Hurricanes and Climate Change: Huge Dangers, Huge Unknowns

By: Dr. Jeff Masters , 9:57 AM GMT on August 05, 2013

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Hurricane Sandy's enormous $65 billion price tag put that great storm in third place for the most expensive weather-related disaster in U.S. (and world) history, and six of the ten most expensive U.S. weather-related disasters since 1980 have been hurricanes. Thus, how the strongest hurricanes may be affected due a changing climate is a topic of critical concern. Since hurricanes are heat engines that extract heat energy from the oceans to power themselves, hurricane scientists are confident that the very strongest storms will get stronger by the end of the century, when Earth's land and ocean temperatures are expected to warm 2 - 3°C, to levels unmatched since the Eemian Era, 115,000 years ago. Computer modeling work consistently indicates that greenhouse warming will cause the globally averaged intensity of tropical cyclones to shift towards stronger storms, with intensity increases of 2–11% by 2100. But hurricanes are fussy creations, and are sensitive to wind shear and dry air. Although the strongest storms should get stronger when "perfect storm" conditions are present, these "perfect storm" conditions may become less frequent in the future, due to the presence of higher wind shear, altered atmospheric circulation patterns, or more dry air at mid levels of the atmosphere. Indeed, the climate models used to formulate the 2007 IPCC report suggested that we might see the strongest hurricanes getting stronger, but a decrease in the total number of hurricanes in the Atlantic (and worldwide) later this century. However, the latest set of models used to formulate the 2013 IPCC report left open the possibility that we might see in increase in the total number of hurricanes, and and increase in their intensity. Given the conflicting model results, we really don't know how global warming will affect the number of hurricanes and their intensity, but we run the risk of making one of humanity's greatest scourges worse.


Figure 1. The list of most expensive U.S. weather-related disasters since 1980 is dominated by hurricanes.

Climate models and hurricane frequency
The database we have on historical hurricanes does not extend far enough into the past and is not of high enough quality to make many judgements on how human-caused climate change may be affecting these great storms. A landmark 2010 review paper, "Tropical Cyclones and Climate Change", authored by ten top hurricane scientists concluded that the U.S. has not seen any long-term increase in landfalling tropical storms and hurricanes, and that "it remains uncertain whether past changes in tropical cyclone activity have exceeded the variability expected from natural causes" (tropical cyclone is the generic term which encompasses tropical depressions, tropical storms, hurricanes, and typhoons.) Based in part on modeling studies using climate models run for the 2007 IPCC report, the scientists concluded that "it is likely that global mean tropical cyclone frequency will either decrease or remain unchanged owing to greenhouse warming." For example, one of the modeling studies the review paper quoted, Knutson et al. (2008), "Simulated reduction in Atlantic hurricane frequency under twenty-first-century warming conditions", projected a decrease in Atlantic tropical storms by 27% and hurricanes by 18% by the end of the century. An important reason that their model predicted these decreases was due to a predicted increase in wind shear. As I explain in my wind shear tutorial, a large change of wind speed with height over a hurricane creates a shearing force that tends to tear the storm apart. The amount of wind shear is critical in determining whether a hurricane can form or survive.

But a July 2013 study by MIT's Dr. Kerry Emanuel, "Downscaling CMIP5 climate models shows increased tropical cyclone activity over the 21st century", challenged this result. Dr. Emanuel argued that tropical cyclones are likely to become both stronger and more frequent as the climate continues to warm. This increase is most likely to occur in Western North Pacific, with smaller increases in the Atlantic. Dr. Emanuel took output from six newer higher-resolution climate models used to formulate the 2013 IPCC report, and used the output to drive a high-resolution hurricane model. The simulations found that the global frequency of tropical cyclones would increase by 11% to 40% by 2100, with intensity increases as well. The combined effects produced a global increase in Category 3 and stronger hurricanes of 40%. The behavior of these strongest hurricanes is critical, since they do most of the damage we observe. Over the past century, Category 3 - 5 hurricanes accounted for 85% of US hurricane damage, despite representing only 24% of U.S. landfalling storms. Category 4 and 5 hurricanes made up only 6% of all U.S. landfalls, but accounted for 48% of all U.S. damage (if normalized to account for increases in U.S. population and wealth, see Pielke et al., 2008.)


