Wasatch Weather Weenies

Radar estimated precipitation from the NSSL MRMS shows the entire Wasatch Front got some precipitation over the past 72 hours.  Hooray! Source: MRMS It looks like pretty much everywhere from Utah County north and eastern Tooele County East got at least 0.15" and most areas got at least 0.50".  Heaviest amounts were to the north along the UT-ID border.  Last night, not only was it cooler and moister, but it smelled wonderful.  A much needed cleaning.   The airport got 0.10" on August 26 and 0.64 inches on August 27.  We'll use the former as one bookend and May 18th when the airport got 0.73" as the other.  Between those two days, the airport received only 0.35" of precipitation, the lowest on record between those dates.   Source: xmACIS2 No doubt it was an exceptionally dry 3+ month run.  In fact, there are only 12 years out of the 152 year record with < 1.00" of rain during that period.  Thanks goodness that streak is over, ...

Our excruciating wait for "real rain" is almost over.  The isolated showers and thunderstorms that have largely missed many portions of the Salt Lake Valley or provided only some paltry precipitation amounts are now in the past.  Today we will see more widespread showers and thunderstorms.   This morning's 1334 UTC (0734 MDT) radar imagery shows fairly widespread precipitatio over the south arm of the Great Salt Lake and Bear River Bay, as well as showers farther south in Utah County and southeast Tooele County. This morning's sounding is "juicy" with a surface dewpoint of 56 and 1.2 inches of precipitable water, which is the depth of water you would have if you condensed out all of the water vapor in the column.  Although not exceptional, it's fairly high.  The daily record for August 26 in the sounding climatology is 1.17", although we have seen values as high as  1.66" on August 14 and 1.43" on September 3.   Source: SPC Models like the...

There's been a few drops of rain around at times the past couple of days, and late yesterday morning those drops put .01" into the rain gauge at the Salt Lake City International Airport. That was the first day with measurable rain since the fourth of July, a 48 day streak, good for the 12th longest on record. Source: https://xmacis.rcc-acis.org/ I wish it didn't end with such a pathetic amount of rain.   There is one record, however, that continues, an that is the lack of rain over the past 3 months.  The period from May 24 to Aug 23 is the 2nd driest on record (.35"), behind only 1958 (.31").  If we go back to May 18, it's the driest on record.  There will be some isolated thunderstorms today, but shower chances will be on the increase tomorrow and remain elevated early next week.  Hopefully we will get some much needed, beneficial rain showers, without too much lightning or flooding.  

I spent today scouting observing sites for a major field campaign that we will be conducting in the northern Wasatch this coming winter involving two mobile weather radars and a whole ton of other goodies.  The high at the Salt Lake City airport hit 101 and it was plenty hot in Huntsville where we were scouting, but it looked like September as there are colors on display already.  I'm not sure how unusual this is, but in general it seems incredibly dry out there in non-irrigated areas and in many areas the foliage just seems to be giving up.  We have to hope we make it through the next few weeks without a major severe wildfire as it seems like everything is primed for explosive fire behavior if we were to get strong winds with a spark.   Back to our scouting.  The program we are planning is called SNOWSCAPE and it will focus on winter storms across the northern Wasatch with a focus on the region from roughly Francis Peak to Ben Lomond, including the Ogden ...

Although a few blessed locations got some measurable rain the past few days, the Salt Lake City International airport continues to be skunked and has gotten no measurable rain so far this month (through yesterday, August 16). If my calculations are correct, this brings our streak of days without measurable rain to 43, good for the 16th longest on record.   If we make it through tomorrow without measurable rain, it will be the driest May 19–Aug 18 period on record.  The current record is .35" in 1889.  We're at .34" currently.   That's a 91 day period and I've picked a length that is somewhat arbitrary, but if you are wondering, the driest 91 day period on record covered the 91 days through 12 November 1952.

You know you are desperate when you get excited about the shallow cumulus that are developing over the Salt Lake Valley today,  Below is a loop showing the development of these clouds looking south from the University of Utah through about 1450 MDT.  There's even some virga!  Those clouds are developing ahead of a weak upper-level trough that is near the Pacific Coast and a weak surface boundary that is in advance of the upper-level trough near the boarder of Idaho and Nevada/Utah.  The 2119 UTC radar image shows that area is producing stronger cells than the "cumulus patheticus" that we've had over the Salt Lake Valley so far today.   Source: NCAR/RAL Moisture will, however, be on the increase through Friday.  This is not a major monsoon surge, but we will see the coverage of clouds and possibility of thunderstorms and precipitation increasing.  Let's have a look at what the Rapid Refresh Forecast System (RRFS) ensemble does over the next few day...

As August airmasses go, this has been a good one.  Visibility today was really incredible.  It was crystal clear this morning on Mt. Baldy. For those of you with the desire for turns, there's still some snow covering the Timpanogos Rock Glacier. Sadly, our brief flirtation with cooler weather is almost over as heat returns this week.  Today's infographis from the NWS is as grating as it gets.  Blah. Source: NWS.  Downloaded 7:03 PM MDT Sunday 10 August 2025

A weak cold front has brought a bit of cooler weather to northern Utah today (Friday).  Today's high at the Salt Lake City International Airport was a pleasant 85 and it looks like we may stay below 90 through the weekend.  But will it ever rain?   I'm starting to wonder. The last measurable rain at the airport was on July 4.  That's a 35 day run.  The record is 63 days, so we have long ways to go to get to that, but the models are still advertising "nonsoon" conditions for the next 10 days.  That would get us to 45 days, which would tie us for the 14th longest streak on record.  If you are wondering, 51 puts us in the top 10. Also of interest, this year we also had a 34 day streak that ended on June 22nd.  That streak began on May 19.  On May 18, we had a soaker, with 0.73" of rain.  Since then we've had 0.34", good for the 4th lowest on record out of 152 years for the period from May 19 to August 8. If we were to make it through A...

Late yesterday afternoon, strong winds associated with outflows from storms to the north brought a brief but intense lake-dust event to the Salt Lake Valley.  Satellite imagery showed this dust moving southward through the Salt Lake and Utah Valleys. Source: CIRA.  Loop also available at  https://col.st/80KK0 .  Take a close look at that look, especially the last few frames, and you can also see an area of dust moving off of the Farmington Bay playa and over the south arm of the Great Salt Lake.  There's also evidence of dust from other sources to the west moving through the Skull, Tooele, and Rush Valleys. Winds at the University of Utah began to pick up at around 1835 MDT when increased to more than 9 mph with gusts to 12 mph.  The peak gust of 20 mph occurred at 1852.  This roughly bracketed a spike in PM2.5 concentrations to just over 8 ug/m3 from 1845-1850 UTC.  Source: Mesowest Although the PM2.5 concentrations were not very high, that measu...

Many people I have spoken to in recent days as commented that this July wasn't that bad temperature wise.  My impression is somewhat similar, but curiously, the numbers tell a more complex story.  With an average temperature of 82.9F at the Salt Lake City International Airport, July 2025 rates as the 12th warmest on record.  With records going back 152 years, that puts it solidly in the top 10% for July warmth.  Additionally, there is no July prior to July 2003 that was hotter.  This July was hotter than any July in the late 19th or entire 20th century.  So why didn't it seem so bad?  A few hypotheses.  For one, it was the coolest July in five years and July 2021, 2022, and 2023 are the three hottest on record, so this July was cooler compared to the recent past.   Second, although the average temperature is high, we did not see high temperature extremes.  There were no record highs set and we only hit 100 3 times.  On those da...