For the Southwest, It's Not Just Bud

As of 9 AM this morning, tropical cyclone Bud was a Category 3 hurricane located about 525 km south southeast of Cabo San Lucas and the southern tip of Baja California.

Bud is getting a lot of attention for a number of reasons.  First, it is likely it will weaken, but remain a tropical storm as it approaches Baja California on Thursday.  Second, it will bring of surge of moisture that will cause heavy rainfall in parts of Mexico, with the remnants moving downstream, perhaps bringing some rain to parched areas of the southwest U.S.

It is important, however, not to fixate solely on Bud, as there's important stuff going on ahead of the main circulation center.  In particular, note in the loop below the surge of moisture pushing northward through the Gulf of California and northwest Mexico ahead of Bud.

This will lead to an increase in thunderstorm potential on Friday in Arizona before the remnant core of Bud reaches the state.  Such an evolution is common for tropical cyclones moving through this part of the world.

Meanwhile, in Utah, the forecast is quite interesting.  We discussed in the previous post that this forecast is characterized by a three-body problem, namely the interaction between Bud, a short-wave trough off the coast of California, and a short-wave trough digging southward over the Pacific Northwest.  In the 84-hour GFS forecast valid 0000 UTC 16 June (5 PM Friday) and plotted below, I've also highlighted three airstreams.  The first is northerly flow up the lower Colorado River Valley associated with the moisture surge.  The second is a much drier southwesterly flow originating over the eastern Pacific and California.  The third is a slightly more humid westerly flow over Nevada and Oregon of North Pacific origin.

Ultimately, all these ingredients create a complex situation on Saturday in which eastern Utah is in the tropical moisture with showers and thunderstorms, portions of west-central and northern Utah including Salt Lake City may be in the "dry slot" created by the dry flow originating over the eastern Pacific and California, and far northern Utah, southern Idaho, and far northern Nevada have just enough north Pacific moisture and forcing from the digging upper-level trough to kick off some showers.

By 1200 UTC (0600 MDT) Sunday, the tropical moisture is declining, but lingering just a touch over eastern Utah, but western Utah and Salt Lake City is in the heart of the southwesterly flow and the associated dry slot.  Showers have associated with the upper level trough have pushed northward.

If you have outdoor plans this weekend, this is a forecast worth monitoring.  There will certainly be times to get in activities, but others during which you could be dealing with thunderstorms, showers, or strong winds depending on time, location, and how all the ingredients come together.  Geographic precision is not possible yet at this lead time.  Clearly, this is a situation that is not well summarized by the icon-based forecasts issued by the local news.

Forecasting Bud Is a "Three Body" Problem

Tropical Cyclone Bud is currently a category 3 hurricane lurking off the Pacific coast of Mexico west of Acapulco.

Source: National Hurricane Center

Interest in this storm is quite high in the southwest U.S., which was extremely dry this past winter, with the four-corners region in the grips of exceptional drought. 

Source: The National Drought Mitigation Center

The situation is so bad that the US Forest Service has plans to close the entire San Juan National Forest to most public entry this week due to wildfire concerns (for more, see this westernslopenow.com article).  

There's no quick fix for exceptional drought, but some models are suggesting that moisture from Bud will stream into the four-corners region late Friday and over the weekend.  Below, for example, is the GFS forecast valid 1200 UTC (0600 MDT) Saturday, showing high numidity and precipitation across southeast Utah, western Colorado, eastern Arizona, and western New Mexico.  

How this all shakes out, and whether or not the southwest will be drinking Bud or Bud Light, will depend on the interaction between three major atmospheric features, identified below in the GFS 102 hour forecast valid 1800 UTC (Noon MDT) Friday.  Think of this as an atmospheric equivalent of the three body problem. 

The first is Bud, the remnants of which are expected to be over southern Baja California noon Friday, with moisture streaming northward.  The second is a short-wave trough over southern California.  The third is a stronger upper-level trough expected to be over the Pacific Northwest.  The interplay between these three features will largely determine the track of Bud and the pathway of moisture into the southwest.

Of course, Colorado has plenty of Bud as it is, so it would be nice if this tropical moisture could find its way to Utah.  

Grandview Peak

One of my goals for this summer is to spend some time hiking in less visited parts of the Wasatch Range outside of the Cottonwoods.