Figure 2. Projected changes in tropical cyclone track density during the 2006-2100 period compared to the 1950-2005 period, using output from six climate models included in the 2013 IPCC report. The global frequency of tropical cyclones is predicted to increase by 11% to 40%, with the largest changes occurring in the Northwest Pacific off the coast of Japan. Smaller increases are predicted for the Atlantic and near Australia. Image credit: Kerry Emanuel, "Downscaling CMIP5 climate models shows increased tropical cyclone activity over the 21st century", Proceedings of the National Academy of Sciences, July 8, 2013, doi: 10.1073/pnas.1301293110.

However, a study by Knutson et al. (2013), using the same latest-generation climate models as used by Emanuel (2013), but using the output from the models to drive a different high-resolution hurricane model, found a 20% decrease in Atlantic tropical storms and hurricanes by 2100. Two other 2013 studies by Villarini et al. and Camargo, also using output from the 2013 IPCC models, found essentially no change in Atlantic tropical cyclones. The reason for the differences, lies, in part, with how much global warming is assumed in the studies. Dr. Emanuel's study, which found an increase in tropical cyclone activity, assumed a worst-case warming situation (RCP 8.5), following the "business as usual" emissions path humanity is currently on. The Knutson et al. study, which found a decrease of 20% in Atlantic tropical cyclones, used a scenario (RCP 4.5) where it was assumed humans will wise up and cause about half of the worst-case greenhouse warming. The study found found "marginally significant" increases in Atlantic Category 4 and 5 hurricanes of 39% - 45% by 2100. These dramatically different results give credence to Dr. Emanuel statement at the end of his paper, "the response of tropical cyclones to projected climate change will remain uncertain for some time to come." The 2013 IPCC report also emphasized the high amount of uncertainty in how climate change might affect hurricanes, stating that there was "low confidence" that we have observed any increases in intense tropical cyclones due to human causes. However, since the 1970s, it is virtually certain (99 - 100% chance) that the frequency and intensity of hurricanes and tropical storms in the North Atlantic has increased, and there is medium confidence that a reduction in small air pollution particles (aerosols) over the North Atlantic caused part of this effect. The report's forecast for the future stated that it is "more likely than not" (50 - 100% chance) that human-caused climate change will cause a substantial increase in intense tropical cyclones in some ocean basins by 2100, with the Western North Pacific and Atlantic being at particular risk. Also, there will likely (66 - 100% chance) be an increase in both global mean tropical cyclone maximum wind speed and rain rates by 2100, and more likely than not (50 - 100% chance) that the increase in the most intense tropical cyclones will be larger than 10% in some basins.


Figure 3. Expected change in Atlantic Category 4 and 5 hurricanes per decade expected by the year 2100, according to Knutson et al. (2013), "Dynamical Downscaling Projections of 21st Century Atlantic Hurricane Activity: CMIP3 and CMIP5 Model-based Scenarios." This research used the latest generation of climate models from the 2013 IPCC report, and found "marginally significant" increases in Atlantic Category 4 and 5 hurricanes of 39% - 45% by 2100.

