Friday, June 30, 2017

Combustible Fourth of July Weekend Forecast

With the Fourth of July next Tuesday, we have a holiday weekend on tap.  My forecast for the weekend can be summarized in one word.  Combustible.

The Brian Head fire gets everyone's attention, but both lightning- and human-sparked fires have been quick to flare up across the state.  Despite a good snow season, fire danger is rated as moderate to high across northern Utah and very high to extreme across southern Utah.

Source: USFS Wild Fire Assessment System
Precipitation has been scant across the state for several weeks, with 50% or less of average falling across much of the state over the past 60 days.

Source: NOAA/NWS
The past 60 days have also been unusually warm.  For example, the period from 29 April through 29 June is the 2nd warmest on record at the Salt Lake City International Airport (ignore the first year in the graph below as it contains several missing days).

Source: NOAA Regional Climate Centers
This has led to tinderbox conditions across most of Utah, with energy release component indexes, a measure of how hot a fire could burn, remarkably high across southern Utah and well above median across most of the rest of the state.  

Now, lets turn to the forecast.  After a refreshing night last night, we're moving into nuclear summer for the weekend.  Forecast highs for the Salt Lake International Airport are in the mid to high 90s.

Source: NWS
St. George?  Triple digits.

Source: NWS
Basically, we are in the Venn diagram overlap region of dangerous fire conditions, hot weather, and a fireworks laden holiday.  If you are wondering, information on fireworks restrictions for Salt Lake County is available here and for the state here.   

Wednesday, June 28, 2017

GOES-16 Rocks!

GOES-16, previously called GOES-R, is a remarkable next-generation satellite that was launched in November.  Although not "official" yet, it has been providing remarkable imagery for several months.
GOES is short for Geostationary Operational Environmental Satellite.  Geostationary means that the satellite is in an orbit in which it remains over the same point on the equator, allowing it to repeatedly sample roughly one half of the Earth at all times.  GOES-16 offers several major advances over previous US geostationary satellites including higher spatial resolution (0.5 km for the 0.64 um visible channel, 1 km for other visible channels, and 2 km for longer wavelength channels), which equates to approximately four times as many pixels, more frequent images (every 5 minutes over the continental US and as often as 30-60 seconds over selected regions), and 16 spectral "bands."  Previous GOES satellites sampled only 5 spectral bands.  The increased number of bands will allow for a remarkable advance in the quality of the imagery and the detection of critical weather and environmental phenomenon.

A nifty site for playing around with GOES-16 imagery and animation is the Cooperative Institute for Research in the Atmosphere's SLIDER.  You can access imagery from both GOES-16 and the comparably equipped Japanes Himawari-8 satellite on this site.

Below is the GeoColor image from 1817 UTC (1217 MDT) this afternoon (click to enlarge).  This is a truly spectacular product, leveraging the GOES-16 capabilities to provide remarkable images far beyond the old black and white imagery of the past.  I've highlighted a few features including the Brian Head fire smoke plume, standing water on the salt flats, and the lava flows in Craters of the Moon National Monument.

Everything points to GOES-16 being a revolutionary advance for weather prediction.  We will make extensive use of it in future posts.

Tuesday, June 27, 2017

Smoke for the Morning Commute and Antecedent Meteorology of Brian Head Fire

An addendum has been added to the end of this post concerning uncertainty about the source of the smoke or dust over the Salt Lake Valley this morning.  

A smoky sunrise in the Avenues
A weak trough passage last night has brought smoke into the Salt Lake Valley, along with a little lake stink.

As far as troughs go, this one was about as weak as it gets and barely put a dent in the near-surface flow.  The trough is, however, more easily seen in upper air (700mb, about crest level) analyses, with the pronounced wind shift moving across the Salt Lake Valley early this morning.

Thus, the smoke is not from the Brian Head fire, but more likely originates from one of the large incidents to our west and northwest over Nevada and Idaho.

