Wasatch Weather Weenies

Major storms have been rumbling through the Pacific Northwest over the weekend and snow is beginning to pile up in the high country.  With snow levels near 4000-4500 feet, it is currently 32ºF with heavy snow at Paradise Ranger Station on Mt. Rainier (~5500 ft), one of more accessible higher elevation locations that you can access by car in the Washington Cascades.  As a result, Paradise is frequently a very good choice for early season turns.   Paradise Ranger Station parking lot, Mt. Rainier National Park.  Source: NPS Although they only have several inches of snow on the ground at present, satellite imagery shows a classic pattern for heavy snowfall today with a continuous fetch of unstable cold air extending from the Gulf of Alaska into the Washington Cascades.   Thus, the forecast calls for more snow, potentially enough given the density of Cascade snow for turns tomorrow. Source: NCEP Conditions will be marginal, but it could be enough ...

Editors note: This post was updated on 24 January 2017 to include the new, updated link for the Summary for Policy Makers (the old one had expired).  The Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (referred to by scientists as the AR5) consists of four reports: Working Group I report on the physical science basis of climate change Working Group II report on impacts, adaptation, and vulnerability Working Group III report on mitigation of climate change The Synthesis Report The final draft of the Working Group I report, which attempts to provide a snapshot of current understanding of climate change, will be released and available at  http://www.ipcc.ch/report/ar5/wg1/ tomorrow.  The Summary for Policy Makers was approved and released on Friday.   Below is a Cliff Notes version of the key figures, provided with as little commentary as possible.  Perhaps we will take a closer look at key findings and areas requiring furt...

Observations from Alta-Collins suggest that 3-5 inches of snow fell overnight, but the big winner in last night's lake-effect lottery looks to be Oquirrh Mountains and the "hallowed backcountry" owned by Kennecott. The Dry Fork Snotel (DRFU1) located at 7160 feet just to the north of the Kennecott's open-pit copper mine picked up a fast 7 inches from 4–10 am this morning with about 0.70 inches of snow-water equivalent. Source: mesowest.utah.edu Mountain snow showers and valley rain showers of the lake- and non-lake variety will continue for a few more hours before this event winds down later today. The best thing that could happen now is that we get a good warmup to melt all this snow.  The last thing we need is a persistent snow cover rotting on north facing aspects and providing all sorts of avalanche booby traps when real winter starts in a few weeks. Addendum @ 11:30 AM:  Reports of mixed snow and rain this morning along I-80 near Tooele and accum...

I like our chances of picking up several inches of mountain snow in the Cottonwoods later today, tonight, and early tomorrow as a cold, "juicy" northwesterly flow develops over northern Utah.  Perhaps we'll do better if the lake effect can kick in with the right orientation.  If we can get high precipitation rates, you might even see some of the white stuff on the benches. Here are some thoughts on lake effect that are relevant for tonight's forecast.  First, lake effect is relatively rare in September.  During the latter half of the month, you can expect an event on average every 4-5 years.  Events are more common later in the fall when there is a higher frequency of trough passages and cold air intrusions. Source: Alcott et al. (2012) Although events are scarce this time of year they do happen.  In addition, if we look at the environmental conditions in which lake effect occurs throughout the cool season, we find that during the fall (and spring),...

Cold air, northwesterly flow, lake stink.  Ah, fall is here, and so is the post-frontal crapshoot. Let's talk about the easy stuff, or what Donald Rumsfield would call the known knowns .  A deep upper-level trough with the coldest air we've seen thusfar this fall will be rumbling through the Intermountain West over the next couple of days.  The coldest and juiciest air is expected to be over northern Utah on Friday morning. At that time, the 700-mb temperature is forecast to be about -5 to -6ºC, which is why the National Weather Service is calling for snow levels down to about 6000 feet.  If we got a strong convective or lake-effect storm, I wouldn't be surprised if we say snow down to the benches. The hard parts of this forecast are what Donald Rumsfield would call the the known unknowns  and the unknown unknowns .  The known unknowns are things that we know we don't know.  In this case, we know we don't know how to predict with...

