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!