Some thoughts on Climate Change

A lot of people have generated a lot of words about the topic of climate change. An awful lot of them really probably shouldn’t because they don’t really know what they are talking about, and all they are doing is spreading misinformation (even if well intentioned) and/or further inflaming an already politically charged debate. Unfortunately, even some people who do know what they are talking about sometimes go beyond their areas of competence and, more importantly, convolve science, policy, and politics.  This is a long post, sorry about that, but complex subjects require thoughtful discussions, and short posts can’t cover the topic. Even this is abbreviated to the point of oversimplification. It is a sad commentary on our society that nuanced discussions are virtually impossible in social media, yet that is increasingly how views are expressed.  Even 24 hour “news” outlets tend to focus on short, sound-byte driven coverage.  But enough whining.

So why am I writing this, and why should you care what I think? A bit of background first … I’ve been involved in climate change research and policy since the mid 1990’s.  I participated in the Intergovernmental Panel on Climate Change RA4, and was invited by both Republican (Bush 43) and Democrat (Obama) administrations to be on the US committee.  I declined both of those invitations, because I was uncomfortable with the political nature and overtones of that process, and preferred to remain in the international realm and not be overly associated with a single government’s viewpoints or policies.  That is not to criticize those who are on the US committee, but I must say was not alone in being uncomfortable with how the US conducts its process, and some pretty prominent scientists have quietly declined to participate in it.  This leads me to my first point.  The IPCC and individual government processes to study climate change were in theory a good idea, but got off track as they have moved further away from science into policy.  There are essentially three aspects to the climate change issues (or any technical issue for that matter):

  1. What are the facts?  In this case, is the climate doing, why is it doing it, and what is it likely to do in the future?
  2. What are the implications and impacts?  In other words, what are the potential impacts of any climate changes?
  3. Given the impacts, what (if anything) do we need to do about it, based on the causes?

(1) and (2) are essentially only science.  What you believe, your politics, your religion, have nothing to do with it.  It’s not simple, but it’s just data and the laws of physics and probability.  The third, on the other hand, is mostly politics.  Sure, science, engineering, and economics will tell you if the policies you want to propose are rational, or will do anything about causes and effects, but ultimately it is a policy question, and that’s a political question that (hopefully) is informed by the science.

In my not so humble opinion, one key problem is the current system tries to do all three in a single process. And that’s a Bad Thing.  Because climate is such a complex and technical issue, and because some scientists have not kept these three things separate, politicians and those who think in political terms have attacked the science because they no longer see it as science, but just another political tactic associated with an agenda. Lets be clear here: I could design a response to the worst projections regarding climate change that would make the ghost of Adam Smith write a new chapter in Wealth of Nations singing its praises, or Zombie Lenin to burst out of the mausoleum and cry Отлично! in the heart of Red Square.  Another key problem is that because the “left” (in quotes, there are no real leftist or liberal movements in the US, but that’s another discussion) has fully taken up the cause because if fits with their worldview, and allows many of their agenda points to be pressed under the rubric of “doing something” even if those things wouldn’t really do much about the underlying problem.  Likewise, much of the opposition on the “right” (and again, in the US, there are no politically conservative movements in the US) is based more on a reaction to the policy proposals of the “left”, and the false concept that anthropogenic climate change is a fake issue to promote those policies.

But I get ahead of myself.  Let’s take the three aspects above in sequence.  First, what are the facts?  While the technical details are complex, it’s really fairly simple.  Humans have in an extremely short time (geologically speaking) radically altered the chemistry of the atmosphere, as well as the surface of the Earth.  These changes must, by the very nature of the Earth’s climate system, result in changes from historical weather and climate patterns because the system is interactive.  That’s the theory, and the theory is backed up by observations at the local level, going back to studies at the turn of the *last* century (late 1800’s) that rain patterns east of Paris began to depend on the day of the week, due to the dust churned up by the city. This is backed up by modern studies (PDF).  At the planetary level, changes are harder to detect, but are also becoming increasingly evident.  So while the details are complex, don’t be drawn in debates over minutia.  While there are scientists that have legitimate, credible concerns about various technical issues like cloud depiction in models, or sensor changes over time (I’m among those who feel tropical cyclone intensity changes are not within the ability of the quality of our historical data to detect), these concerns do not compromise the overarching conclusion:  human activities are causing ahistorical, “unnatural” changes both weather and climate, and those changes are increasing.  It is wrong of activists on the “left” to trash scientists with concerns (I’ve actually been called a “Climate Denier” because I expressed concerns over the hurricane data – and I’m a long time advocate of “doing something that works” on this issue!), just as it is wrong for those on the “right” to attack scientists from the other perspective.  Have no doubt: the science is never perfect, but it is solid, and actionable.