Commentary
Hurricane damages are currently doubling every ten years without the effect of climate change, according to Pielke et al., 2008. This is primarily due to the increasing population along the coast and increased wealth of the population. The authors theorize that the Great Miami Hurricane of 1926, a Category 4 monster that made a direct hit on Miami Beach, would have caused about $150 billion in damage had it hit in 2005. Thus, by 2015, the same hurricane would do $300 billion in damage, and $600 billion by 2025. This is without considering the impact that accelerating sea level rise will have on storm surge damages. Global sea level rise over the past decade has been about double what it was in the 20th century, and the rate of sea level rise is expected to increase further in the coming decades. Storm surge does the majority of damage in major hurricanes, and storm surges riding on top of higher sea levels are going to do a lot more damage in the coming decades. If we toss in the (controversial) increases in Category 3 and stronger storms like Dr. Emanuel suggests may occur, the hurricane damage math gets very impressive. We can also add onto that the relatively non-controversial increase in tropical cyclone rainfall of 20% expected by 2100, which will sharply increase damages due to fresh water river flooding. It is controversial whether or not we are already be seeing an increase in heavy precipitation events associated with tropical cyclones in the U.S., though. The total number of daily rainfall events exceeding 2" associated with tropical cyclones in the Southeast U.S. on a century time scale has not changed significantly, according to Groisman et al., 2004. But a 2010 study by Kunkel et al., "Recent increases in U.S. heavy precipitation associated with tropical cyclones", found that the number of Southeast U.S. tropical cyclone heavy precipitation events, defined as 1-in-5-year events, more than doubled between 1994 - 2008, compared to the long-term average from 1895 - 2008.


Figure 4. Time series of the 15-year running average (plotted at the end point of the 15-yr blocks) of a Tropical Cyclone Heavy Precipitation Index (red) and 15-year running average of U.S. landfalling hurricanes (blue). Note that there has been no long-term increase in U.S. landfalling hurricanes, but there has been a sharp increase in extreme rainfall events associated with landfalling tropical cyclones--the kind of rainfall events most likely to cause damaging flooding. Image credit: Kunkel et al. (2010), "Recent increases in U.S. heavy precipitation associated with tropical cyclones", Geophysical Research Letters.

It is essential that we limit coastal development in vulnerable coastal areas, particularly along barrier islands, to reduce some of the astronomical price tags hurricanes are going to be causing in the future. Adoption and enforcement of strict building standards is also a must, as well as more reforms to the government's National Flood Insurance Program (NFIP), which subsidizes development in high-risk coastal regions that private insurers won't touch. NFIP is now $25 - 30 billion in the red, thanks to Hurricane Katrina and Hurricane Sandy. Reform of NFIP is already underway. In 2012, before Sandy hit, Congress passed the Biggert-Waters Flood Insurance Reform Act, which requires people with NFIP policies to pay large premium increases of about 25% per year over the next five years. Naturally, this move has caused major controversy.

References
Camargo, S., (2013), "Global and regional aspects of tropical cyclone activity in the CMIP5 models," J. Climate.

Emanuel, K.A., 2013, "Downscaling CMIP5 climate models shows increased tropical cyclone activity over the 21st century", PNAS, July 8, 2013, doi: 10.1073/pnas.1301293110

Groisman, Pavel Ya, et al., "Contemporary changes of the hydrological cycle over the contiguous United States: Trends derived from in situ observations," Journal of Hydrometeorology 5.1 (2004): 64-85.

Knutson et al., 2010, "Tropical Cyclones and Climate Change", Nature Geoscience 3, 157 - 163, Published online: 21 February 2010 | doi:10.1038/ngeo779

Knutson et al., 2013, Dynamical Downscaling Projections of 21st Century Atlantic Hurricane Activity: CMIP3 and CMIP5 Model-based Scenarios, Journal of Climate 2013 ; e-View
doi: http://dx.doi.org/10.1175/JCLI-D-12-00539.1

Pielke, R.A, et al., 2008, "Normalized Hurricane Damage in the United States: 1900 - 2005," Natural Hazards Review, DOI:10.1061/ASCE1527-6988(2008)9:1(29)

Villarini, G, and G.A. Vecchi, 2012, "Twenty-first-century projections of North Atlantic tropical storms from CMIP5 models," Nature Clim. Change 2:604–607.

Related posts
Global warming and the frequency of intense Atlantic hurricanes: model results, my 2010 blog post.

Climate Central's analysis of the new 2013 Kerry Emanuel paper.

Goodbye, Miami: Jeff Goodell's sobering 2013 article in Rolling Stone on the challenges Miami faces due to sea level rise and hurricanes.


