Wednesday, March 22, 2017

A Juicy Late March Airmass

Well, it's a juicy one out there this morning.  The meteogram from the Salt Lake City airport shows and abrupt 5ºF drop in temperature and 9ºF rise in dewpoint just before midnight MDT as the flow shifted to NW-N with the passage of a modest cold front.

Source: MesoWest
Source: MesoWest
Dewpoints increased further to the high 40s by about 6 AM and as I write this are lingering around 45ºF.  For the most part, a dewpoint in the high 40s doesn't get much attention, but for us, they are the highest observed in the past 30 days (see blue line below) and possibly much longer than that (MesoWest only provides point-and-click access to the past 30 days).

Source: MesoWest
Thus, my skin and lungs greatly appreciated the pulse of moisture I felt when I went out for the paper at 6 AM.

Although we've cooled off some, temperatures remain above average for a morning in March in both the valleys and the mountains.  In the case of the latter, at 7 AM it was 36ºF at the base of Alta and 33ºF at Alta-Collins (9700 feet).  Alta-Collins picked up 4" of snow last night with 0.81" of water.  It may have started out as rain at that elevation, but I suspect most of the 0.81" fell as snow, so we're talking thick, creamy stuff.  It's tough to say from the web cams, but it appears most of the precipitation below about 9000 feet fell in the form of rain overnight.  What a waste of water!

On my way to the bus at about 7 AM, I saw a number of flashes of lightning over the Wasatch.  Indeed, flashes were detected this morning around the Bear River Migratory Bird Refuge, the south Salt Lake Valley, the Cottonwoods, and Parley's Canyon (see filled circles below).

What you see is what you get and for the rest of the day today, scattered showers and thunderstorms are on tap.  Snow levels will remain high and probably around 8000-9000 feet, but may temporarily drop in heavier precipitation.  

Right now it looks like a pretty good deluge tonight and tomorrow as the main trough comes through, with snow levels mercifully lowering tonight and reaching near bench level by about 8 am tomorrow morning.  This sounds crazy, but the skiing might actually be good tomorrow at upper elevations.  The average water content of the snow will be high, but that will help bury the spring snow, and it should be right-side up.  

Tuesday, March 21, 2017

Let's Get Back to April

The weather over the past week in northern Utah has been pretty outrageous.  Over the past 7 days, maximum temperatures at the Salt Lake City airport have been in the 70s and we will add an 8th today.  The overnight minimum last night was 61ºF, 6ºF warmer than the average high on this day.  We set daily records on four days and have a shot at another today (the current record is 74ºF).

The maximum temperatures during the past week are consistent with the average maximums from mid May to early June.  The lowest maximum temperature observed over the past 7 days is 70ºF, consistent with the average high on May 10.  The highest, 79ºF, is consistent with the average high on June 5th.

Spring is a period of great weather variability so swings from one extreme to another are not unusual.  However, the past week blows everything previously observed completely out of the water.  For the March 14-20 period, we have averaged 60.9ºF, a full 4ºF warmer than the next highest March 14-20 period in 1910.

Source: NOAA Regional Climate Centers
The records at mountain sites are less complete and do not extend back as far, but if we look at Alta, we see a similar story, although the gap relative to #2 (2007) is only 2ºF. 

Source: NOAA Regional Climate Centers
So, the past week has not only been warm, but it has been warmer than any comparable period in the instrumented record.

The impact of this warmth on the snowpack is staggering.  Significant losses in snowpack water equivalent have been observed at many SNOTELs.  Provided below are examples from Ben Lomond Trail (down 7 inches), Farmington Canyon (down 9 inches), and Mill-D North (Big Cottonwood Canyon, down 5 inches).  

Source: Colorado Basin River Forecast Center
That drops each of these SNOTEL stations to near average for the date.  

If you want a better story, you need to find a SNOTEL that is high and protected from the sun.  One example is Snowbird, where snowpack water equivalent has remained steady, illustrating the value of high-altitude north-facing terrain. 

Source: Colorado Basin River Forecast Center
There's been a lot of talk about a "pattern change" and yes, it is going to cool off a bit after today with conditions more like early April through the weekend.  That means unsettled conditions, valley rain and mountain snow.  The hit and miss nature of precipitation during the period makes for a wide range of possible accumulations in the mountains.  For example, the spread in our downscaled Short-Range Ensemble Forecast (SREF) product is pretty ginormous through Friday afternoon (00Z/25) with the driest member generating under 0.1" and the wettest more than 1.6" of water equivalent at Alta.  