Speaking of the Brian Head fire, lets take a few moments to talk a little bit about the meteorology leading up to the event, motivated in part by comments concerning yesterday's post.

Snowfall last winter was impressive in the Brian Head area, leading to an above-median peak snowpack.  However, the ensuing meteorology of the spring has led to very high to extreme fire danger over the region.  

To illustrate this, I've pulled data from two nearby SNOTELs at Midway Valley (9826 ft) and Webster Flat (9158 ft).  There are other SNOTELs in the area, but these had good data coverage and a long-term median.  

Both show a peak snowpack water equivalent well above median.  There are really two major snowpack peaks at each site, one in early March, the other in early April, although the primary maximum is in early March at Webster Flat and early April at Midway Valley.  

Source: CBRFC 

Although the snowpack at both sites was well above median, each site lost significant snowpack during the March heat wave that affected much of Utah and Colorado (dashing Spring Break powder skiing hopes).  Snowfall melt rates after mid April were also quite high.  As a result, the last day of measurable snowcover at Midway Valley was near median (late May) and at Webster Flat was about a week earlier than median.

Long-term observations from sites at high elevations around Bryan Head are somewhat scarce, but the time series from Bryce Canyon below shows that the period from March 10 to June 25th rated as the 2nd warmest on record since 1960.  

NOAA Regional Climate Centers
There are, however, some missing days at that site.  Alternatively, we could look at Cedar City, which is geographically closer, but also much lower.  There, temperatures for the period rate as the 16th warmest on record since 1949.  

Source: NOAA Regional Climate Centers
Finally, we can look at precipitation and see that over the last 90 days, precipitation in the region was 50-100% of average depending on what pixel you choose from Cedar City to Brian Head.

It has been especially dry over the past month or so.  There has been no measurable precipitation in Cedar City since May 16 or at Bryce Canyon since May 11.  

So, despite a fat snowpack in March and early April at upper elevations, snowmelt this spring was rapid, temperatures were above average, and precipitation was scant.  This has contributed to fire danger in the region that sits today over southwest Utah in the very high to extreme categories.  

Bottom line: Warm Dry Spring 1, Fat Snowpack 0.

Addendum at 9 AM MDT:

Spectacular GOES-16 imagery from CIRA leaves me scratching my head about the source of the smoke (or maybe dust) over the Salt Lake Valley this morning.

Addendum at 9:25 AM:

NWS suspects smoke source is fire near Snowville.

Monday, June 26, 2017

Brian Head Fire Satellite Imagery

As of yesterday, the Brian Head in southern Utah was the 8th largest fire in the state since 2003.

The National Interagency Fire Center reports that the fire started approximately 12:13 PM on Saturday June 17th and that the cause is still under investigation.  Their situation report issued at 5:30 MDT this morning reports a size of 42,800 acres, with 1,140 personnel working on the fire, plus 11 helicopters.  Twenty six structures have been lost.

Images below are provided by the MODIS imager on NASA's TERRA satellite, which flies over the area in the early afternoon each day.  One can see a smoke plume, likely associated with the nascent fire, on 17 June.  Media reports suggest that increased wind from the southwest winds caused the fire to jump a line on the evening of the 20th, after which the fire grew rapidly.  An impressive smoke plume is evident on subsequent days.

15 June
17 June
18 June
20 June
22 June
24 June
If you click on the image for the 22nd of June, you can see the top of a distinct pyrocumulus cloud, a cumulus cloud produced by the release of both heat and moisture into the atmosphere by the fire.

Apparently some progress was made by firefighters yesterday, but today looks challenging, with above average temperatures and increasing southwesterly flow.  The NAM forecast for 0000 UTC (1800 MDT) this afternoon shows 700-mb (10,000 ft) temperatures above 16ºC, which is probably 3-5ºC above average, and moderate southwesterly flow in advance of a trough over central Nevada.

