4˚F, slightly cooler than we've seen so far this June.  My blog post from July 23, 2015 (Perspectives on Our Fantastic July) suggests that the month was "fantastic with tolerable temperatures and the occasional showers and thunderstorms to help moisten things up."  

On the other hand, since 2000, there have only been two Julys with an average temperature lower than the 78.9˚F we've had so far this June, 2011 (78.5) and the aforementioned 2015.  This is a small sample size (20 years), but our July climate has shifted so much that it's unclear how useful pre-1990 temperatures are for present day climate.  

My view is that it is looking pretty likely that the average temperature from here until the end of July will be comparable to or higher than what we've seen so far this June.  The odds that it is lower are probably less than 20%, and the odds that it is much lower (say more than 2˚F) are probably less than 5%.  

How's that for positive perspective? 

Heartless Rocky Mountain Power

A few days ago, a notice was hung on our door from Rocky Mountain Power that our power would be shut down tomorrow from 9 am to 3 pm.  

Given that today we are in an excessive heat warning and tomorrow a heat advisory, with a forecast high of 97˚F, this seems like an incredibly foolish time to shut down power.  We have options to leave the house during that period, but I wonder about neighbors and the notice warns that "unexpected difficulties may extend the outage."  

Although they claim that "poor weather may cause the work to be cancelled or postponed," this has not happened yet.  I checked with Rocky Mountain Power via Twitter last night and they are still planning on shutting down the power.  Their response..."sorry for the inconvenience."

I hope they will reconsider this shutdown as it is both reckless and foolhardy to have it this week.  It's not like they don't have the ability to monitor and adapt to the weather.  They have done power shutoffs for fire-weather conditions and, according to their press releases have a meteorologist and emergency management team to monitor evolving weather systems.  

Rocky Mountain Power has been slow to respond to climate change, has fought residential solar, and as of last year still got over 50% of their power from coal.  I guess I shouldn't be surprised.

Lessons in Boundary Layer Mixing, Transport, and Dispersion

A three-alarm fire occurred last night in an office building in Sugarhouse.  Sixty firefighters fought the blaze, which stared around 2 AM and continued into the morning.  One firefighter was injured and we hope they have a speedy recovery.

I observed the smoke plume during a morning hike in the foothills.  At 8 AM, the behavior of the smoke plume was strongly affected by the stable cold pool that forms overnight in the Salt Lake Valley.  The smoke rose perhaps a couple hundred meters before settling back down and being transported by the local flows, as illustrated below.  

I've annotated several key features.  The heating of a fire results in warmer air than the surrounding airmass.  As a result, the air becomes positively buoyant and rises, resulting in an ascending smoke plume.  As it does so, it cools and, if the air is stable as is often the case in the morning near the Earth's surface, it will eventually reach a level where it has the same temperature of the surroundings.  At this level, which is known as the equilibrium level, the air is neutrally buoyant.  However, the air continues to rise because it has momentum, but begins to decelerate.  Eventually, the updraft dies, at the overshooting top.  Here, the air is colder than the environment, and settles back down to the equilibrium level.  

In the photo above, the local flow was westerly at the fire site, resulting in the transport of smoke eastward (the photo is taken looking south).  However, near the time of the photo, there was an eddy present, so the smoke turned northward and then westward.  If you look carefully, you can see some smoke further east, above where I've added the label "old transport and dispersion."  Earlier that morning, there was a pronounced smoke layer here, suggesting that the eddy had just recently developed.  

The behavior of the smoke changed rapidly, however, by 8:46 am.  Note how in the photo below the smoke rises vertically through a much deeper layer.  It is also being transported westward.  

The vertical rise could be related to the warming of the air near the earth's surface.  At the University of Utah, where we collect 1 minute observations, the surface temperature increased about 5˚F during this period.  Another possibility is that the heat related by the combustion increased.  Either of these would result in a a warmer smoke plume able to ascend to greater heights.  In a wildfire, these two effects can be closely related since changes in the ambient atmosphere affect the combustion process such that wildfire intensity often increases during the day.  