What the official climate assessments say about climate change and hurricanes
The 2013 IPCC report gives “low confidence”--a 20% chance--that we have observed a human-caused increase in intense hurricanes in some parts of the world. This is a reduction in odds from the 2007 report, which said that it was more likely than not (greater than 50% chance.) The IPCC likely took note of a landmark 2010 review paper, "Tropical Cyclones and Climate Change", authored by ten top hurricane scientists, which concluded that the U.S. had not seen any long-term increase in landfalling tropical storms and hurricanes, and that "it remains uncertain whether past changes in tropical cyclone activity have exceeded the variability expected from natural causes." The 2013 IPCC report predicts that there is a greater than 50% chance (more likely than not) that we will see a human-caused increase in intense hurricanes by 2100 in some regions; this is also a reduction from the 2007 report, which said this would be likely (66% chance or higher.)

The May 2014 United States National Climate Assessment found that “The intensity, frequency, and duration of North Atlantic hurricanes, as well as the frequency of the strongest (Category 4 and 5) hurricanes, have all increased since the early 1980s. The relative contributions of human and natural causes to these increases are still uncertain. Hurricane-associated storm intensity and rainfall rates are projected to increase as the climate continues to warm.”

Jeff Masters

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Henriette becoming well-organized. A compact eye feature is visible on latest satellite imagery and 18z satellite estimates from TAFB and SAB yield an intensity of 77kts. ADT on the other hand is far more impressed indicating an intensity of about 85kts. Based on this data, it would appear to me that Henriette is easily an 80kt hurricane that continues to intensify.

2013AUG06 183000 4.8 975.2 84.8 4.8 4.8 4.4 MW ON OFF OFF -64.76 -68.43 EMBC N/A 23.9 14.48 132.02 SPRL GOES15 17.3

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Quoting 1762. Doppler22:

Link
LOL.I'm being sarcastic.What I'm really meaning to say is that I don't care for the east pacific :).
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Quoting 1746. RitaEvac:


That's why it'll go north to NOLA and keep us on dry windy burning up side of the storm


2011, Lee...............
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Well folks,this Global Hazards forecast going thru August 20 is bearish for the Atlantic as it has nothing developing.



Link
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1764. Grothar
You have to love the CMC. It develops something all over, while the others do not.



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Quoting 1735. Grothar:
The wave picking up a little steam.




Although these certainly have my attention.


That area over Niger and Mali looks really strong. It has some thunderstorms that are fairly large.
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-
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tropical wave got a spin to it
Member Since: March 12, 2013 Posts: 12 Comments: 19988
Quoting 1750. wunderweatherman123:
Caleb how strong is the storm on that model run? the one in the gulf
Quoting 1750. wunderweatherman123:
Caleb how strong is the storm on that model run? the one in the gulf
60 mph on the 10 meter wind field.

Member Since: June 30, 2013 Posts: 12 Comments: 8022
1759. sar2401
Quoting Grothar:
When I went to take my nap it was 93 deg. 2 hours later it is now 92 deg. Need I say more?

So apparently, your naps coincide with cold fronts in Florida? :-)

I don't know if you've looked at the surface map today but it's really whacky. It looks like you have a stranded stationary front just about over you that extends from a low to the NE which I think contains the remnants of Dorian. We have a low to the NW in Tennessee that has a warm front extending south and moving east. It's already 95 with a dewpoint of 73 here, so it's hard to imagine it getting much warmer without killing us. There's a cold front extending SW from the same low that looks like it's headed SE, although I have no idea where it's getting cold air from. It's attached to a warm from the extends west over the Texas Panhandle that's moving north with almost no precipitation associated with the front.

Doesn't it seem to you like surface maps made more sense when we were young, when they came once a day in the newspaper? 8-)
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Quoting 1742. SLU:


I criticized their July forecast because I thought they were too reliant on the volatile SSTs anomalies and computer models to based their forecasts and lo and behold, they've increased the numbers again because the models predict warmer SSTs for August/September. SMH.

IMO, if perple want a proper hurricane season forecast, they should follow CSU's forecast since they are the most elaborate and to a lesser extent NOAA.



