EM Forum Presentation — April 24, 2013

A Look Back at the 2012 Hurricane Season
and a Look Ahead to 2013 & Beyond

Daniel P. Brown
Senior Hurricane Specialist
Warning Coordination Meteorologist
National Hurricane Center

Amy Sebring
EIIP Moderator

This transcript contains references to slides which can be downloaded from http://www.emforum.org/vforum/NHC/2013update.pdf
A video recording of the live session is available at http://www.emforum.org/pub/eiip/lm130424.wmv
MP3 format at http://www.emforum.org/pub/eiip/lm130424.mp3
or in MP4format at http://www.emforum.org/pub/eiip/lm130424.mp4

[Welcome / Introduction]

Amy Sebring: Good morning/afternoon everyone and welcome to EMForum.org. I am Amy Sebring and will serve as your Host and Moderator today and we are very glad you could join us.

We would be remiss if we did not note the tragic events in the past couple of weeks.  Our hearts go out to not only the families of the victims, but also the public servants who have given their energy, and in some cases their lives to respond.  We are also extremely grateful to the National Hurricane Center for making today’s program possible on rather short notice.

Today’s program is a look back at the 2012 hurricane season and look ahead to changes the NHC will implement for the 2013 season.  We will also hear about what is on the drawing board for the years ahead.

Now it is my pleasure to welcome Daniel Brown, Senior Hurricane Specialist and Warning Coordination Meteorologist at the National Hurricane Center.  As hurricane specialist, he is involved with the issuance of track, intensity, and wind radii forecasts as well as associated watches and warnings for tropical cyclones in the Atlantic and eastern North Pacific Oceans. His role as WCM includes coordinating NHC’s outreach and training activities.

Please see today’s Background Page for further biographical details and links to several related resources that Daniel will be discussing today.  

Welcome Dan, and thank you very much for taking the time to be with us today. I now turn the floor over to you to start us off please.


[Slide 1]

Daniel Brown:  Thank you, Amy.  Welcome to everyone who could join us today.  I am very excited to be able to provide the presentation to you and thankfully I did have a lot of this ready to go on short notice.  It is good to see the presentation on the screen for everyone to see.

I am going to discuss a little bit about the accuracy of the 2012 forecast and discuss some of the forecast challenges the Hurricane Center faced during the 2012 season.  We’ll focus on the storms that affected the United States and then later on we’ll discuss some of the 2013 product changes and lastly some of the in-house experiments that NHC is doing that could potentially lead to some product changes in the future.

[Slide 2]

The good news last year for 2012 when we look back at how the Hurricane Center’s track and intensity forecast did—we set several records for track, which happens often these days, as we have been improving our track forecast over the past couple of decades.  You can see the average forecast error two days out was only out sixty-nine nautical miles.

One thing we did last year was set some records for intensity forecast especially at long range at days three, four and five.  That is somewhat more unusual.  I’ll talk about that in a moment. That we have not been making as much progress in our intensity forecast in the past couple of decades but last year we did break some records.  

Although some of these records were broken probably because we didn’t have too many rapidly intensifying systems in the 2012 season so some of these storms may have been a little easier to forecast.

[Slide 3]

I will illustrate here how the track forecast errors have been reducing and how our forecasts have been getting better over the past 20 or 25 years.  This graph shows our track errors at the various timeframes are.  The red line is our average track error at 24 hours and the green line is 48 hours.
This starts back in 1990.  The average two day forecast error in 1990 was about 200 nautical miles and that has reduced to about 69 miles in 2012.  

We have been making some great improvements.  I’m sure many of you have heard us talk about this in the past.  We used to say we had cut the track errors in half since 1990 but actually it is getting to the point where it is greater than half.

The errors have been cut nearly by about two-thirds during that time.  It is really a great success story in being able to forecast a storm’s future path and location.

[Slide 4]

Now on the other hand our intensity forecasts have not improved much over this same time period.  These are the average intensity errors.  The red line is for 24 hours and the green line is for 48 hours.  You can see these dotted lines are basically flat meaning we have not improved our intensity forecasts over this 20 or 250year period.

I guess there is some good news in that in the very recent time you do see some of these errors coming down very recently.  In the last couple of years we haven’t seen much in the way of rapid strengthening so you see these errors have come down some in the past few hurricane seasons but I think that is because we have had easier storms to forecast.

Iwill note that if you look at the blue line for our five day and this line is for the four day intensity forecast—those trend lines do show some downward motion.  I think some of that is probably because we have improved our track forecast at four and five days so we have a better handle is the storm is going to be over land or over water which contributes to the forecast error.

If we can’t get that right we certainly would likely miss the intensity forecast.  Because the tracks have gotten better the longer range intensity forecasts appear to be improving slightly but there hasn’t been much change for the short term intensity forecast.