The shift in the orientation of the plume is more difficult to explain.  On short time scales of minutes to tens of minutes, turbulence in the atmosphere and other larger-scale eddies can cause smoke dispersion to be fickle.  The outflow from Parleys Canyon typically results in easterly flow (which would transport smoke to the west) in the morning in the Sugarhouse area.  However, this morning at one observing site there was a clear shift in the wind from easterly to southerly at about 8 AM (see the image below), when the flow was weak.  After that, the flow was S-SW.  

These observations don't correlate all that well with the plume evolution, which illustrates the fickle nature of smoke transport and the challenges of using sparse observations to anticipate smoke transport during light wind periods.  This is a major challenge for anticipating the transport of smoke, pollutants, and other hazardous materials produced by fires, accidents, or terrorist incidents, especially during periods of weak flow. 

Forecasting Maximum Temperatures

Next week looks hellish, with the National Weather Service currently predicting (as of 8:25 am Friday 11 June 2021) maximum temperatures for the Salt Lake City International Airport of 102˚F Monday, 103˚F Tuesday, 101˚F on Wednesday, and 100˚F on Thursday.  These are all near record highs for those dates.

How are maximum temperature forecasts produced?  The exact approach may vary depending on your source, but here are the basics.

Numerical weather prediction models form the backbone for weather forecasts.  These models solve the governing equations for the atmosphere, which are based on physical laws such as conservation of momentum, mass, and energy.  On example is the Global Forecast System, or GFS, which is the primary modeling system produced by the National Weather Service for medium-range forecasting.

Forecast models like the GFS have revolutionized weather forecasting.  In the middle of the 20th century, weather forecasting was based almost entirely on painstaking manual analysis of surface and upper level data, forecaster intuition, rules-of-thumb, and other ad hoc techniques.  Forecast models like the GFS have grounded the forecast process in science and greatly improved the accuracy of weather forecasts.  And, they continue to improve with increasing spatial resolution (enabling more detail), better accounting of physical processes related to clouds and radiation, and the assimilation of an increasing array of weather observations, especially those from satellites.

Models like the GFS, however, struggle predicting conditions very near the Earth's surface, including variables like temperature or maximum temperature.  There are a number of reasons for this, but in our part of the world, one of the biggest sources of error is the inability of models like the GFS to resolve the topography.  The GFS is comprised of grid cells that are about 13-km on a side.  As a result, does not account fully account for the topography of the Salt Lake Valley and surrounding ranges.  Since the elevations of the GFS do not match those in the real world, a GFS forecast for the Salt Lake City International Airport is strongly biased.  

This is where machine learning comes in. Around 1970, meteorologists began to train past forecasts with observations to develop techniques to produce better surface weather forecasts.  In a classic paper, Glahn and Lowry (1972) called this technique Model Output Statistics, or MOS.  MOS greatly improves upon direct model forecasts by adjusting for systematic biases and other effects.  For all intents and purposes, it was an early machine learning approach.  

The National Weather Service continues to call forecasts produced using such machine learning techniques MOS.  They also have a new system called the National Blend of Models (NBM) which uses many modeling systems to produce forecasts.  Private sector companies are also using machine learning techniques to produce forecasts, including many of those that you access on your phone.  The quality of such forecasts depends on several factors including the quality of the underlying model or models, length of the training period, and statistical techniques used.  

Where do humans enter the loop?  It depends.  Although machine learning can be quite automated, humans still are involved to some degree in the design of the approach and hopefully the testing an evaluation of the forecasts.  However, after that, most of the forecasts you get on your phone are probably generated automatically with no human intervention.  National Weather Service forecasts can, however, be adjusted by humans using software called the Graphical Forecast Editor.   A reminder here that we're talking strictly about temperature forecasts.  Humans play many essential roles in the forecast process including the issuing of watches and warnings and decision support activities.

All of this physics and statistics is wonderful, but when we have a potentially high-impact weather event, it's good to have some idea of context.  For this, I'm going to use the GFS forecast of 700-mb (about 10,000 feet above sea level) temperature.  This level is high enough that it is not strongly biased by the poor terrain representation, yet it is also strongly coupled to the surface during the summer when intense surface heating drives turbulence that strongly couples that level with the surface.  

