Gradual Cool Down Thankfully Coming

Fall can't come soon enough.  Yesterday's high at the Salt Lake City airport reached 98ºF and was followed by a minimum last night (through 6 AM MDT) of only 74ºF.  Mother Nature really teased us last night as temperatures dropped quickly after 7 PM, but hopes of cool air pouring through the windows were quickly dashed as temperatures flatlined near 80ºF for much of the night.

Source: MesoWest

Today and tonight will probably be near repeats with a high near 98ºF and a low tonight in the mid 70s.  There is hope in the possibility of an isolated thunderstorm.  If you one of the chosen ones to receive rain and evaporatively cooled air, consider yourself fortunate.

The good news is that a gradual cool down is coming.  The GFS 700-mb temperature and wind analysis and forecast loop below shows the slow movement of cooler air associated with the upper-level trough presently over the Pacific Northwest into northern Utah later this week into Saturday morning.

Emphasis, however, on gradual.  Temperatures will be a bit cooler than today on Thursday and Friday, but highs will still likely be in the 90s.  Labor Day Weekend, however, looks quite pleasant.  If you will be in Salt Lake and environs, I think you will like it.

Hawaii in the Gunsights

Picturesque Hawaiian waterfalls could be roaring soon

Two powerful hurricanes have developed over the tropical eastern Pacific and are headed westward toward Hawaii.  Hurricane Madeline is currently (1200 UTC 30 Aug) a category 4 hurricane and will be the first to approach the islands on Wednesday and Thursday.  It is the westernmost hurricane in the image below.  Hurricane Lester is farther upstream (east) and a potential player for the Labor Day Weekend.

Based on analyses from the National Weather Service Central Pacific Hurricane Center, about 22 tropical storms and hurricanes have passed within 200 miles of Hawaii since 1950 and 10 have passed within 75 miles.

Source: NWS/CPHC

Model guidance presently shows a wide range of tracks for Madeline as she approaches Hawaii.  The GFS ensemble has a few bringing it directly over the Big Island, but others push her further south.  

Source: NCAR/RAL

A look at a multi model suite shows a couple of tracks that pass between the Big Island and Maui, but others going to the south.  

The official track cone, which represents the area that is likely to include the probable track of the tropical cyclone center, extends from the center of the Big Island southward.

Madeline is expected to weaken some as it approaches Hawaii, but will still be a dangerous storm with hurricane-force winds possible on the Big Island on Wednesday (depending on track and intensity), heavy rain on the Big Island and possibly other Hawaiian Islands Wednesday through Friday, and dangerous surf.  Official graphics and forecasts are available here.

As a mountain meteorologist, I'm interested in seeing how precipitation is affected by the interaction of the system with the topography of the Big Island.  I plan to keep an eye on this over the next couple of days.

Summer 2016 Destined for "First Loser"

It has been a hot, miserable summer, but it is now apparent that despite all the misery, 2016 is destined to only be the 2nd hottest summer on record in Salt Lake City.  In other words...

First Loser!

With 3 days left in meteorological summer (including today), the average temperature is 80.2ºF, a full degree ahead of 3rd place 2012, but 0.5ºF behind 2013.

Source: NOAA Regional Climate Centers

A half degree doesn't sound like much, but that's a difference in averages over about 90 days and even Ricky Bobby chasing Jean Girard can't make up ground like that.  

But don't be depressed.  If soccer can add extra time, we can add more laps.  We may be 2nd for summer, but we still have a shot at the hottest year on record.  For the year to date, we are only 0.1ºF behind 2015 for hottest on record, so we could go for the annual record.  

Source: NOAA Regional Climate Centers

Of course, breaking that record would probably require a warm November and December.  Let's not go there...

Northwest Utah on Wrong Side of Tracks Again

Did you know that the high yesterday in St. George was 85ºF.  Cedar City reached only 71ºF!  Oh to experience a day like that.  Then there was that tornado in Panguich on Friday.  What gives?

