Which Hurricane Forecast Model Should You Trust?

By: Dr. Jeff Masters , 1:05 PM GMT on August 07, 2013

The National Hurricane Center (NHC) set a new record in 2012 for accuracy of their 1, 2, 3, and 4-day Atlantic tropical cyclone track forecasts, but had almost no skill making intensity forecasts, according to the 2012 National Hurricane Center Forecast Verification Report, issued in March 2013. The new records for track accuracy were set despite the fact that the season’s storms were harder than average to forecast. The average error in a 1-day forecast was 46 miles, and was 79 miles for 2 days, 116 miles for 3 days, 164 miles for 4 days, and 224 miles for 5 days. The official track forecast had a westward bias of 10 - 17 miles for 1 - 3 day forecasts (i.e., the official forecast tended to fall to the west of the verifying position), and was 38 and 75 miles too far to the northeast for the 4- and 5-day forecasts, respectively.


Figure 1. Verification of official NHC hurricane track forecasts for the Atlantic, 1990 - 2012. Over the past 15 - 20 years, 1 - 3 day track forecast errors have been reduced by about 60%. Track forecast error reductions of about 50% have occurred over the past ten years for 4- and 5-day forecasts. Image credit: 2012 National Hurricane Center Forecast Verification Report.

NHC Intensity Forecasts: Little Improvement Since 1990
Official NHC intensity forecasts did better than usual in 2012, and had errors lower than the 5-year average error for 1, 2, 3, 4, and 5-day forecasts. However, 2012's storms were easier to predict than usual, due to due to a lack of rapidly intensifying hurricanes. These rapid intensifiers are typically the source of the largest forecast errors. The skill of official NHC 24-hour intensity forecasts made in 2012 for the Atlantic basin were only about 15% better than a "no-skill" forecast; 2, 3, 4, and 5-day intensity forecasts had no skill.


Figure 2. Verification of official NHC hurricane intensity forecasts for the Atlantic, 1990 - 2012. Intensity forecasts have shown little to no improvement since 1990. Image credit: 2012 National Hurricane Center Forecast Verification Report.

Which Track Model Should You Trust?
As usual, in 2012 the official NHC forecast for Atlantic storms was almost as good as or better than any individual computer models--though NOAA's GFS model did slightly better than the NHC official forecast at 12, 24, and 48-hour periods, and the European model forecast was slightly better at 12-hour forecasts. Despite all the attention given to how the European Center (ECMWF) model outperformed the GFS model for Hurricane Sandy's track at long ranges, the GFS model actually outperformed the European model in 2012 when summing up all track forecasts made for all Atlantic named storms. This occurred, in part, because the European model made a few disastrously bad forecasts for Tropical Storm Debby when it was in the Gulf of Mexico and steering currents were weak. For several runs, the model predicted a Texas landfall, but Debby ended up moving east-northeast to make a Northwest Florida landfall, like the GFS model had predicted. However, the best-performing model averaged over the past three years has been the European Center model, with the GFS model a close second. Wunderground provides a web page with computer model forecasts for many of the best-performing track models used to predict hurricane tracks. The European Center does not permit public display of tropical storm positions from their hurricane tracking module of their model, so we are unable to put ECMWF forecasts on this page. Here are some of the better models NHC regularly looks at:

ECMWF: The European Center's global forecast model
GFS: NOAA's global forecast model
NOGAPS: The Navy's global forecast model (now defunct, replaced by the NAVGEM model in 2013)
UKMET: The United Kingdom Met Office's global forecast model
GFDL: The Geophysical Fluid Dynamics Laboratory's hurricane model, initialized using GFS data
HWRF: The intended successor for the the GFDL hurricane model, also initialized using GFS data
CMC: The Canadian GEM model
BAMM: The very old Beta and Advection Model (Medium layer), which is still useful at longer ranges

If one averages together the track forecasts from the first six of these models, the NHC official forecast will rarely depart much from it. As seen in Figure 3, the HWRF and UKMET were well behind the ECMWF and GFS in forecast accuracy in 2012, but were still respectable. The simple BAMM model did well at 3, 4, and 5-day forecasts. The GFDL and CMC models did quite poorly compared to the ECMWF, GFS, UKMET, and HWRF. The Navy's NOGAPS model also did poorly in 2012, and has been retired. Its replacement for 2013 is called the NAVGEM model.


