Thursday, December 15, 2016

Warm and cold night

Temperatures got warmer throughout the night in Spanish Fork

Now, moving north to the Point of the Mountain...

And finally the Airport. They were stuck in a cold pool all night, then southerly winds mixed out the cold air and temperatures rose quickly to over 54 C

Inversion this morning quite impressive from the morning rawinsonde:

 Check out the time series of Sodar data near the airport as the cold pool mixed out:

Thursday, December 8, 2016

Peter Sinks, Utah: One of the coldest places

The Peter Sinks in Northern Utah (near Bear Lake) is one of the coldest places in the lower 48 states.
Some info here:
and here:
From MesoWest: the PSINK and PSRIM sites at midnight on December 8, 2016

The temperature gradient between the rim and the valley, a 270 foot vertical difference, can be quite large. Over the last two days temperatures have plunged below -40 C.

Max, min, and mean temperatures for the two stations are shown below (need to apply some quality control on the data from the MesoWest API seeing that there is a max temperature in September of over a 105 F, which seems odd) Still, it is often quite cold in the Peter Sinks.

Thursday, December 1, 2016

Comparing the MYNN and MYJ planetary boundary layer schemes for a Lake Breeze event.

I was the lead author for a paper titles "Impact of Lake Breezes on Summer Ozone Concentration in the Salt Lake Valley." This article was recently accepted in the Journal of Applied Meteorology and Climatology. (see article here:

One concern from the reviewers was our use of the MYJ planetary boundary layer scheme. They pointed to evidence that the MYNN scheme was superior, and may improve our results, particularly in the timing of a lake breeze passage on June 18, 2016. We declined to re-run the simulation using the MYNN due to computing resources and time.

I have since re-ran the simulation with the MYNN and found the results are very similar with the MYJ. Below are time series graphs for the stations presented in the paper with the temperature and wind with the MYNN model run overlaid in magenta. The only change between the "WRF" and "MYNN" model data is that the MYNN uses the MYNN PBL scheme instead of the MYJ PBL scheme.
Color and station name denote the observed temperature and wind at the station location. Black dashed is the original WRF simulation, magenta dashed is the same simulation except uses MYNN boundary layer physics.

Temperature and wind patterns between the two runs are very similar. We see that using the MYNN did not change the timing of the lake breeze on this day.

The cause of the observed delay in the lake breeze progression is likely caused by stronger meridional wind component below 5,000 meters (550 mb). In the vertical profiles below, you can see the opposing southerly winds at the Salt Lake City Airport were from the direct south at 10 m/s below an inversion layer at 5,000 m. The HRRR and WRF with MYNN PBL scheme had slightly weaker winds and more from the southwest. This subtle difference is likely the primary reason for the delayed lake breeze on the afternoon of 18 June 2016. The next question is, "how do we fix that subtlety in the model." I'm not sure I know the answer to that.
Vertical profile of potential temperature, mixing ratio, and vector winds at 19 June 2015 00z. Profiles for Salt Lake City Rawinsonde (blue), HRRR analysis (red), HRRR 1-hr forecast (green), and WRF with MYNN PBL Scheme (black) are shown. Notice in the observed sounding the critical level at 5,000 m where there was a temperature inversion. Below this level winds opposed the lake breeze and were directly south while the simulated winds were weaker and more southwesterly than the observed winds. This subtlety is the likely reason why the WRF simulation missed the delayed lake breeze.

Just as a comparison between 3 km and 1 km domains: the lake breeze is much less "sharp" in the outermost domain, run at 3 km (right), than the inner domain run at 1 km (right).
Domain 2 with 1 km grid spacing
Domain 1 with 3 km grid spacing

N. Utah Snow on November 25th, 2016

MODIS Image, 25 Nov 2016
When the clouds clear out, we'll be able to see the snow cover after the last two snow storms :)

Here is the snow on December 2nd

Wednesday, November 23, 2016

HRRR: Top Soil and Surface Temperature

I'm looking at the surface temperature of the Great Salt Look and wondered if the top soil temperature or the surface temperature is what I should be looking at. Turns out, the top soil level and the lowest temperature level (surface temperature) are identical over water

Shown, difference between Soil Temperature (top soil level) and Surface Temperature:

As you can see, there is no difference between the surface temperature and top soil level temperature over the Great Salt Lake (thus, the white color over the lake area).

The same can not be said over mountainous areas, where there are the largest differences.

Tuesday, November 22, 2016

GOES-R Satellite Launched

On 19 Noveber 2016, the GOES-R satellite was successfully launched. This new NOAA satellite is set to make a big impact on weather forecasting over the next decade.

Watch the Launch below

More info can be found here

Friday, November 18, 2016

That was a cold storm

That last blue bar. Yeah, that was yesterday's temperature range. It was cold.

Wednesday, November 16, 2016

Storm's a comin'

The first half of this November has been comically warm. The temperatures at Salt Lake get warmer and warmer.

But our first winter storm is at our doorstep. Temperatures will begin to drop this evening and we'll see some snow in the mountains and the valley floor. Below shows the NAM forecast for 5:00 PM this evening. Going to work tomorrow will be considerably colder than it was this morning. The thermometer in my car said is was 57 F on my way to the train. Tomorrow morning will be closer to freezing.