Not much really.  Northwest Utah has simply been just to the north of the monsoon moisture and the weak disturbances that have helped to initiate thunderstorm activity for most of the summer.  Indeed that was the case yesterday.  As the analysis for 1200 UTC (0600 MDT) yesterday morning shows, a weak trough was centered right over St. George with clouds over most of the southern half of the state.  Once again, we were left high and dry.

I would give anything for grey overcast with steady rain all day.  Until that day comes, I'm resigned to listening to Natalie Merchant and dreaming.

Downscaled Forecasts from the Short-Range Ensemble Forecast (SREF) System

Alex Weech, an extremely capable undergraduate who has been working with me this summer, recently added downscaled precipitation forecasts from the National Centers for Environmental Prediction (NCEP) Short-Range Ensemble Forecast (SREF) system to the suite of products we have available at weather.utah.edu.

The SREF is a 26 member ensemble that includes forecast from two different modeling systems, the NCEP Eulerian non-hydrostatic multi-scale model (NMMB) and the Advanced Research version of the Weather Research and Forecasting Model (WRF-ARW).  Yes, I know these are terrible acronyms.  They don't call NOAA the National Organization for the Advancement of Acronyms for nothing (technically the WRF-ARW is not a NOAA product, but that doesn't make it any easier).

The SREF is initialized at 03, 09, 15, and 21 UTC and produces 87 hour forecasts at 16-km grid spacing.  We then downscale those to 800-m grid spacing using climatological precipitation analyses.  For now, we are generating plots showing precipitation forecasts for the entire 87-hour period.  An example from this morning's 15 UTC run is below.

We are also generating plume diagrams.  Since the weather in northern Utah is pretty uninteresting, here's the plume for Wolf Creek Pass, Colorado.

You will notice in that plume diagram that there is a strong clustering of forecasts by model, with the ARW being wetter and the NMMB being drier.  That's a fairly common characteristic of the SREF and one that we will have to examine to see if it skews the probability statistics for the forecasts.  And, with that being said, I really don't know how good these forecasts will be.  We'll start taking a look and perhaps by ski season we'll know whether or not to continue looking or just come up with a large sum of money to buy the ECMWF ensemble forecasts...

Japow Dreaming

With Dave Hanscomb, Hakuba Valley, Japan, February 1998

For much of my life I have been studying lake-effect and orographic (i.e., mountain) snowfall in some way shape or form.  This includes scientific investigations as well as personal adventures involving face shots, chin ticklers, and bottomless powder.

I was first introduced to the incredible snow climate of Japan in 1998 when I visited the Hakuba Valley during the Nagano Winter Olympics.  I was there for only four days, however, and much of my time was spent conversing with meteorologists involved in weather support for the Games.  I had time for only a brief taste of Japanese powder skiing when the Men's Super-G was cancelled, allowing for a couple of hours of storm skiing at Happo Ono resort.  

Storm skiing, Happo Ono, February 1998.  Just me and a few security guards near the top of the Men's Super-G.

This winter I will finally be traveling back to Japan and hopefully getting another taste of Japow.  I plan to travel to Nagaoka to begin a collaboration with scientists at the Snow and Ice Research Center of Japan's National Research Institute for Earth Science and Disaster Prevention to better understand orographic enhancement of lake-effect precipitation through study of storms across a wide range of geographic and topographic environments.  

I am hoping to tack on a few days of skiing in the Hakuba, Myoko, and/or Tenjin areas.  If you can share any beta on tours or guides, add a comment or send me an e-mail directly (jim.steenburgh at gmail.com).  

What Is a Haboob?

Dan Pope of ABC 4 Utah shared a remarkable photo yesterday of a Haboob near Phoenix, Arizona.  The credit is ambiguous, so I share the full facebook post below to provide as much credit as possible.

A Haboob is a dust storm generated typically in arid regions by the outflow from a thunderstorm, convective cloud, or precipitation system.  Within these clouds and precipitation systems, cooling by precipitation produces a downdraft or downdrafts, a cold pool at the surface, and strong winds.  The leading edge of the cold pool and strong winds is known as a gust front and, in areas where this leads to dust emissions from the surface, typically demarcates the leading edge of the Haboob.  I've taken considerable artistic license to crudely sketch this out in the photo below.