Source: Silverton Mountain This is an entirely unsubstantiated observation, but it seems that in most years Colorado gets an early season dump before the Wasatch.  If this is true, I suspect is is a function of altitude and the great diversity of ranges that they have, which greatly increases the likelihood that somewhere in the state they will get something when a trough rumbles through.   Have faith.  We always win in the end...

Chances are you've heard rumors of flakes in the Uintas yesterday and snow coming to the Wasatch this week.  The setup for the potential snow later this week is something that frequently happens over the north Pacific, especially in the fall.  On Saturday morning [1200 UTC (0600 MDT) 21 Sep] and upper-level short wave trough (red line) was moving eastward over the Sea of Japan, while a plume of moisture (green line) extended northward from the subtropics near the dateline.   IR satellite image and GFS 500-mb geopotential height (black lines) and integrated water vapor (color fill) analysis valid 1200 UTC 21 Sep 2013  Over the past two days, the upper-level trough amplified (western most red line below) and phased with that plume of moisture (green arrows).  This led to an amplification of the pattern downstream with a ridge building over the Aleutian islands (blue line) and a trough digging over the eastern Pacific (easternmost red line). IR satellite ...

It looks windy and warm (by evening standards) for tonight's game, which will surely run to midnight (pictured below, note the very strong flow). Games in recent years have frequently been decided by field goals.  Planning to have that wind at your back in the fourth quarter could prove prescient.  Hopefully Coach Whittingham is either aware or has a good plan to ensure we have a comfortable lead by then.  Given the porous nature of the Ute defense so far this year, I'm not thinking the latter is likely. Finally, regardless of who wins, it is always worth remembering the top-10 reasons why Utah is better than BYU: 10. We have the Great Salt Lake effect, they have the Utah Lake effect 9. We chase tornadoes, they chase honor-code violators 8. We have Alta-Snowbird, they have Sundance 7. The Cottonwoods get blower pow in northwesterly flow, Timpanogos gets nothing 6. The Utah ski team has 10 NCAA championships and more than 60 individual national champions, ...

You will be shedding layers today.  Here's the recipe: 1. Preceding surge of cold air into the region 2. A dry, crystal clear night 3. Development of strong southwesterly flow and the transport of warm air aloft over northern Utah overnight 4. A clear, sunny day with continuing southwesterly flow Thus we'll be rebounding from an overnight minimum of about 48ºF at the airport to something like 83ºF this afternoon. Of course, there are better places to experience a full force temperature swing, such as the Rush Valley south of Tooele where overnight minimum temperatures were as low as 32ºF. At the Faust observing site that reached 32ºF last night, they will likely see a temperature increase today of about 50ºF.  Not too shabby.

Major changes are now underway that should warm the hearts of Utah skiers.  First, I'd like to whet your appetite with the web cam photo from Mt. Washburn in Yellowstone National Park (thanks to Jack Hales' Star Valley Weather Blog for pointing this out). Source: National Park Service Next, we have a couple of opportunities for snow at least in the Wasatch in the coming week.  The first is with the trough passage that will occur this weekend.  Overnight forecasts from the North American Ensemble Forecast System [NAEFS, a combination of the US Global Ensemble Forecast System (GEFS and the Canadian ensemble] include a few members that drop 700-mb temperatures down to 0ºC on Sunday, which would probably get snow levels down to about 8500 ft. Source: NWS On the other hand, the average of those members is a bit warmer than that and the moisture accompanying the trough is pretty limited.  So, this could disappoint, but I thought I'd note the potential for our ...