Agree with that. By the way NOAA will release their August forecast on Thursday.
Member Since: April 29, 2009 Posts: 75 Comments: 14209
Quoting 1748. GTstormChaserCaleb:
Interesting the 12z Euro shows development of the African Tropical Wave and recurves it OTS and shows some vorticity with the AOI east of the Lesser Antilles, but absorbs it into the front draped across FL.

Link


Not really that interesting, the EURO has been showing that way curve and go OTS and its previous runs for a while.


We really need to see some development soon because people are pulling stuff out of no where trying to show signs of development.
Member Since: July 31, 2013 Posts: 0 Comments: 925
Quoting 1748. GTstormChaserCaleb:
Interesting the 12z Euro shows development of the African Tropical Wave and recurves it OTS and shows some vorticity with the AOI east of the Lesser Antilles, but absorbs it into the front draped across FL.

Link


NW Caribbean could get hot next week especially as the MJO moves in.

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1755. bappit
Quoting 1751. Grothar:


Not yet, but I am calculating the vertical instability and MJO in the region by the Islands. In the absence of a baroclinic low sliding under an anti-cyclone, it isn't likely yet. The persistent ULL above them has me concerned though. That, combined with low SST's and SAL, well you know.

So you're saying it's obvious?
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Quoting 1747. hurricanes2018:
GFS is showing it as well although weak. The GOM has been eerily quiet since Andrea back in June, if the steering is right look out.
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Quoting 1738. Doppler22:


Hurricane Henriette in Eastern Pacific
I still don't see it.It must be me then..
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Quoting 1747. hurricanes2018:
I do not like to see a high like that on the east coast that far north..that bad
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1751. Grothar
Quoting 1741. Doppler22:

Any waves with a Blob:con rating?


Not yet, but I am calculating the vertical instability and MJO in the region by the Islands. In the absence of a baroclinic low sliding under an anti-cyclone, it isn't likely yet. The persistent ULL above them has me concerned though. That, combined with low SST's and SAL, well you know.
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Caleb how strong is the storm on that model run? the one in the gulf
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1749. yoboi
Quoting 1722. SouthernIllinois:
Hmmm. Me and the HPC are best friends!!!




How wet will you get????? It's been dry here....
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Interesting the 12z Euro shows development of the African Tropical Wave and recurves it OTS and shows some vorticity with the AOI east of the Lesser Antilles, but absorbs it into the front draped across FL.

Link
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Quoting 1744. StormTrackerScott:


No way a storm can venture toward the Western Gulf with such a persistant trough across the MidWest.


That's why it'll go north to NOLA and keep us on dry windy burning up side of the storm
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Quoting 1725. GTstormChaserCaleb:
12z FIM-7 looks headed for South Texas this run.

Something like Dolly?
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Quoting 1739. RitaEvac:


Or vice versa...


No way a storm can venture toward the Western Gulf with such a persistant trough across the MidWest.
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Quoting 1733. GTstormChaserCaleb:
Don't worry the Death Ridge will meet its demise when a hurricane plows through it. I hope you are prepared this season, Rita.


To be honest I don't see any storms getting anywhere close to the Western Gulf based on the current set up.

Fairly strong trough setting up shop across the Ohio Valley. Bad set up for FL and the coastal SE US.

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1742. SLU
Quoting 1719. Tropicsweatherpr:


Based on current and projected climate signals, North Atlantic basin tropical cyclone activity in 2013 is forecast to be about 20% above the long-term (1950-2012) norm and 20% below the recent 2003-2012 10-year norm. U.S. landfalling hurricane activity is forecast to be close to the 2003-2012 10-year norm.

TSR forecasts:
%u202215 tropical storms including seven hurricanes and three intense hurricanes. This compares to long-term norms of 11, six and three respectively.
%u2022An ACE (Accumulated Cyclone Energy) value of 121 (up slightly from the July forecast of 112). The long-term norm is 103.
%u2022A 49% likelihood that activity will be in the top one-third of years historically (up slightly from the July forecast likelihood of 42%).
%u2022Four tropical storm and two hurricane landfalls on the U.S. mainland.