[Slide 5]

This is a look at the forecast errors for each storm.  If you look at the storms such as Beryl that were early in the season, the forecast errors were pretty low.  These were some of the more successful storms we forecast during the last hurricane season.  You can see the average errors at three, four and five days listed by the line—you can see there are a few storms we really struggled with last year.

We’ll talk more about these.  One of those was tropical storm Debby.  It formed in the Gulf of Mexico early in the season.  That was a real struggle to forecast where that storm was going to go.  I’ll show you the model guidance we had to work with and why that was such a struggle.

There were a couple of storms that were thankfully out over the open ocean that were more of a struggle including Kirk and Nadine, which lasted for several weeks.  Isaac, although we did well in the short range forecast—some of you may remember if you were joining us from the Gulf Coast or from Florida—you may remember some of the early forecasts for Isaac that were more up towards the Florida peninsula more than out into the Gulf and Louisiana where eventually Isaac made landfall.  We will talk more about that.

Sandy on the other hand late in the season was a fairly good forecast success from a track and intensity forecast perspective but there were other challenges we faced forecasting Sandy.  You all may know the dilemma on watches and warnings which I will discuss later.  

[Slide 6]

I’ll start out with Debby and say that if you are familiar with our graphical tropical weather outlook which is on the left side of the screen here—this was a well-forecast system.  We knew it was going to form.  The model guidance did a very good job of forecasting Debby’s formation, but the problem was where was it going to go?

On the top right is the model guidance and how divergent it was and I will walk us through that in a moment.  For those that don’t remember, Debby ended up affecting Florida.  It made landfall as a minimal tropical storm near Steinhatchee, Florida on June 26.  It caused five direct fatalities.

Its main impacts were from both fresh-water flooding from a lot of heavy rainfall and also some storm surge flooding.  It was just a tropical storm but it does illustrate the dangers of storm surge flooding even from a tropical storm along the west coast of Florida where there was inundation in some areas of one to three feet.  Overall Debby caused about $250 million in damages.

[Slide 7]

Here are these model forecasts for Debby when it first formed.  This was the dilemma we faced in the first advisory.  I have to joke a little bit that I was on vacation.  I picked a good day not to be in the office as this was a very difficult forecast.  Two of our better models we have in the past few years—one of them is the European model which had its five day forecast point in Texas and the U.S. Global model, here in black—its five day forecast was east of the Florida peninsula.

You can see how divergent the models were.  A couple of the models favored Texas and a few favored Florida and this made for a very difficult forecast.  Our first forecast put a little more weight on the European model since it had been the best performing model over the previous few hurricane seasons.  Our forecast showed a little bit more of a track toward the west which ultimately did not happen—leading to those large errors. I’ll forward a little over time.

[Slide 8]

In advisory number two the models were still very divergent with some favoring Texas and some Florida.  A lot of people may hear us talk about the consensus models in our tropical cyclone discussions about how we do use the average of many of these models to help us with track although in this case it really didn’t help.  

[Slide 9]

When you average out the tracks over Florida and Texas you get a track towards the northern Gulf Coast which really did not seem plausible in this case.  Those were not much of a help either.

[Slide 10]

Over time you can see the model guidance gradually shifted towards the Florida peninsula in our forecast.

[Slide 11]

Here are all the Hurricane Center forecasts for Debby and you can see how we did struggle.  It just illustrates that even today with the improvements we have seen in track over the past 20 or 25 years that there still occasionally are times when the models very divergent and we will struggle and have less confidence in the Hurricane Center forecast.  A good way to gauge that confidence is by reading our tropical cyclone discussion product.  Hopefully you are familiar with that.

[Slide 12]

Just to review a few of the impacts in Florida—Debby was a significant tornado producer.  There were 24 tornadoes that occurred across Florida.  There were a couple of deaths related to the tornadoes that did occur.  Some of these are fairly spectacular pictures that were taken in Florida of tornadoes that were associated with Debby.

[Slide 13]

The main impacts with Debby were the water hazards or storm surge and heavy rainfall.  This onshore flow that occurred for several days, because Debby was a slow mover, ended up piling up water along the west coast of Florida. Basically from southwest Florida through the Tampa Bay Area all the way up into the Florida Big Ben region ended up getting this onshore flow and storm surge that occurred near the coast and did cause some problems and damage.

[Slide 14]

Now we’ll move over to Hurricane Isaac.  I’m sure many more people remember Isaac.  Isaac formed east of the Caribbean islands and ended up making landfall in Haiti and Eastern Cuba and then moving up across the Florida straits.  Then it made a fairly slow track across the Eastern and Central Gulf of Mexico.  It actually slowed down as it approached the Louisiana Coast.

