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.

Atlantic low, California Fires

The low pressure system NHC is watching continues to develop, and the odds of something spinning up later in the week (Tuesday -Thursday) are increasing.  Here is what it looks like as the sun rises on Monday morning (12 November) …

NHC now give it a 50% chance of formation in the next 48 hours (through Tuesday), and a 90% chance in the next 5 days, so they are increasingly sure it will do something later in the week.  The GFS lowtracker loses it, but the model has a low east of the Bahamas by Thursday, other models (such as the UK models) have it going into the Caribbean.  As usual, with a weak, non-system, just identifying a center, much less predicting where it will go, is difficult. We may have more later today, but check back late tomorrow or Wednesday for a better picture of what it will do.

The situation in California is much clearer, and pretty bad.  Weather the next few days is expected to be favorable for the fires to spread.  Using satellite data, it seems that impacts are on the order of $20 Billion dollars so far – in other words, comparable to the hurricanes this year (Florence and Michael).  Worse, there is over $100 Billion(!) of infrastructure within five  miles of the active fires, which are not as of yet contained (one big fire is only 15% contained).  So it may well get worse …

The Thing In the Atlantic …

A few folks have asked about the press reports talking up a potential late storm in the Atlantic.  NHC has an invest area flagged, with a zero percent (yes, zero, nada, nothing, нуль) chance of formation in the next two days.  Beyond that it might spin up.  Here’s the Haetta/TC impact map based on pretty much sheer speculation and fairy dust …

There isn’t much for the models to go on at this stage, so don’t take this seriously.  Check back in maybe Tuesday to see if this is a real thing or not.  In the meanwhile today (Sunday, 11 November) is Veterans Day in the US, and Armistice Day elsewhere.  It is worth pondering the events of 100 years ago, with the end of the First World War.  In many ways that war is still being fought in places like Israel/Palestine, Kurdistan, across the Middle East, and even Ukraine.  Wars rarely end – they just tend to produce sequels – so please take a moment to think about those who serve in them.

Mind the gap … and California Wildfires

Generally, if you don’t see something here, it’s because there is no significant doom out there, but the last month there have been several disasters  around the world (couple of earthquakes and typhoons) that while I’ve worked professionally, I haven’t been able to post about.  As long time followers know, sometimes I get overwhelmed with work, not to mention family/personal stuff that people have to deal with from time to time, and while I try to do updates here for global events sometimes I just can’t get to it.   Hopefully things will get back to normal soon, but no guarantees!

One of the research things I’m working on are economic risk assessments for wildland fires.  Hopefully will be able to post a bit more on this soon, but meanwhile here is some data from the NASA and NOAA polar orbiters showing where the fires are in Southern California.  Each little flame symbol represents a roughly 374 square meter (1230 foot on a side) square patch of land that the infrared sensor indicates is on fire …

Michael now tropical storm, post-landfall estimate $21 Billion

Unlike most storms, Michael completed a round of intensification just before landfall and may have reached 135 kts (155mph) before landfall just east of Panama City, Florida.  After landfall it rapidly tracked into Georgia, and as of 6am the center (now a tropical storm) is just entering South Carolina north of Augusta. Here is the radar from just before 6am, with active warnings (mostly for flood) …

 

Michael will continue to weaken throughout most of today as it crosses SC, but should the winds will begin to increase again as it interacts with the system that is accelerating the storm to the northeast, and it transitions into a extratropical storm.  Here’s the latest impact swath map …

So how bad?  Unlike several recent bad storms like Harvey, Florence, or even back to Sandy, Michael is a traditional hurricane event where the most intense damage is in a narrow swath along the coast and track of the storm cause by either wind, waves, or storm surge, with inland damage mostly caused by wind.  Economic impacts are likely in the $25 Billion dollar range.    The models are estimating that of that, the FEMA Flood Insurance Program will probably take something like a $3 Billion hit, private insurance $9 to $10 Billion, so that insurance will cover just about 50% of the impacts, which again is much more of a “traditional” storm than the recent events with so much uncovered (by insurance) damage.

Michael at landfall: Damage and Categories, impact now estimated at $16 Billion

Michael will make landfall early this afternoon, and where it makes landfall damage will be pretty epic.  Here is the 6am radar from Eglin Air Force Base …

As always with a hurricane, the two questions are where and how bad.  The where part has always been pretty straightforward with this storm.  Here’s the major models (along with the watch and warning areas) – that’s a really tight grouping, and the meteorology on it is very straightforward that Michael will continue north, then start to turn northeast as it gets caught up in a frontal system that is presently over the southeast (the rain over Georgia yesterday and today is from that, not the Hurricane).