TSR's outlook for U.S. hurricane landfalls employs July tropospheric wind anomalies over North America, the East Pacific and North Atlantic.

The precision of TSR's August forecasts between 1980 and 2012 is high for upcoming Atlantic hurricane activity and moderate for U.S. hurricane activity.

The TSR basin forecast has incresed slightly since early July because North Atlantic sea surface temperatures in August-September 2013 are expected to be slightly warmer than thought previously.




I criticized their July forecast because I thought they were too reliant on the volatile SSTs anomalies and computer models to based their forecasts and lo and behold, they've increased the numbers again because the models predict warmer SSTs for August/September. SMH.

IMO, if people want a proper hurricane season forecast, they should follow CSU's forecast since they are the most elaborate and to a lesser extent NOAA.

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Quoting 1735. Grothar:
The wave picking up a little steam.




Although these certainly have my attention.


Any waves with a Blob:con rating?
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1740. JLPR2
Quoting 1735. Grothar:
The wave picking up a little steam.




Although these certainly have my attention.



Been going Hmmmm... all day to the one sitting right off the coast.
Member Since: September 4, 2007 Posts: 7 Comments: 8641
Quoting 1733. GTstormChaserCaleb:
Don't worry the Death Ridge will meet its demise when a hurricane plows through it. I hope you are prepared this season, Rita.


Or vice versa...
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Quoting 1717. washingtonian115:
Wait there's a hurricane out there?.Where?.I don't see one anywhere?.What is this east pacific?.


Hurricane Henriette in Eastern Pacific
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Quoting 1732. JLPR2:


Sorry, at the moment we are heading in the opposite direction, towards a La Niña.

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1736. bappit
Quoting 1638. tropicalnewbee:


Do you think my original idea has merit? Using non-nuclear MOAB's to disrupt (multiple detonations) to cook the evaporating WV and suck available oxygen out of the area, to take away the latent heat and replace it with hot drier air? This would be temporary given the power of any given system, but that is why my idea calls for multiple timed detonations to create a wave effect to combat the power and re-enforce the previous explosions building on each to keep taking WV out and disrupting the evap process drying the air in the area without going nuclear and all the nasty stuff that goes with it.

You are mistaking the amount of power released in an instant in a small area with the amount of power released over a large area over a significant amount of time. Our explosives are nothing compared to the energy stored in thousands of cubic miles of ocean and atmosphere. Though there is no limit on how big you could make a hydrogen bomb, you'd be crazy to make one big enough to make a dent in a storm.
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1735. Grothar
The wave picking up a little steam.




Although these certainly have my attention.

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Quoting 1730. RitaEvac:


Fuuugggggetabouttttit



Its funny, that model keeps showing that, but 3 days ago the run at 336 showed it in that spot, you would think it would be different since its 3 days later, its like it cant get under the fantasy range.
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Quoting 1724. RitaEvac:


So is Death Ridge and I...

Don't worry the Death Ridge will meet its demise when a hurricane plows through it. I hope you are prepared this season, Rita.
Member Since: June 30, 2013 Posts: 12 Comments: 8022
1732. JLPR2
Quoting 1727. washingtonian115:
I want a El nino.


Sorry, at the moment we are heading in the opposite direction, towards a La Niña.
Member Since: September 4, 2007 Posts: 7 Comments: 8641
1731. sar2401
Quoting MississippiWx:


Caleb, early season trends and clues point to a more active Cape Verde season than we've seen in a while, not the opposite. You don't get 2 tropical cyclones in the Eastern Atlantic in July and not expect an active CV season. Current conditions and model runs that have very little skill beyond 5 days are not useful to go by at this point.

I find it interesting my eight years of posting and several more years of lurking that I've almost never seen a blogger predict even an average, let alone a below average season. I particularly remember 2006, with dire prediction after dire prediction that it was going to be a repeat of 2005. Of course, it didn't turn out that way. I don't think we have enough scientific understanding to really make good predictions about hurricane seasons, and a study looking at how well predictions have done predicting bot numbers of hurricanes and landfalling hurricanes have been only slightly better than chance.