Mark your calendar!! GOES-R Launches this Saturday

The GOES-R satellite is scheduled to launch 19 November 2016 at 3:40 Mountain Time. This satellite is an advancement in modern weather observation systems and will aid in weather forecasting and monitoring.

Thursday, November 3, 2016

Operational RAP/HRRR update for wind gusts

As a note to myself:

AUTHOR:   Stan Benjamin
  DATE:     3-November-16 1459Z

A change was made in the wind gust diagnostic calculation for the operational
RAP and HRRR yesterday (2 Nov 2016) starting with the 14z run. This change
reverted to use of a theta-v profile PBL depth for the wind gust diagnostic
instead of using an alternative hybrid PBL-depth. Use of the hybrid PBL was
resulting in too-strong wind gust fields at nighttime. More information is
available in

Friday, October 28, 2016

Three fall mornings.

The last three days have been quite nice on my morning walk to campus.

And College Game Day is on campus today and tomorrow for the big Utah vs. Washington game. Go Utes!!!

Thursday, October 20, 2016

HRRR Land Use

For reference, here is the land use in the HRRR model:
Categories are based on the MODIS 21 Category data set as indicated below:
1 Evergreen Needleleaf Forest
2 Evergreen Broadleaf Forest
3 Deciduous Needleleaf Forest
4 Deciduous Broadleaf Forest
5 Mixed Forests
6 Closed Shrublands
7 Open Shrublands
8 Woody Savannas
9 Savannas
10 Grasslands
11 Permanent Wetlands
12 Croplands
13 Urban and Built-Up
14 Cropland/Natural Vegetation Mosaic
15 Snow and Ice
16 Barren or Sparsely Vegetated
17 Water
18 Wooded Tundra
19 Mixed Tundra
20 Barren Tundra
21 Lake

Can find other MODIS landuse products here:

Monday, October 17, 2016

Neato clouds in South Africa

My brother currently in South Africa sent me this picture of "Neat-o clouds"

The need for better Numerical Weather Prediction in the United States

There has been a lot of national attention on the weather community in the last few weeks due to Hurricane Mathew and the strong winds in the Pacific Northwest. Numerical weather prediction, the heart of our nations weather forecasting capabilities, provides invaluable information on weather that may disrupt economics, destroy property, and threaten human life.

There was a neat article on weather forecasting in the New York Times worth reading:

Cliff Mass has perhaps been the most outspoken individual on our countries forecasting capabilities. In summary, he says we can do much better. And that is something I believe, too. Seems to me we do a great job as it is, but there is a lot of room for improvement.

The evolution of numerical weather prediction, I think, is much like the evolution of Nintendos Super Mario video games.

The game from the 80s was a lot of fun to play. It's was a classic. But today's Mario has evolved into a high-definition character who can move in more ways than just up/down/left/right. I feel Numerical Weather Prediction is evolving in the same way, with increased resolution so that more features can be shown, and there are increasing capabilities in the models being explored. With continued development, our countries forecasting capabilities will turn from a "fun game" into an outstanding weather forecast system.

Monday, October 10, 2016

Hurricane Matthew: Buckets of Rain

Fayetteville, North Carolina, recorded nearly 15 inches of accumulated rain in a 24 hour hour period on October 8th. This large rain event was due to heavy rain from Hurricane Matthew. Below is the radar at 1620 UTC.

Volunteer weather rangers from the CoCoRaHS network shows the high rain totals in North Carolina, especially Cumberland County.

My dad was on a trip in North Carolina, and his plane home was canceled because of the hurricane.

Thursday, October 6, 2016

Thursday, September 29, 2016

BFlat: New Weather Station at Bonneville Raceway

The MesoWest research group at the University of Utah set up a new weather station at the Bonneville Salt Flats speedway. The data from this weather station will be used to help study how the salt flats change over time.

The data can be viewed here:

The Bonneville Speedway is famous for the land speed records that are recorded there. Racing season is in the summer, when the salt flats are dry.

Today, the salt flats were wet. We had a lot of rain last Thursday. All that rain flowed downhill and pooled on the raceway.

The water at the end of the paved road was about a foot deep. The site for the weather station was three miles off the road. We didn't want to take out truck out there. Lucky, the BLM had an all terrain vehicle to ferry us and our equipment to the station site.

There were a bunch of tourists out to see the salt flats, and then wondering what the heck we were doing out in the water.

The three mile drive in the salt water took about 20 minutes to get to the site. Where the station was located there was less than a half inch of water. But the water was like a mirror. I got a sunburn, and some good pictures of the mountains and sky reflecting in the water.

On the drive back, I was sitting on the outside of the UTV, in the splash zone. After my pants dried, the right leg was white with salt. My face was also speckled. My lips sure were salty.

The salt got everywhere. The UTV was covered and someone managed to get us back to our truck without dying on us. It did have a lot of trouble. The salt water would spray up in the air intake and deposit there. It would also hit the exhaust system and the water would vaporize, leaving the salt behind caking the pipes. On the way back the tail pipe was almost completely closed off by salt. I wonder how much CO I breathed that day

Monday, September 26, 2016

Fall Mountain Snow

Outside my apartment is Mount Timpanogos. It has snow on it.

In fact, there is a lot of snow in the mountains across northern Utah. This is the Terra satellite image from September 25, 2016