So, what about those impacts (aspect number 2).  That is a bit fuzzier, but again the data says there is a problem, and it is getting worse.   We are already seeing significant changes in agriculture, animal migration patterns, disease outbreaks, and a myriad of other indicators.  Note these reinforce point one, and show that this isn’t just a small group of climate specialists – multiple fields are seeing impacts.  So the second aspect is also clear: while exact nature of these impacts is somewhat fuzzy, the best science indicates that there are and will be increasingly negative impacts for both humans and the natural world.

OK, what to we do (aspect 3).  As noted above here is where things have broken down, largely because the politics (which should have been confined to policy decisions) has infected the science.  Much of the climate debate is focused on the IPCC and their periodic reports.  The problem is that this is a fundamentally political process.  The IPCC does not do original research.  It simply periodically compiles and synthesizes the latest research into a comprehensive report.  The problem is that process ultimately goes through review by the political levels of the participant governments.  Then it ends up in what is called a COP, or more formally, the Conference of the Parties to the United Nations Framework Convention on Climate Change.  The 24th such meeting is in progress in Katowice, Poland as I write this.  The current meetings (Sunday, 9 December 2018) have broken down over whether the phrase “welcome” or “takes note” will be used to receive the latest IPCC report. Yeah, seriously, that’s the hang up, although of course that’s just the excuse being used by some parties to sabotage the process.  Rather that let the process work by receiving a technical report (albeit one already tinged by politics), some national governments are using the process to avoid discussing the implications of the report on bogus grounds.  It’s insanity, but it’s the way things work.  But, to be honest, the IPCC/COP process has never worked.  The various agreements as agreed never had any chance of actually doing anything about climate change anyway.  Too many secondary issues involving wealth transfer from first to third world, economics, and so forth became convolved in trying to fix the problem at hand.

How do we fix this broken process?  As “long” as this post is, that would take a lot longer to even begin to discuss.  The first thing is to get the national governments out of the review process for the IPCC technical reports, and disconnect the policy creation process from the technical assessment process at both the national and intergovernmental levels.  People on the “right” need to realize that while the “left” may have been the first to jump on the bandwagon, and push their “solutions” (that, naturally, also address their worldview), there are a lot of options to address the problem, some of which would actually work, and give the average “progressive leftist” a serious case of hives.  Things like nuclear power, or free market approaches to energy production/distribution (the current system isn’t anything approaching a free market).  Another significant problem, especially here in the US, is the fact that some have confused religion into this.  I don’t separate in this discussion politics and religion, mostly because here in the US the two are somewhat inseparable since everything in this benighted land becomes about the two party political system.  But an unfortunate (and incorrect) view has developed particularly in the US that science in general and environmental and biological science in particular are “anti-Christian” in some way.  Again, long discussion involving theology as much as science.  But this also highlights another complex aspect of the problem.  People on the “left” or “right”, or “Christian” vs “Atheist” really don’t understand each other, and don’t communicate.  And it seems like they are more eager to score points and demonize the other than acknowledge the complexity of the discussion, take the time to understand why people hold the views they do, and reach some conclusion based on neutral facts that can be mutually agreed on.

The bottom line is that the climate issue highlights many of the flaws that are inherent in the present system of human governance and decision making at the national and nation-state level.  In the US, it highlights the dysfunctional nature of the media, educational system, and political party systems in particular.   I’m a scientist, not a politician, and I don’t have any good ideas on how to fix the process so that we can address issues like Climate Change in a way that has any hope of working.  But I know for sure we are headed for some really bad times ahead if we don’t.  It’s a pretty planet, with amazing places and wonderful people.  Let’s figure out a way to not screw it up …

Atlantic low: the saga of invest areas

Here we have yet another example as to why you shouldn’t get excited much about invest areas.  At one point yesterday NHC gave the system a 90% chance of becoming a named storm in the next 5 days.  This morning?  Only 40%.  Here is the forecast model map as of 6am Tuesday:

And if you haven’t learned by now reading this blog, it’s also why you have to be careful with track models and not cherry-pick the scariest line.  Notice the lack of nice colored tracks?  That’s because the major models don’t spin it up and can’t track it very far.  Many of those gray curved longer lines are alternative scenarios where an artificial vortex was inserted into the model.  So the most likely scenario for this thing is that it will spread rain across the northern Islands, Puerto Rico, and Haiti, but not become an organized system.