When it comes to forecasting if a hurricane of any intensity will hit a particular area in advance of storm even forming, now we get into never-never land. The few people who even try this, including Joe Bastari, have one or two lucky years, but the rest either significantly under forecast or over forecast even large areas, like a landfall on the Gulf Coast or Central America. I think it's interesting to review what Gray and Klotzbach, the two chief researchers for the CSU forecasts, said in April of this year:

"It is also important that the reader appreciate that these seasonal forecasts are based on statistical schemes which, owing to their intrinsically probabilistic nature, will fail in some years. Moreover, these forecasts do not specifically predict where within the Atlantic basin these storms will strike. The probability of landfall for any one location along the coast is very low and reflects the fact that, in any one season, most U.S. coastal areas will not feel the effects of a hurricane no matter how active the individual season is.”
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Quoting 1725. GTstormChaserCaleb:
12z FIM-7 looks headed for South Texas this run.



Fuuugggggetabouttttit

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Perhaps Dr. Masters could do a piece on vertical instability, and how this may impact our season.

It seems to me that vertical instability is really not a factor by itself, because so many other factors can change it very quickly.


Thanks in advance.
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Quoting 1723. JLPR2:
If Niño region 3.4 keeps cooling we might finally get below -.05 for the first time since the Hurricane Season began.

I want a El nino.
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1726. Grothar
When I went to take my nap it was 93 deg. 2 hours later it is now 92 deg. Need I say more?
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12z FIM-7 looks headed for South Texas this run.

Member Since: June 30, 2013 Posts: 12 Comments: 8022
Quoting 1722. SouthernIllinois:
Hmmm. Me and the HPC are best friends!!!



So is Death Ridge and I...

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1723. JLPR2
If Niño region 3.4 keeps cooling we might finally get below -.05 for the first time since the Hurricane Season began.

Member Since: September 4, 2007 Posts: 7 Comments: 8641
Quoting 1693. opal92nwf:
I wonder when Dr. Masters is going to post a new blog?
Quoting 1693. opal92nwf:
I wonder when Dr. Masters is going to post a new blog?




When Dr m feels like making a new blog
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1720. bappit
Quoting 1380. Greg01:
Rita: I had a good downpour of about 30 minutes in Clear Lake Sunday afternoon.

So you would not call it a heavy downpour, just a good downpour. (I'm pointing out the foolishness of people who rant against using the phrase "heavy downpour".)
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Quoting 1711. GTstormChaserCaleb:
Interesting...The TSR (Tropical Storm Risk) August forecast update anticipates North Atlantic basin tropical cyclone
activity in 2013 will be ~20% above the 1950-2012 long-term norm but ~20% below the recent 2003-
2012 10-year norm.
Looks like numbers similar to 2004. I'll be surprised at anything more than 15 named storms for this season.


Based on current and projected climate signals, North Atlantic basin tropical cyclone activity in 2013 is forecast to be about 20% above the long-term (1950-2012) norm and 20% below the recent 2003-2012 10-year norm. U.S. landfalling hurricane activity is forecast to be close to the 2003-2012 10-year norm.

TSR forecasts:
%u202215 tropical storms including seven hurricanes and three intense hurricanes. This compares to long-term norms of 11, six and three respectively.
%u2022An ACE (Accumulated Cyclone Energy) value of 121 (up slightly from the July forecast of 112). The long-term norm is 103.
%u2022A 49% likelihood that activity will be in the top one-third of years historically (up slightly from the July forecast likelihood of 42%).
%u2022Four tropical storm and two hurricane landfalls on the U.S. mainland.

TSR's outlook for U.S. hurricane landfalls employs July tropospheric wind anomalies over North America, the East Pacific and North Atlantic.

The precision of TSR's August forecasts between 1980 and 2012 is high for upcoming Atlantic hurricane activity and moderate for U.S. hurricane activity.

The TSR basin forecast has incresed slightly since early July because North Atlantic sea surface temperatures in August-September 2013 are expected to be slightly warmer than thought previously.


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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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