Katrina-level storm surges have more than doubled due to global warming

By: Dr. Jeff Masters , 2:08 PM GMT on March 25, 2013

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Since 1923, there has been a ‘Katrina’ magnitude storm surge every 20 years, according to a storm surge index developed by Aslak Grinsted, an assistant professor at the Centre for Ice and Climate at the Niels Bohr Institute. The index uses data from six tide gauges along the U.S. coast from Texas to New Jersey from 1923 - 2011, and is part of a statistical model that links global temperatures to the risk of Katrina-level storm surges. Because of global warming, Katrina-magnitude storm surge events have now more than doubled in frequency since the late 1800s, Grinsted and colleagues argue, in research published in March 2013 in the scientific journal, Proceedings of the National Academy of Science (PNAS). Their statistical model found that an increase of 0.4°C in global temperatures was sufficient to double the odds of Katrina-magnitude storm surges. Since global temperatures have risen 0.6°C since the late 1800s, "we have already crossed the threshold where more than half of all ‘Katrinas’ are due to global warming,” said Grinsted in a press release. Projecting into the future, the model predicts that if the global climate warms as expected by 2°C before the end of the century, Katrina-level storm surge events will become ten times more common, and a Katrina-level surge will occur, on average, every 2 years, instead of every 20 years. Since sea level is steadily rising due to global warming, these future storm surges will also be riding in on top of an elevated ocean surface, and will thus be able to do even greater damage than in the past. Since this is a simple statistical model, I am hopeful that the relationship Grinsted at al. found might break down as the climate warms, due to unexpected changes in hurricane tracks, wind shear, etc. However, this high-end consequence of global warming is quite possible, and is something coastal planners should should consider, particularly since the U.S. population living along the coast is expected to grow from 123 million in 2010 to 134 million people by 2020, according to a NOAA report issued on March 25. We need to retreat from barrier islands highly vulnerable to storm surge, and invest in significantly improved shoreline protection measures in the coming decades.


Figure 1. High water marks on East Ship Island, Mississippi, after Hurricane Katrina in 2005. Katrina brought the highest storm surge ever recorded on the U.S. coast, 27.8' at Pass Christian, MS. Left image: Bark stripped off a tree with salt-burned pine trees in the background (note the 25 ft (7.65 m) long survey rod for scale). Right: Massive beach and over wash erosion illustrated by damaged and snapped pine trees along the beach. Arrows show the the high water mark left by the storm surge. Image credit: Fritz et al., 2007, "Hurricane Katrina storm surge distribution and field observations on the Mississippi Barrier Islands" (PDF File), Estuarine, Coastal, and Shelf Science (2007), doi:10.1016/j.ecss.2007.03.015.


Figure 2. Number of Katrina magnitude surge events per decade for the past and future computed using gridded global temperatures and a statistical model relating global temperatures to storm surges. Confidence intervals of 5% and 16% are shown in the lighter blue colors. Image credit: Niels Bohr Institute at the University of Copenhagen.

References
Grinsted, A., J. C. Moore, and S. Jevrejeva, 2012, "A homogeneous record of Atlantic hurricane surge threat since 1923," PNAS 2012, doi:10.1073/pnas.1209542109

Grinsted, A., J. C. Moore, and S. Jevrejeva, 2012, "Projected Atlantic hurricane surge threat from rising temperatures" PNAS March 18, 2013 201209980, doi: 10.1073/pnas.1209980110

Jeff Masters

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Quoting GeoffreyWPB:
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MIAMI FL
543 PM EDT MON MAR 25 2013

.UPDATE...
THIS IS A QUICK UPDATE FOR THE FIRE SECTION OF THE AFD. THE LATEST
FORECAST MODELS ARE SHOWING THE 20 FOOT WINDS TO BE GREATER 15 MPH
ON TUESDAY OVER SOUTH FLORIDA. AT THE SAME TIME...THE RELATIVE
HUMIDITIES WILL BE IN THE 20S FOR SEVERAL HOURS OVER SOUTH FLORIDA
ALONG WITH THE ENERGY RELEASE COMPONENT (ERC) IN THE UPPER 20S TO
LOWER 30S. SO AT THIS TIME A FIRE WEATHER WATCH HAS BEEN ISSUED
FOR ALL OF SOUTH FLORIDA FOR TUESDAY.