Dramatic Michael Update! (ok, that’s clickbait, nothing changed significantly since this morning but here’s some pretty pictures).

The forecast from NHC at 11am really didn’t change significantly other than some tweaks in the track and intensity.  Watch and warning areas didn’t change, Damage swath, damage estimate from my Haetta/TC model didn’t change much at all.  Timing a little slower inland.  So, if you’re getting ready for a Cat 3 hurricane (and if you’re in the warning area, especially around Panama City, you’re an idiot if you aren’t), or in inland Georgia getting ready for some high winds and rain, keep doing that.  See the earlier post for details.

Here’s an animation of the GFS model. Click to get the full loop.  I hate these things.  Sure, they are dramatic and pretty, but they don’t tell you much of anything about potential damage or who needs to be afraid and who needs to just chill …

And here’s a visual band image of the storm.  Got an eye, and may strengthen some more before landfall.

AL14 (Future Michael), Earthquakes, and other stuff

Several big events over the last two weeks, especially the earthquake/tsunami in Indonesia and the earthquake in Haiti yesterday evening.  And more Pacific tropical stuff.  Have been swamped with research stuff and will try to catch up over the next day or two, but getting lots of queries about the storm off of Belize so will say a few words about that first.  Here’s the noon Sunday satellite view …

Other than gusty winds, for the Caribbean threat is mostly to the west end of Cuba as the storm makes its way out into the Gulf over the next day or so.  The 11am NHC Advisory package for Tropical Depression 14, which will likely reach tropical storm status and be named Michael this evening, has landfall on the Gulf coast of Florida sometime Wednesday.  For those of you who just can’t live without your daily dose of pasta, here’s a look at some of the major forecast model track guidance guidance NHC was taking in to account in creating this forecast.  Some show landfall as far west as Mobile Alabama, some as far east as the “Big Bend” area of Florida, near Steinhatchee.  The big dynamic models bring the storm in as a Hurricane, so if you are on the Gulf Coast pay attention. The overall impacts depend a lot on the track – one of those “duh” things meteorologists like to say.  The further west, the more likely effects will be confined to the coast near landfall, and the storm will degenerate over land.  Further east, especially for a “back door” type storm that makes landfall on the Gulf Coast, exits or skirts the coast of GA/SC/NC, it’s a more widespread problem. 

Just a brief rant (again, sigh) about showing track models maps, especially those sites who show all of the individual tracks as the haze of lines.  Lets look at that brown line on the map above in more detail. Here is JUST the GFS Ensemble model and the members of that ensemble.  So in simple terms the way this works is that the model is run a number of times (in this case 20) using “perturbed” (different) initial conditions based on the uncertainty in the storm position and characteristics, with an averaging program run to get the average track.  The individual runs are interesting for understanding the uncertainty of the forecast, but treating them as “equal probability” outcomes is misleading – and it’s just plain wrong to go ZOMG THE AP20 RUN SHOWS A DIRECT HIT ON SAVANNAH as if that is a stand alone forecast equal to something like HMON or especially the consensus track models (much less the human-assisted official NHC track).  So I’ll say it again: be sure your pasta is cooked by a real chief and chew well before swallowing it 😛

NHC is more or less splitting the difference (as does the consensus model blend) and takes the storm over Panama City.   Fortunately we’re not looking at a Florence/Harvey kind of “move just lnland and stall” scenarios, this looks to be the typical “landfall and move on” 24hr kind of event.  Here’s the impact swath based on the official NHC track forecast (which, as I often rant, is the only thing you should really worry about) …

Notice how broad the wind field gets after landfall, and the big swath of 40mph+ winds that are offshore.  This is typical for a storm that accelerates rapidly after landfall.  For those in Georgia and SC, don’t freak out over maps like this that show the storm as a tropical storm well inland.  First, as you can see here, the strongest storms will likely be well away form the center, and mostly confined right on the coast.  Second, NHC tends to overestimate the inland winds from an impact standpoint.  (said in a different way, while it is true there might be a small patch of winds of tropical storm force 24 hours after landfall, it isn’t likely to be as widespread as models and graphics based on their forecast show).  That’s fine for planning purposes, but don’t get too upset over it just yet.  Again, small changes in this track can produce big changes in impacts, so watch for the official watches and warnings.  A direct hit on the Panama City area by a Category 1 hurricane could be messy – current impact estimates are around $4.5 Billion, but it’s so early that number isn’t very reliable.

