Sunday, September 17, 2017

September Snows

Friday's storm brought a bit of the white stuff to the upper-elevations of the Wasatch Range, providing a boost to the morale of skiers and a nice contrast to the comparatively green grassy slopes remaining in early September.

By and large, the pattern over the next several days is more October like than September like.  First, we have a quick moving trough that gives us a brush-by late Monday and Tuesday.  This isn't a very deep trough and it's a close call on the placement of precipitation, but it could bring some light snow accumulations to the high elevations.

Then we have a deeper trough with the attendant cold front currently progged to push through Thursday morning.  This one is far enough out that we should be cautious about reading into details too much, but its a cold system for September (-4ยบC at 700 mb/10,000 ft) and has some potential to give us a better coating than Friday's storm.

Then, the main upper-level trough and deep cold pocket swing through for next weekend.  Temperatures definitely more like mid October than mid September.

It's been a long time since we had a stretch of weather where things were biased on the cold side of average.  Enjoy!

Saturday, September 16, 2017

Snowbird's Hidden Peak Cam Is Awesome

Snowbird has done a complete upgrade of their web site and perhaps their web cams because they seem so much better than they were a couple of months ago.  The Hidden Peak Cam is amazing.  You can't do it justice with a screengrab, but this morning's is below showing the dusting of snow, but also the abrupt transition of visibility when one gets to the top of what I think is the smoke layer that moved in with the latest cold surge.

Source: Snowbird
This is a meteorological preference, but I'd like to see a time stamp on these images, but I suspect they don't want to spoil them.  There is an indication of how old the images are on the web site.

BTW, it is a bit convoluted how to find the full size images on Snowbird's web site.  The direct link is here.  High frequency animations would also be appreciated (hint hint).

Thursday, September 14, 2017

The Echo Chambers Are Giving Me a Headache

To all the pundits and activists out there acting like you are experts on extreme weather, hurricanes, and climate change, I have only one thing to say.


This is a remarkably complex and difficult subject and you people are running around acting like you have it all figured out.  And there's plenty of room for a beatdown of people on both the right and left of this issue.  Gosh, the articles I am reading and discussions I am seeing are so absolutely horrific and they are setting weather and climate science back decades.

To those on the left who are conflating weather and climate, take a deep breath and let the scientists do their work and figure this out.  Don't lose sight of the fact that the IPCC issued a comprehensive report on extreme weather and climate change in 2012 entitled "Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation."  Here's what they had to say:
"The uncertainties in the historical tropical cyclone records, the incomplete understanding of the physical mechanisms linking tropical cyclone metrics to climate change, and the degree of tropical cyclone variability provide only low confidence for the attribution of any detectable changes in tropical cyclone activity to anthropogenic influences."
"Attribution of single extreme events to anthropogenic climate change is challenging."
And this from the most recent IPCC assessment report, released in 2013.  See in particular the row for "Increases in intense tropical cyclone activity."
Source: IPCC AR5 Summary for Policy Makers
And for those of you on the right who have a smile on your face because of the above comments, wipe it off now.  Note that those statements pertain to cyclone activity.  We know that storm surge associated with tropical cyclones is worsening and will continue to worsen because of sea level rise.  And just because we can't say with confidence that global warming is having a detectable influence on tropical cyclones right now doesn't mean that (i) change isn't happening or (ii) that we won't see a clear trend in the future.  There are good reasons why we expect to see tropical cyclones become more intense and increase in destructive potential with global warming.  Finally, there are also good reasons to expect tropical cyclone precipitation rates to increase as well.  So quit hiding behind the natural variability and we've had storms like this before narrative as if that means we have nothing to worry about.

For those of you interested in a scientific summary of these issues, see Global Warming and Hurricanes on the GFDL web site.  

Ask and You Shall Receive

I know I should be talking about the changes underway in Utah's weather, but I'm still suffering from a case of Irma-itis, amongst other maladies.   So, instead, I want to address some questions being asked by our readers about Irma's track shift.

I am neither a theoretician, nor a hurricane expert, so let me just come out and say it.  I don't understand hurricane dynamics well enough to answer these questions in what I consider a satisfying way.

On the other hand, sometimes it's not worth thinking too much about these things.

The ability to for numerical weather prediction systems (hereafter computer models) to predict the shift in Irma's track reflects the culmination of decades of research not just in atmospheric sciences, but also computer science, remote sensing, and other fields.