20 foot winds?
Member Since: July 17, 2009 Posts: 71 Comments: 28054
Gonna be chilly in South Carolina this week. From Greenville-Spartanburg discussion:

LOOKING AHEAD TO WEDNESDAY NIGHT AND THURSDAY MORNING...TEMPS SHOULD BE AS COLD OR COLDER AS RADIATIONAL COOLING CONDITIONS WILL BE BETTER. IN OTHER WORDS...GET USED TO FROST AND FREEZE WARNINGS OUTSIDE OF THE MOUNTAINS THIS WEEK.
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wow yet another bad one next week???.............
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Zepherhills..another freeze warning for your area............A Freeze Watch is posted for late Tuesday night through early Wednesday morning for Citrus and Hernando counties.
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From the Houston-Galveston forecast discussion:

HIGH PRESSURE WILL SETTLE OVER THE REGION TONIGHT. IDEAL RADIATIONAL CONDITIONS WILL EXIST AS THE AIR MASS IS VERY DRY AND WINDS ARE EXPECTED TO DECOUPLE.

Looks like some records will fall in SE Texas.
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236. etxwx
Quoting AtHomeInTX:


With Easter approaching I'm hoping this is the end of the freezes...again... :)


I'm sure we'll treasure this moment when it's 110F this summer, but yup, I'm ready to be done with the freezes.
Member Since: Posts: Comments:
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MIAMI FL
543 PM EDT MON MAR 25 2013

.UPDATE...
THIS IS A QUICK UPDATE FOR THE FIRE SECTION OF THE AFD. THE LATEST
FORECAST MODELS ARE SHOWING THE 20 FOOT WINDS TO BE GREATER 15 MPH
ON TUESDAY OVER SOUTH FLORIDA. AT THE SAME TIME...THE RELATIVE
HUMIDITIES WILL BE IN THE 20S FOR SEVERAL HOURS OVER SOUTH FLORIDA
ALONG WITH THE ENERGY RELEASE COMPONENT (ERC) IN THE UPPER 20S TO
LOWER 30S. SO AT THIS TIME A FIRE WEATHER WATCH HAS BEEN ISSUED
FOR ALL OF SOUTH FLORIDA FOR TUESDAY.
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Our nor'easter is showing signs of going warm core in the lower atmosphere.



Member Since: August 2, 2006 Posts: 47 Comments: 11908
GFS Next Monday......................
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Quoting TomTaylor:
Thanks for that PPT, interesting stuff.

I agree with them. From my experience, 00z and 12z are generally more accurate/skillful. For the sake of the CMC vs GFS comparison, however, I did provide you with the values for the 00z/12z vs 06/18z 500mb NH ACC and did show that it didn't really make much of a difference...CMC still scores better regardless of the GFS cycle.

Do you have a source where I can read up on this interesting subject regarding the CMC?
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Quoting Doppler22:

Hope for a severe weather season in May?
I hope the world explodes....jk...really...jk..:)
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warm up coming next week..hope it stays this time..
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suns going down and its cooling off Fast.40's tonight here..
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Quoting nrtiwlnvragn:


NCEP would disagree on the "isn't much of a difference"


06Z and 18Z cycles are consistently slightly worse than the other two
cycles. However, since mid-2007 the gap has been reduced. The GFS was
upgraded from sigma to sigma-p vertical coordinate and from SSI to GSI
data assimilation technique in May 2007.

Link
Thanks for that PPT, interesting stuff.

I agree with them. From my experience, 00z and 12z are generally more accurate/skillful. For the sake of the CMC vs GFS comparison, however, I did provide you with the values for the 00z/12z vs 06/18z 500mb NH ACC and did show that it didn't really make much of a difference...CMC still scores better regardless of the GFS cycle.
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Quoting KEEPEROFTHEGATE:
day ten still shows warm up nice with a cool down following behind it




Hmm... perhaps that cooldown will coincide with the possible April 6th storm to form a parting gift from old man winter?

Link

Would be quite a late storm...
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Quoting TropicalAnalystwx13:
Slowly but surely the Arctic Oscillation and Negative Arctic Oscillation will be moving towards the neutral line. Maybe, just maybe, the warmer forecast from the GFS isn't an April Fools joke.




Hope for a severe weather season in May?
Member Since: February 13, 2012 Posts: 11 Comments: 3906
Quoting TomTaylor:
While that makes some sense in theory, from what I've found, a warm Indian Ocean is not necessarily a good thing. The Sahel is actually wetter when the Indian Ocean is cool, and ACE is usually higher when the Indian Ocean is cool (see below). Unfortunately, a warm Indian Ocean also has a decent correlation with the ENSO. So it is hard to tell if a warm Indian Ocean actually has a negative effect on activity over the tropical Atlantic, or if it's just the ENSO's influence creating a warm Indian Ocean while simultaneously making conditions less favorable across the Atlantic.