Here are some interesting perspectives on the summer of 2013 and this wonderful airmass that has pushed into northern Utah. To begin, it looks like we can finally assume that all the 100ºF days are in the books for this year.  We hit 20, 1 shy of tying the all time record.  I guess you can't have everything. Las night our overnight minimum was 56ºF, still higher than the average of 52ºF, but it is likely we will have a minimum either tonight before midnight or tomorrow that is below average, which would be our first day with a below average minimum since August 2nd.  August 2nd is the only day since June 23rd with a below average minimum, as illustrated nicely by the National Weather Service graphs below.   So, over the last 86 days, we have had one with a below average minimum temperature . One!  That is in my view the most remarkable aspect of this summer. Today's high will likely be near 70ºF, which will make it the coolest day since...

The last day of the 2013 monsoon is here.  A parting gift just rumbled through campus.   Get your freak on and celebrate with The Doors.

Sunrise over Salt Lake this morning It hung on for as long as possible, but it is now apparent that our suffering is almost over.  The summer of 2013, characterized by extreme heat in Salt Lake City and an extremely active and prolonged monsoon across much of the state, will end this week.   Change is coming in the form of a midlatitude upper-level trough and cold front that will sweep into the Pacific Northwest and penetrate into northern Utah early Wednesday. By Wednesday afternoon, we will be enjoying the coldest airmass that we have seen around here since at least June, with 700-mb temperatures forecast to be near +2ºC. It's tough to say for certain if this is a true stake-in-the-heart for the monsoon, but the forecasts for the next week or so keep us in large-scale southwesterly to westerly flow.  Temperatures will rebound by later in the week, but it appears the monsoon moisture will remain to the south, which hopefully means that we'll see some ...

Our hearts go out to everyone suffering in the flooding along Colorado's Front Range.  Mother Nature is showing no mercy, with heavy rain returning today.  Although accumulations aren't expected to be as outrageous as a couple of days ago, they will add further insult to injury. Source: NCAR/RAL Now added to the list of mind boggling observations from this storm is how the North Fork of the Big Thompson River at Drake has remained near or above record flood stage now for more than 60 hours. Source: water.weather.gov Assuming the gauge is still functioning correctly, it appears there will be no quick retreat of the flood waters along the Front Range.  Videos of the flood damage are disheartening.  You can find them all over the web, but a large collection is available at The Lede . A couple of perspectives on the flooding that might interest you include the following: Inside the Colorado Deluge by Bob Henson Against the Hundred Year Flood by Roge...

The flooding in Colorado has disrupted telecommunications, halting the the flow and distribution of radar data from the Salt Lake City radar (KMTX).  What is a meteorologist or weather enthusiast to do? One option is to use the Salt Lake City Terminal Doppler Weather Radar (TDWR).  The TDWR is a smaller, shorter-range radar deployed primarily to detect wind shear for aircraft safety.  Nevertheless, it provides high quality radar images just like KMTX.  Below is an example of the imagery of this afternoon's thunderstorms. The TDWR is located near the shore of the Great Salt Lake west of Centerville.  It thus has the advantage of providing radar scans at much lower elevations over the Salt Lake Valley compared to KMTX (which is at 6800 ft on top of Promontory Point).  On the other hand, it is completely blocked by the Wasatch Mountains to the east, and thus provides no guidance on what is happening on the Wasatch Back and beyond. If you need a ...

Widespread flooding in Boulder.  Courtesy Ed Szoke.  It is very rare that I will use the same hyperbole as USA Today (See "Biblical" rains trigger flooding that kills 3 in Colo .), but the storm that hit Boulder and the Colorado Front Range the past two days is so mind boggling that I don't know how else to describe it.  Boulder is home to the National Center for Atmospheric Research, NOAA/EarthSystems Research Lab, and numerous other meteorological organizations and our thoughts go out to our colleagues and other residents of the area. According to the Western Region Climate Center , Boulder has an average annual precipitation of 18.72 inches and an average monthly precipitation in September of 1.53 inches.  Until this event, records for the wettest month and day were 9.59 inches in May 1995 and 4.80 inches on July 31, 1919.  Both of these records have been obliterated. Rainfall estimates from the Advanced Hydrologic Prediction Service show rainfall max...