It became a hurricane shortly before landfall.  Its main hazard was also storm surge.  We saw storm surge inundation as much as ten to seventeen fit across Plaquemines Parish in Southeast Louisiana and eight to twelve feet across Saint Bernard Parish.  Isaac ended up causing about $2 billion in damage.  I’ll talk here about some of the challenges we faced.

[Slide 13]

The next slide shows some of the pictures of the storm surge that occurred.  Something to remember with Isaac is that Isaac was a large storm which does have implications on how much surge a storm will produce.  Because of its large size it produced a rather high storm surge in a storm surge vulnerable area.

Some people seemed to be caught off guard because they ended up with more surge from Isaac than from Katrina in some areas but the reminder is that it took a track that was different than Katrina and its large size helped to contribute to this surge for a storm that was not as intense as Katrina was. Surge was definitely the story with Isaac.

[Slide 15]

This shows the struggles we had early on in the storm.  Some of you may remember that the Republican National Convention was scheduled to occur in Tampa Bay the week that Isaac was forecast to be in the Gulf of Mexico area.  The early forecast showed this threat towards the Florida peninsula.

This is the model guidance we had when it was just entering the eastern Caribbean.  You can see all these models that were pointed up toward Florida and the west coast of Florida near the Tampa Bay region.  It made the forecast difficult.  

Also the intensity forecasts were very tough for Isaac because of the amount of land interaction.  Several of our forecasts—especially early on we had a high bias in the forecast—because Isaac ended up interacting more with the land mass of Dominican Republic, Haiti and Cuba, making those forecasts even more difficult.

[Slide 16]

When Isaac finally exited the north coast of Cuba there was still a fairly large amount of spread in the guidance for where it might impact the Gulf of Mexico.  This is actually a three day forecast with a center right along the northern Gulf Coast.  You can see that the model guidance was basically indicating landfall from anywhere from the Florida panhandle region all the way over into southeast Louisiana.  It was a pretty wide area for three days that the model guidance suggested could be impacted by the center of the storm.  

[Slide 17]

At this point the Hurricane Center forecast was nearly a consensus, or a middle of the model guidance, and we had to swing the forecast a little big left as the model guidance came into better agreement towards southeast Louisiana.

I will point out here that sometimes if you look in white where the actual track of the storm progressed it actually is outside of the guidance once you get beyond about two days.  That happens on occasion.  The storm actually moves outside the sweep of model guidance.  A lot of people now go to the internet and look at the model plots they see.   I caution people because it does not always show you the entire range of possibilities for a given forecast scenario.

[Slide 18]

We’re moving now into Sandy and talk about Sandy’s impacts and also forecast challenges we faced.  Sandy was in late October.  A storm formed here in the central Caribbean, moved northward and began to quickly strengthen as it approached eastern portion of Jamaica and then ended up strengthening into a Category Three storm just before it made landfall in eastern Cuba.

It moved across the Bahamas.  It weakened somewhat and actually became a tropical storm for a brief period of time before re-strengthening and then taking a fairly unusual track and turn back toward the mid-Atlantic and northeast United States.  Its transition from a tropical cyclone which gets its energy source from warm water into more of an extratropical or more winter-time type low pressure area made for some forecast challenges on how we dealt with the watches and warnings.

We will talk about that and I’ll end with some changes that because of Sandy we will be implementing at the Hurricane Center and the weather service this year.

[Slide 19]

As far as Sandy, it did produce hurricane force winds across southern parts of New England and Long Island at least in gusts, and those winds knocked down trees that ended up killing 20 people.  The total death toll in the United States because of Sandy was 72 but a little more than half of those deaths were from storm surge.

Storm surge was again the primary hazard and what produced much of the damage with the significant surge occurring basically from the New Jersey coast through New York and into southern New England.  This map shows the inundation values—really how much water ended up over land that is normally dry.

The highest values were up here in northern New Jersey and also near the Staten Island area of New York, here the highest was around nine feet.  I did have an opportunity with a couple of us here at the Hurricane Center to do an over-flight of this area about a week after Sandy and the devastation was quite striking.  I was an awful event for the folks up in that region.

[Slide 20]

Here are some pictures.  I’m sure everyone has seen various damage pictures from Sandy or perhaps some of you have been on the ground and seen it yourself in person.  It certainly illustrates the devastation storm surge can bring to a region and also how widespread that damage can be.

[Slide 21]

As far as the forecasts for Sandy, I mentioned earlier, that overall the forecasts were pretty good.  Here in black are the track forecasts throughout the entire life of Sandy.  You can see there were a few times where we had it forecast to be a little more offshore or too far east but the model guidance picked up on this turn fairly early such that we were able to shift our forecast a little back to the west and ended up with some very good forecasts several days in advance of landfall in the United States.

