Plume Preview

I'm working work the WRF model and testing the plume function. Imagine inserting a bunch of molecules at a location and watching where they go after they are blown by the wind, like watching smoke disperse.

Smoke Week: August 16 - August 23

Smoke from fires in the Washington, Oregon, Idaho, and California was transported into Utah starting August 15th and didn't clear out for over a week. The red dots in the image below show the location of fires based on MODIS observations on August 20th. These fires include the largest fire in Washington's history. Air quality across Utah was impacted by the smoke. At MtMet between the 18th and 22nd PM 2.5 concentrations were in the moderate range and unhealthy for sensitive groups range. Also shown is the ozone at MtMet during the same time. Other observations at MtMet are here. University of Utah trucks, KSL Chopper, and TRAX drove around measuring ozone on August 19th. All observations available here. Looking towards valley from near Bountiful Peak. Lidar observations on August 20th. On the day with the highest backscatter you can see the upper levels winds from the northwest were relatively strong. Lidar backscatter and winds on August 20, 2015[/caption]   On the bright side, we I enjoyed the orange sunsets! Moab Sunset, August 15, 2015 Mapleton Sunset, August 22, 2015

Hurricane Forecast Improvements

Ten years of atmospheric science and forecasting improvements makes a big difference. Efforts to improve hurricane forecasts in the last decade are shown in the image below. To the left is the hurricane Katrina three-day forecasted path using 2015 technology and science. The right is the forecast issued three-days before Katrina in 2005. The cone of uncertainty is much smaller.

You can read more about improved hurricane forecasts here.

Summer Smoke

There are lots of fires burning in the West, especially in northern Idaho, as indicated in the "Active Fire" map and satellite image.

The smoke sure made for some orange sun sets the last week.

Fortunately, in Utah, the smoke is starting to clear out. You can see the PM 2.5 concentrations have returned to the healthy levels.

This is due to a shift in our weather pattern. Last Tuesday the upper level winds were blowing from the northwest transporting the smoke from the fires to Utah.

Last night you can see the upper level flow has shifted to a more southwest flow, bringing in smoke-free air and a little rain, as I saw yesterday when I got to campus.

Transported Smoke

Aqua Satellite: August 16, 2015

My allergies have been acting up. I'll bet it is caused by all the smoke in the air. Some of this smoke is likely transported from the northern California fires.

PM 2.5 levels increased across northern Utah, as indicated by several air quality monitoring stations:

At the University of Utah you can see the particulate mater and black carbon concentrations rise late in the evening on August 15th and then drop back down. However, PM concentrations have stayed elevated.

The MTMET ceilometer also shows the smoke increasing particles in the air Saturday evening.

You can see a difference in the air quality in this time lapse video from the Neil Armstrong Academy. Looking at the beginning of the video you can clearly see the mountains in the distance. Fast forward to the next day and the smoke has blown in and the thick smoke obstructs the view.



I was in Moab the evening the smoke blew in and witnessed an amazing sunset. Small particles of smoke scatter light which produces these warm orange and red colors in the horizon in the evening.

Large fires in the west are producing a lot of smoke. Not much of the smoke has been transported to Utah, yet. Early next week we may see some smoke as the upper level flow turns more zonal which will blow the smoke directly east of California.

GFS forecast for Monday at Midnight

From yesterday's satellite image you can see from the MODIS satellite images the fire hot-spots and the smoke plume dispersion.

From the satellites we can calculate the optical depth of the atmosphere. Optical depth is a measure of how much light can penetrate a layer of atmosphere. Below shows the same area with high optical depths (reds) at the location of smoke plumes and low optical depth (blues and purples) over clear skies, meaning light goes all the way to the surface without much depletion. Optical depth isn't calculated for clouded areas.

HRRR Geography Data Issues

The High Resolution Rapid Refresh model has a few issues around the Great Salt Lake. One we have noticed is that the modeled lake is too large! This causes increased dew point temperatures around the lake's location than are actually observed. Increased dew point temperatures lead to increased CAPE values, or the potential for thunderstorm development.

On August 10, 2015 at 23:00z the HRRR modeled dew point temperature was at least six degrees higher at the surface than observed during the 00z sounding. This produced nearly 2000 Joules of CAPE in the HRRR when there was actually about 200 Joules of CAPE. This means that the HRRR was saying that thunderstorm development was very favorable when in reality there was marginal potential energy available to cause deep convection. This issue will be looked at further. We intend to modify the lake area to produce more accurate simulations around the Great Salt Lake.

Skew-T diagram of HRRR analysis at 23z on August 8th (thick red) and actual weather balloon observation (thin blue). Surface specific humidity values were less than 7 g/kg, but the HRRR model thinks there are over 10 g/kg. Imagine lifting a parcel with dew point temperatures of 5C rather than 13C, you would get much less CAPE. 

The outer line representing the Great Salt Lake is the lake/land mask used by the HRRR. The inner line is a more accurate representation of the's current size. The coloring represents the specific humidity. Specific humidity is much higher following closer to the large lake boarder. The white dot represents the location of the KSLC sounding site where weather balloons are launched. You can see that this location is in the pink (> 12 g/kg) when in reality the humidity at that location is much less.

