Thursday, June 30, 2016

Record Heat Prospects and Mountain Hail Encounters

With 29 days in the bag for the month, the average temperature at Salt Lake City for this June is 77.3ºF, just 0.2ºF behind 2015 for the hottest of all-time.

Source: NOAA Regional Climate Centers
I've run some quick numbers using the last night's minimum temperature (74ºF) and the forecast maximum for the day (91ºF).  Those will bump this June up about .15ºF, which will put us very close to 2015 (and within the roundoff uncertainty of the monthly mean data I have access to, which is rounded off to the nearest tenth of a degree).  Much will depend on today's maximum and whether or not we get some dramatic cooling from precipitation to lower the minimum.  In either event, 2015 and 2016 will stand as back-to-back Junes of unusual warmth compared to past Junes in the historical record.

Meanwhile, here in the Northeast, yesterday was an "excursion" day at our conference, allowing us to get out into the Adirondack Mountains and climb Giant Mountain.  The day started out optimistically with partly cloudy skies.

The hike up Giant is short, about 2 3/4 miles, but involves about 3000 vertical feet of ascent up an extremely rugged Adirondack trail.

On the summit, we were treated to a nice view of the high peaks.

However, as we summited, we heard a low rumble of thunder and after a couple of minutes on top, it was clear we had to descend and descend fast.

After getting a few hundred vertical feet off the ridge, the skies opened up, initially with rain, but eventually with a deluge of pea-sized hail.

Here's a handful.

Steep Adirondack trails are nasty enough when dry, but even tricker when wet and covered with ball bearings of ice.  We also encountered quite a bit of "hail fog," a shallow fog mainly in the canopy layer due to cooling from melting ice.

Due to the retreat, our group photo was taken about half way down, after things dried out and the camera partially defogged.

Just another day of adventure with the Steenburgh group.

Monday, June 27, 2016

Race on for Hottest June

With four days left in the month, the race is now on for the hottest June on record.  The average temperature so far for this June puts us in 2nd place all time in Salt Lake City, 1.2ºF behind 2015.

Source: NOAA Regional Climate Centers
And the forecast calls for triple digit scorchers today and tomorrow and 90s for the last 2 days of the month with above-average minimum temperatures.

Source: NWS
It's gonna be close.  Although it's unclear which year will end up number one, it's clear we're going to go #1 and #2 for the past two Junes.  Yes, you have bragging rights.

Saturday, June 25, 2016

The View from Here

Looks like Salt Lake has gotten some much needed relief from the heat as I just pulled up the 2 PM MDT observation from the airport and it's only 77ºF with a dewpoint of 19ºF and winds from the northwest at 12 mph gusting to 18.  That must feel so good.

I'm currently in New York visiting family in advance of the American Meteorological Society Conference on Mountain Meteorology, which will be held in Burlington, Vermont next week.  Although we are warming up here and are expected to hit 90ºF tomorrow, it's been pleasant for my stay so far.

Today I did a hike up Snowy Mountain, which is not so snowy by Utah standards, but at 3899 ft, is the highest peak in the southern Adirondacks and requires about a 2000 vertical foot ascent.  Most of the trail is fairly easy, but the last several hundred vertical feet is your classic Adirondack knee breaker, basically a steep creek bed requiring the occasional "vegetable belay," especially on the descent.  A red trail marker on the tree center left confirms that this is the official route.

Many mountains in the Adirondacks still have old fire towers, which are no longer in use, but are greatly appreciated to provide a full 360º perspective given the dense trees on many summits.  When i was a kid, they still had rangers manning many of these towers looking for fires, and it was always a thrill to finish a climb with a visit.  That always seemed like the ultimate job to me, but fortunately I chose a different career path since we do it all with satellites and other tech these days.

From Snowy Mountain you can see the Adirondack "high peaks", a region encapsulating 46 peaks that were once thought to all exceed 4000 feet, although modern surveys reveal a few of these fall short.  I bagged a large number of these peaks with my Dad, but ultimately gave up the quest when I moved west.  No regrets.  The handful we had left required long misadventures with limited views.

The area around Snowy Mountain ain't Manhattan.  It's pretty unspoiled everywhere you look.  Indian Lake, pictured below, has always been one of my favorite large Adirondack lakes.  There are a few homes and camps, but it's fairly undeveloped and the forest is largely impenetrable.