With the cool change arriving on schedule, today was a perfect day to go for a mid-elevation summit in the northern Wasatch.  We elected to bag Grandview Peak, which is the highest point above City Creek Canyon and the most prominent summit between Francis Peak and Murdock Peak, yet seldom visited.

There are a number of potential routes to the summit including from Big Mountain Pass via the Great Western Trail, biking up City Creek and trying to get to it via City Creek Canyon, and from Bountiful to Mueller Park, and then up the ridge above Rudy's Flat.  All of these looked very long and painful.  As such we drove up Skyline Drive out of Bountiful and then Forest Service Road 815, which heads southward along the Wasatch Crest.  We elected to stop just short of the Pipeline Crossing at around 8400 feet, but probably could have pushed my CRV another mile if we were feeling more sporty.  A quick note that the Skyline Drive out of Bountiful is considered passable for passenger cars, but it is in pretty poor shape right now.

After walking along the Forest Service Road and then the jeep trail, one gets to the single-track section of the Great Western Trail in Upper Holbrook Canyon.  Ascending out of Holbrook Canyon takes you through some beautiful forest, including this aspen grove.

I've heard rumors that this part of the Wasatch is pretty snowy for it's elevation.  Snow was scant today, but we found a few patches.

Eventually, one reaches a 9000 foot pass in the Sessions Mountains.  At this point you get your first glimpse of Grandview Peak, with the central Wasatch in the distance.

To get to Grandview, one does a long circumbobulation near the crest of the Sessions.  This is beautiful terrain, somewhat reminiscent of the Wasatch Crest Trail, but without bicycles and people.  We saw only 2 people all day once on the single track Great Western Trail, which in some places is really just a herd path.

Getting to Grandview requires southwestward jaunt off the Great Western Trail near the divide between Mill Creek and City Creek.  We didn't have much trouble finding it, but the trail up Grandview fades in and out.  The general route is, however, fairly easy to follow.

The summit is at 9410 feet and provides great views in all directions.  The view below is looking down upper Cottonwood Gulch and then City Creek Canyon.  In winter and spring, this gulch holds the prominent snowfield that looks so inviting from downtown Salt Lake City.

Here's the view toward the central Wasatch, showing quite nicely the high terrain surrounding the Cottonwoods and the decline in height as one moves eastward toward Park City.  An odd aspect of the central Wasatch is that the highest terrain is not on the hydrologic divide, but instead west of it, and this is important for understanding the distribution of snowfall.  I kept wondering how cool it would be to operate a scanning radar from this location (not that I'd deface the summit to do that).

A few more views on the hike out of the northern Wasatch, the Sessions Mountains, and the Oquirrh and Stansbury Mountains down Mill Creek Canyon (how many Mill Creeks and Twin Peaks are there in this mountain range?).  

According to my phone, total distance round trip from our starting point was about 12.5 miles.  A medium duty vehicle is probably needed to get to that point.  You could shorten it a bit if you push it farther, have a higher clearance vehicle, or opt to mountain bike the first part of the route.  

The Kilauea Eruption

"Civilization exists by geological consent, subject to change without notice."

- Will Durant

The quote above is one that I think of regularly and is perhaps the most important to remember if you work at all in areas related to natural (or in some cases "unnatural") disasters.

During December 2015, we did something highly unusual for someone who's twitter handle is Professor Powder, and took the family to Hawaii for the holidays.  Really, the holiday season is a good time to get the hell out of Dodge, as even if it snows, the crowds in the canyons are quite overwhelming.

For the most part, I disdain the tropics, but I have a soft spot for Hawaii.  You may see it as a tropical paradise, but I see it as a meteorological paradise.  The topographic, precipitation, and ecological contrasts are incredible, especially for a mountain meteorologist.  

The Kilauea Volcano is embedded in the Hawaii Volcanoes National Park, certainly one of the most fascinating parks in our incredible National Park system.  In 2015, Kilauea was fairly quiet.  A bit of smoke from the crater, with a lava glow visible only at night.  

That has all changed in the past few weeks, as lava flows have devoured neighborhoods in southeast Hawaii.  

As can be seen above, lava from this most recent episode as covered portions of the Leilani Estates, with flows pushing to Kapoho Bay and the coastline just east of MacKenzie State Recreation Area.

This was an area that we visited during the trip.  I recall walking to the Kapoho Tide pools through some beautiful neighborhoods that are now likely gone.  I'm not sure if the tide pools pictured below have been overtaken by this latest lava flow, but I suspect that they have.  