Haboobs occur in arid regions around the world.  Areas where the land surface has been disturbed, enabling or enhancing the potential for dust emissions, are vulnerable to Haboob development.  Many iconic photos from the Dust Bowl are Haboobs with dust emissions in that area strongly related to poor agricultural practices combined with long-term drought.  Even today in Arizona and much of the American Southwest, land-surface disturbance is an aggravating factor in Haboob frequency and intensity.

Welcome Back!

New Student Welcome, Saturday, August 20, 2016

Today is the first day of classes for the 2016–17 academic year at the University of Utah.  One of the great things about being a professor is you experience renewal each fall as the school year begins anew.  In addition, the start of classes each year reminds me that winter is coming and summer is nearly in the rear view mirror.

It has been both a hot and dry summer.  We are currently just behind 2013 for the hottest all time in the Salt Lake Valley (I'll forgo the graph this time) and have had only 0.67 inches of precipitation at the Salt Lake City airport since June 1, which ranks as the 16th driest since 1874.  It's been so dry that the sight of virga this morning made me positively giddy.  

For the most part this summer the monsoon has been a total bust in northern Utah.  We've had neither the large-scale pattern nor the disturbances necessary to bring in moisture from the south and initiate widespread shower and thunderstorm activity on a regular basis.  Every now and then we get a weak monsoon surge and a few showers and thunderstorms, but that's it.  

Let's hope Mother Nature is saving it up for late October and November.  

Smoky Skies, Dry Vegetation

The Wasatch Range from Neil Armstrong Academy (West Valley City).  Courtesy MesoWest.

If you happened to up and about early, you would have noticed that the moon was made with a bit of cheddar cheese this morning as it had a hint of an orange hue, usually an indication of smoke in the air.  Indeed yesterday things were starting to look smoky (if not even earlier) and this morning the view of the Wasatch is degraded by a bit of smoke.  

I'm not sure where the smoke is coming from, but yesterday we had a very weak trough passage, resulting in a brief period of northwesterly flow at 700-mb, as indicated in the analysis below for 6 PM (0000 UTC). 

NASA Worldview imagery from yesterday shows smoke across much of the Intermountain West, but the greatest concentrations were over northwest Nevada and southern Idaho, so perhaps that northwesterly flow brought in some of that smoke.

So far this fire season I think northern Utah has been quite fortunate.  We've had some incidents (e.g., Antelope Island), but for the most part it's been pretty quiet considering that the landscape is a tinderbox right now.  Hiking and biking the past couple of weeks I've noticed that not only the grass is dry, which is pretty typical for late summer, but even many of the trees, shrubs, and vegetation is looking pretty brown.  Low areas and seeps that often stay green through the summer look quite stressed and dry as well.  Let's hope we make it to the snows of fall without major incidents.

Weather Monotony

By and large we are embedded in and will continue to be dominated for the next few days by a fairly boring weather pattern characterized by light flow aloft, the passage of a large-scale "ripple" now and then, and perhaps a few showers or a thunderstorm here or there.  Perhaps one of those thunderstorms will prove exciting, but otherwise weather monotony will predominate.

A quick update on our quest for the hottest summer on record.  Through yesterday, we are in a dead heat with 2013.

Source: NOAA Regional Climate Centers

Everything will depend on how things evolve over the next couple of weeks.

They Grow Up Too Fast

Today was my final hike with my son Erik before he moves into the dorms at the University of Utah tomorrow.  Due to packing and last minute purchases, time was tight, so we opted for a quick ascent to the Salt Lake Overlook in Mill Creek Canyon.

Words cannot describe the myriad of feelings I have this weekend.  Pride, excitement, and joy as he heads off on this new adventure.   Melancholy as I experience this parenthood transition.  Life surely does fly by in the blink of an eye.  It seems like only yesterday I was showing him the routes in the Avenues foothills.

