Wednesday, December 13, 2017

Incredible PM2.5 Observations from KSL Chopper

Following up on the previous post, our intrepid MesoWest Team has partnered with KSL-TV to collect PM2.5 observations from their helicopter, Chopper 5 (much thanks to KSL for enabling this incredible resource).  The data today is simply incredible.

Below shows one period during which the chopper was flying across the Salt Lake Valley and over portions of the Wasatch Front.  The chopper position varies, as well as its altitude, and it is clear that sometimes it it flying in clean air (blues) other times "dirty" air with much higher PM2.5 values (red).

The scattergram below illustrates all the PM2.5 measurements during that period based on altitude. Below about 2100 meters, the helicopter frequently flew in the valley pollution.  PM2.5 values were generally above 35 ug/m3.  There are, however, a few places at those elevations where the air was fairly clean.  This is not surprising given the tendency for there to be waves and other features on the inversion. 

Between about 2100 and 2600 meters, the air is mostly clean.  All observations were below about 30 ug/m3 and the vast majority were < 5 ug/m3.  

However, go higher up and there are some horrible PM2.5 values again, some as high (or higher) as in the polluted air in the valley.  This is what I suspect is the smoke from the California fires.  This smoke isn't uniform.  There are some pockets of clean air, but the PM2.5 levels are quite high in some locations.  

This is simply incredible data.  I've never seen anything like it.  Wintertime pollution trapped in the valley.  Smoke from extreme wildfires at upper levels.  Remarkable.  Thanks to the MesoWest team and KSL for making this happen.  Note that this data is freely available in real time at http://utahaq.chpc.utah.edu/

Smoke from California May Have Arrived in the Mountains

Many people over the past few days have wondered if some of our pollution is from the California fires and up until today, the answer was no.

If you live in the lowlands along the Wasatch Front, the answer to that question is probably still no.  We are in a soup of locally produced pollution that is quite isolated from changes aloft.

However, in the mountains, the answer might be yes.

I went up to Alta this morning for a quick tour and workout, and was quite surprised to see some dense haze in the canyon.  This haze was especially apparent looking down canyon from the upper Albion lot.


After our climb, the view toward Heber showed some dense haze that appeared to be thicker aloft than right near the surface in the valley.


What was quite strange was how spotty and variable the haze was.  At times, the air looked quite clear in one area, but hazy in another.  One thing that was clear is that there didn't seem to be any spread of pollution from the valley to high elevations, as suggested by the photo below.


Thus, I don't think the mountain haze is from the valley pollution.  Providing further evidence of this, the morning sounding at KSLC showed an incredibly strong inversion, with the temperature within the inversion increasing more than 10ºC.  My experience with such strong inversions is that the air is typically quite clean once you are above them.


I wonder if instead some smoke from the California fires has finally crested the ridge and dropped down into northern Utah. Over the past several days, that smoke has been pushed offshore and at times northward along the Pacific Coast.  Monday's Modis image, for example, shows the smoke offshore, along the coast, and wrapping northward off the Northwest Coast.

Modis Image 11 December 2017.  Source: NASA
Yesterday, however, that smoke had spread inland across much of Washington and Oregon, and possibly across northern Idaho.

Modis Image 11 December 2017.  Source: NASA
 Thus, it is possible that the northwest flow has finally transported that smoke into our area.  As I write this, we haven't gotten a Modis overpass yet, but one will be coming soon and it should be interesting to see what it shows.

Note that this does not mean that the smoke is contributing to our problems in the valley.  The smoke is likely elevated and the inversion that prevents the pollution from entering the valley, also limits the spread of smoke aloft into the cold pool.  The smoke instead simply adds to the misery by reducing the clarity in the mountains.

Tuesday, December 12, 2017

Inversion Tidbits and Long-Range Prospects

Yesterday's satellite imagery summarized the ridge-dominated weather of western North America quite well with extensive fog found in the major basins, many of the valleys of British Columbia and the Northwest United States, and the Great Salt Lake Basin.  At the same time, smoke from the California Fires covered much of the offshore eastern Pacific Ocean.  If you look carefully, it appears that some of this smoke has been carried northward to the Queen Charlotte Islands.

Composite MODIS image from NASA.
Within the Salt Lake Valley, the pollution went into overdrive yesterday, with PM2.5 levels skyrocketing in the morning to unhealthy levels.  Unlike previous nights, when PM2.5 dropped considerably, levels declined only modestly overnight and remain unhealthy for sensitive groups. 

