Wasatch Weather Weenies

The Salt Lake City International Airport has had 4.19 inches of precipitation so far in May, good for the 6th wettest in Salt Lake since 1874.  Most of the state is well above average for precipitation. If you are wondering if the drought is over, it isn't.  The U.S. Drought Monitor released this week shows long-term abnormally dry conditions in the northeastern portion of the state to extreme drought in the west desert. This might seem surprising given how wet it has been, but long-term drought is a 6 month to multiyear phenomenon and considers indicators that include groundwater levels and reservoir storage.  Although it's been really wet the past month, we have considerable ground to make up in these and other areas affected by long-term precipitation deficits.

Amongst the more interesting aspects of this past winter and spring is the contrast in snowpack evolution between the mid and upper elevations.  It's a great example of why, in a warming climate, high-elevation ski terrain and resorts are likely to have an increasing "competitive advantage" with regards to natural snowpack compared to low-elevation ski terrain and resorts.    We begin at the Mill-D North SNOTEL at 8967 ft in Big Cottonwood Canyon.  Here the snowpack crested well below median, but it also melted out from mid-March to late April.  With the wet weather this month, there have been a couple of events that have laid down some snow, but there's been no recovery in the snowpack at all.   If we go a little higher to the 9640 ft SNOTEL at Snowbird, we see that the melt out began later (this is a result of not only altitude but also aspect as the Mill D SNOTEL has more sun exposure) and that over the past month the snowpack has been able t...

The newest model in modeling suite at the National Centers for Environmental Prediction is the High Resolution Rapid Refresh or HRRR (pronounced Hur, although you get bonus points if you can let the r drag on for a while). With 3-km grid spacing and radar data assimilation, the HRRR is the first operational US modeling system capable of near-storm-scale prediction. Here's an example from today.  At 1445 UTC (0845 MDT) an area of precipitation was located over northwest Utah and was moving eastward. Here's the HRRR forecast from 1300 UTC (0700 MDT) through 1800 UTC (1200 MDT).  For the first part of the loop, I've overlaid the HRRR reflectivity on top of the observed.  After that, you see the HRRR forecast reflectivity, which calls for showers to be located over the Salt Lake Valley at 1700 UTC (1100 MDT).  That's about the time I walk across campus for a swim.  I'll keep an eye on the radar and adjust my plans if necessary. Radar data assimilation ...

I know you're thinking that I'm nuts, but as a meteorologist, I hate falling just shy of key thresholds and records. So far this month, the National Weather Service has recorded 3.88 inches of precipitation.  That's only good for the 8th wettest May on record if we use the Salt Lake City International Airport record for the past several decades and other nearby observing sites to go back to the late 1800s. Source: NOAA Regional Climate Centers It is, however, the 4th wettest since the mid 20th century, behind 1993 (3.99"), 1997 (4.76"), and 2011 (5.14").  The wettest year if you go way back is 1908 (5.76"). I think the key psyche points are 4" just because it's a nice round number and 4.27" as that would get us into the top 5 all time.  Given the hit and miss nature of these storms, I make no specific predictions, but climbing up the list is certainly possible and if we can get a big dump right at the airport, perhaps we'll do...

I have a reputation for giving Coloradoans a hard time about their lack of snow, but it is well worth a trip to the Centennial State when they are having a spring like this one. Most of Colorado did not have a great ski season if you measure it by the peak snowpack.  However, the spring has been outstanding for two reasons.  First, it has stayed cold and snowy.  Second, a lot of that snow has been of the sticky, high density variety and it has coated just about everything and the cover is exceptional above 11,000 feet. Here's an example from the Grizzly Peak snotel at 11,100 ft in Arapaho Basin.  The highest snowpack snow water equivalent of the water year is right now.  It's about at the median peak for this site, but that typically happens in early April rather than late May, putting them way above average for so late in the year. Source: NRCS For the Memorial Day holiday, my son and I decided to check out this snowpack for ourselves.  We spent ...

In the Harold Ramis directed movie Groundhog Day , a weatherman played by Bill Murray relives the same day over and over and over again.   I've thought of that movie a lot the past week or two and it suspect you will to as we move forward through Memorial Day weekend. The bottom line is that the unsettled weather will likely persist over the state through the weekend.  Just watch the NAM forecast below which runs through Sunday afternoon and you get a good idea of what we're looking at.   Yup, showers and thunderstorms with some variations in the timing, coverage and intensity of precipitation from day to day.  That's the pessimistic view.  The optimistic view is that there will be  some breaks where you can get in outdoor activities and there are no unusually cold airmasses making an appearance.  Nevertheless, keep the shower and thunderstorm threat in mind during your outdoor recreating.  Move indoors or into a closed vehicle if y...

For a good part of this past Northern Hemisphere winter, above average sea-surface temperatures (SST) persisted near the dateline (180º) in the equatorial Pacific.  For example, the image below shows the weekly SST anomaly (anomaly means departure from a 30-year climatology) for the last week of February with the positive SST anomalies centered on the dateline in the equatorial Pacific. Source: ESRL/PSD Since then, positive SST anomalies consistent with weak to moderate El Nino conditions have strengthened and developed across the eastern Pacific and now extend to the coast of South America. Here's another perspective based on a loop of the SST anomalies since late February, showing very nicely the development of the weak to moderate El Nino.   Source: CPC Concurrently, enhanced convection and cloud cover developed over most of the central and eastern tropical Pacific, especially just to the north of the equator along the Intertropical Convergence Zone (ITCZ). ...