One can argue that southeast Hawaii is an especially vulnerable area, but many of us live in areas where geologic or meteorological hazards can disrupt our homes and lives.  My thoughts go out to the displaced residents of the area.

On the other hand, I think a lot about meteorological hazards and what we will be facing in the future.  I often tell people that our society is not adapted to the climate of the 20th century, let alone the climate of the 21st century.  Water is the agent that delivers many meteorological impacts and the evidence tells us that extreme precipitation events are and will become more intense and frequent and coastlines will become more vulnerable to sea level rise.   Even in the absence of climate change, growth in development in vulnerable areas, such as coastlines, has greatly increased our exposure to flooding and storm surge.  As concluded in a recent paper by Phil Klotzbach in the Bulletin of the American Meteorological Society, 

"Unfortunately, the risks associated with more people and vulnerable exposure came to fruition in Texas and Florida during the 2017 season following the landfalls of hurricanes Harvey and Irma. Total economic damage from those two storms exceeded $125 billion. Growth in coastal population and exposure is likely to continue in the future, and when hurricane landfalls do occur, this will likely lead to greater damage costs than previously seen."

So, to paraphrase Will Durant, "Civilization exists by geological AND meteorological consent, subject to change without notice."   We have a long ways to go to decrease our exposure and increase our resliliency to natural hazards.  

Cool Change This Weekend

Cool change is an Australian term for cold frontal passages in which hot, dry, northerly flow is replaced by cooler southwesterly flow from the Southern Ocean.  Those long in the tooth may remember the hit song Cool Change, by the Melbourne-based Little River Band, written by Glenn Shorrock, which was released in 1979 and is considered one of the top 30 Australian songs of all time by the Australasian Performing Right Association.



The stuff you can find on Wikipedia!

Utah will have it's own cool change this weekend as the hot, southerly to southwesterly from the American southwest are replaced by westerly to northwesterly flow originating over the Pacific Ocean.  I am counting the minutes!

The NWS forecast calls for above average temperatures to predominate through Saturday, with high temperatures for today, Friday, and Saturday, of 93˚F, 91˚F, and 97˚F, respectively.  The GFS forecast for 6 PM MDT Saturday (0000 UTC 10 June) shows hot, continental, southwesterly flow across Utah.  However, it also shows an approaching cold front over central and eastern Nevada, with a 22˚C 700-mb temperature contrast from central Utah to northern California.

By midnight MDT (0600 MDT 10 June), the cold front and the start of the cool change is forecast to be moving across northern Utah.

And, but noon MDT sunday (1800 UTC 10 June), we are solidly in the post-frontal airmass and 700-mb temperatures have dropped to just below 0˚C.  Splendid!

The GFS time height section shows the situation, with a very well defined cold front moving across the Salt Lake City International Airport just after 0600 UTC Sunday.  The front is predominantly dry and will probably produce no precipitation, but it could produce a few low clouds over the mountains.

There is some uncertainty in the precise timing of the front, but a weekend in which Saturday is a scorcher and Sunday is much cooler looks to be a lock.  Enjoy the cool change.

Rapid Snowmelt to Our North

The snowpack was phat this year in northwest Wyoming and western Montana, but the melt this spring has been rapid.  Here are a few examples.

The Grand Targhee SNOTEL peaked at about 55 inches of snowpack water equivalent, which was above median, but the melt has been rapid and the site now sits below median for the period of record. 

Source: NRCS

At the Fisher Creek SNOTEL near Cooke City, Montana, the snowpack water equivalent nearly reached 60 inches, well above median.  The early and rapid snowmelt, however, has caused the snowpack to begin to converge on the median.  It now sits at 36.4 inches, compared to a median of 29.7.  

Source: NRCS

Despite the phat end of season snowpack, the end of snow cover at that site will probably be near median.  

Finally, there is Mount Lockhart in the Lewis Range east of Kalispell.  Mount Lockhart is on the eastern (drier) side of the range, with lower snowpack water equivalents than found at Grand Targhee or Fisher Creek, but the peak near 30 inches was well above median.  So much for that.  The rapid snowmelt has destroyed the snowpack and the end of snow cover at that site looks like it will be very close to median.  

Source: NRCS

These are tough times for the cryosphere, but they are going to get tougher.