Wednesday, April 22, 2015

Smoke from Asia

The last few days have been quite smokey. Here's a look from the Suncrest camera:
April 20, 2015
And a Satellite image:
April 18, 2015
It's a little early in the year for summer pollution, so what is this gunk in our air? It's from Asia. Many brush fires got out of control due high winds. In the satellite image below you can see the massive smoke plume. Each red dot is a surface hot spot identifying the location of fires.
April 14, 2015
It only takes a couple days for air over Asia to reach the United States.

Backward trajectories show that the air over the Eastern US was over Asia just a few days earlier.

Friday, April 17, 2015

"Where is it now"

Remember that crazy storm that passed through Utah earlier this week? Today it's snowing in Colorado Wyoming and causing more problems. Here's a view of I-80: 33 semi trucks and 12 cars piled up on the roads.
photo from KSL

Thursday, April 16, 2015

Cool Wave Clouds

With warm, stable air blowing over the mountains we get these neat waves of clouds in the lee of the mountains. Below is the MODIS image from this afternoon.

It's not often that Salt Lake is on the lee side of the mountain. The 500 mb winds show the winds blowing from the north-east.

Here's a look from the visible satellite.

And you can even pick out the wave clouds in this video...

Why do these form? Because stable air from upstream is forced over the mountain barrier. The air oscillates about it's equilibrium level, kind of like a spring, until it it is damped out.

Wednesday, April 15, 2015

And then there was Snow

It may be hard to believe, but this time yesterday's high temperature was 76 degrees at the airport. Right now it's 30. Since yesterday we've lived through extremely gusty winds (over 90 mph gusts in Parley's Canyon), a dust storm, muddy rain, and snow. The only thing that would have made it worse is a wildfire. Oh, wait. That happened too. Lots of active weather, which made for an exciting day--flight delays, accidents, jammed freeways, downed trees, "hey Dad, where is the trampoline". A power outage in Murray caused the train I was on to be delayed because the track switcher thing wasn't working. Add those delays to the delays in the morning and I spend a grand total of seven on public transit. Perhaps my worst commute day ever.

In Provo this morning there wasn't any snow accumulation. At the Eyring Science Center there was 0.23 inches of rain. In Spanish Fork my home only got 0.12 inches.

This morning on campus I was happy to see 6.5 inches of snow! Sure has been a long time since I've seen the white stuff.

CoCoRaHS observations show quite a bit of snow across the valley. It looks like the forecast was more or less right for most of the valley.
My Grandpa was begging me for some snow. Looks like Logan got a good share of it too...

From the radar you can see that it's still snowing over much of the northern part of the state.

The camera display shows the snow too...

How long will the snow last? By the late afternoon.

Thursday through Sunday our temperatures will creep back up to more spring appropriate temperatures.

My mom sent me this picture. Looks like it's snowing in southern parts of Utah County now.


Tuesday, April 14, 2015

Weather Update

Here I am stuck on the Frontrunner after an incident causing an hour or longer delay. I'm late for class, so I'll just look at the weather and take a closer look at this cold front moving in. 

Currently, it is 61 degrees and sunny at the airport. The southerly winds have also contributed to the warm morning.
Looks like it's going to be a nice day, but don't be fooled.

An approaching cold front is expected to reach Utah this afternoon. I would expect some big changes in the weather around 3:00 PM. In the radar image below you can see the front over Nevada this morning.

Looking at the NWS point forecast for this afternoon and evening. Our high temperature of the day will be at 11:00 AM. Then, in the afternoon when we usually keep warming due to solar heating, the temperature drops steadily to evening. Looks like temperatures behind the cold front are about 25 degrees colder than it is right now. Brrrrr! Oh, and it will be pretty windy, too.

Since yesterday, the precipitation ensembles is forecasting slightly more rain and snow. The ensemble mean suggests 0.5 inches of water. There is one outlier model that thinks we'll only get a sprinkling, but I would say that case is pretty unlikely today. Many of the individual members are predicting a bit more, about 0.7 inches of water. Safer to expect a half inch of water.
It doesn't look Provo will get this much water. 

Since the cold front will bring much colder this rain will turn into snow as we approach the evening hours. By morning we could wake up to an inch or two. The thirsty mountains will sure love this spring storm.

UPDATE: April 14, 2015 2:00 PM
The cold front is at our doorstep. Look at the shift in winds between Dugway and the Salt Lake Valley. Numbers on the map are wind gusts in miles per hour. I-80 has been closed due to tipped over semi trucks.

Below is a time lapse showing the blowing dust in the valley. It looks kind of nasty out there.

Where is the dust coming from? It's from the west desert. I'm still waiting for the TERRA satellite to pass over Utah to get another look at the dust, but by the next orbit we might be socked in with clouds.

From the University of Utah, it's pretty difficult to see anything in the distance. Plus, here is a "storm selfie" of me and some of my classmates:

In the TRAX air quality measurements show unhealthy levels of PM 2.5.

The front is about to reach the University of Utah. If you thought it was dusty two hours ago (12:45 PM), look outside now (2:45 PM)!
William Browning Building 12:45 PM

William Browning Building 2:45 PM
And now we can look at the cold front passage at the airport. Yay!

The best way to classify a cold front is by cold air. In the last half hour, temperatures at the airport have dropped 20 degrees.

 Also, note that winds at the airport have shifted from the south to the west, northwest. It's incredible that winds are gusting at 65 miles per hour!

An an updated view of PM 2.5 in the valley: at the Neil Armstrong Academy concentrations are almost at 250!!! Downtown is also extremely polluted. This air is not good to breathe. 

Compare the camera image at 3:17 PM with the one at the top of this post from this morning...

Update 4:16 PM
Now with the front passage and some rain, the dust has cleared out quite a bit. Visibility has improved at the Neil Armstrong Academy.