Wedding Weather Review

Radar Aug 7 at 10:20 PM

The weather couldn't have been much better for the wedding than what we got. The weather all day was as expected. We got a few random thunderstorms, but they didn't affect any of the daily events. The night before the wedding we had quite the lightning show that we watched from out garage. It rained pretty hard around 8:40, but had completely passed by morning.

We drove to the temple and saw an amazing cap cloud over Mount Timpanogos. It is so neat to see the waves in the atmosphere. When we got out of the temple I noticed quite a bit of convection over the mountains had developed that was a little worry some, but the skies remained sunny during the pictures. Right after we were done taking pictures outside the temple, a few of the people who left last drove to Provo in a heavy downpour! Perfect timing for that storm to happen right after we left. I feel bad for the other weddings getting out at that time, but the storm was moving quick and was short lived.

Radar Aug 8 at 1:15 PM

The luncheon was hot and a little breeze, but we were under a shaded pavilion, so that was nice. I could see the large storm cloud over Orem and American Fork (see radar image) and we could hear thunder from it. I was glad it was moving north and would not hit us in Provo.

Radar Aug 8 at 5:30 PM

We had a few hours between the luncheon and the reception so some of my friends and cousins went bowling before we headed back home to help set up the reception. I took a nap on the grass because I didn't know what to do to help. I figured if I was needed someone would come get me. Right before we were getting started it started to sprinkle. There was a small thunderstorm cell just to our north. Some of the rain drops must have been blown over our backyard. We got pretty lucky that this didn't develop and pass right over us or things would have been a little soggy to start of of the reception.

The temperature was pleasant in our shaded backyard. It was about 78 degrees when the reception started and by the end it cooled to 72. Couldn't have asked for better weather for an August summer day.

Lenticular or Cap Cloud

A pretty cool lenticular-ish or cap cloud over Mt. Timpanogos. Photo cred. to my sister!

Wedding Weather: UPDATE

Looks pretty good outside!

Wedding Weather UPDATE

Today there is widespread rain across the state, but the weather is still looking favorable for Saturday's wedding. The rain will exit the state by 7:00 AM Saturday morning. Clouds will decrease into the afternoon which will warm us up to nearly 80 degrees for a pleasant luncheon and evening reception. I still have some concerns about wind. Around noon winds will be from the southwest at 10 mph. That breeze is enough to blow paper plates off the tables. Winds will die down in the afternoon and the evening winds will be calm during the reception. (You're welcome, Mom)

Did you feel that cold front??

There was quite the cold front this evening pass us in Provo. Did you feel it? It didn't notice it get any colder, but it was windy. Playing volleyball, everyone got sand in their eyes. Just after 19:00 (7:00 PM) you can see the temperature decrease about 8 degrees and the wind suddenly shifted from a calm southeast wind to a 19 mph wind!

Wedding Weather

My brother is getting married this Saturday, so I better put together a forecast and update it each day to keep an eye on things. There are three events that day: 1) The marriage will happen in the morning at the Mt. Timpanogos Temple, 2) the luncheon will happen outside at a park in Provo, and 3) the reception that evening in Spanish Fork.

Overall Weather Pattern: A trough will enter Utah Friday afternoon bringing cooler temperatures and widespread rain. By Saturday morning the rain will exit Utah. That's good news for the wedding!

NAM Forecast issued 08-05-2015 12:00z
Source: weather.utah.edu

Some lingering clouds my be around the morning when my brother is married, but I don't expect any rain the rest of the day. In the afternoon the clouds will decrease and the sun will steadily warm us up. The high temperature for the afternoon will be in the mid 80s. Should be nice enough at the park to kick the soccer ball while we wait for the bride and groom to show up. The afternoon reception will also be dry, though the thing to worry about will be the winds. Nothing too fast, but it could be a bit gusty, enough to blow the paper plates off the tables.

It looks like the 18:00z NAM forecast is almost out, so we'll take a look at that soon.

UPDATE: August 6, 2015 2:00 PM

Below is the Short Range Ensemble forecast for Friday at 6:00 PM. Shown is the percent of models producing more than 0.01 inches of rain.

Now look at Saturday morning at 3:00 AM. Notice that the band of rain has moved north. I expect on Saturday morning the grass will be wet but the skies will start to clear.

Saturday at Noon

Saturday at 6:00 PM

So good news, this reception wont be rained out.
Looking at all the model members, yep, doesn't look like we'll get any new rain on Saturday after the sun rises. Still, it would be wise to keep an eye on the radar for any pop-up thunderstorm over the west mountains that could blow over.

Another thing to look at are the winds. The 4-km NAM forecast shows winds less than 10 mph in Utah county from the north, northwest in the evening during the reception. It may be a bit gusty, but no outrageous winds.

Incredible Satellite images of Moon and Earth

Images from NASA new DSCOVR satellite. Image of Earth on July 16

You can see hurricane Dolores off the Baja peninsula. 

This is the MODIS image from that day:

June through July Ozone Clock

Below are a few "Ozone Clocks" for June and July 2015 from measurement stations around northern Utah. These should convince you that the best time to exercise outside out be in the morning when ozone pollution is always low. The afternoon and evening hours ozone concentrations are frequently higher. You can create your own ozone roses and clocks on my website here: http://home.chpc.utah.edu/~u0553130/BB_home/cgi-bin/ozone_rose.cgi