Wasatch Weather Weenies

The Bonneville Salt Flats, a remarkable geological wonder, in July 2008 The Bonneville Salt Flats are a remarkable geological wonder and well worth a visit and a hike of a nearby mountain.  Most people drive through them at a high rate of speed trying to get to Nevada or California as quickly as possible, but even a quick stop reveals a world completely different than any other you have experienced. The Bonneville Salt Flats are perhaps best known for land-speed events that take place on the hard salt crust to the northeast of Wendover.  In recent years, however, that salt crust has thinned and degraded, forcing cancellations or restrictions in speed events and sparking controversy concerning management of the salt flats . Brenda Bowen, a professor of Geology and Geophysics and director of the Global Change and Sustainability Center at the University of Utah, is leading a 3-year study to improve understanding of the Salt Flats and their recent change (see this Scienti...

Since the 2010/11 ski season, the Wasatch Range has experienced below average snowfall years.  Data from the Utah Avalanche Center shows an average seasonal (October-April) snowfall at Alta of 497 inches since 1945/45, but over the last five seasons we've received only 330, 383, 358, 268, and 393 inches.   I am often asked if these poor snowfall years are due to climate change.   The answer is no.   Many people are surprised to hear this, but here's why I do not think the recent poor snowfall years at Alta are due to climate change.   First, the base of Alta is at 8500 feet, well above the freezing levels of most storms during the winter.  While it is possible that you can experience a brief rain-on-snow or drizzle-on-snow event at Alta, nearly all of the precipitation that falls there during the cool season falls as snow.  The low numbers over the past five years are not due to more wintertime precipitation falling as rain, but instea...

Dude, I can barely see the Oquirrhs! I hope this isn't a harbinger of things to come, but there is actually an elevated air quality event underway over Salt Lake with some characteristics similar to what we see during the winter. As everyone is aware, late last week and last weekend and deep upper-level trough and associated cold-air intrusion rumbled through Utah.  The maximum temperature on Friday was only 51ºF. As the trough moved downstream, a high-amplitude upper-level ridge built rapidly over the western United States.  This led to significant warming in the mid- and upper-levels of the atmosphere at a rate faster than solar heating could warm the colder air near the surface. As a result, yesterday afternoon, the atmosphere over the Salt Lake Valley was capped by a series of stable layers.  The lowest of these stable layers was only a few hundred meters above the valley floor. Source: Storm Prediction Center Weather camera images yesterday showed a c...

White capped mountains signal that fall is finally here Meteorological summer ended earlier this month.  Astronomical summer ended on Friday.  Although temperatures will rebound some this week, summer is finally over.  Good riddance.  Don't let the door hit you in the butt on the way out. The climate numbers for summer (June–August) were released last week by the National Centers for Environmental Information.  You already know that this summer was the 2nd hottest on record at the Salt Lake City airport, but how did things go statewide? Well, it was a hot summer by old-timers standards, but not for the young.  With a statewide average temperature of 71.6ºF, this summer was tied for only the 5th warmest on record.  However, the four ahead of this year, as well as the other years tied with it, have all occurred since 1994.   Source: NCEI So, compared to the climate of the latter 19th century and most of the 20th century, this was ...

Wow, what insanity.  After a meteorologically boring summer, fall comes in with a bang.  I'll go into rapid-fire mode for this one: 1. Ogden Supercell? : Yesterday afternoon, a long-lived thunderstorm with supercell-like characteristics developed near Dugway Proving Ground and tracked to the Ogden Area over about a 2.5-hour period.  It was a right-moving storm , in that it was moving somewhat to the right of the steering-layer flow and the tracks of other convective cells.  This is common characteristic of supercell thunderstorms, which are long-lived thunderstorms with rotating updrafts (note: there are also left-moving storms, but they are less common).  The Doppler velocity signature of the storm, however, wasn't especially pronounced, so I'll leave it to the severe convective storms experts to ascertain whether or not the storm qualifies for Supercell status. Long-lived svr t-strm tracked from Dugway to Ogden area this aft. 75 mph gust at Hill AFB. W...

Editors Note : Post has been updated to include correct SPC categorization of thunderstorm risk, which was erroneously called "severe" in the original. Yesterday evening, the northern portion of the state won the thunderstorm lottery with strong storms developing over the West Desert and Great Salt Lake and moving across the Northern Wasatch Front, Box Elder County, and Cache County. Strong wind gusts were reported at a remote observing site east of Snowville (78 mph) and the Logan airport (61 mph).  Lightning data shows numerous cloud-to-ground strikes across that area, but none south of Ogden or over the Salt Lake Valley.   Source: lightningmaps.org The National Weather Service watches, warnings, and advisories map is lit up statewide today. Source: NWS Issues of concern for today include flooding and flash flooding, high winds, and severe thunderstorms.  The Storm Prediction Center has upped our severe thunderstorm risk from severe  margin...

Forecasts haven't changed much overnight, except that moisture is streaming into northern Utah a bit earlier than expected today, increasing the potential for scattered thunderstorms this afternoon. Over the years, I've learned to pay careful attention to weather situations that involve the interaction of upper-level troughs in the midlatitude westerlies with monsoon moisture as this often leads to the development of severe convective storms.  The pattern through Thursday night fits this description and demands this careful attention.  Patterns of this type have the three key ingredients for convective storms: Instability, Moisture, and Lift.  With regards to instability and moisture, I've cherry-picked a couple of soundings from the 0600 UTC NAM forecast for Salt Lake City (below).  In these soundings, plotted on a thermodynamic diagram known as a Skew-T, the forecast environmental temperature and dewpoint are displayed as red lines (with temperature > dew...