PM2.5 concentrations at Hawthorne Elementary.  Source: DAQ
Looking for a brightside?  The frosty trees make for a beautiful Christmassy scene.  


We are so desperate for weather that I feel the need to mention that there is actually a weak short-wave trough dropping down the back (eastern) side of the ridge and passing through our area Wednesday night.  


Yup, that's your weather for the week.  It will bring somewhat cooler temperatures to the mountains, perhaps helping with the snowmaking efforts and might stir the upper part of the inversion a bit.  Emphasis on might.  Low elevations will likely remained mired in pollution. 

I am a bit more optimistic that the trough on Saturday is strong enough to give us at least a partial mix out.  It's still soon to say if it will scour it all out.  Sometimes, the coldest, most polluted air at the lowest elevations can be quite stingy. 


Snowfall totals for the mountains presently look paltry.  About half the members in our downscaled NAEFS ensemble generate 2 inches or less.  A few members go for more.  A game changer is unlikely. 

The word "pattern change" is being thrown around a lot, but I bet you'll have a hard time finding anyone who can tell you what that means.  I have yet to see any indication from any ensembles that we are going to shift from the high-amplitude pattern that has dominated for weeks and in which there are very deep ridges and troughs at upper levels, to a more progressive pattern with stronger westerly flow.  Instead, there may be some shifts in the position of the ridges and troughs.  For example, some of the GEFS 10-day forecast members below have a ridge upstream of the west coast of North America, rather than near its present location along the west coast or just inland. 

Source: Penn State E-wall
Those shifts could be important if they lead to a slowly evolving but wet pattern for Utah.  However, looking at the GEFS solutions above, some might bring us some snow, others keep us dry.  Why waste time talking about this range of possibilities?  Like thermonuclear war, the best option is not to play.  


Thus, hope we get something from the trough on Saturday and at minimum hope it cracks the inversion.  It's the only slim hope we have for mountain snow over the next week.  After that, your guess is as good as mine. 

Monday, December 11, 2017

Diurnal Intricacies of the Inversion

PM2.5 concentrations during our current inversion event have shown remarkable variations from day to night.

Below is a time series of PM2.5 measured at our mountain meteorology lab at the University of Utah showing a clear long-term upward trend, but also a tendency for PM2.5 concentrations to spike just before noon, remain elevated until mid to late afternoon, and then decline.

Source: MesoWest
What are the causes of this diurnal behavior.  There are several possible contributors.

First, there is the possibility that photochemistry - chemical reactions occurring in the presence of sunlight, are contributing.  Comparison of the above plot with the incoming solar radiation below shows some relationship, with the PM2.5 exhibiting a bit of a lag relative to the solar radiation.

Source: MesoWest

Another possibility is that temperature is playing a role since it also affects the PM2.5 chemistry.  Again, there is some correlation.  

Source: MesoWest
Finally, there is the transport possibility as the winds are also changing diurnally, with a good correlation between wind direction and PM2.5 concentrations.  

Source: MesoWest
Another perspective is provided by the someone hacked-up graphs below, based on data collected at the University of Utah by our MesoWest team over the 24-hour period ending this morning at 10 AM (the hacking reflects my splicing of their multiple graphs together).  The top figure is derived using a laser that is shot vertically through the pollution.  The color fill is backscatter, a measure of how much of the laser light is reflected back to the ground, with higher values roughly correlated with greater PM2.5 concentrations (brown-white being the dirtiest air).

The plot begins on the left at 10 AM on Sunday when the local flow just shifted to predominantly westerly (some variability from SW-NW).  Surface PM2.5 concentrations during this period are quite high and, in addition, the pollution is quite deep.  At just after 1700 MST (5 PM), the flow shifts abruptly to ENE, which reflects the onset of down valley flow from Red Butte Canyon.  This marks the beginning of a gradual decline of surface PM2.5 concentrations, as well as a decrease in PM2.5 concentrations aloft.

Source: MesoWest
There is a brief lull in the wind that occurs just before 2300 MST (11 PM MDT), with the flow becoming somewhat erratic.  Without the inflow of cleaner air from Red Butte Canyon during this period, the surface PM2.5 values climb, although things don't change too much aloft.  Finally, after midnight, the ENE flow returns and PM2.5 values drop again, although there are a few spikes during the night that may correlate with declines in wind speed (I haven't bothered to check yet...so take this comment for what it is worth).

At the end of the time period, the PM2.5 values climb again, abruptly, when the flow shifts to westerly.