Thus, this is indeed like April.  Good skiing will require a good dumpage and we're just going to have to wait and see if that happens and how quickly things add up.  The snow we do get is likely to be higher density, which is probably what we want at this stage. 

Sunday, March 19, 2017

Going Solar

Last July, we closed on a new home and moved to another location in the Avenues.  Our first order of business was to replace the roof, which was nearing end-of-life, and install solar.

We worked through the University of Utah's Community Solar program, which provides a discount on solar installations.  The install was done by Creative Energies, who did a great job.  Due to the popularity of the program, we had to wait a couple of months for install, which finally happened in early December.

Solar install in early December.
We are fortunate to have great exposure for solar, with a roof that faces south-southwest and has no major shadowing from local buildings or trees.  We lose just a little solar late in the day due to coniferous trees on the west side of the home, but the impact is small and the cooling we receive from those trees in the summer probably reduces our electrical usage more than what we would gain if we removed them.

There was some anxiety in terms of the grid-tie capabilities being connected by Rocky Mountain Power.  They take a few weeks to do this and we were hoping to be able to take the tax rebates during the 2016 tax year.  Incredibly, they connected the system on December 31st, just sneaking in under the wire.

Production in January and February was pretty limited due to snow cover, cloud cover, and low sun angle, but this month we've been killing it.  Our biggest production day was last Wednesday, when we reached a total production of 34.4 kilowatt hours.  Production totals every 15 minutes for that day show an optimal situation with no cloud cover.  We lose just a bit of production late in the day due to tree shading.

Of course, solar production is at the whims of the weather and a more typical day with occasional clouds yields a production curve with more gaps.

How large of a system to purchase was based on our desire to produced as much power as we use, but given that this is a new home for us, we had to do some guesswork.  We suspect that we are going to end up producing more power than we are consuming over the full year and that this gap will grow some as we perform upgrades to the home to reduce electrical consumption.   We figure when we buy an electric vehicle, we can put the surplus to good use.  We also have room on the roof for expansion of the solar array if we desire to do so in the future.

Saturday, March 18, 2017

Poof Goes the Snowpack

It's no surprise that this week's record setting warmth has destroyed the the low-elevation snowpack.  We have precious few low-elevation SNOTEL locations, but the one at Ben Lomond Trail has lost about 4 inches of water equivalent through yesterday and I suspect it will see another couple of inches go away today.  On the plus side, it still sits well above average for this time of year, although it is located in an area that is somewhat shaded from the afternoon sun.

Curiously, some of the upper-elevation SNOTEL sites have shown declines the past couple of days including Brighton and Mill-D.

I haven't been out in the central Wasatch during this warm spell and don't have a good feel for what is happening at those sites.  Although it has been warm, I suspect the snowpack is not ripe yet and that those declines are not necessarily due to melt.  It's possible they are due to sublimation given how hot and dry it has been.  The graphs above don't include today, which is a worst-case scenario for sublimational losses given the extreme warmth and wind.  It may be worth a look tomorrow.

A quick look at the latest observations through 3:55 PM MDT shows we've been flirting with 79ºF at the Salt Lake Airport, but I haven't seen anything pushing 80 in the 5 minute data yet.  We'll see if we can hit the psyche point.

Friday, March 17, 2017

Freaky Friday Forecast

OK, this is getting ridiculous.

If that forecast verifies, it will be the earliest 79ºF recorded at KSLC.  The record high for March is 80ºF, recorded on March 31, 2012.

Thursday, March 16, 2017

First Half of March Doesn't Make Top 10

Shockingly, given the blistering heat of late, the first half of March (through the 15th), only rates as the 11th warmest all time in the Salt Lake area.

Source: NOAA Regional Climate Centers
Granted, we are still running well above average, and we're not too far behind the warmer "half Marches", but still not in record territory.

A big reason we're behind is the two cold surges that occurred around the first of the month and then on the 6th.  

The one on the 6th really knocked the temperatures down.  Ah, the good old days!

Tuesday, March 14, 2017

Life Isn't Always Fair

Living in northern Utah is about playing the odds.  You have a better chance of finding good skiing here than anywhere else in the US, at least statistically.

But climate is what you expect, and weather is what you get.

Today's high at the Salt Lake City airport looks to be somewhere around 73ºF.  74 would tie a record for the day.  The National Weather Service noted that this afternoon temperatures at KSLC were 6ºF higher than in Orlando.


