Wasatch Weather Weenies

City Creek Canyon has to be one of the most remarkably accessible and spectacular canyons in the United States.  It's mouth is just a couple of hundred yards (if that) from downtown Salt Lake City, with the upper basin reaching altitudes of over 9000 feet.  It is also an important source of water for Salt Lake City. Looking up the canyon from the Avenues foothills this afternoon makes you wonder where all that water comes from.  It was a poor snow season in the lower elevations and, remarkably, there's already very little snow visible in the canyon. Indeed, the Louis Meadow SNOTEL at 6700 ft in City Creek Canyon bottomed out and went snow free today.  However, City Creek is a very deceptive canyon.  It is very hard to see City Creek's upper basin (purple area below) between Grandview Peak (also pictured above) and Lookout Peak (blocked in the photo above by Black Mountain) from either downtown Salt Lake City or the Avenues foothills (approx location and v...

Ted Booker of the Watertown Daily Times (NY) attended a talk I gave in upstate NY on lake effect.  Interactions of this type between scientists and reporters are becoming less common in Utah (Photo: Ted Booker) My career has spanned a remarkable transformation in the way that we communicate and receive news.  As an undergraduate, the Internet was still confined to a small cluster of institutions and Universities.  I received my first e-mail address when I started graduate school and it was a big deal at the time (1989) to access the National Center for Atmospheric Research Supercomputer (a Cray Y-MP, about as fast as today's iPad) using the Internet.  Just a few years later, when I completed my Ph.D., we were running forecast models on desktop computers and distributing the output via the Internet.  At the time I remember arguing with colleagues about whether or not anyone would ever make money with the Internet.  I defended my dissertation in Fe...

Last night, temperatures fell little from yesterday afternoon's peak.  At the University of Utah, for example, we peaked at 72ºF yesterday afternoon.  Climatologically, the overnight minimum is roughly 20ºF lower than the afternoon maximum, but last night temperatures remained mild all night, dropping only briefly to a minimum of 61ºF. Source: MesoWest The recipe for a warm night is relatively well known.  Rather than clear and calm, you want clouds and wind, and we had them both last night.  But what makes the clouds and winds so effective at keeping temperatures elevated? Let's start with the clouds.  It is often said that clouds act like a blanket, but this is a terrible analogy if ever there was one.  A blanket keeps you warm because it prevents the mixing of air near your body with cooler environmental air.  This slows the net loss of heat from your body to the atmosphere. In contrast, clouds contribute to warmer nights by providing an addi...

Altitude strongly affects the timing of peak snowpack [snow water equivalent (SWE)] and melt throughout the central Wasatch.  Here's how things are progressing this year. The lowest SNOTEL station in the Wasatch Mountains is Ben Lomond Trail in the northern Wasatch (6000 ft).  This is a remarkably snowy location for its elevation.  On average, Ben Lomond Trail reaches a peak SWE of almost 20 inches in late March.  This year, however, the peak of about 16 inches occurred in early march, afterwhich the snowpack clung to life until early April when it began to melt rapidly.  More than half of the peak SWE is already gone as of today. Source: CBRFC In the central Wasatch Mountains, Parley's summit is the lowest SNOTEL (7500 ft).  Here, the average peak SWE of about 15" occurs somewhere in mid-March to April 1st (more data is needed for a smoother curve!).  This year, Parley's has behaved a bit like a low-elevation station that experiences mid-seaso...

Much has been made of the so-called global warming "pause" or "hiatus", a term that has been used to describe the slowdown in the rate of increase of surface temperatures over the past 10–15 years.  As we have discussed in previous posts (e.g., Global Warming Hasn't Stopped ), this period has been marked by continued warming of the ocean, melting of ice, and warming of the land surface, so there is every reason to expect a return to more rapidly rising surface temperatures in the future. In addition, there is some potential that we will see a new global surface temperature record in 2014 or 2015.  It is looking increasingly likely that El Nino will develop this summer or fall, with some indicators suggesting that it could be a moderate or strong event.   El Nino is characterized by relatively warm sea surface temperatures in the tropical Pacific Ocean which, along with other accompanying changes in atmospheric and oceanic circulations, typically leads to...

We frequently talk about how the tropics and subtropics visit Utah in the form of cool-season atmospheric rivers, but there are situations in which high- or mid-latitude airmasses plunge southward into the tropics.  This is especially common to the east of the Rocky Mountains and Sierra Madre, which frequently act to channel relatively cool airmasses to Central America or, in extreme events, northern South America. A great example of these Central American Cold Surges is affecting Mexico and Central America today.  Note in the loop below (especially the lower panel), the surge of relatively cool high pressure from the central United States into Central America.   To save bandwidth, I haven't plotted a longer loop to fully show the history of this event, but the airmass currently plunging into Central America originates in northwest Canada.  Brrr... As these cold surges move southward, they are modified and warmed, but they are still relatively cold when they ...

Some strong winds accompanied a band of showers and thunderstorms that moved through the Salt Lake Valley just after midnight MDT/0600 UTC last night. Source: NCAR/RAL The award for highest lowland wind gust goes to the Meteorological Solutions Inc. observing site in Olympus Cove where a peak gust of 63 mph at 0105 MDT/0705 UTC. Note the dramatic drop in temperature and increase in wind speed. Source: MesoWest Other peak gusts include 60 mph on the Eyring Science Center @ BYU, 60 in Vernon, 57 at the University of Utah, and 52 at the Salt Lake City International Airport.   Two inches of snow at Alta combined with the cooler weather should yield some "interesting" dust-on-crust conditions in the Wasatch for today.