All of this illustrates some of the intricacies of these inversion events.  Pollution concentrations vary in the vertical (yes, there is clean air up there), although if you look carefully at the plot above, you can see that it's not as simple as polluted air near the ground and non-polluted air aloft.  There are layers.  In addition, pollutant concentrations vary horizontally and at the University of Utah one can clearly see the migration of pollutant-laden air onto campus when the wind shifts to westerly in the morning.

What role photochemistry and temperature play in all of this is unclear to me.  I suspect it plays a secondary role compared to meteorological factors, but I am not an atmospheric chemist and over the years I've learned that when all you have is a hammer, everything looks like a nail.  In other words, as a meteorologist, I might be guilty of placing too much weight on meteorological factors.

One thing to keep in mind is that not all inversions look or behave like this and even this one might behave differently in the days to come.  As a scientist, I think what we see over the next few days will be "interesting."  As a citizen, I wish the damn thing would just blow away.

Saturday, December 9, 2017

Scenes from the Inversion

Classic inversion conditions are now apparent over northern Utah.  Here are a few photos.

First, the view of the valley smoke that befuddled me, and is discussed in the previous post.  It sure looked like clouds this morning, but as soon as I descended down into it, I smelled campfire and knew I was in error.  Turns out it was smoke from a major arson fire near 500 South and 200 East. 


In contrast to the cesspool in Salt Lake, morning at Alta was splendid and whiter than expected.


A bit later.  A good example that no matter where you are in the Salt Lake Valley today, you're only a few hundred meters (vertically) from clean, pristine air. 


Valley cold pools can be found just about everywhere over northern Utah right now.  If there's emissions, there's pollution.  The smog below is in the Heber Valley. 


Just about anyone who has skied in Little Cottonwood knows this view.  Unfortunately, it is common in the wintertime.


And, this afternoon back in the Avenues.  Ick. 


On the positive side, air quality remains in the moderate category so far. 
Source: DAQ
On the negative side, we have at least 5 days left of this, and air quality is going to worsen.

Overnight Stratus Formation?

I woke up this morning and was surprised to see a shallow layer of stratus already beginning to form over the northeast portion of the Salt Lake Valley.


I thought it might be smoke in the early morning light, but after watching it for a little while, I think it's cloud.  It's a bit unusual for the first stratus in an inversion to form in this part of the valley.  Typically it happens at lower elevations and near the airport, but perhaps the distribution of cloud cover is having an effect.

As one might surmise from the photo, the atmosphere is now quite stable over the Salt Lake Valley.  The morning sounding shows temperatures increasing from -4.7ºC at the surface to 3.4ºC at 763 mb (8200 feet).

Source: RAL
We're stuck with this now for several days.

You're going to hear a lot of talk about a possible trough passage toward next weekend, but the strength, structure, timing, and implications for northern Utah vary quite a bit across the various GEFS ensemble members.  

Source: GEFS
Keep the faith.

Friday, December 8, 2017

Heartbreak Ridge Tightening the Inversion Noose

Noontime smog yesterday, looking southwest from the Natural History Museum of Utah, University of Utah
Given that our last storm was winding down on Monday, I'll call today Day 4 of Heartbreak Ridge.

So far, the pollution buildup has been modest.  Because the center of the ridge has been along the Pacific Coast, we've been on the downstream side, temperatures aloft have been cool, and the inversion relatively weak and elevated.  This has enabled some vertical mixing of pollutants through a decent portion of the valley atmosphere.  As a result, the increase in pollution has been gradual and we've been fluctuating between good and moderate air quality.  

Source: Utah Division of Air Quality
However, Heartbreak Ridge is sliding eastward and the inversion is strengthening, as can be seen in the soundings from yesterday afternoon (top panel below) and this morning (bottom panel below).  


Source: University of Wyoming
Note in particular the warming in the layer between about 800 and 700 mb (6500–10000 feet), which equates to a strengthening of the "lid" over the valley atmosphere.  This morning, temperatures near the base of that layer increase about 5ºC through a depth of around 50 mb (1500 feet). 

The NAM sounding loop below (note: this is a skew-t diagram, not directly comparable to the diagrams above) shows further warming aloft over next two days, with temperatures aloft warming an additional 5ºC.  
Thus, the inversion will be strengthening and lowering through the weekend.  It appears we will be in the grips of the inversion at least through the next work week, unless a system stronger than presently advertised slides down the back side of the ridge and gives it a stir. 