Florence Update for Thursday, 13 September 2018

Florence continues to “barrel” (funny how some words get stuck in the media) towards the southern North Carolina shoreline.  The short version is that for the immediate landfall area, not too much has changed.  Watches and warnings are the same, expected “worst case” impacts haven’t changed, etc.  There is some good news in the sense that the storm may not be as intense as forecast when it makes landfall, it’s down to Saffir Simpson category 2 levels.  That DOES NOT mean those in the warning areas should fail to prepare for a Cat 3 – there could be a bump in intensity before landfall, but signs are for a weaker storm than expected.  Still, will be bad enough, so if you haven’t gotten out, do it this morning before conditions deteriorate rapidly later today.  Winds along the coast are light so far (looks like 10-15 knots peak right now), but that is going to change rapidly.  Here’s a composite radar view from the two closest sites (Wilmington, range indicated in white, and Morehead City, range indicated in green).  Classic eye and banding structures becoming visible …

The various forecast track models and other simulations are in pretty good agreement that the storm will make landfall, then stall out for at least two days near the SC/NC border, over the Grand Strand. Here is the impact estimate based on the official NHC forecast as of 5am this morning:

This is the tricky part of the forecast – if it’s on the shore, or near the short, it can maintain intensity, and pump more rain inland.  If it’s even 50 miles further inland, the intensity and rain rates will drop off pretty quickly.  On the current track, the worst wind damage will stay in North Carolina.  Direct impacts should be around $10 Billion.  The big question is rain and flooding.  The current estimates are for about $5 Billion in additional impacts from rain related flooding.  But a longer pause could double that number; likewise, if the storm is even 50, much less 100 miles inland, that could easily drop to a Billion or so.  It’s a great unknown …

For folks in Savannah GA and the Beaufort/Hilton Head area, things look pretty good on this track.  We’re on the weak, dry side of the storm.  Winds will be offshore, so storm surge flooding will be nothing to worry about.  Right on the coast, waves and wave setup might cause some issues, and rip currents will remain dangerous.  Depending on wobbles, we may get rain, or just as easily get a clear if breezy day in the subsidence zone.  But dangerous conditions (other than on the beach) just don’t seem to be in the cards right now.

Florence 11am ET Update: No changes to official track, models shifting again …

For more detail on model tracks and why you shouldn’t focus on them, see my post from earlier today.  But if you need an example, let’s look at the changes over the last 6 hours in just one global model, the NCEP GFS model, in comparison to the official forecast track (which didn’t change):

The official track didn’t change very much.  Still looking at the same folks who should be evacuating by now, same watch and warning areas, same damage estimate (around $15 Billion).  Here’s the map:

So for people in southern South Carolina, and especially those in Georgia, I again say don’t eat poorly cooked pasta.  It will give you indigestion …

Hurricane Florence: a deeper look at track models (Wed. Morning, 12 Sept)

This is another long read, with some SCIENCE!, but the details of this matter – I hope you will be patient and read on.  While I often touch on hurricane track forecast models, I normally stick with the official NHC forecast track when discussing the impacts of storms.  There are a lot of good reasons for doing this.  First, track forecasting is a very specialized profession, with a lot of complex factors involved.  NHC has specialists to do that, and while I sometimes disagree with details, they are very good at it. Interpreting the multitude of track models is not an easy task.   Second, given it is their responsibility to do official watches and warning, diluting their message to the general public is not a good idea.  Some may say this is a bit hypocritical on my part, given my criticisms of Emergency Managers and evacuations, but there is a key difference – NHC are professionals who consistently do a good job.  Governors issuing evacuations orders have a much spottier track record, in my clearly not so humble opinion 🙂 , so I feel free to trash them.