The intensity forecast also ended up being very good for Sandy especially for the approach to the United States.  We did struggle, which we often do, with the rapid strengthening that occurred near eastern Cuba.  

[Slide 22]

Here is a slide to illustrate that.  Here is the picture of Sandy as it made landfall in eastern Cuba.  You can see in this graph on the bottom left in white is basically what happened—the intensity of the storm at every six hours through its life.  All the lines in light blue are the actual Hurricane Center intensity forecasts.

You can see highlighted in this purple circle that the Hurricane Center forecast did not forecast this rapid change in strength just before landfall.  That is something we still struggle with.  We don’t have the intensity model guidance that can predict these real rapid changes in strength.

There are several reasons for this.  One is that with intensity forecasting it is really a much smaller scale phenomenon or mechanism that is causing the rapid changes in strength.  We can look at the overall storm environment to see whether it is favorable or not but it really is oftentimes these small scale things that are going on inside the storm, so it is difficult to observe and model that. We don’t have quite high enough resolution models and there is some understanding we don’t have as to these processes that go on.

It is something the Hurricane Center and NOAA are working on.  As you see on this slide there is a project called the Hurricane Forecast Improvement Program. It is trying to tackle some of these issues.  It is a ten year program that hopefully will provide the Hurricane Center with some better modeling efforts which we are starting to see now in real time.  Sandy really did illustrate this problem we have with forecasting rapid changes in strength.

[Slide 23]

As far as the warning challenge in Sandy leading up to Sandy’s landfall in the United States—our model guidance forecast that Sandy was likely to make this transition from a pure tropical system to an extratropical system, more like a wintertime low where it gets its energy more from the contrast of air masses and various fronts that are tied to it.

This led to some difficulty because once the Hurricane Center starts issuing warnings it is difficult for us to switch between the tropical cyclone or tropical storm and hurricane watches and warnings and the non-tropical warnings and watches that are issued by local weather forecast offices.  It left three scenarios that were not very appealing during the event.

One was that if this occurred, even if it occurred a couple of days before landfall, that the Hurricane Center, if it were no longer a tropical system, would cease to issue advisories and transfer the responsibility to other local weather offices as well as the Hydrometeorological Prediction Center.  At that point we would be required to drop the hurricane watches and warnings.  

That was a solution we really didn’t want to see happen because we heard from a lot of emergency managers and others that they didn’t want to see us change the warning type during the middle of the event because that could be confusing.  

The other possible thing was to just continue calling Sandy a hurricane, even if it really wasn’t one.  That could have been more than a day or two before landfall—the timing of when the transition would occur was not well known. We felt that could misrepresent the situation also and damage our credibility as you can only really stretch the science and also calling it what it was for so long.  

The third would be to actually continue issuing advisories on this system even after it became non-tropical or what we call post-tropical but we had advertised in years past when we switched to this new naming convention for post-tropicals that whenever we issued a post-tropical advisory it would be the final advisory.

Being able to disseminate additional advisories after the one which we called the post-tropical we felt could end up breaking some dissemination processes that are in place by the media and other vendors that use our products.  We just didn’t know that the flow of information would continue after that transition so we felt we shouldn’t try that in real time during this.  

So what we decided during several meetings was to eventually issue these non-tropical warnings to north with the forecast that it was going to transition.  The local offices issued the appropriate high wind warnings and covered the event that way.  

I’ll talk a little now about what has happened since Sandy’s landfall. As you all know, Sandy really transitioned late in its life over the water and transitioned as it made landfall and became post-tropical just a couple of hours before landfall in New Jersey.

[Slide 24]

What are we doing to meet this kind of warning challenge for this year and beyond?  Based on what happened last year, and I will talk about this more in a minute, the Weather Service has basically broadened its tropical storm and hurricane  warning and watch definitions to allow them to be used for post-tropical cyclones that pose a significant risk to life and property.

Some of you may have heard about this change already.  This change, the Weather Service and NOAA is doing an assessment of its products and services during Sandy which it typically does for big events, and this question was posed to some emergency managers and users of our products.  Preliminary information is that everyone thinks this is a good change and that is why it is being implemented for 2013.

This is going to give us the option to continue issuing advisory products on post-tropical cyclones that pose a risk to life and property and also when the transfer of responsibility from the Hurricane Center to another national office will result in this unacceptable discontinuity of services. It gives us more options in a case such as Sandy in the future.

The other news you may have heard about is that the Hurricane Center for several years has looked at the possibility of issuing storm surge watches and warnings.  We have been looking at this for the past decade.  With many recent storms such as Katrina, Ike, then Isaac and Sandy this year illustrating that we need to get more public response, make sure we get appropriate public response to the actual hazard that poses the greatest risk to life and property. And that is storm surge. That is why we do evacuate from the coast.  