I haven't read it yet, but given the weather we have had the past two weeks, I think we should all run out and pick up Cynthia Barnett's new book Rain .   Over the past 14 days, precipitation is well above average statewide, with large portions of the state running more than 300% above average.   Source: weather.gov In the Salt Lake Valley, Alta is the climatologically wettest regular observing site and has picked up 7.65 inches of precipitation so far this month (not including overnight and possibly part of the day yesterday).  A good chunk of that total fell over the weekend when the upper elevations got 16 inches of high density snow.   Source: NOAA Regional Climate Centers The Salt Lake City International Airport is the climatologically driest location and has still recorded 3.38" of precipitation (through midnight MST last night), nearly three times average.    How does that stack up relative to past Mays?  Records are...

From an old T-shirt that I have... Feel free to add more in comments.

After depriving us of quality powder for most of the winter, Mother Nature turned on the spigot big time last night.  Automated observations from the Alta-Collins observing station (9662 ft) show the total snow depth increasing from around 64 inches yesterday (multi-hour average) to 80 inches as of 7 am this morning.  I'm calling it a 16 inch storm total, although it looks like 14 inches of that fell after 6 PM yesterday.  Total water during this period was a whopping 2.41 inches.   Radar images from last night show the remarkably juicy northwesterly flow and how Alta was fortuitously located in the narrowing band as the night dragged on.   Source: NCAR/RAL Source: NCAR/RAL I've looked at some radar loops and there may have been some lake augmentation at times, but the large-scale precipitation band was an important component of this storm (note how it extends well upstream of the lake in the images above).   The Utah Avalanche Center...

More snow at Alta this afternoon. Sorry kid, you have to earn your turns today. The reward for hard work was more creamy goodness. Want some?  Get up early tomorrow as the snow won't last long.  Be careful as the snowpack could be cranky especially if it keeps snowing and if it warms tomorrow.  Further, the snow is high density and any wet sloughs or slabs will pack a much bigger wallop than we Utahn's are used to.

Things are coming together for several inches of fresh today and tonight in the upper-elevations of the Wasatch for those of you who still feel the need to feed the habit (count me in). As of 7:45 this morning, all was relatively quiet over the Salt Lake Valley and the Wasatch Mountains to the east.  Given the southwesterly pre-frontal flow, an orographic cloud hung over Lone Peak and the downstream central Wasatch Mountains. However, a glance to the west shows the Oquirrhs shrouded in cloud cover and light snow.  A harbinger of things to come? Indeed, the regional radar looks optimistic with returns to our west that will slowly spread over the area and into the central Wasatch this morning.  Source: NCAR/RAL The NAM calls for valley rain and high elevation snow this afternoon.  Below is the accumulated snow-water equivalent from 3PM to 6 PM MDT.  No yard work today! And the grid point output for Alta shows about 0.75" of SWE and ...

It may be deja vu all over again this weekend.  Alta-Collins has had 0.4" of water equivalent in the past 24 hours and will likely see some snow in fits and spurts today as well.  Then we have the potential for snow this weekend. My approach when it comes to spring storms is to get out during or just following periods of significant snowfall.  If you wait too long, everything gets warm and manky, which not only results in poorer skiing, but also the potential for wet avalanches. We spoke in the previous post ( This NAM Forecast Is a Work of Art ) about the dramatic comma-shaped character of the cloud and precipitation pattern for Saturday, as well as the pronounced dry slot.  Today's 1200 UTC NAM shows a similar pattern for 1500 UTC (0900 MDT) Saturday, with much of the area around Salt Lake City in the cyclonically wrapped dry slot, but precipitation just to our south. Eventually the band of precipitation moves moves into northern Utah, but not until later ...

We rarely see such a beautiful comma cloud and precipitation pattern over the Intermountain West as forecast by the NAM for 0900 UTC (0300 MDT) Saturday.  Simply spectacular! 0600 UTC 14 May 2015 NAM forecast of 500-mb wind (vectors), temperature (red contours every 1ºC) 3-h accumulated precipitation, and outgoing long-wave radiation valid 0900 UTC 16 May 2015 Patterns like this are associated with well developed upper-level troughs, but often such troughs have cloud and precipitation patterns that are broken up by the topography of the west. That's not the case in the NAM forecast above. The beautiful comma cloud and hook-shaped precipitation pattern is associated with two major airstreams.  The first is sometimes called the TROWAL (TRough Of Warm air ALoft) airstream.  The TROWAL airstream is associated with warm advection and ascends along a tongue of warm air that wraps round the back side of the upper level low, forming the comma.   The second ...

Although Utah is home to the Greatest Snow on Earth during winter (except for perhaps this year), once spring rolls around, I'm more inclined to think about skiing elsewhere.  There are big lines and beautiful views to be had around the west, but this year, you might have to work a bit harder than usual to find some that are adequately snow covered. Below is the basin-wide percent of average snowpack analysis for the western U.S. from the NRCS.  These numbers are simply heinous for most of the west.  Only portions of Colorado and SE Wyoming are near average (the high numbers in SE Utah are either spurious or the result of what we call the "statistics of small numbers" — there's very little snow there). In the Sierra and Cascades, the snowpack is non-existent or <10% of average in most basins.  One plus is that with no low-elevation snow, access to higher elevation tours is much easier than it typically is in May.  For example, the road to the South Cli...