The HRRR Has Arrived

I'm pleased to announce that forecasts from the 3-km High Resolution Rapid Refresh (HRRR) are now available on weather.utah.edu.  Here's the 6-hour forecast valid at 0000 UTC (1800 MDT) this afternoon.  No showers or thunderstorms in the Salt Lake Valley.  Apply the sunblock liberally!

The HRRR is the highest-resolution operational model run by the National Weather Service.  Employing radar and other data assimilation wizardry, it produces 15-hour short-range forecasts every hour.  For now, I'm downloading a subset of HRRR output for the western United States and providing a couple of surface diagnostic loops, one that includes 10-meter winds and model-derived radar reflectivity, the other that includes 10-meter winds and 1-hour accumulated precipitation.  The loops on weather.utah.edu also include analysis frames going back into the past as knowledge of the past is always handy for predicting the future.

More information on the HRRR is available here.  It should be handy for ski forecasting this coming winter.

May Was Wet, But Summer Aridity Starts Today

The National Centers for Environmental Information (formerly the National Climatic Data Center) has released the Utah climate data for May.  It was a wet one.  On a statewide basis, it ranks as the 2nd wettest with a total of 3.03", behind only 1995, which recorded 3.06".

For all intents and purposes, the two years plus 1898 (2.97") are essentially indistinguishable given the sparseness, quality, and uncertainties of the precipitation observations.  Basically, it was really wet, but you didn't need a meteorologist to tell you that.

In fact, it was so wet that the January-May precipitation is now a touch above average, despite the tremendous precipitation deficits observed from January-March.

For the October-May water year, however, we're still below average.

We were granted one final burst of thunderstorms yesterday, which was quite enjoyable, but all that rain is in the rearview now.  Summer aridity starts today.

The Summer Bake Begins

We have a slight chance of a thunderstorm later today and if we get it, be thankful.  The summer bake begins tomorrow.  The GFS time-height section for Salt Lake City International Airport shows bone dry conditions for the next week after midnight tonight.  Temperatures will be at or above seasonal averages during the period.  

The mountains were spectacularly green and lush this past weekend.  Get out and enjoy before everything dries out. 

El Niño Likely for the 2015-16 Winter

The National Weather Service Climate Prediction Center issued their latest El Niño/Southern Oscillation (ENSO) Diagnostic Discussion yesterday went mostly (but not quite all) in for El Niño to reign for the rest of the year and through the 2015-16 winter.

There is a greater than 90% chance that El Niño will continue through Northern Hemisphere fall 2015, and around an 85% chance it will last through the 2015-16 winter. - NOAA/NWS/CPC ENSO Diagnostic Discussion, 11 June 2015

An ongoing and strengthening El Niño is already in place over the equatorial Pacific Ocean.  Anomalously warm sea surface temperatures extend from the coast of South America across the Pacific to the dateline.

Source: CPC

Most of the climate models call for El Niño to strengthen over the next few months.  The plot below shows their projected sea surface temperature anomalies in the tropical Pacific from 120–150W and most are calling for strenthening anomalies through the fall, persisting into winter.  Some are calling for a strong El Niño., although there are a few that go for moderate to weak.

Source: CPC

All of this sounds exciting, but for the central Wasatch, there's very little correlation between El Niño and snowfall.  The graph below shows the relationship between 3-month snowfall and an index of El Niño/La Niña strength.  Nothing really to bank on here.

Three month (NDJ, DJF, JFM, FMA) accumulated snowfall at Alta–Guard vs. the corresponding ONI (labeled ENSO index). 
Courtesy Jeff Massey.

For the southwest, however, El Niño loads the dice for a wetter than normal winter, for the northwest, warmer than normal (and drier in the interior, but not necessarily the Cascades, although the warm temps often cause problems there for snowfall at temperature sensitive elevations during El Niño due to a greater fraction of precipitation falling as rain), as reflected in the seasonal outlooks produced by the CPC for Dec–Feb.

Source: CPC

Source: CPC

Personally, I hope a strong El Niño comes through.  The southwest could use some action and an active southern branch of the jet will give me some new blogging material next winter.

Salt Lake Skunkage

Much of Utah saw shower and thunderstorm activity yesterday, but the Salt Lake Valley was largely skunked except for a brief shower that affected the west valley during the late afternoon.  Rainfall totals yesterday included 1.44" at Joe's Valley Reservoir and 1.26" at Bryce Canyon airport.  Some strong winds were found near storms, including a gust of 70 mph on Flattop Mountain in the northern San Rafael Swell area and 69 mph at Laketown near Bear Lake.

The HRRR forecast through 8 PM tonight shows a very active day in central, southern, and northeast Utah, but less activity over northwest Utah.  The Salt Lake Valley is on the fringes of activity.  We'll have to hope we get something so I can keep my sprinkler-free spring going.

The NWS has a flash flood watch out for southern Utah through this evening.

Source: NWS

Warnings were issued last night for a number of drainages and slot canyons, including Spooky and Peakaboo, two of my favorites.  If the remains of the cow that got lodged in the latter during winter haven't already been removed, hopefully Mother Nature did the job last night.

Blanca Pays a Visit

Former Hurricane Blanca is "spreading her ashes" over the southwest U.S. this week, with help from a weak upper-level trough camped off the California coast.

Some interesting tidbits from this event so far:

• Several stations in SoCal reported measurable precipitation yesterday, including 0.30" at the Santa Barbara airport.  Average rainfall for the month at that location is 0.07".   They are now covered for the next four Junes.

• The dewpoint at the Boulder City municipal airport in southern Nevada peaked at 61ºF this morning and currently sits at a still muggy (by Nevada standards) 59ºF.  No word on if Las Vegas is considering extracting moisture from the atmosphere to meet future water needs...

Source: MesoWest

• But it's a dry heat in Arizona right?  Peak dewpoints so far for include 72ºF in Yuma, 70ºF at Buckey municipal airport west of Phoenix, 67ºF at Sky Harbor airport in Phoenix, and 73ºF at Tucson Ryan Field.  Steamy!

• Although it is not uncommon to find high integrated water vapor levels (a.k.a., precipitable water) over the southwest during the monsoon, the value measured yesterday afternoon at Tucson (1.62", black square below) appears to be the highest in the measurement record so early in the season. 

Climatology source: NOAA/SPC

Blanca began to spread her ashes over Utah last night and there's a good chance of showers and thunderstorms statewide today.  Time will tell if she decides to leave a deposit at your place.  

Addendum @ 12:45 PM:

I just noticed on the Madweather blog that the integrated water vapor yesterday morning in Tucson was even higher than it was yesterday afternoon (latter plotted above).