Wasatch Weather Weenies

The last few days, the ensembles have been producing a pretty wide range of possible forecast outcomes for the central Wasatch for the storm that begins tonight and extends, potentially , into Monday.  This was discussed in the prior post ( Shift in the Weather ), and continues to be a forecast issue today.   Last night's Utah Snow Ensemble exhibits some spread in the forecasts through 0000 UTC 2 February (5 PM MST Saturday; red line below), but the means of the ECMWF ENS and GEFS ensembles are relatively similar and around 0.72" of water and 6.5" of high-density snow for Alta Collins.  The latest GFS and HRRR are also around about 7" of snow, so going for something in the 5-10" range through 5 PM MST Saturday makes sense.  After that, the two ensemble systems diverge, with the ECMWF going for less water and snow than the GEFS, although there is some overlap of the members from each ensemble.  The reason for this, and the uncertainty in the forecasts throug...

The models have been hinting at a pattern shift for the start of February, with the west-coast ridge weakening and a new high-over-low blocking pattern developing farther upstream over the Pacific.   The GFS forecast valid 0000 UTC 2 February (5 PM MST Saturday) shows the high-over low block well upstream of the Pacific Coast with the confluence of two very different airstreams downstream of it over western North America.  The first is a colder airstream originating over the high latitudes that turns counterclockwise (cyclonically in meteorological speak) and into the Pacific Northwest (see northernmost yellow arrow below).  The second is a warmer, moister airstream originating over the subtropics that extends northeastward and eastward over the Great Basin (see southernmost yellow arros).  This second airstream is also associated with an Atmospheric River that extends across northern California and into northern Utah (see red arrow). The confluence of these two...

This year marks my 30th as a tenure-track faculty member at the University of Utah, a position that I have enjoyed immensely.  I've been able to pursue my scientific and educational passions with zeal and I've been able to work with a lot of great students, faculty, and staff.  I think it was the perfect place for me to land.  Plus the skiing was great! However, things have changed in recent years, perhaps reflecting an acceleration of long-term trends in higher education.  The U has become increasingly top heavy, with more administrators being paid increasingly high salaries.  There's less interest and respect for the knowledge and perspectives of the regular faculty and more top-down management.  There's increasing digital bureaucracy, often obtuse in design, interfering with our ability to work "efficiently" (I put that in quotes because that word is being thrown around a lot these days as if it were the holy grail of higher education).  More and mo...

If you've ever seen the Rankin-Bass holiday classic "A Year Without A Santa Claus" you know that there is a long negotiation between Mrs. Claus, Snow Miser, Heat Miser, and Mother Nature to bring snow for just one day to Southtown.  If you have seen it, then maybe like me you were thinking of it yesterday when it was snowing along the Gulf Coast.  And if you haven't seen it, you should check it out as it is a must for the meteorologically inclined. In any event, the snow totals from the Gulf Coast are impressive, with many CoCoRAHS observers from Louisiana to the Florida Panhandle coming in at more than 8.3 inches (red shade below). Source: CoCoRAHS The highest amounts reported by state were 13.3" in Grand Cotaeu (LA), 10.5" in Waveland (MS), 9" in Summerdale (AL), and 9.4" in Pennsacola (FL).   I'm not versed in southeast meteorology, but it appears that this was truly a historic event.  For example, the Pensacola News Journal was reporting th...

The sun had not yet crested the Wasatch this morning when I awoke and when I looked out the window I saw this odd band of white extending at low levels through the western Salt Lake Valley.   My first thought was what the hell is that.  It's too shallow to be a lake band and it doesn't look like fog.  I took a look at the weather observations and the relative humidity in that area was less than 60%.  What could it be.  I then looked at PurpleAir thinking it might be dust, but even then the PM2.5 numbers didn't seem very impressive.   I kept digging, soliciting the input of some meteorological friends.  Eventually, with some help of specialized observing sites, satellite imagery, and weather cams, it became clear that it was blowing dust originating from the exposed Great Salt Lake bed east of Antelope Island.   A quick look at the evidence.  The most damning was a video of web cam images from the MesoWest web cam at Syracuse ne...

In the previous post ( Real Winter ), I commented that the storm for Friday Night and Saturday was "a crap shoot situation given the limited moisture" and that "much will depend on instability, lake influences, and, for Little Cottonwood Canyon which might have the best chance of something, maybe some Alta magic." In hindsight, I really didn't have any idea how complicated and productive the storm was going to be and that it was really "Snowbird Magic" that we were going to get.   What Actually Happened Automated data from Alta-Collins showed that at upper-elevations in Collins Gulch (9962 ft), about 11 inches fell with only 0.5" of water, yielding a 22:1 snow to liquid ratio or 4.5% water content. In other words, very low density snow, even if the use of gauge water equivalent measurements, which often don't catch all the snowfall, might result in a low estimate of water content.  However, remarkable contrasts of snowfall occurred in Little C...