With this and the events that recently occurred we at the Weather Service have made a decision to move forward with the storm surge watch and warning.  This will be issued independently of where the actual hurricane wind warning could be issued.  Right now the target date is for this to be operational by the 2015 hurricane season.  I will talk more about this in a few slides.

[Slide 25]

Here is a prototype of the storm surge warning.  It would be issued for areas right along the coast.  This would be a collaborative process between folks in our Hurricane Center Storm Surge Unit and also the local weather offices around the country.  This is something planned to debut in the 2015 hurricane system.

[Slide 26]

Another potential upgrade to our storm surge guidance and products is a storm surge inundation graphic.  This graphic is based upon some probabilistic storm surge guidance that is created at the Hurricane Center which takes the forecast track and looks for average errors.  Then takes storms of varying intensities and sizes into the coast spots to get the chance of surge being X number of feet at this location.

Those products are already available at the Hurricane Center website.  This takes that information and provides the most realistic worst case scenario is from a potential hurricane landfall.  This graphic is still being fine-tuned here at the Hurricane Center.  It has been tested with some focus groups and most people feel there is a lot of benefit and need for this graphic.

This is something that could potentially be available for hurricane landfall during the 2013 hurricane season.  A final decision has not been made as to whether it will be available for this year or next year but it may be available in the 2013 season.

[Slide 27]

Some other 2013 changes that are going to occur here this season—one of these is that the definitions of tropical storm and hurricane watches and warnings have been broadened.  The issuance criteria of our advisories have changed to allow us the option to use both for tropical cyclones that pose a threat to life and property as I discussed a few slides ago.  Now if we had a similar Tropical case like Sandy we could issue and maintain a tropical storm or hurricane watch and warning for systems that might transition before landfall.  The Hurricane Center can continue to issue advisory products on that.

I’ll go over the other three on this slide.  I’ll talk about the new use of our National Hurricane Center Cyclone Update product and a planned extension of the Tropical Weather Outlook up to five days in the next few slides.  

[Slide 28]

Whenever a storm was approaching the coast and could be tracked pretty easily on radar the Hurricane Center issues advisories every two hours and in between those two hourly updates there would be a tropical cyclone position estimate product that would come out.  

The test product used to tell you where the storm was located, how many miles it is from a major city and what the current intensity and movement is.  In order to streamline our product suite we actually discontinued this product in favor of issuing this in a current existing product called the tropical cyclone update.

[Slide 29]

The tropical cyclone update is issued when unexpected changes occur in a cyclone if we need to issue international watches or warnings in between advisory times.  A new use for that will be for these one hour updates whenever the storm is making landfall and it can be fairly easily tracked on radar.  

We also sometimes use this product to tell people when landfall has occurred.  Oftentimes the media wants to know when landfall has taken place so it is product we can use for all those reasons.  It is not a huge change for folks out there but it is another place to get a continuous flow of information when a hurricane is making landfall.

[Slide 30]

One change I think all of you will really like for the 2013 season—this is something that is not going to begin on June first.  Over the past few years we have been looking at extending the time period covered by our tropical weather outlook.  The current tropical weather outlook covers a two day or 48 hour period.

In the past several years we have been assigning the chances of systems forming over the next five day period, kind of behind the scenes.  We have done verifications of that and it has proven to be fairly accurate.  Beginning this season, at some point during the season—we are going to be doing some in-house testing and we still have some technical issues we need to work out in the early part of the season—but I would think by July or August timeframe you will start to see this in our text product.

That is—you will get a chance of what this system’s formation potential for the first two days and also the chance of formation over five days.  I’ll give you a little more information about the longer term of the system becoming a tropical depression or tropical storm.  This is how this will look in the current existing text tropical weather outlook.

It makes the paragraph a little longer but you can see here we mentioned the 40% chance of formation in the next 48 hours and later on in the paragraph it tells you there is an 80 percent chance of it becoming a tropical cyclone during the next five days.  We get both of these probabilities now in the outlook beginning in July or August.

[Slide 31]

The other good news is that we are working on a graphic to go along with that.  We are not sure if this will be ready to debut in 2013.  We still have technical issues to overcome but this is a prototype of that graphic.  

The current tropical outlook graphic that you see with the satellite image showing the current location will not change but this graphic will be in addition to that and will show where the disturbance is located currently by an X and then will show the area of possible formation over that five day period and also show using low/medium/high categories what the chances are.  

[Slide 32]

If you click on these you will be able to actually see what the probabilities are as you click.  Some of these areas will overlap and each one will have its own separate graphic as well and you can get the probabilities right on the graphic.  I think this is a good addition to help people have a little more time for planning when systems are forming near land or near the East Coast of United States or Gulf of Mexico.