SST Anomalies during the Top 10 ACE Years, notice how cold the Indian Ocean is.




Overall, I'd say a warm Indian Ocean is not a beneficial thing to activity in the tropical Atlantic. More rising air in one basin generally means less in the others.

I like the way you cite sources to backup your opinion.

Edit: On this post anyway. LOL Regarding a subsequent post, nrtiwlnvragn is reliable as usual.
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Slowly but surely the Arctic Oscillation and Negative Arctic Oscillation will be moving towards the neutral line. Maybe, just maybe, the warmer forecast from the GFS isn't an April Fools joke.



Member Since: July 6, 2010 Posts: 113 Comments: 34193
Quoting etxwx:


Meanwhile etxwx gathers up old sheets and goes out to cover up the tomatoes and squash muttering "Dang it!! I thought we already had blackberry winter..."


With Easter approaching I'm hoping this is the end of the freezes...again... :)
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222. etxwx
Quoting AtHomeInTX:


Well it's not doing much for my disposition anyway. UGH! lol

Freeze Warning in effect Tonight for most of Southeast Texas

The National Weather Service in Lake Charles has issued a Freeze Warning...which is in effect from 3 am to 8 am Tuesday. This warning upgrades the freeze watch previously in effect.



Meanwhile etxwx gathers up old sheets and goes out to cover up the tomatoes and squash muttering "Dang it!! I thought we already had blackberry winter..."
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From Ryan Maue's Twitter feed

Ryan Maue‏@RyanMaue2h
During last 60-months, 103 global major tropical cyclones (Apr 2008 - March 2013). Previous 60-months had 131 -- 20% decrease over decade.


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Quoting TomTaylor:
True. However, it has been shown that 5 days out there isn't much of a difference in skill scores between the different cycles of the GFS. From the last 31 Days of NH 500mb forecasts ACC looks like this: 00z at 0.890, 06z at 0.892, 12z at 0.882, and 18z at 0.887. Not much variation really.

Yes, it was upgraded on the 13th of February. Horizontal resolution went from 33km to 25km and some changes in physics and data assimilation were also made. Here's a link to the details Sorry, it's from weatherbell which you need a subscription for.

NCEP does it's own verification, however, here's the link to that.


NCEP would disagree on the "isn't much of a difference"


06Z and 18Z cycles are consistently slightly worse than the other two
cycles. However, since mid-2007 the gap has been reduced. The GFS was
upgraded from sigma to sigma-p vertical coordinate and from SSI to GSI
data assimilation technique in May 2007.

Link
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Quoting KEEPEROFTHEGATE:
quiet here this evening must be the late winter shock doing everyone in


Well it's not doing much for my disposition anyway. UGH! lol

Freeze Warning in effect Tonight for most of Southeast Texas

The National Weather Service in Lake Charles has issued a Freeze Warning...which is in effect from 3 am to 8 am Tuesday. This warning upgrades the freeze watch previously in effect.

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Beautimus week for West Palm Beach...Also some possible record lows in some locations...

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Quoting KEEPEROFTHEGATE:
nice warm shot at the end of the run that will cvome with a price



Some pretty aggressive snow melt and flooding downstream in parts of the mid-West and Mississippi floodplain basin....
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Quoting yonzabam:
Arctic Ocean sea ice area is now past the maximum extent, and has now started to 'dive'. It's a fair bit below the 2012 extent for this time of year.

2012 set a new minimum sea ice area in September of last year, by a huge margin. This was partly due to an unusual summer storm, which broke the ice up, accelerating the melt.

The current 'dive' might be a temporary fluctuation, but as cold air has flowed out of the Arctic, bringing unseasonally low temperatures to North America and Europe, warm air has move north into the Arctic, so this might be more of a long term trend.

Will 2013 beat the 2012 record? I doubt it, because of the magnitude of the 2012 record. But, we wait and see.
The storm last August definitely helped stir things up a bit, but given how badly previous record minimums in area, extent, and volume were beat, researchers think it's highly likely records would have been broken anyway. As for this year, a volume record (the truest metric) is almost certain to happen--I'd put the odds at about 90%. Odds in either area and extent are less likely, though it's entirely within the realm of possibility that records will be set in both those, as well.
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Spring vs. Winter
Member Since: February 13, 2012 Posts: 11 Comments: 3906
The GFS shows warm weather building across the East starting on April 1.

