Wasatch Weather Weenies

I woke up this morning thinking it must be the end of July.  Heat.  Thunderstorms. Basic yuckiness.  Graphs from the National Weather Service show only 6 days this month with a maximum temperature below "normal" and only 4 days with a minimum temperature below normal.   Normal for the National Weather Service is currently based on the 30-year average for 1991-2020, but warming of the climate system and expansion of the Wasatch Front urban area was already having an influence during that period.  Thus, I thought I'd take a look back at how this June so far compares with the Julys we used to have around here.   So far, this June (based on data from the 1st to the 26th) has an average temperature at KSLC of 77.3°F.  It is evident from the graph below that this is much warmer than the typical range of temperatures observed prior to about 2000.  In fact, it is the 2nd warmest such period on record, behind only 2021.   Source: h...

Data collected from the USGS at Salt Air suggests that the elevation of the south arm of the Great Salt Lake reached its seasonal maximum in May at about 4195 feet and is now declining.   Source: https://waterdata.usgs.gov/ Data for this location extend back to 1847, so we can put the 4195 foot elevation into historical context.  There are two prior periods where lake levels dropped below 4195 feet.  The first was from about 1934–1946 when the lake episodically went below 4195 feet.  The second was from about 1959–1971 when the lake dropped to just below 4192 feet and was below 4195 feet for a several year stretch with episodic drops below that level in surrounding years.   https://waterdata.usgs.gov/ The north arm remains lower than the south arm and is currently at an elevation of about 4193 feet.   A real question moving forward from here is will our string of high snowfall winters continue?  Let's hope so.

Mother Nature delivered the cold air as promised and we have a wonderful mid-June airmass in place over northern Utah this morning.   Temperatures reported within the 1 hour ending at 1324 UTC (0724 MDT) show 40s in the Salt Lake Valley with 20s and a few 20s in the mountain valleys on the Wasatch Back.   A few minimum temperatures (so far) that caught my eye:  Natural History Museum of Utah 36, Alta-Guard 25, Top of Snowbird Tram 19, and I80/Silver Creek Junction 24.   The aiport reports minimum temperatures every six hours and at 6 AM their minimum was 45. There's a chance it could go a degree below that.  If you are wondering, the record low for today is 37 (set in 1928), so that's safe.   It could be a long time until we see temperatures this low again.  Enjoy.  

Wednesday: 99. Thursday: 100. Had enough?   I have some good news. The forecast high for today is only 95F. Hooray! But it get's better.  We will see a gradual cooling trend through early next week.  First, the ridge that has tortured us this week moves downstream and a broad upper-level trough gradually moves overthe western US. By 0000 UTC 16 June (6 PM MDT Saturday), northern Utah is in southwesterly flow aloft and in the leading edge of cooler air.   That cooler air gradually bleeds in until Monday when an even stronger trough and surge of bonafide cold air push into the state.   The NWS forecast nicely shows the high temperatures for the airport dropping each day from yesterday's 100 to today's 95, Saturday's 89, Sunday's 83, Monday's 79, and Tuesdays 70.  The trend is our friend. If you extrapolate that forward, winter will be here later this month! Sadly that's not the case, but I am looking forward to the cooler air.  Tuesday mig...

There has been a lot of talk about hitting 100 today or tomorrow.  As I type this, the National Weather Service Forecast National Blend of Models, which forecasts a distribution of max temperatures based on forecasts from many modeling systems, is producing a median forecast of 99°F for the airport today.  The middle 50% of forecasts, also known and the interquartile range, is between 98°F and 100°F.   Source: https://hwp-viz.gsd.esrl.noaa.gov/wave1d/?location=KSLC One way to interpret that is that it is more likely than not we'll be at 99 or a bit lower, but the odds of 100 or a bit higher are roughly 25% (I'd need access to higher precision data to provide a more detailed estimate). Tomorrow, the numbers edge up slightly, with 100°F being the median forecast, so we'll call it 50/50 for tomorrow.  Source: https://hwp-viz.gsd.esrl.noaa.gov/wave1d/?location=KSLC Is this unusual?  Yes.  Since record keeping began in 1874, there have been 10 days wit...

I was recently asked about the large difference in snowfall this past season reported by Alta Guard and Alta Ski Area and thought I would take this opportunity to talk about why they might differ and some of the challenges of observing new snow amounts.   The Utah Avalanche Center provides a long record of snowfall at Alta Guard at https://utahavalanchecenter.org/alta-monthly-snowfall.  For this past season (November through April), their spreadsheet reports only 432 inches. In contrast, for the same period, Alta Ski Area reported 606.5" (see  https://www.alta.com/weather ..note that I've subtracted 21.5" that fell in October from their seasonal total through April).  I am often asked how can there be such a large difference since they are "right across the street from each other."  Actually, the observing sites are not right across the street from each other.  The Alta-Guard observing site is located just on the north side of SR-210 just down can...

The Avenues foothills (and perhaps other areas long the benches, seem remarkably lush and green for early June.  Yesterday evening I did my first hike since returning from Scotland and was blown away by the vegetation.   It's not unusual for the foothills to green up in the spring and for there to be wildflowers.  Often by the start of June, things are browning up, but the emerald foothills are hanging on this year.  Additionally, the coverage and height of the grasses and other vegetation in many areas seems exceptional, in some areas reaching or exceeding the height of my treking poles, which were set to 120 cm (48 inches).   These are purely anecdotal observations.  I'd be curious to hear other perspectives.  One thing is for sure, things will be browning and crisping up more rapidly in the coming days as we move into hotter drier weather.