[Slide 33]

Just to remind folks about the forecast cone—with our improvements in track forecasting our cone continues to shrink in size.  It is constructed by circles that are around each of the forecast times in which two-thirds of the verifying forecast should fall within that circle.  This is based on the five year error distribution from our previous errors in the previous five hurricane seasons.

As our forecasts continue to improve the size of the circles has continued to shrink.  I would remind folks that storm size has not changed.  It just means that you can get more impacts outside of the cone.  We know the cone is a great briefing tool because it provides where the center of the path of the storm is likely to go but it doesn’t tell you much about impacts.

[Slide 34]

With the improvements in track forecasting the size of the cone is going to shrink again by about three to eight or nine percent than it was last year.  It is not a huge change.  You probably won’t notice much but if you do go back and look at cones from several seasons ago to today you will certainly notice a difference.

[Slide 35]

Here is the cone from Isaac advisory in 2013 if it had the 2008 size cone on there.  If you look at the edge of the cone it is at about Jacksonville, Florida all the way to extreme southwest Louisiana.  If you move forward and apply what the 2013 cone would look like you’ll see it is much smaller stopping at the edge of the Florida panhandle and over central Louisiana.  

[Slide 36]

That is not the change from last year to this year—that is the change over a five year period.  The change from last year to this year is pretty small.   It is just to illustrate how the cone has been shrinking over the past 10 to 15 years since we introduced the cone.

[Slide 37]

I’ll move now into some other potential improvements beyond the 2013 time period—some in-house experiments we are working on here at the Hurricane Center.  One of those I have already mentioned is the storm surge warning being planned for 2015 and the inundation graphic that might be available this season but if not it will be available in the 2014 season.  

Some other things we are working on here are producing track and intensity forecasts for disturbances—for systems that have not yet become a tropical cyclone and whether or not we could start to issue watches and warnings for those systems.  The radar image on the screen is the system Tomas back in 2010 that was formed very near the Caribbean islands.

It actually strengthened quickly and became a hurricane as it moved over the islands.  It impacted in such short order that that wasn’t much lead time on the tropical storm or hurricane watches and warnings.  We are looking at ways to issue watches or warnings before systems form.  We are also looking, as our model guidance has gotten better, at the extension of our forecast out to seven days.

[Slide 38]

This is a forecast we issued in the upper right hand corner before Irene actually formed.  This was a forecast about a day before Irene.  In the black is the forecast we actually laid out.  The actual track is in white.  We did a pretty good job of forecasting where it would go even before it actually formed.  We were making these forecasts a couple of years ago and we have been making them in-house.

Right now the forecasts are pretty good but not as good as the forecaster systems that have already formed for normal tropical storm or hurricane forecasts but it is something we are looking at.   At some point we are hoping to be maybe be able to issue watches and warnings before a system forms.

[Slide 39]

Here are a couple of prototype graphics of how that might be done.  We are still working out the details on this.  We don’t know whether we would issue a full advisory of products for a system like this that is still a disturbance or may only issue a watch or warning on one of our existing products like the tropical weather outlook.

Again this would be in coordination with the local National Weather Service offices.  I suspect this would be two or three years down the road at the earliest but it is something we are thinking about here at the Hurricane Center.  I look at Sandy and what happened with the watches and warnings and we are fixing that on the back end of a system when it transition—this is looking at the watch and warning problem as it forms or at the front end of a system.

[Slide 40]

Lastly I’ll finish up with a six and seven day forecasts as the models have improved.  We have started looking at issuing six and seven day forecasts.  The good news is last year we did pretty well on the six and seven day forecasts.  This graph shows in black the Hurricane Center verifying six and seven day forecasts.

You can see the average error at day six was about 240 nautical miles and at day seven it was about 300 miles.  In red and blue are our two primary best models that we get—the U.S. Global Forecast system and the European model.  You can see we, the forecasters here, actually outperformed both of those models at days six and seven.

[Slide 41]

We are planning to do an in-house test on this again this year.  I will mention that when you take those 240 nautical miles and 300 nautical miles errors and place them back on the graph I showed at the beginning of the presentation it shows you the day six forecast is pretty close to what the day four forecasts were about a decade ago when we introduced those. The day seven forecast of about 300 nautical miles is also now equal to about what the day five forecasts were a decade ago.

It shows that we probably will start issuing six and seven day forecasts in the near future.  We haven’t decided exactly how we will do that and I think that is some discussion we are still having—whether we extend the current cone graphics out to day six and seven or display these in a different manner because there is more uncertainty in the longer range forecasts than the shorter range forecasts..

