Sunday, August 28, 2016

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.

Friday, August 26, 2016

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...

Wednesday, August 24, 2016

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).  

Tuesday, August 23, 2016

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.

Monday, August 22, 2016

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.  

Friday, August 19, 2016

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.