The 0600 UTC initialized GFS forecasts 700-mb temperatures at the Salt Lake City International Airport of 17.7˚C on Monday afternoon, 19.4˚C on Tuesday afternoon, 18.0˚C on Wednesday afternoon, and 18.4˚C on Thursday afternoon.  These are exceptionally high relative to past upper-air observations.  The highest 700-mb temperature in the upper-air record at the airport is 20.2˚C on the afternoon of 13 July 2002 when Salt Lake City hit its all time record high of 107˚F.  The highest 700-mb temperature measured in June is 19.0˚C on the afternoon of 29 June 2013 when we set the June record of 105˚F (note: The prior day also hit 105˚F with a 700-mb temperature of 18.2˚C).  

Also catching my attention is that the airmass that will be in place early next week is remarkably dry and the low-level flow is southwesterly, as illustrated by the time height section below

These are also consistent with high maximum temperatures at the Salt Lake City Airport.  I took a quick look at the Euro and its numbers are close to the GFS.  On Tuesday afternoon, it has 700-mb temperatures of 19-20˚C over the Salt Lake Valley.  

We could also also take a look at an ensemble product.  Below is the NBM guidance from the National Weather Service based on many ensemble modeling systems.  Box-and-Whisker plots for maximum and minimum temperature are on the left and a graph of the median hourly temperature and dewpoint forecast is on the right.  We'll focus on the former.  The median forecast maximum temperature for Tuesday afternoon is 105˚F.  The interquartile range, or middle 50% of forecasts, lie between 103˚F and 106˚F.  The extremes look to be about 100˚F and 107˚F.  

A temperature of 105˚F would be unprecedented for so early in the season.  The earliest 104˚F was recorded on June 21, 1961 and the earliest 105˚F was recorded on June 28, 2013.  I suspect the duration of heat next week will probably make the average maximum temperature for the period the highest on record for that period. 

Uncharted Meteorological Territory and the Evolving Hot Drought

 Don't let today's cool weather fool you, this June has been and will continue to be a disaster meteorologically, further exacerbating extreme to exceptional drought and fire weather conditions across the State of Utah.

In the previous post, we discussed the remarkable heat of the first 6 days of June.  Here's an update.  The average temperature at the Salt Lake City International Airport for the first 9 days of the month was an incredible 79.8˚F.  This is the warmest start to any June on record.

Source: http://xmacis.rcc-acis.org/

Let's take a closer look at the graph above.  Until 2016, the highest average June 1-9 temperature was 73.6˚F (1977).  We were 6.2˚F warmer than that!  In Salt Lake City, the urban heat island may be a local contributor, but even Alta had an average June 1-9 temperature of 59.3˚F, which is its highest on record.  Ah but the records there are spottier and only go back to the early 1970s.  How about we look at Tooele.  Records back to 1896.  Even there, June 1-9 has never been hotter.  

Source: http://xmacis.rcc-acis.org/

We are in uncharted meteorological territory.  

Today's cold frontal passage will bring pleasant temperatures to northern Utah, but this is a brief respite.  The computer model forecasts call for us to return quickly to exceptional warmth.  For example, look at the GFS forecast below for 0000 UTC 14 June (6 PM Sunday).  Deep trough off the west coast, high amplitude ridge over the upper plains, and Utah in the intermediate hot, dry southwesterly flow.  

The NWS forecast is as ugly as it gets.  One day of cool weather today.  By Friday, we're already back to a near average 81˚F.  After that, 92, 98, 100, 101, 99....

Source: NWS.  Downloaded 8 am MDT 10 June 2021.

This is the epitome of "hot drought" in which aridity is exacerbated by high temperatures, which increases evaporation and transpiration and the demand for water for irrigation.  It is estimated that approximately 1/3 of the decline in Colorado River runoff in recent years is due to higher temperatures.  

This has been anticipated for some time.  The Blue Ribbon Advisory Council on Climate Change Report to Governor Jon Huntsman, Jr. published on October 3, 2007 (available here) includes a chapter prepared by several Utah climate scientists including myself.  Amongst our conclusions:

•  "Utah is projected to warm more than the average for the entire globe and the expected consequences of this warming are fewer frost days, longer growing seasons, and more heat waves."

• "Ongoing greenhouse gas emissions at or above current levels will likely result in a decline in Utah's mountain snowpack and the threat of severe and prolonged episodic drought in Utah is real."

