Wasatch Weather Weenies

Following up on the previous post ( New HRRR Products on weather.utah.edu ), I've now added new GFS model soundings and time-height sections as well.  They are under the GFS-0.25 deg tab. The soundings are plotted on a thermodynamic diagram known as a "Skew-T," so called because a line of constant temperature is skewed 45˚ from the horizontal (grey lines that slope upward to the right below).  There is a wealth of information on these charts, but there's a summary available here . The diagram lines, described in greater depth at that link, include pressure (horizontal grey), dry adiabats (red dotted), moist adiabats (blue dotted), and mixing ratio (green).  The red and green lines are the model forecast temperature and dewpoint.   The black line is the theoretical profile a parcel of air would have if it were lifted.  In this case, I am plotting the "most unstable" parcel.  That is, the parcel with the most Convective Available Potential Energy (CAPE)....

I've added some new HRRR products on weather.utah.edu.  In fact, I've completely upgraded our HRRR postprocessing suite over the past couple of weeks, migrating to python and building in a lot of capabilities that should improve reliability and produce far superior graphics than those that have been around now for 20 years.  In particular, the code uses Amazon Web Services as the primary access point for the data, with a fall back to the National Weather Service if there's a hiccup.  It will auto backfill if products are not produced (assuming our servers are up).  It's also parallelized and, for the three product types that are currently being produced, and download and process an 18-hour HRRR forecast in three and a half minutes.  The color schemes are also supposed to be more color-blind friendly.   The three products that are available are composite reflectivity and IR, hourly precipitation, and total precipitation.   On weather.utah.edu,...

I thought I would beat the heat with an early morning ride of Flying Dog above Jeremy Ranch this morning.  The trailheads there are usually some of the cooler spots around, but cloud cover, humidity, and a bit of a breeze prevented much overnight cooling.  The site at the bottom of Woodward Park City, for example, dropped below 60˚F each of the previous four nights, but last night only got down to 65˚F.  Ick. My car thermometer measured 73˚F at the trailhead at 7:45, which was probably close and wasn't much lower than the overnight minimum at the Salt Lake City airport (77˚F).   Fortunately, the cloud cover masked the sun on the ride, so perhaps it was a reasonable tradeoff.   Regardless, I'm so sick of this heat.  Based on the most recent 30-year climate "normals" (whatever that means anymore, the hottest days of the year at the Salt Lake City airport are from July 23-27 (Average high and low 96 and 70, respectively).  Call this climatologic...

Storm Peak Lab is a permanent mountain-top research facility located at 3220 m (10,564 ft) near the summit of Steamboat Springs ski area.  The lab has been in existence for more than 40 years, with equipment initially operated from a small trailer and now as a permanent facility.   Storm Peak Lab This summer, ownership and operation of the lab transition from the Desert Research Institute to the University of Utah under the direction of Dr. Gannet Hallar, with significant support for the lab coming from the National Science Foundation and other agencies.  Earlier this week, I made my first visit to the lab with a group of undergraduates who are participating in our Research Experience in ALpine Meteorology program (REALM). REALM students and other visiting scientists and students at Storm Peak Lab There are remarkably few mountain-top or high-altitude scientific laboratories in the world that collect a comprehensive suite of meteorological, cloud, trace gas, and othe...

Yesterday's high at the Salt Lake City International Airport of 107˚F set a record for the calendar day and tied the the all-time high temperature reached previously on 26 July 1960, 13 July 2002, and 15 June 2021. Nearly all stations reporting to MesoWest at elevations below 5000 feet elevation in the Salt Lake Valley were at or above 100˚F.  Record highs for the calendar day were also set at the City Creek water plant (98˚F), BYU (104˚F), and Tooele (105˚F).   I fielded a number of question yesterday about why the airport is so warm and whether or not the instrument is properly calibrated.  We have dealt with such questions many times since I started this blog over 10 years ago (for example, see What's Up @KSLC ).  Only the National Weather Service can comment on the current calibration of the KSLC instrument.  I'll address here the representativeness (or lack thereof) of the airport observing location.   Urban and near-urban areas exhibit large...

I've never been a fan of July and sadly it is only getting worse. Let's begin looking at the first two weeks of July at the Salt Lake City International Airport.  The average temperature was 87.1˚F, the hottest on record.   Source: http://xmacis.rcc-acis.org/ A few more numbers.  The lowest  maximum temperature so far this July was 96˚F on July 1st.  96!  Maximum temperatures have ranged from 96 to 104 and there have been 7 days at 100 or more.  If we add June, there have been 10 days at 100 or more so far this summer. The lowest minimum temperature so far this July was 68˚F on July 11.  Minimum temperatures have ranged from 68 to (gulp) 81.  81!  In fact the average temperature on that day (July 3) was 90˚F, although that was beaten on July 9 when the average temperature reached 90.5˚F.  To date, there have only been 21 days in the historical record with an average temperature of 90˚F or more.  19 of these days have...