Model Products Information

We have been having some problems with the server that hosts weather.utah.edu and it has been down intermittently the past two days.  Behind the scenes (and unrelated to the outages), I've been updating some of our products.  Options for the GFS now include global and regional plots from the 0.25 degree latitude-longitude grid (we've been using the old 0.5 degree grids), higher frequency (every 3-h to 240 hours), more regional sectors (e.g.,  Intermountain, Northwest, Southwest), and time-height section options that match the time period of the NAM for comparison.  Some little used plots are gone, such as the Indian Ocean sector.  




Thursday, December 7, 2017

Posts Written But Not Published

Source: https://sarkaimak.wordpress.com/2013/04/15/unpublished/
I noticed yesterday that sometime in October, the Wasatch Weather Weenies reached 2500 posts.  Unbelievable.  I've written about 99.99% of those and that is an obscene amount of work!

Our top-10 most viewed posts are popular for a mixture of reasons including Google-search happenstance, popular posts for a moment in time, and content that is timeless.

10. Blast from the Past: Ski Magazine February 1978.  Powder and Alta nostalgia.  Always a winner.

9. Powder Explosion. Photo collage from our snow adventures on the Tug Hill Plateau.  Nice to see the eastern US makes an appearance.

8. El Niño Likely for the 2015-16 Winter.  Seasonal outlooks and posts on El Niño/La Niña get huge readership, despite the fact that I almost always conclude that such information has little value for skiers in Utah.

7. Disastrous Heartbreak Ridge to Develop.  Wow.  This one is only a few days old and it has skyrocketed into the top 10.  If it bleeds, it ledes, and Heartbreak Ridge bleeds.

6. Pound for Pound the Snowiest Place in Utah.  I love Ben Lomond Peak and the north Ogden Valley.  Good to see you do too.

5. The "Official 2017/18 Ski Season Outlook.  Another seasonal outlook, although this one was written with tongue firmly in cheek.  The outlook, republished below, looks to be verifying well in California and Nevada, as well as Hawaii, but the "Better than Colorado" for Utah could be in jeopardy if this ridge hangs around.


4. West To Be Tickled by Fabio.  A good example of gaming the system with a frequently googled name.  In this case, Fabio was a former eastern Pacific hurricane with remnants spreading into the western US.

3. Tour de France Weather.  Weather always affects the tour, and this post continues to get a lot of traffic.

2. Outlook for the 2013–2014 Ski Season.  Another seasonal outlook.  This one was popular, because the outlook we issued was basic and honest.  WE HAVE NO IDEA!

1. Let's Rock.  Sort of a shame that this short post is #1, simply because there are so many people Googling Let's Rock.  There's no other reason to go here.

OK, so that's the top 10 based on page views, but there's another top-10 list (technically a top 7 list) that is more interesting, and that is the list of posts never published.  There aren't many of these because I am stubborn as hell.  Typically when I write a post I get an idea, I think it will take 5 or 10 minutes, I start to write it up, and I realize I'm in over my head.  I polish the turd quickly and hit the "publish" button and move on, hoping for the best.

However, every now I realize that there's no polishing the turd.  This typically occurs with politically controversial topics related to climate change, or more philosophical posts about science and weather forecasting.

With that being said, here are the seven posts never published out of 2500+:

7. Science Is Never Settled

6. Air Quality Irony

5. What Tree Rings Tell Us about Utah Climate

4. Obama's Carbon Reduction Plans

3. Climate Change: "Action is Urgently Needed"

2. Do Climate Scientists Really Ignore Natural Climate Forcings?

1. The Future of the Weather Forecaster

These posts were written with good intentions, but haven't yet made it to blog-worthiness.  However,  there's no such thing as good writing, only good rewriting.  Perhaps they will appear in the future.

Wednesday, December 6, 2017

A Great Month of Outreach, Education, and Radar Meteorology with DOW7

Professor Powder attempts to keep DOW7 from leaving
After more than a month in Salt Lake City, DOW7 departed the University of Utah campus and began its trip home to Boulder this morning.

It had a great run in northern Utah, despite an uncooperative Mother Nature who was quite stingy providing storms.  We exhibited the DOW for 1500 visitors at the Natural History Museum of Utah and 300 at the University of Utah.

Meteorological outreach at the Natural History Museum of Utah.  DOW in the background. 
In the DOW during sidewalk exhibit at the University of Utah

Several graduate students are now fully trained DOW operators.  Students in our cloud microphysics, synoptic meteorology, mountain meteorology and a radar special topics class were able to participate in operations either on campus or in the field.  My mountain meteorology class is presenting results this afternoon from their initial analysis of a precipitation event in the Ogden Valley.