The expected outlook this morning states that "in the next 24 hrs could have active crown fire along northern flank with the return of the southerly winds. Potential spread distance 2-3 miles."

More info is at

Thursday, June 22, 2017

Icelandic Meteorology and Scenery

Greetings from Reykjavik.  I am on a 2-week trip to Iceland involving a week of vacation to drive and hike around the Ring Road, which encircles the island, and attend the International Conference on Alpine Meteorology.  I return to Salt Lake and the blistering heat of the American Southwest on Saturday.  Over the past 12 days, I haven't seen a temperature above 15ºC (59ºF).  Wonderful!

Iceland is a spectacular country and a great place for a meteorologists (and geologists).  Think of it as a larger, lower version of Hawaii, with colder, windier weather, ice caps and glaciers, and bigger rivers and waterfalls.  The island is pretty much entirely volcanic.  There are few trees.  It lies near the Atlantic storm track, at the intersection of the Arctic and Atlantic Oceans, near the Arctic Ice Cap (for now) and east of Greenland Ice Sheet.  Volcanic eruptions, sometimes violent due to the presence of ice and water, are frequent, as are volcanic dust storms.  What a place for meteorological mischief!
Moisture transport to Iceland is typically strongest and most frequent from the northeast through southwest and least frequent from the northwest.

Source: Crochet et al. (2007)
As a result, precipitation is greatest in higher elevation areas along the south and southeast coast, including the Myrdalsjokull and Vetnajokull ice caps, and in the mountains of the East Fjords.  Lowland areas on the norther side of the island, which lie downstream of high terrain during SW, S, SE, and E flow, are drier.
Source: Icelandic Meteorological Office (site locations annotated by the author)
The Iceland Met Office provides avalanche forecasts for the East Fjords, Trollaskagi (Troll Peninsula), and West Fjords.  Although precipitation is more limited, I found the mountains surrounding the Eyjafjörður Fjord near and north of Akureyri to be alluring.

Mountains along the Ring Road east of Akureyri 
East side of the Troll Peninsula
Snow fences above the town of Siglufjörður
Mountains on the west side of the Troll Peninsula
No skiing was done on this trip, but perhaps in the future.

A cultural highlight of the trip was meeting the President of Iceland Guðni Jóhannesson.

He gave a great speech for all the attendees of our meeting, who he hosted at a residence outside of Reykjavik.  Iceland sets quite an example for the rest of the world in areas such as standard of living, gender equality, and green power.  In the case of the latter, Iceland's electricity comes almost entirely from hydroelectric and geothermal sources. We were told by one of our hosts to "turn up the heat as much as we want because energy is cheap in Iceland."  

Iceland is a great place to visit for cultural reasons as the people here are remarkably friendly.  Given the massive surge in tourism over the past few years, one could understand if the locals were somewhat jaded toward tourists, but we've detected nothing of the sort.  The sole negative of a visit is that Icleand very expensive.  Peanut butter and jelly and stops at coffee shops with all you can eat fish soup and bread have proven to be essential for dietary sustenance.  Avoiding hotels and staying in less expensive guest houses has allowed us to make new friends and learn a lot about Icelandic culture.

A visual tour of a few highlights is provided below, courtesy of my cheap point-and-shoot camera.



Black sand beach

Fjaðrárgljúfur canyon
No idea what the name of this one is.  These things are everywhere.
Icelandic glacier scene

Beautiful basalt columns are common in Iceland
Ski area near Neskaupstadur in the East Fjords.  Too foggy for a real photo!

Approaching Hengifoss 
Drier region on northern half of Iceland east of Lake Myvatn

Dettifoss from the east side.  You can practically put your toe in on this side (I didn't).
Dettifoss from the west
Kayakers below Godafoss
Below Godafoss (not me)

Snaefellsnes Peninsula
Iceland slot canyon

A rare "white" sand beach

Beer brewed with whale testicles at the Stedji Brewery.  When in Rome....