Figure 3. Skill of computer model forecasts of Atlantic named storms in 2012, compared to a "no skill" model called "CLIPER5" that uses just climatology and persistence to make a hurricane track forecast (persistence means that a storm will tend to keep going in the direction it's current going.) OFCL=Official NHC forecast; GFS=Global Forecast System model; GFDL=Geophysical Fluid Dynamic Laboratory model; HWRF=Hurricane Weather Research Forecasting model; UKMET=United Kingdom Met Office model; ECMWF=European Center for Medium Range Weather Forecasting model; TVCA=one of the consensus models that lends together several of the above models; CMC=Canadian Meteorological Center (GEM) model; BAMM=Beta Advection Model (Medium depth.) Image credit: National Hurricane Center 2012 verification report.

Which Intensity Model Should You Trust?
Don't trust any of them. NHC has two main statistical intensity models, LGEM and DSHP (the SHIPS model with inland decay of a storm factored in.) In addition, four dynamical models that are also use to track hurricanes--the GFS, ECMWF, HWRF, and GFDL models--all offer intensity forecasts. With the exception of the GFS model, which had a skill just 5% better than a "no-skill" intensity forecast for predictions going out 36 hours, all of these models had no skill in their intensity forecasts during 2012. The ECMWF and HWRF models were the worst models for intensity forecasts of 3, 4, and 5 days, with a skill of 20% - 60% lower than a "no-skill" forecast. The LGEM model, which was a decent intensity model in 2011, tanked badly in 2012 and had near-zero skill. The only model that was any good in 2012 was the IVCN "consensus" model, which averages together the intensity forecasts of two or more of the intensity models such as LGEM, GFDL, HWRF, and DSHP.

Some Promising Models From the Hurricane Forecast Improvement Project (HFIP)
Last year was the fourth year of a ten-year project, called the Hurricane Forecast Improvement Project (HFIP), aimed at reducing hurricane track and intensity errors by 50%. The new experimental models from HFIP generally performed poorly in 2012. However, the new FIM9 15-km global model was competitive with the ECMWF and GFS models for track, and the new CIRA Statistical Intensity Consensus (SPC3) model for intensity performed better than many of the traditional intensity models.

For those interested in learning more about the hurricane forecast models, NOAA has a 1-hour training video (updated for 2011.) Additional information about the guidance models used at the NHC can be found at NHC and the NOAA/HRD Hurricane FAQ.

Sources of Model Data
You can view 7-day ECMWF and 16-day GFS forecasts on wunderground's wundermap with the model layer turned on.
Longer ten-day ECMWF forecasts are available from the ECMWF web site.
FSU's experimental hurricane forecast page (CMC, ECMWF, GFDL, GFS, HWRF, and NAVGEM models)
NOAA's HFIP model comparison page (GFS, ECMWF, FIM, FIM9, UKMET, and CMC models.)
Experimental HFIP models

Quiet in the Atlantic
There are no tropical cyclone threat areas in the Atlantic to discuss today, and none of the reliable models for tropical cyclone formation is predicting development during the coming seven days. I plan on having a detailed update on Friday to discuss the latest long-range forecasts for the coming peak part of hurricane season.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

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Quoting 476. clwstmchasr:


I keep reading on here that conditions are becoming much for favorable but I'm not seeing it yet. Case in point - the yellow circle on the TWO the NCH says that conditions are expected to be "unfavorable" for the next several days. They didn't even say somewhat or marginally favorable. It is August 7th and climatology would tell us that conditions should become favorable soon. But I am not yet seeing it.

oh yes it is. Mjo is expected and conditions will be favorable.
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Quoting 472. Patrap:
..Eye's keepa one eye out fer that GOM Sauna, Landlubber'





I don't always watch the tropics, but when I do I prefer the GOM.