With all ends come new beginnings.  Although he was accepted at many great schools, the U was an obvious choice for a strong student who craves outdoor adventures.  Plus, shopping for schools gave me new appreciation for just what a bargain the University of Utah is (Confession: Dependents of faculty members and full-time U employees also get a 50% tuition reduction).

I'm hoping he's having so much fun that he's home sparingly, but hungry enough he lets me treat him to lunch and hear about his adventures every couple of weeks.

Silly Season Returns

Silly season has returned as people descend from bull s--t mountain to provide forecasts or projections for the coming winter.  Accuweather, which recently extended its highly dubious and scientifically unjustified 45-day forecast to 90 days, is the first in line, getting coverage on Unofficial Networks.  

Do yourself a favor, ignore all this crap.  Remember all the hype last year about El Nino?  How did that work out for you?  Now we have a 55–60% chance of La Nina developing this winter (see the Climate Prediction Center Diagnostic discussion released 11 August), so you can expect a healthy does of La Nina hype this fall.  That means lots of forecasts like the one above, which have no discussion of probabilities and suggest high confidence.  That goes over well in the media and makes a good story, but the reality is that La Nina merely weights the weather odds in some portions of the country (not Wasatch snowfall though).  Plus, it's unclear at this time how strong La Nina will be and how much of an impact it will have on the storm track.

So, what kind of ski season will we have in the Wasatch Range?

 I don't know. 

And nobody else does either.   

It's a Beautiful Day!

Wow, was that a great night last night near campus.  Lightning, thunder, and the best rain we've had at my house in many weeks.  Really, it wasn't much of an event, but everything is relative.  Some of you had have storms in recent days, but I haven't seen that good of one at my place in some time.

Walking around this morning the air just seems so pleasant.  A one month temperature trace from the Salt Lake City airport shows why.  Although we've had a handful of days with morning temperature's as low as this mornings, the relative humidity is higher than we have seen in the past month.  The combination of lower temperatures and higher (but not too high) dewpoints after a good washout last night makes the air seem unusually fresh.

We certainly have more summer ahead, but I'm starting to notice a shortening day and a lower sun angle.  Change is coming slowly but surely!  The energy balance of the northern hemisphere is starting to change in our favor.  The seasons are changing, and not a moment too soon!

Thank You Senator Whitehouse

University of Utah, Utah State University, and Brigham Young University scientists with US Senator Sheldon Whitehouse D-RI, 3rd from left)

Last night I had the great honor of attending a dinner with US Senator Sheldon Whitehouse (D-RI) and several scientists from the University of Utah, Utah State University, and Brigham Young University.  It is quite remarkable that a sitting US Senator flew across the country and dedicated two and a half hours to meet with a handful of scientists far away from his home state.  The Senator and his staff also deserve kudos for inviting a graduate student and post-doc to the meeting and providing a great opportunity for young scientists to discuss science and policy with our political leaders.

Over the years I have met with many legislators and staffers about climate change.  I typically do not seek these meetings, but I believe it is vital for scientists to interact with our political leaders when asked.  The quality of these conversations, either one-on-one or in committee hearings varies.  At the low end, legislators or their staff are simply milking your for information to support their ideological views, or they might be looking to score some political points with voters.  At the high end, there are legislators who are trying to understand the science or policy options, engage in spirited discussion, and are capable of analysis and reason.  Whether or not such conversations fall on the low or high end of the spectrum doesn't necessarily depend on political persuasion.  I have engaged conversations with both republicans and democrats, and more difficult, ideological conversations with individuals from each party too.  

Senator Whitehouse fell into the high-end category as he was down to earth and fully engaged.  He also answered many questions that we had about policy and how to better communicate our science.  His wife is a marine scientist and he had an unusually deep understanding the perspectives and challenges facing science and higher education today.  

It was a very rewarding evening and I thank Senator Whitehouse for the invitation.

Addendum at 3 PM: More on Senator Whitehouse's visit at the Deseret News.

How "Dry" Is This Summer?

Brown, the official color of summer

Some of you have commented about how dry it is this summer.  Let's have a look at some data, focusing on the Salt Lake City area.

In Salt Lake City, the total precipitation so far this summer (1 June – 7 August) is 0.59 inches, making it the 19th driest since 1874.