Meanwhile, the folks in the northeast are getting a pounding.  My sister sent the photos below from her place in upstate NY.

 Enjoy it easterners.  We will extract our revenge eventually.

Saturday, March 11, 2017

I See Your 60s and Raise You To the 70s

Saturday, March 11.  The fourth day in a row and 6th day this month with a high temperature in the 60s.  Such a shame.

A weak short-wave trough passage will keep drop temperatures a bit tomorrow, but after that there's a gradual warming trend and we will likely take a run at the big 70 on Tuesday and Wednesday.  It's not in the bag, but it looks like we have a shot.  Here's the latest NWS Forecast for KSLC, with max temps of 71ºF Tuesday and Wednesday.

Neither 71 would represent a record, but where has the snow miser gone?

Thursday, March 9, 2017

Spring Break Ain't What It Used to Be

Next week is spring break at the University of Utah.  The timing is perfect.  The terrain and climate of Utah lend itself to March adventuring, with the possibility of good skiing in the mountains if it is cold and snowy, or treks to southern Utah if it is sunny and warm.

Over the past couple of decades, however, the dice have become increasingly loaded to favor the latter.  There have been only four Marches since 1989 with a statewide average temperature below the 20th century (1901-2000) mean, and those months were barely below the average.

In fact, the average March temperature for the past 30 years (1987-2016) is 40.2ºF, 3.3ºF warmer than the previous 30 year period (1957-1986).  Given that the mean temperature from March 1st to April 1st increases about 8ºF, that's about the equivalent of moving Spring Break almost 2 weeks later into the year.  Basically, the weather of a mid-March Spring Break today is more like a late-March spring Break for your older professors when they were in college.  Basically, the odds of good powder skiing for spring break are declining and the odds of spring conditions are increasing.

Next week's Spring Break looks to be consistent with recent trends.  The GFS forecast below is valid for 6 PM MDT Monday and shows a high-amplitude ridge and associated warm weather parked firmly over the western U.S.  It certainly looks like Spring Break will get off to a warm start.

The latter part of spring break is far enough out that we'll have to see what happens, but my money is on the week ending up well above average for temperature and below average for precipitation.

If this continues, snow-loving students should lobby the University to move Spring Break to the last week of February or first week of March.  Those who want warmth can go to Ft. Lauderdale or Arizona like other college students!

Wednesday, March 8, 2017

Honoring Joanne Simpson

Source: USA Today
Given that today is International Women's Day, I'd like to take a few moments to honor a pioneer in meteorology, Joanne Simpson.  

Joanne was the first woman to earn a Ph.D. in meteorology and the first woman elected President of the American Meteorological Society.  She was also a winner of the Rossby Medal, the highest award given by the American Meteorological Society, which is "presented to individuals on the basis of outstanding contributions to the understanding of the structure or behavior of the atmosphere."

A comprehensive biography of Joanne's life by John Weier is available at the NASA Earth Observatory web site.  It is well worth a read (be sure to drag or click down through the various sections).  He notes that after graduation, she was repeatedly turned down for a job because of her gender.  She eventually took a position at the Illinois Institute of Technology, followed by tenures at Woods Hole Oceanographic Institution, UCLA, NOAA, the University of Virginia, and finally NASA Goddard Space Flight Center.  As described by John Weier, her move from Virginia to NASA goddard was at least partially related to the fact that women faculty were held in low regard, but NASA provided a "far more favorable environment in which to work."  

Joanne's contributions to meteorology span cloud processes and deep convection, weather modification, and tropical meteorology, and include over 190 authored or co-authored articles. 

Joanne died in 2010 at the age of 86.  Additional tributes to her are available from the American Meteorological Society and Boston Globe.  

Tuesday, March 7, 2017

NOAA Budget Cuts Are Bad For National Defense and Homeland Security

"Know the enemy, know yourself; your victory will never be endangered. Know the ground, know the weather; your victory will then be total."
- Sun Tzu, The Art of War

"The US military is doing just fine...but let's cut NOAA's budget by 15%. Maybe we'll be like the Japanese navy in the 12th century...won't see the hurricane that hits us."
- University of Utah Atmospheric Sciences Alumnus
Budget proposals being considered by the Trump Administration and reported by The Washington Post last week include substantial increases in military spending ($54 Billion) and a 17% cut to the National Oceanic and Atmospheric Administration (NOAA).  As summarized by the Capital Weather Gang, plans for the NOAA budget include cuts of $513 million to the National Environmental Satelite, Data, and Information Service (NESDIS), $126 million to the Office of Oceanic and Atmospheric Research (OAR), and $53 million to the National Weather Service.