A human, even with all the incredible observations we have today, could never have anticipated that shift with such precision days in advance without computer models.  The problem with the way that humans think is that we have to simplify and categorize things.  We need to take shortcuts.  We rely on analogs to past events.  We tend to think linearly, whereas the atmosphere is nonlinear and doesn't always behave in straightforward ways.

In contrast, computer models are not constrained by excessive simplifications, past analogs, or linear thinking. They solve a set of equations based on the conservation of momentum, conservation of mass, conservation of energy, and ideal gas law.  In other words, the laws of physics, and those laws are a beautiful thing.  

Of course, since we are doing this on a computer, some approximations are needed.  In addition, we are limited by computer time and this means we can't directly simulate every physical process.   Nevertheless, a model based on the laws of physics can do things we might not anticipate as humans.  It can predict events that have never happened before.  It does not rely on simplistic, linear thinking, like most humans do.

Our computer modeling capabilities have improved steadily and dramatically since they were first developed circa 1950.  First, we have made huge advances in how we create "initial conditions" for these models, through the development of improved observing systems (especially satellite based) and new techniques for bringing all of that data together into an analysis.  We have been able to add more detail to the simulation (called "resolution"), resulting in the improved simulation of physical processes that influence hurricane intensity and track.  We have developed ensemble modeling systems that produce many forecasts to try to account for the chaotic nature of the atmosphere so that we recognize the uncertainties in the forecast.

So, where does this leave us?  The bottom line is this.  Computer models today largely show us the way.  Yes, there are some phenomenon we struggle with mightily (snowfall in the Wasatch for example) and you can bet there will be a future hurricane that is not as well forecast as Harvey or Irma.  However, no human can integrate the laws of physics in their head.  Meteorologists aren't spending a lot of time on "why," but instead the "what", as in what are the possibilities, what are the hazards and impacts, what are the uncertainties.  Then there is the issue of communicating all of this complexity to the public and decision makers.  It's an end to end process that is imperfect, but the good news, it's getting better and I think there is every reason to be very optimistic that it will get even better in the future.  

Tuesday, September 12, 2017

More Not So Deep Thoughts on Irma Plus Utah Weather

I'm still feeling frisky this morning about several issues, so the not so deep thoughts continue.

Anderson Cooper is clueless
With Irma still threatening the southeast, I continue to scan the news coverage and find appalling statements.  Anderson Cooper has been especially effective at getting under the nerves of this meteorologist.

Last night, while interviewing the Mayor of Jacksonville, which was hit with severe flooding yesterday, he made the dumbfounding statement that "clearly people were caught off guard."  No Anderson, people in mandatory evacuation zones were not caught off guard. 

Social media and other communications challenges
It's been clear in the snippets that I've caught of Anderson that he really likes the caught off guard/surprise narrative.  This is very common amongst reporters because people love that angle.  It makes the story more interesting.

Anderson has frequently brought up the "westward shift" of Irma and how it surprised people.  As a meteorologist, I find this to be grating as well, but in contrast to saying people in mandatory evacuation zones were caught off guard, this has some merit, depending on where you get your weather information from.

Official forecasts from the National Hurricane Center were very cautious not to endorse a specific storm track up either the east or west coast of Florida at long lead time.  They also issued hurricane and storm surge warnings on both coasts, as well as the south coast and Key West.

However, many people do not see those forecasts.  Instead, they see national news, local news, and social media.  In that echo chamber, there is a tendency to gravitate toward especially extreme model forecasts and clusters of model ensembles that do not fully account for uncertainty.

Also an issue are misinterpretations of the NHC "cone of uncertainty."  That graphic is not intuitive for the general public, and needs improvement, but even some broadcast meteorologists don't understand it.

Let me show and example of how this effects the information that people receive.  Below and at left is a summary of the Key Messages for Hurricane Irma issued about 3.5 days prior to the landfall of Irma on Marcos Island.  The cone of uncertainty, which encapsulates the entire Florida peninsula and offshore waters.  The National Hurricane Center simply says that there's a treat of hurricane impacts over the weekend and early next week, with a likelihood of hurricane watches being issued on Thursday.

The right hand side provides an example of what people are seeing on social media, which says very strongly that Irma will hit Miami at Cat 4 or 5 on Sunday.  At that time, one could find model forecasts calling for that track and intensity, and advising people to leave was warranted, but the tweet suggests much greater confidence than evident in National Hurricane Center forecasts.