For city residents, the effects of drought are not always readily apparent, but they are severe and costly.  The National Integrated Drought Information System estimates that since 1980, 26 major national droughts have cost the U.S. at least $249 billion.  Amongst natural disasters, only hurricanes have caused more damage in that period (see https://www.drought.gov/news/high-cost-drought).  

This drought is not an act of God.  It is a reflection of weather and climate variability supercharged by anthropogenic climate change.  The climate of the 20th century is over.  This is a new world of change.  

Real Cooling Is Coming

The start of June has, in my view, sucked meteorologically.

High temperatures at the Salt Lake City Airport for the first six days of the month were 88, 91, 97, 100, 97, and 92.  

This is off the charts hot.  The average maximum temperature for the 6-day period was 94.2˚F, 3.2˚F warmer than that of any prior year on record.  In fact, there are only two other such periods with an average maximum temparature above 90: 2016 (90.5˚F) and 2020 (91.0˚F).  

Source: http://xmacis.rcc-acis.org/

Although there were a few thunderstorms around on Saturday, the airport received only a trace, so they haven't had measurable rain yet this month either.  With warmth continuing and wind on the rise, the National Weather Service has issued a red flag warning through late Wednesday for the Salt Lake Valley as well as much of the state of Utah.

Source: NWS, 2:40 PM MDT 7 June 2021

The good news is that we should see significant cooling on Thursday.  The GFS forecast valid 2100 UTC (1500 MDT) Thursday shows a surface cold-front over central Utah with northwest Utah in the...dare I say it...cooler post-frontal westerly to northwesterly flow.  

The 700-mb temperature forecast is around 0˚C over the Salt Lake Valley, which would equate to surface temperatures in the...wait for it...60s Thursday afternoon.  

Looking forward to it. 

Early Summer Heat

The National Weather Service has issued an Excessive Heat Warning for the northern Wasatch Front, Salt Lake Valley, Utah Valley, and the Great SaltLake desert for noon Friday to 6 AM Saturday.  Below is the warning issued this (Thursday) morning at 3:24 AM.

Below is the infographic from their page showing comparisons of forecast and record highs for today (Thursday) and tomorrow (Friday).  If we hit 100 tomorrow, it would be the earliest on record by a day.  

When it comes to susceptibility to heat, there's a lot more going on than just temperatures.  All else being equal, early season heat tends to affect people more severely.  Overnight temperatures matter for individuals without access to air conditioning.  Exposure to the sun can be critical, and with a strong ridge in place and the summer solstice near, we will see near-maximum possible ultraviolet radiation intensity.  

For some long-term context, below is a graph showing the dates of the first and last 100˚F day each summer in Salt Lake City since 1895.  Except for a brief period during the 1930s, days of 100 or more were relatively uncommon.  They have become more common since 1960.  On or before June 25, 100 or more has occurred only 20 times and on or before June 11 only 5 times.  

Source: http://xmacis.rcc-acis.org/

Expect more of this in the future.  Sadly.  

May: Warm and Dry Conditions Deepen Drought

For me, May was a delightful month.  I haven't had to run the air conditioning, the mountain biking has been delightful, and there have been new trails to explore in the Avenues foothills which have been green and full of wildflowers, although that is changing now.

The numbers for temperature, precipitation and drought, however, are more sobering.  Officially at the Salt Lake City International Airport the average temperature for the month was 62.7˚F, making it the 19th warmest May since record keeping began in 1875.  Rainfall was only 0.65 inches, which was not exceptionally dry, but still below the average of 1.82 inches.  Spring precipitation can be spotty, so any one station can sometimes not be regionally representative.  However, a statewide analysis of precipitation shows nearly the entire state received below average precipitation, with the southwest exceptionally dry.  

Source: NWS Advanced Hydrologic Prediction Service

The combination of above average temperatures and below average precipitation has further deepened the drought statewide.  The entire state is now experiencing moderate drought or worse, with 62% experiencing exceptional drought.  

Source: https://droughtmonitor.unl.edu/CurrentMap/StateDroughtMonitor.aspx?UT

Today (June 1) is the start of meteorological summer.  Sadly, it's going to feel like it this week.  Below is a National Weather Service infographic illustrating the potential for record breaking temperatures.

I'm not looking forward to it and such temperature will only exacerbate the drought.