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Quoting 479. stormpetrol:


It is , I've been watching it for sometime, according to the Obs I'm seeing it might have weak closed low circulation too.



wow!!
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Link
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Quoting 469. 69Viking:


Not this year in NW Florida. This year it means you won't go more than 3 days without rain!


We have been going through the same thing here, seems like whenever it has been a 30% of rain we get rain 100% of the time. I believe it's called bad forecasting!
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Quoting 475. TropicalAnalystwx13:
It's an interesting little buddy.



It is , I've been watching it for sometime, according to the Obs I'm seeing it might have weak closed low circulation too.
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People are still arguing about Camille????

This argument has lasted longer than the storm itself.
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Quoting 472. Patrap:
..Eye's keepa one eye out fer that GOM Sauna, Landlubber'





I agree, waters are warm and moisture is starting to build...
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It's an interesting little buddy.

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Quoting 285. Patrap:
A Lady Called Camille



Im a bit behind on the blog after watching the video A Lady Called Camille. Thanks for the video Pat.....had not seen it before.
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..Eye's keepa one eye out fer that GOM Sauna, Landlubber'



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Quoting 467. Patrap:

Are those thunderstorms in the gulf from that front?
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Wet time ahead for Jamaica it would seems.

MetServiceJA ‏@MetserviceJA 3h

The Wave moves into the Jamaica area near Aug 14 and is enhanced by an upper Trough, likely to create strong afternoon showers + T.storms.
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Quoting 460. NasBahMan:


Not so, when a particular place is forecast to have a 30% chance of rain it simply means that for every 10 days that you have a 30% chance of rain you should actually get rain on 3 of those 10 days.


Not this year in NW Florida. This year it means you won't go more than 3 days without rain!
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Quoting 462. Grothar:




:(
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I just want to put this into perspective, the 2010 season did not produce its 4th named storm until august 21st.
We spawned our Fourth in july (no pun intended).
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Squall passing by South Sound, Grand Cayman this afternoon.
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Quoting NasBahMan:


The level of damage really is a matter of how well buildings are constructed. In the Bahamas very rarely do concrete structures suffer more than some shingle or other roof damage unless they are right on the coast and are low lying in which case they can be damaged by the storm surge rather than the winds. In a lot of the older settlements in Abaco and Eleuthera there are many old wooden homes that were constructed in the 1700's and 1800's and they have been through dozens of Hurricanes and a number of major hurricanes suffering little or no damage as most were constructed by people that had ship building experience and they used that knowledge to construct their homes.

I was in St. George's, Grenada right after Ivan in 2004. For those of you not familiar with St. George's, it's a harbor that's built on an old volcanic caldera. It's a beautiful place but really bad location when a hurricane hits and the storm surge hits the harbor. The hills rise to about 600 feet behind the harbor. This a picture of St. George's on a nice day in 2010, after rebuilding.



This is what it looked like when I got there:



The US had rebuilt many government buildings to modern standards after the 1983 invasion, or liberation, depending on your point of view. These were primarily concrete and well built. This picture is pretty typical of the damage:



The large white building to the left was the main hospital. The concrete shell remained standing but it was completely unroofed and a constructive total loss. The damage was all due to wind. The large cathedral was also destroyed in the same way. The structures on the waterfront were subject to a 22 foot storm surge and suffered proportionately less damage that the new structures higher on the hill, that were more exposed to the wind, estimated at 170 mph. Many of the structures right on the harbor were repairable, but not the ones that took the full force of the wind. Well built concrete structures seem to be able to withstand sea surge damage but even modern structures, when exposed to high enough winds, get unroofed and then the structure itself suffers irreparable damage. St. George's is in a particularly bad location in terms of wind damage, but I could only look at that damage when I was there and wonder how bad it would be of the same type of storm hit anywhere from Miami to Pensacola.
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This is what lack of soil moisture and heat looks like in "Pink/Purple"



Not only do you feel the heat....you can SEE the heat
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Quoting 434. Levi32:


Looks like somebody pirated Allan Huffman's pay-walled content.



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day microphysics of west Africa

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Quoting 423. SecretStormNerd:


My friends dad works for SFWMD and says that they use the percentages to say for instance, "there will be rain in 30% of the area today." Which makes more sense to me.