The how bad part has changed from yesterday, maybe not as much as the hype of going from category 2 to category 4 might indicate although the dollar value did take a big jump.  Yesterday morning the intensification had paused, and there was a descent chance it would stay at the high 2/low 3 range (that’s what I thought would happen), but outflow increased and shear decreased and the intensification picked up again.  But it’s important to keep perspective, especially away from landfall.  Right at landfall, yes, that 20 or 30mph wind increase makes a big difference.  But that should be in an area where people have evacuated (anyone who stayed on the Florida coast in the warning area was unbelievably foolish). What you do for a Cat 3 and a Cat 4 are the same: get out.

Although landfall will be near Panama City, Storm surge will actually be worst in places like Port St. Joe and Apalachicola, both because surge is worst to the right of landfall (where the winds stay onshore and the water piles up) and due to the unusual shape of the Big Bend of Florida, that kink in the shore line caused by Apalachee Bay just south of Crawfordville to Perry.  Surges could be as much as 18 feet in Apalachicola bay where the water piles up. Here’s one storm surge estimate:

The economic impact estimate doubled from approximately $7 Billion yesterday to nearly $16 Billion based on this morning’s simulation.  Will take a closer look at that in the next post.  Here is my Haetta/TC impact swath estimate, based on the 5am National Hurricane Center forecast:

So what about inland?  This is a potentially a bit worse for far south Georgia, but the storm should rapidly decay once inland and as it interacts with the front.  Trees down, power outages, those in any mobile home in the southwest corner of Georgia (the area SW of a line from Columbus-Albany-Valdosta, such as the Moultrie and Thomasville or Bainbridge areas), and anyone in the orange band in this map in a mobile home that is not securely strapped down, or in an older mobile home – 25 years or older – or RV type vehicle should move to a secure shelter.  Tornadoes are always a concern with this kind of storm so keep your weather alert radio nearby.  As for the coast of GA/SC/NC, tides will run 2 or 3 feet above normal, and right now “normal” is already  about a foot above average due to the fall equinox (“King Tides”).  Here local knowledge is key, so check with the products from your local National Weather Service office (www.weather.gov).  In the Savannah area, for example, that means places like US80 (the road to Tybee Island) will flood around high tide, other low-lying areas near the marsh or on Tybee itself will get some shallow flooding.  Given the speed the storm is moving it shouldn’t be nearly as bad as storms the last few years like Irma and Mathew, but if you are near the water beware.  Otherwise, gusty winds, rains (and street flooding or inland flash floods on creeks in the usual vulnerable areas), and again the occasional tornado must be watched for.  Power is going to go out.  Sigh.  Glad I have a 15kw solar backup 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.

Hurricane Michael Update, Tuesday Morning 9 October: pre-landfall estimate $7 to $10 Billion

The potential impacts of Michael on Florida have become somewhat clearer now that the storm has entered the warm putrid waters of the Gulf of Mexico (sorry folks who live on the Gulf, as someone who lives on the Atlantic coast, it just smells funny to me).  The short version is that while Michael is still “only” a Category 1 with 90mph winds, this is a potentially serious storm that could reach 120 mph or Category 3 strength before landfall.  If you live in the Florida panhandle in the warning areas take immediate action to protect life and property!

Not much to fuss over about the forecast track – the major model families agree on the big picture, with landfall near Panama City.  Here’s the major models, along with the official track (in Red) and the watch and warning areas noted:

Intensity forecast is tricky.  While there are conditions that are favorable for further strengthening, there are also some factors working against it.  I’ve heard speculation saying Michael could reach Category 4 intensity (130mph), but I think that’s increasingly unlikely (in fact I doubt it will be much over 100mph at landfall).  But for planning purposes people in the warning areas should plan on a Category 3 – if it’s not that strong, super, if more, it won’t likely be much more because NHC is pretty careful about underestimating landfall intensity.

As for impacts, there are three areas to talk about: the 80 mile wide (30mi left, 50mi right) swath right around where the eyewall hits land, the Gulf Coast (especially the Big Bend area), and the inland and Atlantic coast.  The landfall area will get hit pretty hard by “traditional” hurricane impacts – extreme winds, rain, waves, and storm surge.  If Panama City takes a direct hit it will be ugly, current estimate is $7 to $10 Billion in damage. Of course, wobbles and things breaking that shouldn’t (or stuff not breaking that in theory should) matter for those kinds of estimates. As the storm decays inland trees down, flash flooding, power outages, that sort of thing begins to dominate.  Another factor for storms like this are tornadoes – these tend to spawn more than a few.  Michael won’t be a Florence/Harvey kind of storm where most of the damage is due to rain flooding after landfall, this is more of a “traditional” 24 hour hurricane event.  But that still means flash flooding along the track.  The second area to watch are areas south of Perry FL, in the “Big Bend” areal  The geometry of the shoreline and strong onshore winds could create some pretty impressive storm surges even away from the usual place you worry about such things to the 80 miles or so to the right of the location of landfall.  If you live in coastal areas prone to flooding, pay attention and take action.