Let's be frank about this.  Increasing military spending while hampering NOAA is penny wise and pound foolish.  Ultimately, these proposed cuts represent a serious threat to National Defense and Homeland Security. 

Weather observations and forecasting are absolutely vital to the success of the U.S. military, but don't take my word for it.  Here's Fred Lewis, University of Utah alumnus (Ph.D. '79), retired brigadier general (US Air Force), former Director of Air Force Weather, and Senior Vice President for Sutron Corporation.

The U.S. military supports their own computer modeling systems and battlefield observations, but weather forecasting today "takes a village."  Satellite data is the background of modern weather forecasting, representing over 99% of the observations ingested by numerical weather prediction systems.  Polar orbiting satellites, which fly in low-Earth orbits that pass over or nearly over the north and south poles, are especially important. The cuts being proposed by the Trump Administration would delay the launch of two polar-orbiting satellites, increasing the likelihood of gaps in coverage as older satellites are retired or fail.  Such delays or gaps would reduce military forecasting capabilities, as well as civilian.

Speaking of civilian forecasting.  We are on the cusp of revolutionary advances in weather prediction as we move to newer "cloud-permitting" high-resolution ensemble modeling systems.  These modeling systems will have grid spacings smaller than 4 km, enabling much better simulation of cloud processes, hurricane eyewall dynamics, severe convective storms, and other phenomenon. By producing a suite of forecasts, rather than a single solution, these models will provide improved guidance on the range of possibilities and their likelihood prior to high-impact storms.  Nevertheless, these models are under development, and cuts to the Office of Oceanic and Atmospheric Research (OAR) will delay that development.  Cuts to satellite and other observation programs will also limit the capabilities of these modeling systems.

Of course the irony of these cuts is that they are being proposed during a time of tremendous excitement in the meteorological community as the new, revolutionary, GOES-16 satellite is now in orbit and being tested prior to becoming operational.  You've never seen anything like it.  High resolution, frequently updated satellite imagery.  Lightning mapping.  Space weather monitoring.  Three times more "channels" than the satellites it replaces, enabling improved identification of a wide-range of atmospheric phenomenon.  Here's a tease from the Cooperative Institute for Research in the Atmosphere.

I don't wish to suggest that the NOAA (and National Weather Service) budget should not be scrutinized carefully.  I consider such efforts to be essential.  However, the proposed cuts are severe and will have an impact on the weather prediction capabilities for both National Defense and Homeland Security.

Disclosures: The author receives funding from the NOAA/National Weather Service and the Office of Naval Research.  

Monday, March 6, 2017

A Night of Extreme Change

The "Steenburgh Effect" was in full play this weekend as I was out of town skiing in Jackson Hole and of course missed out blogging about the best frontal passage we've had in months.  Nevertheless, I saw what was coming and we ended up getting off the mountain at 1 PM yesterday, and racing home via Evanston, experiencing the full force of the pre-frontal southerlies, but arriving home just ahead of the post-frontal snowmaggedon.

I took a quick gander through the wind reports over northern Utah and it appears that nobody escaped the full force of the winds.  Gusts over 70 mph were reported at all elevations and in many areas that you might think of as being "sheltered."  Here are a few selected peak gusts, all of which were recorded in the pre-frontal environment.

Arrowhead Summit (Sundance): SSW 110 mph (0010 UTC)
Windy Peak (Uinta Mts): SW 97 mph (0100 UTC)
Mt. Baldy (Central Wasatch): SSW 96 mph (0000 UTC)
Big Mountain Pass: SW 96 mph (2220 UTC)
Ogden Peak: S 89 mph (1530 UTC)

Mid-Elevation Hills and Canyons
Eureka (6584 ft): W 95 mph (2240 UTC)
Vernon Hill (5761 ft): SE 90 mph (2230 UTC)
Deer Creek Dam (5429 ft): SSW 83 mph (0110 UTC)
Mayflower Summit/US-40 (6929 ft): S 81 mph (0120 UTC)
S-Turns Big Cottonwood (6235 ft): W 78 mph (2230 UTC)

Salt Lake Valley
SR-201/I-80: WSW 82 (2310 UTC)
Olympus Cove (4960 ft): SW 73 mph (0030 UTC)
Kennecott Tailings Magna (4440 ft): SW 72 mph (0000 UTC)
Draper (5052 ft): W 68 mph (2140 UTC)
University of Utah: S 64 mph (2315 UTC)

The driver of these strong winds was a strong cold front that developed over the Great Basin and moved across northern Utah yesterday afternoon.  The intense surface trough accompanying the front featured strong pre- and post-frontal pressure gradients.

