Wednesday, July 23, 2014

The Weather

It was cloudy in Boulder, Colorado today. South of Denver had some larger storms. Below is the radar base reflectivity and the radar velocity. A gusty outflow boundary is visible on both maps.

Base reflectivity measures the presence of particles such as precipitation and dust (and sometimes even birds and bugs). 
Velocity measures the speed of the particles relative to the Doppler's location. Orange colors indicate particles moving away from the radar, and greens indicate particles moving toward the radar.
Meanwhile, the Wasatch Front is experiencing some hot weather and scattered thunderstorms. The MesoWest observations on the left show today's high temperatures. The radar image on the right shows thunderstorms near Ogden. (Click the images to make them bigger.)

Monday, July 21, 2014

What is WRF?

WRF stands for the Weather and Research Forecast Model. Pretty much, it's thousands of lines of FORTRAN code that, when executed, predict the weather. This is known as numerical weather prediction (NWP). Learning a little about NWP will help you appreciate your cute little weather app on your phone. 

I'm in Boulder at the University Corporation for Atmospheric Research (UCAR) for the WRF Tutorial Training. There are at least 40 people here from all kinds of professions and literally from every continent (yes, even Antarctica is represented. A researcher from England is headed to the South Pole later this year.)

To run the WRF model, all you need is a Linux computer. You can download the model for free and then make your own weather forecasts for any area in the world you are interested in. Ok, it's a little more difficult than that. That's why I'm here for a week.

A weather forecast first starts as data. You need weather observations taken from weather stations, weather balloons, and satellites. Oh, and you also need another weather forecast. That piece might seem unnecessary. Why do you need a forecast to make a forecast? 

The GFS (global) and NAM (North America) model data is created at low resolution. Have you ever seen a pixelated picture? That's what the GFS model looks like.
When you increase the resolution, the picture looks much more realistic...
Obviously, the second picture of Mario is better. That is why WRF is used. Weather forecasts made by WRF use the coarse forecasts to increase the resolution of the forecast. These forecasts can be tuned for specific purposes.

WRF looks good, so why don't we just use that? Or why not run the GFS or NAM at higher resolutions? Well, there are several problems. The most obvious problem is computing power. Computers aren't powerful or fast enough to create a global weather forecast at this high resolution.

WRF is like a weather playground. The code allows the user to change anything you want. Imagine, all the knobs and buttons that control the weather in your control!!! Have you ever wondered what the weather would be like if there were no mountains? What if the lake was 5 degrees warmer? How can we make it snow? How does the weather change after a volcano erupts? Why was the forecast wrong and how can we get the forecast right next time?

Why is this useful? Scientists can investigate ways to make weather forecasts more accurate during specific situations. There is a high resolution WRF model run over Utah, and you can get the data from the National Weather Service. You can get the WRF forecast for Utah here: The trick is interpreting all this data. That's why meteorologist have jobs.

For my research the the University of Utah, I'll be using WRF to better understand the dreaded inversions and cold air pools that cause unhealthy air quality in the winters. Inversions are not accurately modeled in large scale models like the GFS or NAM. Hopefully with the WRF we'll learn how to better forecast these events.

And this is Warf, who joined us for our WRF lectures...

Sunday, July 20, 2014

Tail Wind

On my way to the WRF Training Workshop in Boulder Colorado. WRF is the Weather Research and Forecast Model used by scientists and meteorologist for weather related research, mesoscale weather forecasting, and developing weather models. Looks like we'll have a tail wind heading to Denver.

Update: Our flight was a short one. We left a half hour late and arrived in Denver on-time. We were only at cruising altitude (31,000 ft) for less than 15 minutes and then we were making our approach to Denver.
Stable layer with stratus clouds and an overshooting top of a cumulus cloud. 

Convection caused a bit of turbulence.

Saturday, July 19, 2014


I've seen a few friends from across the country sharing pictures of pretty orange sunsets the last two days. The reason for these orange sunsets is all the smoke in the air. It's even hard to see the mountains. 
University of Utah, WBB building looking West to downtown Salt Lake City.

The Aqua and Terra satellites show hot spots and smoke in Washington and Oregon.

The map below shows the location of fires and smoke across the country.

We've had strong westerly winds that are responsible for transporting all the smoke. Today's 700 mb mesoanlysis shows these winds. 
And speaking of fires, there was a field fire in Spanish Fork today...

Monday, July 14, 2014

Hottest Day -- So Far

Today was a hot one. Spanish Fork maxed out at 103 F this afternoon! That is the hottest day of the far. Below show the max temperatures for Utah County.

Salt Lake County experienced similar temperatures, and some dust. Thunderstorms in northern Utah are causing gusty winds as fast as 50 mph. The strong winds are blowing quite a bit of dust into the Salt Lake Valley. In the radar image below you can see the outflow boundary...