Not so, when a particular place is forecast to have a 30% chance of rain it simply means that for every 10 days that you have a 30% chance of rain you should actually get rain on 3 of those 10 days.
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BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE CLEVELAND OH
301 PM EDT WED AUG 7 2013

THE NATIONAL WEATHER SERVICE IN CLEVELAND HAS ISSUED A

* TORNADO WARNING FOR...
WESTERN STARK COUNTY IN NORTHEAST OHIO...
EASTERN WAYNE COUNTY IN NORTHEAST OHIO...

* UNTIL 345 PM EDT

* AT 256 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS
STORM WAS LOCATED NEAR ORRVILLE...OR 8 MILES EAST OF WOOSTER...AND
MOVING EAST AT 30 MPH.

* LOCATIONS IMPACTED INCLUDE...
DALTON...BREWSTER...MASSILLON...NAVARRE...NORTH LAWRENCE AND CANAL
FULTON.
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Quoting 406. wxgeek723:


I feel like Sandy was more a meteotsunami than anything else.


Again a lot to do with types of construction and also property that is low lying and vulnerable to storm surge. Hurricane Sandy went over Eleuthera in the Bahamas as a high Cat 1 with wind gusts just over 100 MPH and it caused little to no damage.
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Quoting 434. Levi32:


Looks like somebody pirated Allan Huffman's pay-walled content.
Here?Link
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here the tropical waves I am going to watch for the next five days
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Probably cause the euro is having too many problems lately. Least it's trying.
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Quoting 451. washingtonian115:
So much for favorable conditions in the atlantic?.lol.
Conditions are actually decent and getting better by the day.
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Quoting NasBahMan:


The level of damage really is a matter of how well buildings are constructed. In the Bahamas very rarely do concrete structures suffer more than some shingle or other roof damage unless they are right on the coast and are low lying in which case they can be damaged by the storm surge rather than the winds. In a lot of the older settlements in Abaco and Eleuthera there are many old wooden homes that were constructed in the 1700's and 1800's and they have been through dozens of Hurricanes and a number of major hurricanes suffering little or no damage as most were constructed by people that had ship building experience and they used that knowledge to construct their homes.

Agreed. Most concrete structures will be able to withstand hurricane force winds as long as these structures follow strict building codes. The roofs windows and doors would be the most vulnerable to wind damage.
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Quoting 416. GTstormChaserCaleb:
12z ECMWF...Cape-Verde and Western Caribbean. Link
Shows nothing
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Quoting 450. GTstormChaserCaleb:
It appears the African wave would develop first, but the model kills both systems.
So much for favorable conditions in the atlantic?.lol.
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Quoting 439. washingtonian115:
Doesn't matter I for one am grateful!.Question.So which one develops first?.The caribbean storm or the African wave?.
It appears the African wave would develop first, but the model kills both systems.
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Do we really have to talk about Hurricane Camille?
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nice tropical waves here!
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Quoting 397. TropicalAnalystwx13:
Winds well above Category 5 intensity were recorded along the Gulf Coast when Camille made landfall. It was without a doubt a Category 5 hurricane.

I actually know the people doing the reanalysis for Camille. It's not even being considered a downgradeable storm.






I could not find any evidence anywhere of winds being recorded "well above category 5 intensity". They mention that wind gusts were only estimated to be that high:


"The precise wind speed at landfall will never be known because all measuring instruments were destroyed during the hurricane's impact (it is estimated that gusts reached 322 km/h [200 mph]). Electricity also went out as the storm approached."

While some may have estimated winds to be that strong. I haven't seen damage footage that suggests winds were that extreme.
However, the worst building destruction was actually inflicted by its storm surge:

"Hurricane Camille created the highest storm surge recorded at that time in the Atlantic Basin at 7.5 m (24.6 ft). This measurement was based upon high water marks inside the three surviving buildings (the V.F.W. Club, the Avalon Theatre, and one house) and debris lines in Pass Christian, MS."