Traditional and social media today provides a firehose of content that is unfiltered and often without context.  At one time, it was difficult to see the forest through the trees.  Today, it is difficult to see the information through the misinformation.  Note that not all misinformation is malicious.  Sometimes it simply doesn't provide the necessary broader perspective.

This is why, in the case of tropical storms and hurricanes, I strongly urge people to monitor forecasts from the National Hurricane Center and local National Weather Service Offices.  While no forecast is perfect, these are the most reliable available.  The National Hurricane Center, in particular, has a remarkable team of scientists, with strong ties to the research and emergency management communities.  Finally, heed the recommendation of local officials.

OK, now that I've warned you about misinformation, let me provide a snippet from the latest forecast.  A bonafide midlatitude trough is expected to move over the Great Basin later this week.  Oh, it is a thing of beauty.

And here's the summary from the National Weather Service [note to my friends their, you forgot your logo :-)]

Source: NWS
I'm not counting the minutes.  I'm counting the seconds.

Monday, September 11, 2017

Not So Deep Thoughts on Irma

Hurricane Irma made two landfalls in Florida yesterday, one in the Keys, the other near Marcos Island on the southwest coast.  The low center subsequently tracked through west Florida and as of 8 AM EDT (6 AM MDT) was near the Florida coast west of Gainesville. 

Source: National Hurricane Center
Impacts cover the entire Florida Peninsula and Keys.  Although "worst case" scenarios did not play out for some, others are suffering severely.  Do not fixate on the news coverage, which shows a small microcosm of storm damage.  Everglades City, for example, wasn't even mentioned in the coverage I viewed yesterday, but reports heavy damage this morning.  Jacksonville is currently experiencing river and storm surge flooding.  News reports suggest almost 6 million people are without power.  Florida took a serious blow along nearly its entirely coastline and interior and it will take some time until we know the scope of it.  Recovery will take much longer.  

News Coverage

If you want to see a race to the bottom, just follow the news coverage of Irma, which has been like a David Letterman stupid human tricks skit.  How many people do we need to see attempting to report in eyewall rain and winds who just a couple of days previously chastised locals who elected not to evacuate and ride out the storm?  I know the first rule in news is "if it bleeds, it ledes," but imagine instead coverage that provides detailed information concerning storm details, winds, surge, and the like.  Something people could actually use.  Even The Weather Channel spent far to much time showing their people in the field and far too little providing information that might be of value to people.  Such a shame.

Official Forecasts

In my view, computer model and official forecasts of Irma's track and intensity from the National Hurricane Center were impressive.  @WxBDM tweeted this marvelous map yesterday showing the National Hurricane Center forecast uncertainty cones from Irma's inception to Florida landfall.  That cone represents the area in which there is a 2/3 chance that Irma will track.  Irma has always been inside that cone, and I believe that includes it's track through its current position in northern Florida.  

Intensity forecasts were also quite good, although perhaps made easier by the fact that Irma had the peddle to the metal for much of it's lifetime.  I read a majority of the discussions and forecast advisories issued by the National Hurricane Center with great interest and detail given my Mom's residence in central Florida and I didn't see anything in Irma's subsequent behavior that was not anticipated by the forecasters.  

This is not to say that the forecasts were perfect.  Track uncertainty was even larger north of Florida.  Specificity on wind, surge, and other impacts had shortcomings, although those in part reflect the state of the science.  We now we need to continue to advance the science and improve future forecasts to improve better decision making, but in the context of historical forecasts, Irma's represent a significant achievement. 

Traditional and Social Media

What one "sees" and the impressions one gets today are strongly shaped by both traditional and social media and represents a blessing and a curse.  I can't emphasize enough the importance of tuning out all that chatter and focusing on National Weather Service forecasts and the recommendations of local officials during hazardous weather.  While not perfect, those forecasts and recommendations are the most reliable, don't cherry pick one possible outcome or track unless justified, and offer you the opportunity of taking the best action possible.  

Thoughts on Today, 9/11

Sixteen years ago today, terrorists inflicted a horrific attack on our nation.  In the wake of that attack, first responders and many other heroes answered the call to duty, in some cases giving their lives or sacrificing their long-term health to help others.  Let us remember their sacrifices, and that the call to duty is being answered by many in Florida and the broader southeast US during Irma.