The third area to watch are places right on the coast of Georgia, SC, and NC.  While they will see gusty winds and rain, places right on the shoreline are at risk of some flooding around high tide Wednesday Evening, and the two tides on Thursday.  On the Georgia coast, high tides are already running a foot or so above normal because we are near the Fall Equinox, when the sun and moon are lined up and we have higher than average tides.  Add a foot or two of water on top of that and it can cause problems in low lying areas.  For example, in the Savannah area, using the Fort Pulaski tide gauge for reference, the average high tide is about 7.5 feet.  The “no wind” forecast for the Thursday morning high tide (10:23am) is for about 8.4 feet.  US 80 starts to flood around 9.4 feet, and parts of Tybee (14th street) flood at about 10 feet.  So if Michael adds one to two feet to that tide, which seems reasonable at this point, US 80 will flood, and parts of Tybee may see some *shallow* flooding at the time of high tide.  It won’t be dangerous unless you do something dumb, but will be hazardous and inconvenient.

So you see local knowledge is key here – beware of getting tide gauge references and topographic map datums mixed up!  Tide gauges are referenced to something called “Mean Lower Low Water” or MLLW because boats generally care more about not enough water (eg how low) than how high over fears of running aground.  Topographic maps used to be referenced to mean sea level (MSL) – which on the GA coast is 3.5 feet *higher* than MLLW.  But today topography is usually referenced to the WGS 84 datum, which is close to but not exactly MSL.  I often see local TV weathercasters screw this up and scare the crap out of people because they mixed up MSL and MLLW.  Your local NWS office (www.weather.gov, then click on your location) usually has information to sort all that out in their “Hurricane Local Statements” and other products.

Here’s the Haetta/TC (my new impact model) estimated impacts, using the official NHC Forecast for the track and intensity of the storm.

Hurricane Michael update for mid-day, Monday 8 October 2018

First here’s the obligatory pretty satellite image.  Michael continues to organize but still doesn’t have the “classic” presentation with an eye …

As for the where it’s going part of the analysis, NHC has been trying to avoid a common problem with weaker storms that are likely to intensify rapidly (which Michael is showing signs of doing, it’s now a hurricane).  That problem is known in the business as the “windshield wiper effect.”  Track models will swing wildly from left to right depending on the initial position (and knowing the center of a storm to within 100 miles is hard in the early stages of a storm), and the evolution of the storm has a strong interactive impact with the track forecasts.  This is a huge problem in the Gulf, since storms that form in the western Caribbean tend to be weak until they clear the Yucatan straights, but can spin up very rapidly. Yesterday things were trending east, but this morning are trending west even though the storm initial position has been trending east.  Here’s some of the latest track forecast models, along with the key thing to monitor, where the official watch and warning areas are.  Note that the NHC official 5am forecast track is now on right hand edge of the models available as forecast time …

Bottom line on “where”: if you are in western Cuba, or the gulf coast of Florida, take the storm seriously and prepare.  So how bad when it gets where it’s going?  The “best guess” is the storm will hit a peak of near category three, but shear and interaction with land may drop the landfall intensity to Category two. Plan of a three to be safe if you are in the pink (Hurricane Watch) area of the above map.  Here’s the possible impacts, and the new NHC official track as of 11am …

Depending on exactly where the eyewall crosses and how strong, Michael could cause anywhere from $2 (exact track shown) to $5 Billion (left wobble putting eyewall over Panama City) in damage.  Inland, as typical for a storm like this, you will see trees down, weaker structures damaged, and the inevitable power outages.  Michael should be a fast moving storm, so unlike Harvey or Florence catastrophic flooding isn’t too likely, but it could still drop lots of rain into already wet areas, so flash flooding and more misery for SC/NC are unfortunately in the cards.  Otherwise, for the Atlantic coast, rip currents and coastal flooding are possible from Georgia up through Virginia on this track, along with some trees down and power outages, but nothing catastrophic.  That doesn’t mean you shouldn’t prepare, especially for those impacts, and especially in flood prone areas, but for perspective it’s not like the Gulf Coast is facing, or that NC and northern NC experienced (actually, are still experiencing) with Florence.  Here’s the WPC Rain swath map.  Not the 30″ catastrophe of Florence, peaks a bit over 10″ with 7″ inland across Georgia, maybe 4-5″ in SC/NC, but even a few inches in a short time can certainly cause flash flooding.  If in a flood prone area, beware …

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.