Source: NOAA Regional Climate Centers

Most of that precipitation fell in June, however.  The total precipitation since July 1 is only 0.07", good for 10th driest.

Source: NOAA Regional Climate Centers

However, "dryness" reflects not only precipitation, but also evapotranspiration.  Evapotranspiration is the transfer of water from the soil to the atmosphere through evaporation and transpiration.  Many factors effect evapotranspiration, including humidity, wind speed, and temperature.  I don't have access to historical humidity or wind records, so I'm going to ignore them here.  For temperature, however, the summer so far is the warmest on record, with an average temperature of 80.6ºF.

Source: NOAA Regional Climate Centers

Since July 1, we're in 4th place (not shown), so it has been an exceptionally hot summer too, and that is a major driver of the extreme dryness, increased irrigation demand, and stress on plants.  

Elsewhere in northern Utah, a few places may have benefited from showers and thunderstorms the past couple of days, but for the most part, it's been a dry and hot summer regionally.  

Summertime precipitation shows a great deal of variability spatially and from year-to-year.  Remember that last year was remarkably wet.  Temperature also exhibits year-to-year variations, but the trend is clearly up, with heat waves becoming stronger and more persistent.  It is because of these temperature trends that we expect summers to become increasingly arid over northern Utah in the coming decades.  

Return to Nuclear Summer

After a week in the cooler but muggier confines of upstate NY, I returned late last night to Utah.  It appears that I missed the worst of "nuclear summer" while I was out of town.  Yesterday's high of 95ºF broke a string of 9 consecutive days with a maximum temperature of 100ºF or higher, which ties for the 2nd longest stretch of 100ºF days at the airport, falling just short of the record of 10 set in 2003.

Don't be disappointed thought.  The streak of 95ºF or higher days reached 21, which I believe is a new record, eclipsing the 20 consecutive days observed in 1960 and 1978.  It looks likely that streak will also end today thanks to a weak overnight trough passage, which ushered in a shallow, but somewhat cooler airmass, along with extensive smoke.

In case you are wondering, the summer to date (June 1 - Aug 4) is 0.6ºF warmer than any other comparable period on record.

Source: NOAA Regional Climate Centers

Time will tell if the entire summer (June–August) will be one for the record books, but looking at the extended range forecasts, I think we have a pretty good shot unless we see a major pattern shift in the latter half of the month.

Mother Nature's Natural AC Can No Longer Do the Job in July

July is in the rear-view mirror and not a moment too soon.  Despite the heat of the past couple of weeks, it enters the record books with an average temperature of 83.1ºF, good for 4th warmest on record, behind 2003, 2007, and 2013.

Source: NOAA Regional Climate Centers

Preventing us from the record was the July 10-11 cold surge.  Surely you remember the maximum temperature of 76ºF on July 11?  Ah, the good old days.  

Although July wasn't a record breaker, the average temperature for the first 2/3 of summer (June–July) was the hottest on record, topping 2013 by 0.6ºF.  

Source: NOAA Regional Climate Centers

During June and July we saw 14 days with a maximum temperature of 100ºF or higher.  That ties for the 5th most on record.  

Source: NOAA Regional Ccimate Centers

As we have noted before, however, it is the minimum temperatures that are bringing true misery to the region.  The chart below shows the number of days in June and July with a minimum temperature at or above 75ºF.  This year's 11 is the highest on record.

Source: NOAA Regional Climate Centers

If we use 70ºF instead, this years June and July ranks 2nd behind 2013. 

Source: NOAA Regional Climate Centers

The graphs above show that we entered a new summertime climate regime in the first part of the 21st century.  At the Salt Lake City airport, the 9 warmest Julys on record all occurred since 2002 and nights are clearly much warmer than they used to be.  How much of this is due to global warming, regional climate variability, urbanization effects, or characteristics of the Salt Lake City airport observing site warrants a deeper investigation than I can do for this blog post, but one thing is clear.  Mother Nature's natural air conditioning can no longer do the job in the Salt Lake Valley in July.