Probably just a cruel April Fools joke.
Member Since: July 6, 2010 Posts: 113 Comments: 34193
Went over 80, 2nd day in a row, 80.6F....
Member Since: February 29, 2012 Posts: 0 Comments: 6796
quiet here this evening must be the late winter shock doing everyone in
Member Since: July 15, 2006 Posts: 192 Comments: 59083
Baltimore broke the 80 year old snowfall record (2.5" in 1933).
Member Since: February 13, 2012 Posts: 11 Comments: 3906
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day ten still shows warm up nice with a cool down following behind it

Member Since: July 15, 2006 Posts: 192 Comments: 59083
165 yonzabam: The viral epidemic. Strange it wasn't mentioned in the BBC story.

Turns out it was reported as a porcine circovirus rather than an influenza virus.
Unsurprisingly considering the degree of corruption amongst the local officials, more-than-13,000 dead pigs found floating and still the "Water quality in the Huangpu River has been normal up to now," [according to an] official at the Shanghai Information Office. He also stressed that porcine circovirus cannot be contracted by humans. cough cough
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Quoting MississippiWx:


Speaking of the wave train, something that is often overlooked is the warmth of the Indian Ocean. It could be considered the breeding ground of our tropical waves. When the Indian Ocean is anomalously warm, like now, it can make our waves much stronger. That is also a place to keep an eye on as we get closer to the season.

While that makes some sense in theory, from what I've found, a warm Indian Ocean is not necessarily a good thing. The Sahel is actually wetter when the Indian Ocean is cool, and ACE is usually higher when the Indian Ocean is cool (see below). Unfortunately, a warm Indian Ocean also has a decent correlation with the ENSO. So it is hard to tell if a warm Indian Ocean actually has a negative effect on activity over the tropical Atlantic, or if it's just the ENSO's influence creating a warm Indian Ocean while simultaneously making conditions less favorable across the Atlantic.


SST Anomalies during the Top 10 ACE Years, notice how cold the Indian Ocean is.




Overall, I'd say a warm Indian Ocean is not a beneficial thing to activity in the tropical Atlantic. More rising air in one basin generally means less in the others.
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nice warm shot at the end of the run that will cvome with a price

Member Since: July 15, 2006 Posts: 192 Comments: 59083
205. VR46L
I wonder if the east coast storm is the last winter storm ... Look at what is in the Northern Pacific...




Sorry this image wont update as its one you have to rehost
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Quoting Gearsts:
So with the CMC upgraded it won't create monster randomly in the atlantic?

I think I remember reading in the update statement that the number of ghost storms the model showed wasn't going to change. Not completely positive.
Member Since: July 6, 2010 Posts: 113 Comments: 34193
Quoting Gearsts:
So with the CMC upgraded it won't create monster randomly in the atlantic?

Quoting CMC:
OVERALL, THE GDPS-3.0.0 SHOWS A SIGNIFICANT INCREASE IN TC HIT RATE, AND A REDUCTION IN THE INTENSITY BIAS, RESULTING FROM THE INCREASED RESOLUTION OF BOTH THE FORECAST AND ANALYSES COMPONENTS. THIS IS MORE EVIDENT OVER THE ATLANTIC AND EAST PACIFIC BASINS, WHERE SMALL-SCALE TCS OCCUR MORE FREQUENTLY. NO SIGNIFICANT CHANGES WERE FOUND IN THE AVERAGE TC POSITION ERRORS OR IN THE NUMBER OF FALSE ALARMS.


source
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202. VR46L
Quoting Gearsts:
So with the CMC upgraded it won't create monster randomly in the atlantic?


Or doom the east coast when the other models trend west.....
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RE 162 TropicsWeather

Hi, there! Thanks for the update.

Looks like I'll get the day of sun for the visit tomorrow. Then, bring the rain on! A bunch of us were talking about it today and we realized that this side of the island is almost three months without a good rainfall.

I actually thought about it and our Carnival is next month, and along with that, come the rains. But I'm afraid they won't come soon enough. I'm sitting here typing, glaring at all that metal shelving, with the tools....and actually starting to laugh over it. I sorely need the cistern reading but I just know the minute I decide to move it all, the rain WILL arrive!

Thanks again!

Lindy
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Quoting nrtiwlnvragn:


A fairer comparison would be to only use the 00Z and 12Z data for the GFS also.
True. However, it has been shown that 5 days out there isn't much of a difference in skill scores between the different cycles of the GFS. From the last 31 Days of NH 500mb forecasts ACC looks like this: 00z at 0.890, 06z at 0.892, 12z at 0.882, and 18z at 0.887. Not much variation really.

Quoting StormTrackerScott:


Hi Tom, I've been wondering if the CMC was upgraded because as that model has been mirroring the Euro of late. Examples below from the 12Z as both the Euro and CMC show a weak low in the NE GULF while the GFS shows nothing.