Seven people stuffed in the DOW.  A common scene during field operations. 
Officially, we did eight "intensive observing periods", or IOPs:

IOP0- Practice IOP scanning some weak snow showers over the northern Wasatch (Location: Antelope Island Marina)

IOP1- Leeside precipitation in the Ogden Valley (Location: Huntsville)

IOP2- Frontal precipitation over the Salt Lake Valley and mountain-induced precipitation over the northern Wasatch (Location: Fielding Garr Ranch, Antelope Island)

IOP3- Exploratory effort to examine precipitation over Ben Lomond (Location: Just south of Willard Bay)

IOP4- Exploratory effort for eared grebe migration (Location: Lakepoint)

DOW near Lakepoint in the Tooele Valley scanning for eared grebes on November 25th.  National Weather Service radar imagery showed the first signs of migration last night, so the truck returned to Boulder just a little too soon. 
IOP5- Cold front with topographic interactions over Tooele Valley (Location: Stansbury Island Causeway)

IOP6- Cold front, influence of Oquirrh and Wasatch range on precipitation, small-scale precipitation structure in and around Cottonwoods (Location: South Jordan Trax Station)

DOW at the South Jordan Trax Station with frontal/orographic cloud over Wasatch
IOP7- Mountain and lake-effect precipitation (Location: Baccus Highway near 7000 South)

Mother Nature's stinginess forced us to take what we could get and do a couple of all-night operations.  IOP1 and IOP2 covered the same storm.  We just moved the DOW from Huntsville to Antelope Island as the storm slid south, changing the IOP number.  IOP6 and IOP7 were also the same storm and we just moved the radar from the South Jordan Trax Station to the Baccus Highway as the winds veered and orographic and lake-effect precipitation evolved.  Knowledge of meteorology, terrain, and potential site characteristics are a real key to making such efforts successful.  Not to mention some motivated graduate students willing to work graveyard shifts.  During such operations, we rotate crews and bring in a fresh driver for moving the DOW in the morning.

Special thanks goes to our sponsor, the National Science Foundation, and the operators of the DOW, the Center for Severe Weather Research, for making the visit possible.  The Center for Severe Weather Research extended the DOW visit a few days to let us capture our most recent storm and for that we are grateful.  I'm fairly certain that storm will make it into at least one master's thesis and maybe more.

Tuesday, December 5, 2017

Heartbreak Ridge Provides One Blutarski of Precipitation Through Mid December

The Sunday Storm delivered at the upper end of expectations, which was great for skiers and storm chasers.  That's the good news.  The bad news is that Heartbreak Ridge is here, and maybe to stay, at least for a while.

The latest GFS dynamic tropopause (jet-stream level) forecast below ain't mobile friendly, but it tells it like it is.  A ginormous ridge is building over western North America this week, diverting the storm track into northwest Canada and Alaska.  Although that ridge eventually weakens and moves downstream, another builds behind it.


Total precipitation produced by the GFS in Utah over the next 10 days is precisely "one Blutarski."  In other words, zero-point-zero.


For those of you who don't know what a Blutarski is, watch this clip from Animal House and work harder to expand your educational horizons. 


Most medium-range ensemble members are similarly going for dry conditions over the area and nearly the entire mountain west.  Perhaps the ridge will be weaker than advertised, shift a bit westward allowing something to spill over the top, or go north enough for the southern branch of the jet to come into our area.  That's about all we can hope for.

I'm not one to extrapolate already medium-range forecasts even farther into the future.  Much can happen at long lead times.  Blocking patterns like this can be very persistent, but I'm inclined not to make forecasts for the 2nd half of December at this time. 

For Wasatch Front dwellers, now is the time to reduce driving, carpool, and take transit.  The inversion begins to develop today and the cold pool it isolates in the Salt Lake Valley and adjoining lowlands probably won't be going anywhere for a long time unless we can get some sort of dry cold front to slide down the back side of the ridge.  That's not impossible, but I wouldn't count on it.  Expect today's emissions to be tomorrow's smog.

Monday, December 4, 2017

A Day and Night of Great Utah Storm Chasing

Finally, a decent storm!  Our storm chasing activities this month were somewhat curtailed by Mother Nature.  Storms were limited, but we made the most of the three major opportunities we had, including our efforts yesterday and today.

Yesterday, we set up camp in the South Jordan Train Station parking lot for the frontal passage and post-frontal precipitation.