Unfortunately, there is a trend in the media to talk about specific track models at the expense of the official forecast, and to publicly second guess or anticipate the next NHC forecast.  Part of this is because beautiful, dynamic animations are available for individual track models.  These graphics are great for TV, and the temptation to show a graphic that passes over or near your viewing areas is overwhelming.  But it can also be very misleading.  So let’s take a closer look at track model outputs for Florence, and what they mean.  Here’s the track model map available at about 4am this morning:

The Global models (exemplified by the dark blue GFS line show the storm pulling up short of the NC shoreline before diving south.  The dedicated hurricane models such as HMON (the replacement for the GFDL, shown in light green), the HWRF (shown in light blue) and the official track (red lines) don’t have the sharp right turn.  There are a lot of reasons for this.  For the objective models, it is important to realize that while they are often good at forecasting hurricanes, and are used to provide “boundary” conditions for specialized models, they are not specialized, high resolution track forecast models. They often lack the detailed coupling to ocean models, and have less sophisticated model physics than the dedicated models.  This gap has closed in recent years as global models have gotten better, but the gap remains.  In their forecast package development, NHC takes in to account factors like this using their involvement in, and detailed knowledge of, these models.  They also realize that models can shift radically from one iteration to the next.  Every 6 hours, data from weather stations and satellites is collected globally and used to create a picture of what the atmosphere looks like at that time.  These are the initial conditions.  Those initial conditions are then used to spin up the global models, as well as the dedicated tropical cyclone models.  That’s the simple version, but the details are very complex.  Not all initial conditions are created equal.  One small example: the 00Z (8pm ET) and 12Z (8am ET) initial conditions are often “better” than the 06Z (2am) and 18z (2pm) data sets.  This is because most upper air observation sited only launch two balloons per day, at 00 and 12z.  Sometimes you get a satellite pass over a storm at the right time, sometimes its 3 or 4 hours earlier.  Sometimes you have airplane data, sometimes not.  So when I fuss at meteorologists, weathercasters, and storm watchers for latching on to a model shift, that’s one reason why.  It’s also why the NHC sometimes seems slow to shift tracks to follow what seems to be shifting model data – they realize that it can just as easily shift back 6 or 12 hours later.  There is much more to it than this, but I hope that gives you at least a glimpse into the fact this isn’t simple, or for amateurs.

Another factor is that the storm isn’t just some line on the map: it’s a broad, complex system.  Let’s look at the impact from two very different model simulations.  Here’s the HMON run, and for comparison, the CTCX run, which shows the storm hitting Savannah, GA …

Note especially the impacts onshore.  If you compare the areas of severe impacts, despite the fact that the track line is scary for people in Savannah and southern SC, the dangerous, life threatening impacts are all contained within the warning areas NHC has set.  Now here is the impact estimate based on the official track:

What about economic impacts?  On the official track we are still looking at about $12 Billion in direct impacts.  The HMON track would product “only” $5 or $6 Billion, while the CTCX track would likely cause $3 or $4Billion, because the stronger winds would stay offshore!

And what about the infamous “cone of uncertainty?”  I see people making much of this or that city being “touched by the cone.”  Well, to be honest, who cares.  I hate that graphic.  What you should care about is how strong the storm will be if and when it gets to you. As NHC notes, bad impacts can exist outside the cone.  But the opposite is also true.   If the death cone touches you on day 5, when the storm is inland and barely even a tropical depression, and you probably wouldn’t even know it was a storm if somebody didn’t tell you, so what?

So despite all the rending of garments and gnashing of teeth, because of the intensity of the storms on the scary scenarios showing a turn along the coast, the storm would weaken fairly radically, and the impacts would be less.  So the conservative path for NHC is to continue to slowly shift the track south (assuming the forecasts continue that trend), adjust the intensity accordingly.  And, as you can see, the present watch and warning areas are in fact perfectly fine for this storm.

Bottom line: yes, the forecast tracks are shifting. Yes, forecasting is not an exact science. But it’s not really as big a deal as some would like to make it out to be.  Stay cool …

Florence Evening Update for Tuesday 11 September 2018

First some advice.  Don’t freak out over any one computer model forecast, and be skeptical about folks who show you dramatic graphics and talk about tracks while not discussing the official National Hurricane Center forecast all that much.  Tropical Cyclone Forecasting is specialized, and understanding all of the nuances of track models takes a lot of experience.  Most of what you read here is either an interpretation of or derived from NHC forecasts using my active research work on natural hazard damage models.  While I work on forecast models of various kinds, and have a deep understanding of numerical weather models, for the most part I leave that end of the business to the folks who do it every day.  Why are my discussions often less dramatic than other sources?  Probably because my income doesn’t depend on hits, viewers, or selling you stuff 🙂  But let’s start with the obligatory dramatic satellite picture anyway …

