Wasatch Weather Weenies

A varnish of snow at higher elevations in the Wasatch this morning Last night proved to be quite productive in terms of wind and valley rain with car-wash-like conditions for a while.  At the University of Utah, a sharp front passed just after midnight, resulting in a rapid temperature drop of more than 15ºF, a shift in wind direction to NNW, and wind gusts reaching over 55 mph.  Strong winds with gusts in excess of 30 mph continued for about 2 hours during which about 0.34" fell (data below courtesy MesoWest). Reports to the National Weather Service show some locations received event greater precipitation amounts including 0.71" at one site in the Salt Lake City area (5102 ft). It was a relatively warm event in the mountains, but at least a dusting of the white stuff extends down to about 8000 feet based on web cam imagery.  The Alta-Collins snowstake sits at about 2".  Woot woot! Is this the start of a trend?  I don't think so.  Another weak...

Big Beacon is the nickname given to the 7143 foot peak immediately east of Research Park and the University of Utah with a small tower on top of it.  Officially on USGS maps it is known as Mt. Wire, but Big Beacon is easier to remember. I've hiked it many times, usually in bad weather.  The peak is fairly exposed to southwesterly flow and it can be quite breezy, as it was today.  It has, however, a nice view of the central Wasatch and I like to visualize the flow and its impacts on cloud development from the summit. Today we were on the summit at about 1430 MDT when the crest-level flow was out of the south-southwest, as illustrated by the vector wind time series from Mt. Baldy above Alta. Source: MesoWest From Big Beacon, one looks south-southeastward toward the high terrain of the central Wasatch.  The view is not perfectly perpendicular to the flow, but close enough for meteorology.  One could see very well the influence of that high terrain on the ...

A major slug of tropical and subtropical moisture reached California late yesterday in advance of a land-falling upper-level trough and began to push inland overnight.  As of 1200 UTC (6 AM MDT) this morning. a narrow band of heavy precipitation was pushing through the Central Valley with a broader band of precipitation extending inland from northern California to southwest Idaho.  Some scattered showers were found over northern Utah, although only a few drops were reaching the ground. Precipitable water, a measure of the depth of water you would have if you condensed all of the water vapor out of the atmosphere, is very high with this event, reaching 40 mm along the southern California coast.  Although losses to precipitation and other factors favor a decline in precipitable water as airmasses move inland, we're still looking at relatively juicy air over northern Utah by late October standards.  Precipitable water in this morning's sounding at the Salt Lake Air...

World Record?  I don't think so.  Credit: CBS All observations are bad; some are useful .  This paraphrasing of George Box's famous quote, "all models are wrong; some are useful" is something I preach to students in my weather analysis and forecasting classes.  Given the spatial complexity of the atmosphere, meteorologists are data starved and we tend to worship any observations we can get our hands on.  However, observations, even those collected by and through "official" channels do have errors and uncertainties, and these are critical to consider in operational or research applications. This is especially true when it comes to extreme events.  By their very nature, extreme events are rare and highly unusual.  Observations of extreme events, especially in isolation, require careful analysis and vetting.  As Carl Sagan used to say, "extraordinary claims require extraordinary evidence." There are a number of world or national weather ...

Yesterday was a net loss for what little snowpack that we had at pretty much all but the highest elevations.  We didn't have a lot of snow on the ground yesterday morning, but a couple of inches was lingering on shady north aspects, and most of that snow is gone today. Yesterday.  Source: Alta.com. Today.  Source: Alta.com. Here's another perspective looking up Collins Gulch.  Yesterday there was a white strip in High Rustler and environs, and spotty snow down almost all the way to the base (unfortunately I didn't grab an image).  Today, gone. Today.  Source: Alta.com During fall and winter, it's very hard to melt snow on north aspects when skies are clear, even when the temperature is well above the melting point (0ºC).  On these aspects, there is simply not enough energy from the sun to melt snow when the sun angle is low, and the energy transferred from the relatively warm atmosphere to the snowpack is insufficient to drive significa...

