Rime

Rime is created by supercooled water droplets that freeze on contact with surfaces. It is pretty common in mountains because of the cold temperatures. At the University of Utah Flight Park South weather station, we replaced a precipitation sensor, and saw a lot of riming on the fence and all the weather instruments.

Freezing Rain

Freezing rain is a pretty rare occurrence in Utah. We had an event in January which gave everyone trouble. And here we are again with another event likely to happen.

This morning's sounding (data from a weather balloon) from the Salt Lake International Airport shows the surface is really cold and the air above us is warm. This is called an inversion. 

The inversion is partly responsible for the poor air quality right now, shown below...

If you take a look outside, you can't see much of the valley...

This storm will help clear this out.

The Thursday morning the NAM shows a pressure trough approaching Utah bringing moisture. We're expected to get precipitation out of this shown in the bottom right panel. But the temperatures at 700mb (about at the top of the mountains) is above freezing. The falling snow will melt in the warm layer, and freeze on contact with the surface in our cold valley. This will create some slippery roads, so be careful!

weather.utah.edu

Statewide Snow

Coming Break in Poor Air Quality

University of Utah, William Browning Building webcam

Have you noticed the smog in Salt Lake county this Thanksgiving weekend? If you're familiar with winter time weather in Utah, you know the inversion is the culprit. It's pretty dirty, and the chart below proves it. In the last two days, one hour PM 2.5 concentrations have reached the "red" air quality category. (In case you didn't know, PM 2.5 is not good to breath. PM 2.5 is made of tiny particles, smaller than 2.5 micrometers, and get in your lungs causing respiratory problems.)

Salt Lake City

November 25-30, 2013

airquality.utah.gov

What we need is a big storm. Storms help improve air quality because they bring a new air mass with clean air (although, the air is usually cold becomes it comes from our north). Also, storms are generally windy and can mix out the inversion. Pollution can then be mixed out and diluted vertically.

Fortunately, we have a storm on it's way. Yea!! The November 30, 00z GFS model run shows a strong cold front will enter Utah Tuesday morning. Of course, a good snow storm will accompany this cold front. More good news for skiers!

GFS Forecast for Tuesday December 3, 6:00 pm

weather.utah.edu

American Geophysical Union

Next week is the AGU conference in San Francisco. At the conference I will present a poster on my work this summer with NASA's Student Airborne Research Program.

Click the image below to see my poster

You can read more about the work I did this summer here:

Final presentation
Student Airborne Research Program