Source: e-trailer.com Some weather excitement is on the schedule for later this week as the first significant mid-latitude trough of the fall taps into monsoon moisture to give us a wild ride.   Phase 1 covers today and tonight, although northern Utah isn't really in on the action.  An upper-level trough dropping into the western U.S. helps to coax a monsoon surge and the remnants of Hurricane Paine (doesn't that just roll of the tongue) into the southeast US, with showers and thunderstorms affecting a broad area from SoCal and BaCal through southeast Utah and California.   Although for us its "No Paine No Gain" today and tonight, the monsoon surge establishes a reservoir of moisture over the southwest that is pulled into northern Utah as the upper-level trough subsequently develops along the west coast and the surface cold front impinges on northern Utah. Thus, tomorrow (Wednesday) will be at transition day as moisture streams northward.  After tha...

Yesterday evening served up the quintessential "Spectacular September Sunset."  Golden hues everywhere.  My old cell phone doesn't do it justice, but if you were out, you know what I'm talking about.   The computer models are suggesting that this coming week will be the most exciting meteorologically in months.  The main culprit is a midlatitude upper-level trough that will develop along the west coast over the next couple of days.  First it will toy with the remnants of Hurricane Paine and bring a pronounced monsoon surge into the southwest (missing us though).  Then, as the trough amplifies and migrates eastward, a major precipitation event will develop over much of the interior west with showers, thunderstorms, frontal precipitation, and the like.  Very interesting! The pattern above suggests a very active period later in the week with the bottom falling out temperature wise.  We haven't seen anything like this in mo...

I am often asked why I am not more actively involved in advocacy regarding climate change.  This is a complicated issue and I'd like to share some personal perspectives. I think it is important for scientists to share their knowledge, understanding, and perspectives with the public.  In doing so, striving to describe what we know as accurately as possible is paramount.  As Nobel Prize winning physicist Richard Feynman once said: "The only way to have real success in science is to describe the evidence very carefully without regard to the way you feel it should be  (my emphasis)." This doesn't mean that scientists need to be dispassionate or lack political views and perspectives.  I write and give talks on climate change and sometimes express strong viewpoints. It also doesn't mean that scientists are infallible.  Science is a human endeavor and errors and mistakes occur.   Commitment to the truth means that results are checked and triple-chec...

OK, I'm stretching the climate data a bit here, and admittedly scanned the table of maximum and minimum temperatures over the past few months awfully fast, but it appears this afternoon and tomorrow morning will offer up the lowest maximum and minimum temperatures at the airport since May. Today the maximum temperature looks to be in the high 60s, which will make it the first day with a maximum below 70 since May 25th.  The minimum tonight looks to dip into the high 40s, making it the first day below 50 since May 26. It feels good to be nestled in a fleece jacket!

Well, I have to admit that I was caught off guard by the coverage and intensity of thunderstorms late yesterday and overnight.  Months of drought has dulled my senses and lowered my expectations.  It was great to see rain, lightning, and thunder again, although I could have lived without the rapid, heart-pegged ascent to my house at the end of my ride as I raced an approaching storm.   Nevertheless, it was worth the price of admission. And, we even have the first snow of the season in the high Wasatch, as caught by one of the Snowbird cams this morning. Source: Snowbird Looks like a dusting down to perhaps 10,500 feet or so.  A reminder that winter is coming and none too soon.

Late in the day yesterday, a cold front pushed into northern Utah, ushering in a period of strong northerly winds and blowing dust.  The plot below shows the situation at 9 PM MDT (0300 UTC), with sustained winds on top of Fremont Island of 46 mph and strong flow across much of the Great Salt Lake and adjoining salt playa.  Strong flow also penetrated into the western Salt Lake Valley.  At this time, the area around the University of Utah was relatively protected, with lighter winds. Source: Mesowest Colleagues at the University of Utah are operating an observing site on the playa just east of Antelope Island.  The flow at this site was northerly to north-northeasterly for most of the afternoon, but increased dramatically at about 1900 MDT (7 PM) to about 25 mph with higher gusts.  The temperature at this time also dropped dramatically.   Source: MesoWest The Great Salt Lake is currently remarkably low with a great deal of exposed playa.  ...

I don't want to get everyone too excited, but the latest GFS forecast has below zero 700-mb (10,000 ft) temperatures at 1800 UTC (1200 MDT) Wednesday. I'm so desperate for material that I'll just mention this and, given the cold trough, the potential for perhaps seeing a flake or two in the highest elevation. It's not much to go on, but it's something. Plus, if my quick skim of the temperatures over the past few months is correct, Wednesday's high @KSLC, which right now looks to be around 70-72ºF, will be the lowest maximum temperature since May 25th, when we hit only 68ºF.  Wunderbar!

Ah, how I enjoy watching some prognosticators make seasonal climate predictions.  Like sports pundits predicting the winners of college football games each Saturday, they confidently predict what will happen during the coming winter.  If only Mother Nature was persuaded by bravado instead of the laws of physics and the behavior of chaotic systems. A great beat-down of the seasonal outlooks from last winter was written last week by Joel Gratz of opensnow.com.  My disdain for the "deterministic" nature of these outlooks is well documented, and something described in depth in my post from March 20th, 2016 reflecting on last winter and more recent post Silly Season Returns . The usual approach taken in producing these outlooks is to decide whether or not the coming winter will feature El Nino, La Nina, or ENSO neutral conditions (i.e., neither El Nino or La Nina) and then make predictions based on past events.  In both of these steps, the outcomes need to be assesse...