The airport is probably having a great day. For all you airplane nerds out there, you can listen to airtraffic control here: Plus, you can watch planes land in Salt Lake International here:

Below shows the MesoWest observations at the airport at the time of the gust front blew past the airport...

Sunday, July 13, 2014

The Maiden Voyage - Provo River

The moisture from earlier this week pulled out and left this weekend warm and sunny. It was a perfect day for a river float and my vessel's maiden voyage. We started our float at the base of Deer Creek Dam and floated to Vivian Park, about a 4.3 mile float. 

Analysis for the time of our float ( It was warm, and cloud free, except for the mountain peaks where convective clouds were billowing. 

Tuesday, July 8, 2014

Monsoon Moisture

The high pressure sitting over us is moving east. This will cause upper levels winds to come from the south, bringing our way wetter air. The additional moisture will help those clouds develop into larger thunderstorms across the southern part of Utah.
Right now, thunderstorms in the Southwest are bubbling up.

For more information about the North American Monsoon, see this post: Monsoon Convection.

Saturday, July 5, 2014


Fireworks are the best part about the 4th of July. Click Here for some cool pictures from Capital Weather Gang. And here's a cool video of a firework show from a drone's perspective:

Now that Utah legalized aerial fireworks we can enjoy the explosions from our front yard! 

Since I like checking air quality just for fun, I'll share this...It's interesting to see the pollution levels "blow up" when the entire state is exploding stuff. Notice the spike in PM 2.5 pollution across northern Utah just before midnight on July 4th...
The measurement in Weber County probably isn't correct. It looks like they shot fireworks straight into the sensor or they dipped the sensor in dirt.

Timpanogos Hike on Independence Day (we are so Patriotic)

My brother and I celebrated the Fourth of July with an impromptu Mount Timpanogos hike. We started from the Timpanooke Trailhead and took a little under 4.5 hours to get to the summit.

Hike slideshow: Auto Loop



  1. Snow slide
  2. Timpanogos Skiing
  3. Timpanogos Skiing, round 2. (This is why my camera is now broken.)
  4. Family in Spanish Fork watching our signal mirror (first flash at 30 seconds).
  5. More with the signal mirror

The above videos shows my family watching our signal mirror from the summit. Surprisingly, you can see our flashes of light from as far as Spanish Fork, over twenty miles away!

View from the summit looking southwest. The large body of water is Utah Lake.

Looking north...

On the way down, looking back at the summit:

Wild Flower Slideshow: Auto Loop


And now for the weather...
First, a look at the terrain and a UU2DVAR temperature analysis:
 The left panel shows the topography of the Wasatch Front. Mount Timpanogos is the second tallest peak in Utah County at 11,752 feet. The right image shows the 2.5 km UU2DVAR temperature analysis run at the University of Utah (notice the scale is in Celsius). The time shown here is the same time my brother and I were at the summit. While the valley was experiencing a warm day near 90, my brother and I enjoyed temperatures in the low to mid 60s on the mountain.

The MesoWest observations can confirm these temperatures. Shown below are the noon temperatures. Unfortunately, there are not weather stations on the top of Timp, but the station on Arrowhead Summit reported 68 degrees at noon with 18 mph winds from the southwest.

At the summit I was fascinated that there where no clouds above us on Timp. Usually clouds love to develop right above the mountain peaks on a hot day. There were, however, some exciting thunderstorm activity over the Uintah mountains. This is especially interesting because the weather models got this detail right

Below is a Terra satellite image on July 4th.

Below is the NAM forecast created a few hours before hiking. The left panel shows humidity and winds at 700 milibars (about the height of Timp's summit). The right panel shows precipitation and surface winds. 
Notice the dry air on the west side of Utah. This drier air is what limited cloud development over Timp. The precipitation forecast correctly predicted rain over the Uintah mountains. That is pretty cool if you ask me.

And stole this from online, but pretty cool video of the Timpanogos Summit from the perspective of a quadcopter.

Wednesday, July 2, 2014

Almost Hurricane Arthur

In honor of 2014's first soon-to-be hurricane in the Atlantic, here is a post on Arthur...

First, a view of Arthur from space...
Terra Satellite
Aqua Satellite
Hurricanes are classified by the Saffir-Simpson Scale as a function of wind speed. A tropical storm becomes a category one hurricane when the sustained winds exceed 74 mph.

Arthur will likely become a category one hurricane late Thursday night and early Friday. Its predicted path will ride up the North Carolina coastline bringing strong winds and heavy rain.

Meanwhile, Virginia is experiencing some exciting thunderstorms this evening. I love watching clouds boil like this...

And here are some pictures of lightning in New York at this same time (link).

Weather in Utah has been a bit boring. We are sitting under a ridge of high pressure and it's very dry. We're also dealing with high ozone levels. We need a good storm to push it all out.

Along the Utah Nevada border there are pockets of bubbling cumulus clouds. I like to call these types of clouds "Toy Story Clouds."
Terra Satellite
Aqua Satellite