Although the strongest gusts were generally observed ahead of the front, the winds behind the cold front were nothing to laugh about either.  Here at the University of Utah, the peak gust of 64 mph occurred about 90 minutes ahead of the frontal wind shift.  Although there was a temporary drop in the wind speeds following the frontal passage, they picked up again, with a prolonged period of W-NW flow and gusts above 30 knots, as the frontal precipitation band came through.

The lag between the surface based front, as indicated by the pressure trough, and the precipitation band was clearly evident in the analysis for 0200 UTC below.

The combination of heavy snow and strong W-NW flow made for a quick coating of white at our place in the upper Avenues (about 5000 feet) by about 8 PM MST.  It's always hard to take night-time pictures of snow, especially with an old cell phone, but the combination of snow and wind made for about the nastiest weather I've seen in the valley this winter.

I suspect this morning provided a rude awakening for many as temperatures on campus are around 24ºF with NW winds gusting from 15-20 mph over the past couple of hours.  Throw in icy sidewalks and you have conditions best described as "sporting."  After a high on campus yesterday of 59ºF, it is safe to say that it was a night of extreme change.

Also this morning in the post-frontal environment we have some beautiful orographic clouds draped over the mountains, such as these over the Oquirrh Mountains as I walked to the bus at about 7 am.

Thanks to the post-frontal convection, graupel has been falling at times on campus.

Enjoy this taste of winter.

Friday, March 3, 2017

Something to Hope for

Albion Basin, 26 June 2011
We are in the midst of a bit of a break in the storminess.  It's a shame I couldn't get out and ski this week, so hopefully you did some turns for me.

I was wondering this morning what the peak snow depth was at Alta-Collins during the 10/11 season.  For some reason I had 230 inches in my head, but it turns out that was wrong.  Instead it was 207 inches, achieved at 1300 UTC (7 AM MDT) on April 30.

That year we were still at 186 inches on June 1 and 108 inches on July 1.  Yes, that's right, over 100 inches on the ground on July 1.  I took the photo at top on 26 June while skiing in Grizzly Gulch.  Stupendous!

I'm skeptical we will have a run like that this year, only because the climatological odds are against it, but it is something to hope for...

Wednesday, March 1, 2017

Blast from the Past: Ski Magazine February 1978

Thanks to Dr. Google, every now and then I run across some great old article that puts a smile on my face.  Recently, I ran across the article provided at the bottom of this post, which appeared in Ski Magazine in February 1978 and examines both the avalanche history and its famed reputation for powder at Alta.  I especially liked that it referred to a quote from Ed LaChapelle in a 1962 Forest Service report on Alta snow, which I also used a portion of for my book Secrets of the Greatest Snow on Earth:
"The highest snow densities in terms of grams of water content per cubic centimeter of snow are found at Alta...This reflects a fact known to the experienced snow ranger but usually ignored by the average skier: the best deep powder skiing is not found in the lightest snow, but rather in snow with enough 'body' to provide good flotation for the running ski"
For those of you who want further context, the Forest Service report, entitled The Density Distribution of New Snow, is available online from the Marriott Library (they are always on top of things!).

The report compares 24-hour snow densities from avalanche study sites at Alta, Stevens Pass (WA), Berthoud Pass (CO), Squaw Valley (CA), and Girdwood (AK).  The surprising finding of this work was that the mean snow density at Alta was higher than any of those sites, hence Ed's comment above that the highest snow densities were found at Alta.

That finding has always been perplexing to me, particularly Alta having higher snow densities than Stevens Pass and Squaw Valley, and, although Ed attempts to explain it, I never found his reasoning in that article to be all that compelling.  Altitude, wind exposure, and many other factors can influence snow-density measurements and I've always wondered if the data he used was representative of the general snow characteristics at each site.  At Alta, for example, one would find higher snow densities if data was collected in an area affected by wind transport and related densification.

Nevertheless, I always liked the latter part of the quote about the best deep powder skiing not being found in the driest snow, but rather in snow with enough body to provide good floatation.  That has always been my experience.  In my view, great powder skiing is found in snow that is "stacked" right, with the low-density stuff sitting on top of the high-density stuff which is optimal for ski flotation as well as face shots.

Enjoy the below (click to enlarge).