This time of year, clouds are good.  It's hot, but without direct sun, the help cut the intensity of the heat. Monday night, a little monsoonal moisture made it into northern Utah, increasing the cloud cover yesterday and producing a few showers and gusty winds.  Most of the precipitation evaporated, but I saw a few drops hit the ground.   A look at the weather observations at the Salt Lake City International Airport shows the increasing moisture well.  The green line below is the dewpoint, which is a measure of the absolute water content of the atmosphere at the surface.  Values have climbed steadily over the past five days and are now just a bit over 50˚F. The HRRR cloud and radar forecast for this afternoon shows convective storms developing over northern Utah.   The HRRR can't reliably predict the location of convective storms, so where and when such storms develop is difficult to say, but expect some showers, thunderstorms, and gusty winds th...

 I rose early this morning and hiked up Sunset Peak from Brighton.  As I sat on the summit, stared westward over Alta, Snowbird, and the Alpine Ridge and wondered if there was any skiable snow remaining.  Shortly thereafter I got a text from my son saying he skied the main chute, so apparently there is.  He described it as "awesome, but really scary."  I don't really know how to interpret that, but I guess it still goes.   I haven't seen pictures, but imagine the white ribbon of death that remains won't survive long.  I haven't had the courage to look at the models, but I took at peak at the NWS forecast for the airport and the highs are: Monday 96 Tuesday 100 Wednesday 101 Thursday 100 Friday 99 Saturday 99 Sunday 99 The forecast low for tonight is, however, 69˚F.  We'll see if that verifies, but it will be the first sub-70 reading of the month if it does.  

The Great Salt Lake is expected to set a new historical low elevation at the Saltair Boat Harbor this year and provisional data from the USGS suggests it is pretty close to that level right now. Below is yesterday's MODIS image from NASA's Aqua satellite showing the large area of exposed playa the northern and southern arms of the lake, including the former Farmington Bay immediately adjacent to Antelope Island and the Salt Lake Valley.   Observations from the USGS at the Saltair Boat Harbor show that the highest lake elevations since 2007 were achieved in 2013 when the lake was near 4199 feet.  Last year, we bottomed out at 4190.4 feet, which is the record low at this site.  The recovery this spring was limited.   The latest provisional data since June 1 shows the general downward trend with measurements since July 2 near or below 4190.4 feet, the current record.  Lake-elevation observations are tricky, so the USGS will need to weigh in on whether or ...

Heat, wind, low relative humidity.  Hairdryer conditions are dominating the weather story over northern Utah this holiday weekend.   Meteograms for the Salt Lake City International Airport (KSLC) over the 24-hour period ending at just after noon today (Sunday, July 3rd) illustrate this well.  Yesterday afternoon, temperatures hovered near 100˚F (the official high was 101˚F) with dewpoints in the mid 20's and the relative humidity below 10%.  Winds gusted as high as 38 mph.   Today is pretty much a repeat.   For drying out the landscape, this is about as bad of a pattern as you can have.   Sadly, the monsoon moisture isn't that far away.  The NAM forecast for this afternoon shows a sharp contrast in low-level relative humidity between western Utah and western Colorado (see lower left panel below), with considerable shower and thunderstorm activity over the latter.   Both regions are in southwesterly flow.  The dif...

I have very little intuition for what Utah experienced in June.  I was gone for nearly the entire month.  I didn't see a temperature above 80˚F for 3 weeks in Ireland and England and experienced a 12-day stretch in Ireland when I didn't see anything above 70˚F.  In a word.  WONDERFUL.   The numbers for KSLC, however, show that June was warm compared to climatological norms with an average temperature of 74.7˚F, rating as the 8th warmest on record. Source: NOAA Regional Climate Centers A look at the time series above and the top-10 warmest June's on record below shows that the dice have been loaded for warm Junes at KSLC in the 21st century and especially since 2010.   Source: NOAA Regional Climate Centers For precipitation, 0.56" was recorded at KSLC, which is a shade below median for the month.  Anecdotally, it seems it's remarkably green around here for late June, so perhaps the timing or antecedent moisture have been good for the plant hea...