We operated here in 2011 when it was in the boondocks.  Although development is spreading westward (note the building behind the DOW), we were able to use it effectively yesterday, although we may need to find an alternative for future deployments.

There was a great deal going on and I suspect we have a great dataset for both an MS thesis and at least one paper.  Here are a few snippets.

The photo below from U undergraduate Spencer Fielding is taken facing ESE shows the situation shortly after the surface cold front has passed and was located just south of Point of the Mountain.  A pronounced cloud rope was evident above the frontal interface with the cloud structure suggesting ascent in the strong southwesterly flow over and downstream of the front.  It was black as coal over the Cottonwoods, but we saw very little on radar during this period.  Instead, the precipitation was falling further downstream (relative to the flow aloft) in the area east of Mill Creek Canyon.  This appeared to be a classic situation of precipitation growth, transport, and fallout with the growth happening in the ascent region, but the particles needing sufficient time to grow big enough to fall out, which happened further downstream.  It was unclear if the mountains really mattered at all in this period.  Making all of this easy to see was the fact we seemed to be in a rain shadow east of the Oquirrh Mountains.


That Oquirrh rainshadow was a prominent feature for a couple of hours after frontal passage.  The image below is a vertical slice taken facing northwest toward the Oquirrh Mountains (Grey region marked with an "OM."  The color fill is Doppler velocity, which measures the speed of the flow toward (cool colors) or away (warm colors) from the radar.  The northwesterly flow is clearly evident.  Note how it descends into the Salt Lake Valley southeast of the Oquirrh Mountains.


That descending flow is quite consistent with surface observations at the time which showed WNW flow at most sites along and east of the Mountain View Corridor (highway 85) in the western Valley.  This was about the time of the frontal passage at our location.


An hour later, the front had pushed through Point of the Mountain.  There was a clear boundary over the southwest Salt Lake Valley between the downslope westerlies and the along-valley northerlies.  Curiously, the downslope flow was colder than the northerly flow to the east.  Downsloping air warms compressionally, so for that to occur, precipitation must have cooled the airmass.


The photo below was taken shortly after the MesoWest analysis above and was taken facing NNW.  Here you can see quite well the dark, low-level clouds that accompanied the front into the Salt Lake Valley.  To the left, however, one can see snow (fibrous clouds) that is spilling over into the lee of the Oquirrhs.  The sublimation of that snow presumably contributed to the cooling of the airmass.  Note also how the subsidence has eroded the low-level cloud away on the west side of the photo.


Looking west, you can see this spillover really well in the radar reflectivity.  Note in particluar the shallowing of the echoes toward the radar due to the downslope flow.  One might think of this as a "snow foot."



Eventually, the cold air deepened and the flow aloft veered (turned clockwise) to westerly and eventually westnorthwesterly and we got quite a treat as the area around Little Cottonwood Canyon finally lit up.  One example is below, which is a vertical slice taken facing east directly up Little Cottonwood Canyon.  The bright yellow/orange colors are ground clutter produced by the sloping canyon floor.  Above that clutter, there's not much happening in the lower canyon, but from mid canyon up, there are strong returns, indicating heavy snowfall.


The photo below was taken about 2 hours earlier when it was still light, but shows perhaps what was happening with little or no precipitation falling at the base of the mountains and in the lower canyon (v-shaped notch in background to left of radar dish), with heavy snow in the middle and upper canyon.  


At times, away from the mountains, we also saw some beautiful fall streaks.


Google it and look at the photos and you'll know what I mean.

We eventually deployed to a site we could scan further north for the orographic and lake-effect precipitation that fell overnight.  I went home and tried to sleep, but it was largely a night spent looking at the radar and hoping we were getting great data, which we were.  You'll probably hear a lot of talk about the snow being lake effect, but in the mountains, most of it wasn't.  It was just good old mountain lifting doing the job until early this morning when we got a bit of lake effect.

We surveyed the lake-effect showers for most of the morning.  At one point, we decided to forget about doing anything except two rapid fire vertical slices taken through the lake-effect convection as it moved inland.  A still is below, but these slices were taken every 16 seconds.  I can't wait to process the data and see a video.


All of this brings to an end the OREO field phase.  Although storms were limited, we actually have some great data from three major storm cycles, and the students enjoyed a smorgasbord of precipitation and wind phenomenon.  

Special thanks to the National Science Foundation for sponsoring this visit and the Center for Severe Weather Research (CSWR) for making it happen.  The CSWR deserves extra special thanks for letting us keep the DOW a few extra days to catch this latest storm.