It's good to be back "in the green."

Thursday, June 23, 2016

It's a Two Horse Race for Hottest June

Here are two ways to look at the temperature for June so far.  In the first, we compare the mean temperature for June 1–22 to similar periods in the past.  This year stands as the hottest such period on record, 0.1ºF warmer than June 1–22, 1918.

Source: NOAA Regional Climate Centers
In the second, we compare the mean temperature for June 1–22 to that of prior Junes (i.e., June 1-30).  The mean temperature for June so far would rate as the 2nd warmest on record, behind only last June.
Source: NOAA Regional Climate Centers
Although there's a cool down on tap for Friday and Saturday, we look to rebound again for the remainder of the month.  It looks like a two horse race for hottest June on record between 2015 and 2016.  My money is on the latter.

Tuesday, June 21, 2016

Heat Waves Are Going to Get Worse

Here are a few temperature "highlights" from yesterday:

  • The Salt Lake City Airport hit 100ºF, the first triple digit reading of the summer.  Was it a record?  Nope.  June 20, 1936 hit 101ºF.  
  • The Salt Lake City Airport also set a record high minimum for the day of 77ºF, trouncing the old record of 69ºF set in 2003
  • Alta hit 79ºF, breaking the old record for the day of 75ºF set in 2007
  • Numerous daily record maximum and high minimum temperatures were set in SoCal, including:
    •  122ºF in Palm Springs, which was 1ºF off their all-time record (123ºF) and also equates to 50.0ºC, precisely half way between freezing and boiling. 
    • 111ºF at Bob Hope Airport (Burbank), tying their June record
    • 125ºF in Needles, setting a new record for June and tying their all-time high (set in 1925 and 2005)
    • 126ºF in Death Valley, a record for the day
People often ask me if such heat waves are what we will be facing with global warming. This heat wave is not the future.  The future is worse.

We are still in the early stages of global warming.  Natural climate variability remains a major driver of extreme events like this (although global warming does tip the scales a bit).  When one looks at projections for the future under a "high-emissions" scenario, things don't get really ugly until the middle to late 21st century.  Gurshunov et al. (2013) provide an illustration of this for the most recent Southwest Climate Change Assessment Report.  They define heat waves as days when the maximum or minimum temperature exceeds that of the hottest 5% of summer days or nights (May–September) in the 1971–2000 climatology.   The heat wave index is the cumulative total number of degrees above the hottest 5% temperature threshold on these heat wave days. 

As shown in the graph below, for either maximum or minimum temperature, a clear long-term upward trend in maximum temperature heat waves over the U.S. Southwest has yet to be clearly detected (brown dashed and solid lines, with the latter representing the 5-year running mean), but there is some upward trend in minimum temperature heat waves.  

Source: Gurshunov et al. (2013)
 Heat waves are, however, projected to increase at an accelerating rate during the 21st century (black lines), with the climb for minimum temperature heat waves stronger than that of maximum temperature heat waves.  Studies examining southern California suggest that today's 100-year event becomes a 10-year (or shorter) event in the latter half of the 21st century.  Minimum temperatures are expected to climb faster than maximum temperature (consistent with the larger heat-wave index above), so the character of heat waves will also change, with less nighttime cooling.  

The graphs above are based on a high-emissions scenario in which we remain welded to fossil fuels for future energy demands.  Heat waves are going to get worse, but how much worse ultimately depends on the energy choices we make today and in the coming decades. 

Monday, June 20, 2016

Hot and Cold in SoCal

Although Arizona got some attention in the lead up to the current southeast heatwave, SoCal felt the heat yesterday too.
Source: Penn State
The temperature contrasts along the coast can be quite remarkable in patterns like this.  This morning at about 10 AM PDT, it was 98ºF at USC and 79ºF in Inglewood.  Out at Oxnard, with a decent onshore flow, it's a cool 69ºF.  Location, location, location.

Source: MesoWest
But perhaps the most remarkable temperature goes to Avalon Catalina Airport on Santa Catalina Island.  The airport is 1578 ft above sea level and above the marine layer.  The 11 am temperature was a whopping 101ºF.  Check out their temperature trace over the last 5 days.  Simply nasty.

Source: MesoWest
In case you are wondering, the average high at Avalon Catalina Airport in June is 67.6ºF.