As usual, lets will look at the track, the likely impacts on that track, followed by the implications of those impacts in both economic and human terms.  This is a bit of a tough forecast situation.  There is a high pressure ridge to the north of the storm that is currently guiding it towards North Carolina.  That should control the motion for the next two days (until Thursday).  But then things get a bit less clear.  This morning, most indications were that a “weakness” in that ridge would cause the winds steering the storm to slow down or even stop as it makes landfall over North Carolina, drifting for a couple of days, then begin to move northestward, dumping a bunch of rain in the process.  Today, however, the dramatic ECMWF model runs making the rounds in social media show the storm “bouncing” off the high and moving SW,  showing Florence heading south and perhaps even hitting again as far south as Georgia.  Most models, however, just show some kind of jog  offshore rather than just inshore as was the case this morning. So the big picture is more or less the same Here’s some of the track models as of 4pm this afternoon (ECMWF isn’t shown for licensing reasons) …

So what does all that mean?  Well, let’s see what the experts have to say.  Here is the 5pm NHC forecast track.  I added in the 5am track from this morning in yellow for comparison.  Not so different, huh?  From their forecast discussion, “there remains no significant change to the previous forecast track or reasoning.” 

So what’s the bottom line? No major developments. The areas under watches/warnings/evacuations are not changed. The damage estimates are about the same – somewhere around $14 Billion in direct damages, flood damages highly dependent on exactly where Florence stalls out and how much rain gets dumped.  Folks in the immediate path of this thing should get out of the way.  IF the storm does do the stop and turn shown above, that’s good: it will be weaker, and cause less damage.  If it follows the ECMWF scenario, it will almost certainly not be in very good shape as storms don’t like to run in to walls of air and get shove at a 90 degree angle … so there is still no need to panic, just keep watching the official forecasts, smile (and don’t make any sudden moves) at folks who are freaking out and latching on to every weird variation in this complex situation, overreacting to pretty pictures, and stay cool …

Florence: NC most likely landfall as Category 4 on Thursday/Friday

Today is a major day for decision and action as Florence is clearly headed towards North Carolina.  Here is the current NHC forecast track (read with hurricane symbols), with the estimated damage zones based on my Haetta/TC model.  Also shown, in yellow, is the official forecast track from yesterday morning.  For all of the talk of uncertainty and track models among the chattering classes, the official forecast has been remarkably consistent:

Notice the area of catastrophic, severe, and widespread damage. Seems small, given the talk, doesn’t it?  The thing to keep in mind with hurricanes is that the swath of actual severe damage most times, even for a major hurricane, isn’t all that wide.  Media folks love to talk about how big the cloud shield is, or the extent of the over water tropical storm force winds, but for Florence, severe effects will extend about 120 miles to the right (north) of landfall, and 80 miles to the south.  Of course the problem is we don’t know exactly where that 200 mile wide swath of damage will be in 3-4 days when it hits, thus the 600 mile wide watch and warning zones.  Don’t be mislead by fluctuations in intensity, or brief north or south wobbles.  For example, this morning the storm is going through an eye replacement cycle.  It may even be a cat 5 at times.  Along the coast the damage will be epic if the storm stays as strong as it is. 25, maybe even 30 foot storm surges in places where the water can pile up.  Even inland, damage will be severe, with trees down and structures damaged.  But especially scary is a detail in that map: notice that landfall is expected in 3 days – then the storm moves only 50 or 60 miles over the next two days.  While the intensity will drop quickly after landfall, enough of the circulation is likely to remain over water to pump immense amounts of moisture over NC and VA.  That means the potential for tremendous inland flooding.  If you live near a creek, stream, or other flood feature, be aware that the waters may rise quickly.  Local knowledge is everything in this kind of situation, but with so much water, and so much development (which changes radically the hydrology of an area) areas that have never flooded will probably flood.  Comparisons are being made with Harvey.  That may not be far-fetched.

My damage models are still showing approximately $20 Billion in damage, with as much as $15 Billion in additional flood damage possible depending on variables like how long the storm sits and now much rain is dumped into Virginia.  Florence is definitely on track to enter the top ten most damaging storms.