Yeah, it's only October, but it's worth a quick look at the snow season so far. Outside of Utah, aggressive resorts are getting on it, mainly with the help of artificial snow.  Arapahoe Basin, CO opened last weekend.  Killington, VT opens this week.  Mt. Rose, NV planned to open October 31 based on early-season natural returns, although looking at their web cams, I wonder if that is now a pipe dream.  You want natural snow?  Grand Targhee remains the big winner in the interior west so far, as we mentioned previously, and some high-altitude areas of the North Cascades might offer up some skiing as well.  The Northwest Avalanche Center observing site at Washington Pass has a 21 inch base this morning.  If you really want to feel jealous, even Vermont got some this weekend. Chowdah report from @Smugglers_Notch . Man does this make us smile! pic.twitter.com/ZQmn6F8qa7 — SKI THE EAST (@SKITHEEAST) October 23, 2016 Here in Utah, we remain on hold. ...

A quick look at yesterday afternoon's sounding shows that inversion season is indeed upon us.  The afternoon boundary in which surface heating drives turbulence and mixing, extended to only 850 mb, just a couple hundred meters or so above the valley floor.  This mixed layer was capped by a series of stable layers and inversions, effectively putting a cap or lid on the valley atmosphere.  In other words, what you emit is what you breath.   Source: SPC Welcome to late October.  We are now moving into the time of year during which surface heating is often not enough to mix out the valley atmosphere.  In other words, its inversion season.  However, don't blame the inversion for our air pollution problems.  In fact, meteorologists like myself hate it when people say "the pollution is bad because of the inversion."  Nope.  The pollution is bad because of emissions.  We have met the enemy and it is us.   A shallow layer of po...

As future Senator Blutarski said in Animal House, nothing is over until we decide it is. Or, in the case of the seasons, nothing is over until Mother Nature decides it is, and she still hasn't decided to call it over on the 2016 monsoon season. Model forecasts are showing another monsoon surge into Utah late on Sunday, with the potential for some scattered showers and thunderstorms through Monday night. Right now, it appears we'll squeak the UAE (Utah Education Association) weekend in with good weather, although there's a chance something will sneak into southern Utah late on Sunday.  After that, we'll see how things look in a couple of days.

With the climate data now in and processed, I thought we would take a quick look back at the month of September locally and globally. For the State of Utah, the mean temperature for September was about as close as you can get to the 20th century average.   Source: NCEI Given that September is typically a "Goldilocks Month" in the Salt Lake Valley (not too hot, not too cold, but just right), the month overall rated as quite pleasant in my book, requiring neither air conditioning or heating of the home and most of the days.   While the whims of the jet stream looked favorably on us, globally September was still beastly warm, rating as the 2nd hottest in the instrumented record.   Source: NCEI That's a fairly significant change as the last month that did not set a record for the hottest all time based on analyses by the National Centers for Environmental Information was April 2015.  That's quite a stretch of record setting warmth, although there a...

Yes, you could be skiing this weekend, but not in the Wasatch Range. A quick look at the snowpack snow water equivalent (SWE) at western U.S. SNOTELs shows the highest values are nearby at the 9200 foot Grand Targhee site.  Take a quick gander, and you'll see a yellow dot near the Wyoming–Idaho border at that site. Source: NRCS Observations show a snowpack SWE of 8.1 inches.  Pretty healthy for October and the equivalent to the climatological median in late November. Source: NRCS Web cams show a wintery scene. Source: Grand Targhee If you go, add your report to the comments. Note : To my knowledge, the ski area will not be open.  I don't know their policy for access this time of year.  You will need to earn your turns, possibly outside the resort boundary.

It was great to be woken up last night by wind, rain, and even a bolt of lightning as a frontal precipitation system pushed through northern Utah. This is fall, as it should be — blustery, chilly, and wet, with blowing leaves and a dusting of snow in the mountains. Although it appears change is upon us, don't wax your skis yet.  Accumulations have so far been minimal in this storm and the remaining snow showers this morning won't add up to much.  A colder storm will bring some mountain snow showers Tuesday and Tuesday night, but nothing to get excited about.  However, the trails should be tacky and the riding good as we approach the weekend, so keep the cardio up until the snow really flies.