CMC


Euro


GFS


Yes, it was upgraded on the 13th of February. Horizontal resolution went from 33km to 25km and some changes in physics and data assimilation were also made. Here's a link to the details
Quoting Tropicsweatherpr:


Very interesting the model wars going on. Do you have the source to the graphics?
Sorry, it's from weatherbell which you need a subscription for.

NCEP does it's own verification, however, here's the link to that.
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79.6 here Airport is 82 ..... Last day for these higher temps ...........
Member Since: February 29, 2012 Posts: 0 Comments: 6796
Quoting MississippiWx:
Anyone else feel like that eddy in the Eastern Gulf of Mexico is providing an omen? I spy an eye.

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Anyone else feel like that eddy in the Eastern Gulf of Mexico is providing an omen? I spy an eye.

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Arctic Ocean sea ice area is now past the maximum extent, and has now started to 'dive'. It's a fair bit below the 2012 extent for this time of year.

2012 set a new minimum sea ice area in September of last year, by a huge margin. This was partly due to an unusual summer storm, which broke the ice up, accelerating the melt.

The current 'dive' might be a temporary fluctuation, but as cold air has flowed out of the Arctic, bringing unseasonally low temperatures to North America and Europe, warm air has move north into the Arctic, so this might be more of a long term trend.

Will 2013 beat the 2012 record? I doubt it, because of the magnitude of the 2012 record. But, we wait and see.

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Quoting Neapolitan:
So is it your contention that sea level rise will only be a problem if it occurs over the course of a particular person's homebuying years? Because that seems a bit illogical. The thing is, it ultimately doesn't matter whether the waves rise two feet or four feet over a person's 20-year homebuying range; underwater is underwater, and an area rendered unsuitable for building my home because of rising seas will be unsuitable for everyone else.

While what you say about some humans living for today and not worrying much about tomorrow has validity, that's certainly not a blanket statement true of everyone. If it were, there'd be no need for financial planning, or life insurance, or the writing of wills, or zoning, or corporate continuation plans, or annuities, or what have you. While some folks will certainly stumble through their lives blissfully unprepared for the future, others care enough about themselves, their children, their planet, and their legacy to want to avoid the foolish--and in the face of rising seas, it doesn't get more foolish than (re)building a home on a transient and ephemeral barrier beach.



You seem to be suggesting that I was contending it is preferable or desirable to live for the moment and not plan for the future. I was not saying that, I was saying that many in fact do just that. And believe it or not, a lot of those who buy waterfront property are the sorts of folks who care not about the future of their heirs, much less others with whom they do not associate with directly. I know this from personal experience. And most such folks are not stupid, ignorant or uneducated, they are just selfish.

Many people would place buying insurance, formulating investments and making wills into an entirely different mental compartment from such issues as sea level rise, if you stop to think about it objectively. In fact, they typically just hand such things off to their financial advisor or attorney and say, "handle it, handle it!" Corporate financial responsibilities are another matter altogether, especially for publicly traded companies. And government decisions are beholden to many factors, including but not limited to the possible effects of sea level rise.

My only point was that people here were wondering why anyone would buy property on low-lying and vulnerable coastal areas, why those who have been poorly affected already as a result of doing that would be able to sell to someone else who might be considered to be "clueless" and so on. I was just trying to provide a valid reason why this happens, not endorsing it as sound policy.

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Quoting TomTaylor:
GFS has fallen back to the fourth best global model. ECMWF and UKMET have long been ahead of the GFS and with the recent upgrade to the CMC, the CMC has also passed the GFS. It is important to keep in mind that each model has its strengths, weaknesses, and biases. For example, the GFS is likely still a better model when it comes to forecasting tropical cyclones in the Atlantic. Nonetheless, when it comes to the extratropical pattern evolution (arguably the most important metric for determining a model's skill), our beloved GFS is now firmly in fourth place.

CMC NH 500mb ACC




GFS NH 500mb ACC





Very interesting the model wars going on. Do you have the source to the graphics?
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Quoting Gearsts:
So with the CMC upgraded it won't create monster randomly in the atlantic?


No promises. :-D
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Quoting TomTaylor:
Yep. Also supposed to be wet around Ethiopia and near the Sahel. Good signs for the future of the wave train.

GFS 8 Day Precipitation Anomaly



Speaking of the wave train, something that is often overlooked is the warmth of the Indian Ocean. It could be considered the breeding ground of our tropical waves. When the Indian Ocean is anomalously warm, like now, it can make our waves much stronger. That is also a place to keep an eye on as we get closer to the season.

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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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