At this point it is fairly clear who needs to take clear, decisive action.  NHC has issued a hurricane watch for the coastline from Edisto Beach SC to the NC/VA border.  I expect a watch or warning of some kind for parts of Virginia today are possible depending on minor track shifts and timing.  Especially for those in Myrtle Beach and the northeast corner of SC, and all of eastern North Carolina, the hyperbole isn’t really that wrong here.  If on the coast, or in low lying areas, get out.  If within 50 miles of the coast in anything other than a substantial structure that you know can stand up to high winds, get out.  If you are in the NHC watch areas you really need to take action and be gone before Thursday morning.

That said, I again want to point out that for far southern South Carolina, south of Edisto Island, the risks are decreasing rapidly other than for rip currents and waves right on the beach in the surf zone.  For Georgia, the risk at this point is vanishingly small.  It will probably be a nice day as we (I live in Savannah GA) will be in the subsidence zone at the fringes of the storm, but don’t plan on going to the beach and swimming, as again waves and rip currents will be dangerous.

Florence update, Monday evening, 10 Sept 2018

No doubt about it, Florence is truly a monster category 4 storm now, here the eye seen at 5pm  …

So the questions are, as usual, where is it going, how bad when it gets there, and what to do?  Where is more or less clear.  The track guidance is fairly well clustered on the lower NC coast, and has been shifting a bit northward during the day.  Note the blue track of the NOAA GFS model doing a loop offshore.  That’s not a glitch – that could really happen, although it’s not likely.  Here’s the latest map using tracks available as of 4pm or so, with the latest NHC forecast track in bright red (the previous track is in darker red) …

How bad?  Pretty bad.  Here’s the forecast damage swath, using the official NHC forecast track.  The track didn’t shift that much during the day today, a little bit north, but the broad swath of impacts still covers much of the northeastern corner of South Carolina and all of Eastern North Carolina.  Storm surges could easily be in the 25 foot range in places.  Damage along the coast will be catastrophic if the intensity holds, with severe damage as far inland as the Research Triangle area.  

On this track it’s a $20 Billion dollar storm at least, with many estimates coming in at $25 to $30 Billion.

As for what to do, this is a seriously bad storm.  If you are in on the coast of South Carolina in or north of the Charleston area, or North Carolina, you need to evacuate.  It’s a no brainer.  Get out, and if inland in a secure structure, button up.  If in mobile homes get out even if inland.  You really need to listen to local emergency management on this one, hyperbole aside, it is a very dangerous hurricane.


For the Georgia and far southern SC coast (Beaufort/Hilton Head), the bad impacts will likely all be to the north, and the risk decreases with every hour.  This raises an interesting (and tough political) question, given the state boundary between SC and Georgia.  The Governor of SC has ordered mandatory evacuations for all zones for the entire coastline.  So we have the odd situation where people on Tybee are under no instructions to do anything, while folks across the river who they can literally see are being told to flee for their lives.  One of my complaints about the way evacuation decisions are made is that they are often set up as canned responses with little room for flexibility.  There are a variety of legal and operational reasons for this beyond the scope of this post.  While there is some coordination between the states, most of these decisions are stovepiped, and given the different political considerations in each state, along with different skill levels and experience of personnel, things like this happen.  To folks in Georgia, don’t freak out.  While you should carefully listen out for a possible change of direction, again the risk is decreasing.  For people in the Hilton Head area, you have a choice to make – follow the directions of your emergency managers, or take a chance, given the odds are likely very much in your favor since it would take a pretty radical change in track to bring life threatening condition to your area?  In general I support following the advice of local EMA’s.  Here, I personally think a more targeted approach would have been appropriate.  I can absolutely see getting ready to evacuate special needs populations, etc. I can see putting the communities on notice.   But a general evacuation carries risks – evacuating Sun City and HHI will very possibly kill some people due to stress, traffic accidents, etc.  It risks clogging up the roads and  taking up hotel and shelter space for people who absolutely must get out of the way.  Unfortunately, this is a discussion that tends not to happen until a storm is “barreling” into the coastline, and it devolves in to a “follow evacuation orders or die” kind of thing.  We need to have a nuanced discussion about this, and some better planning and coordination at the *national* level.  That said, the bottom line is that EMA’s are often a bit conservative, and sometimes have operational, political, and legal considerations that aren’t always in the best interests of every individual, but for the most part they are trying their best and deserve your respect and attention.  In this case in the far southern counties of SC (Beaufort, Jasper) those other factors might be in play.