[Slide 42]
I will caution folks that even though we did well last year not all forecasts will be perfect.  Here is our six and seven day forecast for Sandy and you can see it is a large spread.  Here is the European model that was the first to show landfall at day seven.  The USGFS model is out here in black well off the East Coast of the U.S., and at the time this was the Hurricane Center forecast circled in red. It would not have been a very good seven day forecast—much higher than the average I showed on the other screen.  

[Slide 43, 44]

A day or so later the day six forecast begins shifting back toward the U.S. and by day five the forecasts were pretty good.  You can see a little word of caution about the use of six and seven day forecasts and how we might want to display those forecasts.

[Slide 45]

The Hurricane Center is using social media.  I know a lot of emergency management agencies are also using social media.  Our social media accounts have been pretty popular.  We have about 208,000 followers now on our Facebook page and about 110,000 followers on our Twitter feed.  The main Hurricane Center Twitter feed is actually an automated tweet of our advisory products when they come out, but I would also mention that the NHC Storm Surge Unit and Rick Knabb, the Hurricane Center director, are also very active on Twitter if you like to follow them.

For those of you who have social media accounts in the last couple of years we did some public service announcements that were recorded before the hurricane season. This is an example of one—we actually re-recorded those this off-season to freshen those up.  Those should be released in the next few weeks via YouTube.  Please look for that on our website and through our social media.  

I suggest you could use those during National Hurricane Preparedness Week which is the last week of May or perhaps you could link to them on your accounts as well. It talks about the various subjects that are discussed during Hurricane Preparedness Week and also it has some NHC forecasters and Craig Fugate from FEMA doing some of the recordings.  

[Slide 46]

I’m sure every time there is a hurricane threat or major threat you see this uptick in number of followers or users and that was the case last year with Debby and Sandy and some of the major upticks in users.  It is interesting to follow that.

[Slide 47]

For those of you that want to see the faces behind the forecasts I’ll leave this slide up as I answer questions.  These are your hurricane specialists.  You’ll see their names at the bottom of advisories.  It is a pretty tight knit group of folks and we certainly love and enjoy our jobs and hopefully working with you all to make coastal residents better prepared and help them make better decisions when a storm is threatening the area.

Amy Sebring: Thank you very much Dan.  Great presentation. I welcome back to this slide in a moment.  We will move to the Q&A portion.

[Audience Questions & Answers]

Darren Thraen: Can you touch on what is being predicted for the 2013 hurricane season?
Daniel Brown:  NOAA’s seasonal outlook is issued jointly here with the Hurricane Center and  also the Climate Prediction Center.  That forecast will be issued on May 23—towards the middle to late part of May.  I’m sure some of you have seen some of the other season forecasts that have been issued to date.  

Most of these are suggesting we will have another active hurricane season.  I will throw a word of caution in—I know that others may have heard folks in the Hurricane Center reiterating this—seasonal forecasts at this point do not tell you where the storms are going to go and where they will make landfall so as coastal residents and emergency managers there is not much you can do with a seasonal forecast.  You have to prepare each season as if you are going to get hit.  It only takes one to hit your area for it to be a bad year.  

The classic illustration of that is back in 1992 we only had seven named storms—four hurricanes and one major—a very inactive year if you look at it in terms of overall numbers. That one major hurricane was Andrew which struck Florida as a category five storm.  Then you go to 2010 that had nineteen named storms and twelve of those were hurricanes but none of those hurricanes impacted the United States.

Use the seasonal forecast to get people to understand and know that the season is upcoming and as a sign for preparedness.  Besides that there is not a lot of utility in the seasonal forecast on an individual preparedness basis.

Nader Mehravari: Can you comment on reports that the European UK center ECMWF had forecasted hurricane Sandy hitting NY/NJ regions as early as 8 days ahead of time. Are they using tools and techniques that are not available to NOAA?
Daniel Brown: If you remember the slide a couple of slides (slide 42) ago it illustrates that the European model was the first to predict Sandy’s turn back to the United States.  The European model is a very good model.  For the past two or three hurricane seasons it was the best model.  One of the metrics we look at is a two day forecast and compare all the models and it was the best at two days for two or three hurricane seasons in a row.

This past year the USGFS model actually edged the European model out at the two day metric.  Yes, the Europeans do have some different tools and techniques they are do.  That model is finer resolution than the current US model.  Really and truly I would say both the USGFS and the European are the two models we rely on the most here at the Hurricane Center.

I would just caution folks that when they are looking at some of the model guidance to trust the Hurricane Center forecast.  We may have reasons why we go with various models at various times but as you saw with the slide looking at the five, six and seven day forecasts, the Hurricane Center tends to beat the individual models long range for an entire season.

Perhaps in individual time periods the models might beat us but over the long haul the Hurricane Center outperforms most of the individual models.