The GFS 500-mb forecast for 1800 UTC 19 January (1100 MST Sunday) is one that should put a smile on the face of anyone who misses "real winter."  An incredibly deep and broad trough, centered near Hudson Bay, covers most of North America.   As a result, the 5-day average forecast surface temperature anomalies, or the departure from average, centered on that period is negative (or below average) across much of the United States and Canada, with a bull's-eye near the border of North Dakota and Saskatchewan.   Source: tropicaltidbits.com It's nice to know that Mother Nature can bring it still from time to time.   It will be getting cold in Utah, but really we are going to miss out on the coldest of the air thanks to protection from the Continental Divide.  Forecasts from the National Weather Service National Blend of Models for KSLC show maximum temperatures dropping from 39-43F today to the low 30s tomorrow and then possibly into the 27-32F range on...

The current snowdepth at Alta Collins sits at 83" after peaking at 92" on Saturday. Some people have asked me about the prospects of a Steenburgh Winter this year, that period from when Alta-Collins first reaches 100 inches to February 10th when the mid day sun angle and day length start to really increase and have an increasingly caustic influence on snow, first on south aspects and eventually as we go deeper into spring on all aspects.  Steenburgh winter is the creme-de-la-creme of backcountry ski conditions with a deep snowpack to enable good coverage across a lot of terrain and low-angle sun for powder preservation. The potential for the start of Steenburgh winter looks quite low for the next ten days.  Ridging is in firm control currently along the Pacific coast this morning. That ridge meanders a bit, but remains in place really for the next 10 days or so.  About all we can hope for is a trough to slide down its front side and drop into our area.  Unfortunatel...

There's so much bad news on the weather front in the US due to the wildfire catastrophe in SoCal, that I thought I would talk about something more uplifting: The remarkable snow season that they are having in Japan.   I like to say that if Utah has the Greatest Snow on Earth , but Japan has the Greatest Snow Climate on Earth .  Really, there is nothing like Japan's "Gosetsu Chitai" or heavy snow region near the Sea of Japan.  It is the snowiest, densely populated region on Earth with Sapporo the snowiest city in the world with a population of more than 1 million and Sukayu Onsen in the Hakkoda Mountains in northern Honshu the snowiest inhabited place on Earth.  The numbers below are based on 1981-2010 climate normals. There are three things that make Japan's Gosetsu Chitai so special for snow.  First, it lies downstream of Eurasia, the world's biggest continent, which results in frequent and prolonged cold-air outbreaks over the Sea of Japan during the East...

Impressive snow totals and snowfall rates occurred yesterday in Little Cottonwood Canyon.  The big winner was Alta.  As readers of this blog are well aware, the Alta Ski Patrol maintains a great snow-study plot in the upper elevations of Collins Gulch.  The hourly measurements from this site are a treasure trove to meteorologists like me who are starved for observations from higher-altitude locations.  The "snow interval" data below is collected by an ultrasonic snow-depth sensor that is mounted on a pole above a white snowboard that is wiped every 12-hours.  It recorded 20" of snow over and 11 hour period prior to being wiped just after 1600 MST.   Really, the 20" mark was attained in only 9 hours, from 0400 to 1300 MST, yielding a mean snowfall rate of more than 2 inches and hour for that period, with a peak snowfall rate of 5 inches from 0600 to 0700 MST.  Due to roundoff of the measurement, there is a little uncertainty in that estimate, but i...

Final numbers will become available in a few days, but it is likely that 2024 will be the warmest year on record globally.  I'm not sure if the difference from 2023 will be statistically significant, but that doesn't really change the story of long-term warming.   With an average temperature of 57.4F, it was also the warmest year on record in the Salt Lake City area based on observations collected by the National Weather Service, and by a pretty wide margin. Source: https://xmacis.rcc-acis.org/ If fact, it beat the previous record holder, 2012, by 0.8F.  Given the inevitable grousing about the representativeness of the airport site, I'll also add that this was also the warmest year on record at the Bountiful Bench site, which has continuous records back to 1975. That site observed an average temperature of 55.0F, topping the previous record holder, 2012, by 0.6F.   Precipitation for the year at the airport was 14.78" which was just a skiff below normal...