I've lived in Utah for over 20 years, yet still find new places to visit.  My son and I spent the past three days in southern Utah enjoying Fall Break and on a whim elected to return home over State Route 153, which climbs over the Tushar Mountains from Junction to Beaver.  The drive is spectacular (closed in winter and partially dirt) with great views. Along the way, we elected to bag Delano Peak, which at 12,169 feet (you can find other heights online, but I'll use this since this is what it said on the sign on top) makes the Tushars the third highest range in Utah (behind the Uinta and La Sal Mountains).   The route begins along the Piute ATV trail, which I had no problem accessing via my minivan from SR-153.  There's no trailhead sign, but you start just before Poison Creek (there is a trail marked on USGS topo maps).  The route is fairly straightforward.  You just climb until you can't go any higher. About sixteen or seventeen hundred ve...

For the Pacific Coast of the northwest U.S. and southwest Canada, the doldrums of summer are officially over.  Two major cyclones are expected to bring strong winds to the area, along with a litany of other impacts, although the precise locations of the most intense winds with each cyclone remains unclear. The first windstorm is associated with a midlatitude cyclone expected to develop off the coast of Oregon and Washington tomorrow and track northeastward toward Vancouver Island or the Olympic Peninsula.  The 0600 UTC NAM placed the ~970 mb low center very near the tip of the Olympic Peninsula at 0900 UTC Friday, a near optimal location for strong winds over western Washington. The GFS solution was not quite as deep and has the low center making landfall along the central coast of Vancouver Island.  In terms of the severity and location of the strongest winds, much will depend on the precise track of the system. As if that's not enough, a second cyclone follows ...

For those of you who use our downscaled North American Ensemble Forecast System (NAEFS) products on weather.utah.edu, they have recently been updated.  We have a new algorithm for doing the downscaling that we believe reduces bias, especially the tendency for overforecasting. We now believe, as Donald Trump would say, that this product is so tremendous, absolutely tremendous, that you are going to love it.

When it comes to biases, meteorologists have to deal with at least three. The first is bias in our modeling systems .  All modeling systems have shortcomings and tendencies.  Some of these are systematic, in that they appear frequently (but not necessarily consistently).  For example, many lower resolution ensemble modeling systems underpredict the frequency of significant precipitation events over the western United States. Let's take a look at the Global Ensemble Forecast System as an example.  The GEFS is based on a relatively low resolution model and it struggles to predict major precipitation events at mountain locations in the western U.S.  The plot below shows the frequency of occurrence of observed events at SNOTEL stations compared to that produced by the GEFS control and GEFS mean.  The key line is the black dotted one, which is the ratio frequency of observed events compared to that predicted by the GEFS control (known as frequency bias, scal...

We are now up to 4001 days without a major hurricane landfall in the United States. The center of Hurricane Matthew has yet to cross the coast of Florida and remained far enough offshore that most (maybe all) of the southern and central coastline escaped hurricane force winds.  The loop above shows tardar imagery from 1045–1840 UTC this morning and shows how the eyewall just grazed Cape Canaveral, which likely saw the strongest winds along the central coast.  I have seen reports of gusts on Cape Canaveral of just over 100 mph, but am not sure what the sustained winds were and if these measurements were taken at standard instrument height. The strong winds of a hurricane tend to be very tightly wrapped the low center with the eyewall.  If the storm shifted just a bit west, the winds would have been far worse.  The track was about as close as you can get without producing hurricane force winds at the coast. Although Matthew has weakened a bit, it is still a ve...

KAMX (Miami) radar loop from 1328–1644 UTC October 6 It has been 4000 days since a category 3 or higher hurricane has made landfall in the United States, but that could change tonight or tomorrow, as Hurricane Matthew tracks of the Florida-Atlantic coast.  Technically, landfall requires the center of the storm to move across the coast and it is possible that the center of Matthew will remain offshore.  My read of the latest model guidance suggests, however, that landfall is more likely than not to happen.  Regardless of whether or not Matthew makes an official landfall, this is an extremely dangerous storm.  As noted by the National Hurricane Center this morning, " Matthew is likely to produce devastating impacts from storm surge, extreme winds, and heavy rains in the central and northwestern Bahamas today and along portions of the east coast of Florida tonight. "  More info below. Source: National Hurricane Center The last official update from the Na...