Any Sebring:  From storm to storm you may have varying levels of confidence in the forecast you pick up in the tropical cyclone discussion.  Has the National Hurricane Center considered trying to quantify the level of uncertainty in a forecast by storm?

Daniel Brown:  That is a really good question. Right now we more or less subjectively talk about forecast confidence in our cyclone discussion.  You’ll see us talk about the model spread.  Our confidence in forecasts is often dictated by the spread of the guidance.  Some of you may be familiar with some products we issued called wind speed probability products.  These provide you the chances of receiving a tropical storm of 58 mile per hour and also hurricane force winds at individual locations.

The technique that produces those uses our past errors to help compute those chances.  That technique also takes into account this model spread.  It has varying confidence levels.  Typically when the spread of the models is lower the Hurricane Center forecasts are better.

We have thought about using that same technique where it looks at the spread of the models to have varying cone sizes in cases where the spread of the models is low and we have high confidence the cone size would be a little smaller.  In times where there is a lot less confidence in a forecast the cone would be larger.

We have not gotten to the point to incorporate that yet.  It is something we have thought about.  If we do at that point we would put something in the discussion that would quantify it such as confidence in this forecast is low, medium or high.  That could be something that might be done in the future.  

I think we want to include that somewhere in our products because there are others that use our numbers to make their own cones.  This would provide them guidance as to which cone size we are going to employ for a given forecast scenario.  Right now none of this is occurring.  The cone size stays the same for the entire season and is not based on model spread.

James Lewis Free: Does NHC have plans to significantly update its platform of real-time maps and infuse them with GIS? Are there plans to eliminate all caps text products?  Thanks for the great presentation.

Daniel Brown:  Yes to the first question—the Hurricane Center has a lot of its products already available in GIS format but yes, we would like to do more and better products in GIS.  Some of that is a resource limitation currently but over time hopefully we would continue to provide more in GIS.  Some of the storm surge inundation, and other things, we would like to get that not only as a static graphic but also in GIS.

The use of caps—why we use all caps goes back to the days of teletype and the World Meteorological Organization and making sure all our products get down to the lowest dissemination method.  That regulation was recently loosened by the World Meteorological Organization and the Weather Service has begun to experiment with mixed case products.

The Hurricane Center was thinking about trying that with our tropical cyclone discussion for the upcoming season but because of technical resource limitations that will wait until 2014 because we have higher priority projects and things like you saw me present here that we want to get out the door first before we spent the time to go to the mixed case.

Hopefully in the next few years you will see us start embracing mixed case like other parts of the Weather Service have.

Ray Pena: It seems you use cyclone and hurricane interchangeably.  Why not stick with hurricane?  (I have also heard cyclone used interchangeably with tornado.)
Daniel Brown:  I know that when we do presentations we sometimes get into the technical jargon.  I used the term “tropical cyclone” because it really is a catch-all for tropical depressions, tropical storms and hurricanes.  All of those are classified as tropical cyclones.  A tropical cyclone is classified using its wind speed into the depression, storm and hurricane categories.

That is why we sometimes lump the word “tropical cyclone” to mean all of those—depressions, storms and hurricanes.  The post-tropical cyclone is a term that simply means it is no longer a tropical cyclone.  It was once one but it is no longer. That term, we have been using for a couple of years, but it got widespread use during Sandy and then the media really began the coin the term “superstorm”.  

Amy Sebring:  You talked about the ten year improvement program.  Is there anything on the horizon that holds promise for improvements in the intensity forecast?

Daniel Brown:  There is one of the early results that shows promise.  When the NOAA hurricane hunters fly out into the storms those aircraft have Doppler radar on the aircraft that can collect Doppler radar data.  That has been used to initialize some of these higher resolution models.  It shows some promise.

I mentioned during the discussion is that one of the difficulties we have is to observe the current structure of the storm.  Having that data into the models to accurately depict the current structure of the storm goes a long way to helping the forecast.  We don’t get the aircraft data, especially from the NOAA aircraft, all that much but this is something that is starting to hold some promise and could be helpful in the future.  It will probably be several years.


Amy Sebring: On behalf of Avagene, myself, and all our participants today, thank you very much Dan for joining us today and sharing this information with us.  While we hope that the 2013 season will not be too active, we do wish you the best.

Our next program is scheduled for May 8th when we will feature the Silver Jackets program, an initiative that provides an opportunity to bring together multiple state, federal, and sometimes tribal and local agencies to learn from one another and apply their knowledge to reduce risk from flooding. Our guests will include the national program manager, Jennifer Dunn, as well as a number of state participants. Please make plans to join us then.

Thanks to everyone for participating today and have a great afternoon!  We are adjourned.