Also here are some in total facts about Camille:

"In total, 19,577 homes received major damage or were completely destroyed, 257 people lost their lives, and a total of $1.42 billion (1969 USD) worth of damage occurred as a result of Hurricane Camille."

Clearly it was indeed a very violent hurricane, likely due most notably to surge. What's interesting about this though is that it does bring to question the way we rate hurricanes. Did Katrina really deserve to be rated at landfall what it was? For a long time people assumed a 20 ft surge must occur with a hurricane with category 5 winds, which I believe likely is truly why Camille became well accepted as easily a category 5 hurricane because of its devastating surge.

We now know though obviously because of hurricanes like Ike and Katrina, that such is not necessarily the case. Again though, it does bring to question if a hurricane should really be rated in category entirely on wind speed alone.

Camille just doesn't actually have raw proof that it had category 5 winds at landfall. Could it have been? Sure. But again, some here are acting as if estimation was actual observation. Yes tornadoes are based on estimate speeds, but hurricanes are not. I may not be a certified to estimate wind speeds, but I've seen footage from an awful a lot of high end hurricanes and tornadoes, and I just haven't seen evidence of wind damage that seems consistent with 160 mph sustained winds and 200 mph gusts.

The one possible option is that storm surge already submerged many areas as winds at such strength reached the regions at claimed values of over 200 mph. However, the problem with that is how can one estimate winds with any accuracy if its just blowing across floodwater. Generally speaking, winds are estimated based on their effects and natural landscape such as trees along with their impacts to man made structures.


Ultimately, some here seem to say its pointless to question where it had category 5 winds or not. I don't think its pointless, I think its normal for anyone who is science minded. Again, questioning whether it had category 5 winds does not lessen the historic significance of its impact, it was devastating, regardless of if category 5 winds impacted land or not. If anything, hurricanes like Katrina or Camille that are surge dominate vs wind dominate hurricanes like Charley or Andrew prove that surge/flooding really should be the most feared aspect of a hurricane since there is overwhelming proof that flooding from hurricanes takes way more lives than wind.


I think its worth discussing, but there really is no way to no for sure given the limited amount of data so to me its just a fun discussion.


Link
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Quoting 421. opal92nwf:
I'll be back later, and don't forget to be looking for a new blog post of mine on my experience with Tropical Storm Claudette in 2009!

69Viking: No worries (:


I've been through so many storms I don't even remember Claudette and the center went right over where I live LOL!
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Quoting 439. washingtonian115:
Doesn't matter I for one am grateful!.Question.So which one develops first?.The caribbean storm or the African wave?.


Good question. All I know is that the season hasn't even really started and I'm ready to fast forward to Winter lol.
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Good afternoon all!

Kingston Jamaica weather station
( updated Wed, 07 Aug 2013 12:59 pm EST )

30°C
High: 31°C | Low: 26°C
Showers in the Vicinity

Sunrise: 5:46 am
Sunset: 6:36 pm
Visibility: 9.99 km
Feels like: 30°C
Humidity: 74%
Wind: 16.09 km/h
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Quoting 410. StormTrackerScott:


I agree! One poster on here already mentioned that 170mph winds where measure on an Oil Rig 60 miles offshore before the anemometer gave out. Also once the storm surge came onshore that when the 200mph winds came in. Point is lots of structures were already underwater once the intense winds came in.


And the anemometers onshore all broke due to the intensity of the winds. I also read that when it came ashore the eye was only 12 miles wide and hurricane force winds only extended out to 60 miles, that's a small storm so some areas close to the storm could have easily missed out on major damage.
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Quoting 435. MississippiWx:


How did you get this? Isn't this a pay-model site?
Doesn't matter I for one am grateful!.Question.So which one develops first?.The caribbean storm or the African wave?.
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Was just looking at a local surf report/forecast site and it said to watch the area of low pressure over the Bahamas as it moves west into the Gulf. It seems to my untrained eye to have upper and mid level circulation? probably me being wishful of some surf but curious with it being so quiet why no one on here is mentioning it?
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Quoting 434. Levi32:


Looks like somebody pirated Allan Huffman's pay-walled content.


Lol. Beat me by a few seconds.
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436. 789
I like looking around north africa
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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather