91L no concern; more postcards from the AMS hurricane conference

By: Dr. Jeff Masters , 1:12 PM GMT on April 18, 2012

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I'm in Ponte Vedra Beach, Florida this week, where the world's hurricane experts are gathered to attend the 30th Conference on Hurricanes and Tropical Meteorology of the American Meteorological Society. Most of the Hurricane Specialists from the National Hurricane Center are here, and they are keeping an eye on the waters a few hundred miles east of Bermuda, where an extratropical storm has cut off from the jet stream and is slowly acquiring tropical characteristics. This system was designated Invest 91L last night by NHC. Ocean temperatures are around 20°C (68°F) in the region, which is well below the 26°C usually needed for a tropical storm to form. Wind shear is a high 20 - 30 knots. Nevertheless, 91L has managed to develop a small amount of heavy thunderstorm activity near its center, and may continue to show more organization as it moves slowly southeastward over the next day or two. I give 91L a close to 0% chance of becoming a named storm in the next two days, and NHC seems to have stopped issuing new products for the system. By the end of the week, 91L should get picked up by a trough of low pressure and move off to the northeast. The storm is not a threat to any land areas.


Figure 1. Morning satellite image of Invest 91L. The island of Bermuda is seen at the left side of the image.

Global tropical cyclones and climate: current signal
Now, I'll summarize a few of the excellent talks given at this week's AMS hurricane conference. Dr. Greg Holland of the National Center for Atmospheric Research talked about the impact of global warming on hurricane intensities. Using data beginning in 1975, the beginning of the satellite era, he showed that while the total number of hurricanes globally has decreased in recent years, the proportion of hurricanes that are of Category 4 - 5 intensity has increased by 40%. He showed that this change could be related to a 0.8°C increase in global temperature during the period. He concluded that when hurricanes form, they are finding that it is easier for them to reach higher intensities.

Sensitivity of the strongest hurricanes to ocean surface warmth
Dr. Jim Elsner of Florida State University showed that observations indicate a sensitivity of hurricane winds of 8.2 m/s +/- 1.19 per degree Centigrade of ocean warmth, using data in the Atlantic from 1981 - 2010 (for oceans areas warmer than 25°C.) Using a high resolution model (HiRAM) with 50 km resolution, a sensitivity of only 1.5 +/- .6 m/s was found, calling into question the usefulness of current models for assessing future hurricane activity.

How will climate change affect hurricane tracks?
Angela Colbert of the University of Miami used 17 global climate models, the BAM hurricane tracking model, and the Atlantic historical HURDAT data base to see how hurricane tracks might change in the future. She classified storms as either straight moving (which tend to hit the Caribbean or U.S. Gulf Coast), recurving landfalling (U.S. East Coast impacts), or recurving ocean storms that miss landfall. She projected a 6% increase in recurving ocean storms and an 8% decrease in straight-moving storms by the end of the century, due to climate change. A decrease of 1- 2 storms per decade is predicted for the Caribbean and Gulf of Mexico, and an increase of 1 - 2 storms per decade in the waters of the mid-Atlantic, and along the East Coast of Florida. This occurs primarily because of an increase in westerly winds over the Central Atlantic, and to a lesser degree, an eastward change in genesis location closer to the coast of Africa. Both of these factors would tend to increase the number of recurving storms.

Jeff Masters

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Quoting ScottLincoln:


The long range CPC forecasts are not binary, and as such, you cannot have "the complete opposite of what was forecasted." The forecasts are probabilistic in nature, and generally show the probability of three choices... above normal, below normal, equal chances. An area indicated as "above normal" with a 50% contour does not mean a forecast of above normal; it means there is a 50% chance of above normal with a 50% chance of normal or below normal.

A 60% contour must be forecasted before you really even reach a true forecast for either below/above to be the most likely scenario.

I think what RitaEvac meant is that the long-range forecasts were maintaining the drought, with a high probability for below-normal rain. What ended up happening was well-above normal rainfall.

Many of us understand forecasts in general are probabilistic in nature. But in long-range forecasts, any time there is a 50% chance of one trend maintaining (below normal rainfall), and the opposite happens (above normal rainfall), it is safe to say that the exact opposite of the forecast happened. In other words... reality bucked the forecast probabilities. (I'd start busting out math with standard deviations and such... but I'm lazy)
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[q]This occurs primarily because of an increase in westerly winds over the Central Atlantic, and to a lesser degree,[/q]

What exactly is the explanation of why global warming should increase westerlies?

This is the way I see this situation.

If the greenhouse effect works the way it has been described, by trapping heat globally, and of course bringing the planet closer and closer to equilibrium by distributing much of the excess heat to the polar regions, then why would westerly winds in the steering layers or the surface increase?

If the difference in temperature between different latitudes and longitudes decreases due to a thermal blanket effect, then that should decrease the maximum thermodynamic potential between any two points at the same elevation, which should in turn decrease maximum potential non-tropical winds.

This is not to be confused with potential tropical cyclone winds, because tropical cyclones are powered by differences in temperature vertically, while westerlies are powered by horizontal differences in temperature.

If the temperature of the poles will be increasing faster than the temperature at the equator and mid-latitudes; for example, the pole increases by 6C and the equator increases by like 1C, then the difference between the two is reduced by 5C, but average global temperature might be just 2C or 3C warmer than today by then. That means a lower thermodynamic potential between the equator and the poles. This should translate into weaker troughs, which will fail to pick up hurricanes, and therefore fail to pull them northwards.


Combining both of these effects, then this should translate to stronger, slower moving, persistent hurricanes which track more west.



Now that's my highly intuitive understanding based on thermodynamics 101.


If anyone cares to explain why I'm wrong, I'm willing to be "educated".
Member Since: January 25, 2012 Posts: 33 Comments: 1520
Quoting StormTracker2K:


Hi Pat, The 12Z GFS has this low just to your south at 1000 milibars. It also shows heavy rain banding into your location Saturday with maybe some strong winds.


Should be nice to observe as it evolves.


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Quoting StormTracker2K:
What a powerhouse low the 12Z GFS is blowing up in the Gulf right underneath the ULL. There maybe a slim chance this could become Alberto


This will NOT be Alberto. It will be a cold core system when it develops and will not have enough time over the warm Gulf to transition into anything warm core. It won't even have enough time to take on Sub-tropical characteristics. It will most likely create a solid line of convection in the warm sector of the storm with overunning rain north of the warm front. Still some questions on where that sets up, but this will not be tropical at all.
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Quoting jeffs713:
If by close, you mean "200 miles away", sure. The 12z run has the low just off the coast, and doesn't swing it out far enough to catch the loop current. To catch the loop current in its current position, you need the low to get even with Naples/Key West. As the model goes so far (out to 96 hours), it doesn't even get to the level of Tampa - much less Naples/KW.


No it isn't. I think the Loop Current is further north right now. I'll check that. Thanks man!



Link
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Quoting Patrap:
All links that are outside of the wunderground, will automatically call up the Warning prompt for the site linked.

as here: North American Surface Analysis


One can then decide to go there or not.


wunderground.com did that about 2 years ago after some viruses were embedded here that caused a lil temp grief.


Hi Pat, The 12Z GFS has this low just to your south at 1000 milibars. It also shows heavy rain banding into your location Saturday with maybe some strong winds.
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did anyone see the CMC 00Z last run?







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Senate Panel Would Shake Up Satellite Program

Excerpt:

The Commerce, Justice, Science and Related Agencies Subcommittee of the Senate Appropriations Committee today approved a fiscal year 2013 appropriations bill that would shift responsibility for building four major satellite systems from the National Oceanic and Atmospheric Administration (NOAA) to NASA. The move—which would need approval from the full Senate, the U.S. House of Representatives and the White House to become reality—marks the latest twist in a long and contentious debate over how to sustain an expensive and delay-prone satellite fleet.


Also:

Bill Markup Summary (PDF)

Excerpt:

National Oceanic and Atmospheric Administration (NOAA) – The bill provides $3.4 billion for NOAA, which is $1.47 billion below the fiscal year 2012 enacted level. The bill does not support proposed cuts to NOAA’s operations that would hurt local communities, such as eliminating local weather forecasting staff and reducing the U.S. Tsunami Warning Network. Instead, the committee finds financial savings by consolidating management offices and reducing government overhead. The bill transfers funding needed for weather satellite acquisition from NOAA to NASA, resulting in a savings of $117 million in fiscal year 2013.
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Quoting StormTracker2K:
12Z GFS has this very close to the LOOP CURRENT where SST's are in the low 80's. Also this run is slower now close to the Euro.
If by close, you mean "200 miles away", sure. The 12z run has the low just off the coast, and doesn't swing it out far enough to catch the loop current. To catch the loop current in its current position, you need the low to get even with Naples/Key West. As the model goes so far (out to 96 hours), it doesn't even get to the level of Tampa - much less Naples/KW.
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Quoting bohonkweatherman:
I hope you are right, getting ready to start out 5th week without rain here which for April is unusual. I know East and Southeast Texas got some good rains but high pressure is keeping the rains pretty far from South Central Texas since March. Need a tropical system to go Westward thru Texas and give those areas some soaking rains West of Austin.


Hermine was a perfect event, S TX gets it, and South Central/Hill country gets it, even SE TX got in the action with a large feeder band from Hermine. Overall perfect path, size, and event for TX.
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Quoting RitaEvac:


Not looking good out there, still can get major rain events into May, It's about that time TX is gonna get a tropical storm in June, that may be the missing link needed
I hope you are right, getting ready to start out 5th week without rain here which for April is unusual. I know East and Southeast Texas got some good rains but high pressure is keeping the rains pretty far from South Central Texas since March. Need a tropical system to go Westward thru Texas and give those areas some soaking rains West of Austin.
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Quoting RitaEvac:


And complete opposite of what was forecasted, that's why I don't listen to long range forecast.


The long range CPC forecasts are not binary, and as such, you cannot have "the complete opposite of what was forecasted." The forecasts are probabilistic in nature, and generally show the probability of three choices... above normal, below normal, equal chances. An area indicated as "above normal" with a 50% contour does not mean a forecast of above normal; it means there is a 50% chance of above normal with a 50% chance of normal or below normal.

A 60% contour must be forecasted before you really even reach a true forecast for either below/above to be the most likely scenario.
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Pretty soon the talk of a mini 93' Super Storm will be commencing soon...
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12Z GFS has this very close to the LOOP CURRENT where SST's are in the low 80's. Also this run is slower now close to the Euro.
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Quoting StormTracker2K:
WOW!!



Now in the water on this 12z run.
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What a powerhouse low the 12Z GFS is blowing up in the Gulf right underneath the ULL. There maybe a slim chance this could become Alberto
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WOW!!

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Quoting icmoore:
So it sounds like the possibility of interesting weather here in Madeira Beach on Sat. Always glad to have this blog during those times :)


It is a great blog with lots of many different personalities:)
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I think we may have Joe Bastardi among us here in the blog.
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Quoting MahFL:
This weekends low, has it formed yet ? Where are the pre cursers to it ?



you can find all the models at my site...but here you go...click the graphic below.



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All links that are outside of the wunderground, will automatically call up the Warning prompt for the site linked.

as here: North American Surface Analysis


One can then decide to go there or not.


wunderground.com did that about 2 years ago after some viruses were embedded here that caused a lil temp grief.
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Quoting MahFL:
This weekends low, has it formed yet ? Where are the pre cursers to it ?


No the trough is still in Montana.
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Quoting aspectre:
Just because it's worth reposting to correct a broken address...
33 MontanaZephyr: Gulf seafood deformities alarm scientists


Thanks for the kindness and taking the time.

I default to posting the actually url text so that people can directly see the ID and domain of the site that they would be going to.

It seems more the civic thing to do with a relatively educated and sophisticated group, the members of which will generally think it no trouble to copy/paste. On more common sites, a clickable link is customary, but that can lead to hidden spams and viruses and so on.

Group: Please advise as to what is preferred.

Thanks.
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So it sounds like the possibility of interesting weather here in Madeira Beach on Sat. Always glad to have this blog during those times :)
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NOLA Disco

Friday will be transitional day across the area...as a strong long
wave trough begins to rapidly deepen over the plains states.
Increasing southerly flow will develop in advance of this trough
across the forecast. Expect strong low level moisture advection to
develop by Friday afternoon...with deeper moisture moving in by
Friday night. With this increase in moisture...additional
increasing cloud cover can also be expected by Friday evening.
Overnight lows will also be higher...with readings only cooling
into the lower to middle 60s across the region.

By late Friday night...a closed low will begin to form at the base of the long wave trough axis. The low will be fairly vertically stacked...with surface low in nearly the same position as the middle to upper level
low. The closed low will descend south and east...and will transit over the forecast area this coming weekend.


A cold front is
expected to develop at the base of the surface low over the
Southern Plains Friday night. As this front develops...a line
of convection may develop along the front and race into the
forecast area by late Friday night. Although the severe threat is
low...there could be an isolated stronger thunderstorm embedded
within the line of convection. Have went with chance probability of precipitation for the
area late Friday night to reflect the expected line of convection.
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This weekends low, has it formed yet ? Where are the pre cursers to it ?
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Quoting jeffs713:
I'll just take the Bugatti.
I was going to say, I wish I had one..:)
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http://vortex.accuweather.com/adc2004/pub/includes/ columns/newsstory/2012/300x200_04181443_eaststormb rewing.jpg
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From the CIMSS, Look closely, and you can see the gravity waves on top of the storm... 1-km resolution MODIS 6.7 µm water vapor channel image at 04:17 UTC displayed an elongated north-to-south oriented wave packet along the advancing cold frontal boundary from Nebraska into Kansas — and there was a pilot report of severe turbulence at a flight altitude of 31,000 feet over this water vapor wave signature. These waves were not seen in the corresponding 04:17 UTC MODIS IR imagef 375-meter resolution Suomi NPP VIIRS 0.64 µm visible channel, 11.45 µm IR channel, and 3.74 µm shortwave IR channel images centered near the Dodge City, Kansas (KDDC) area (below) showed a pair of well-defined “enhanced-V” signatures (with cold/warm thermal couplet IR brightness temperatures in excess of 25º C), which also exhibited anvil plumes extending downwind (to the northeast) of the vertex of each enhanced-V. The enhanced-V storm just to the southeast of Dodge City was producing a tornado and 1.75-inch diameter hail at the time of the VIIRS images. In addition, the IR and shortwave IR images revealed a number of southwest-to-northeast oriented swaths of cooler ground (lighter gray enhancement) due to heavy rainfall from the recent passage of thunderstorms.
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Quoting hydrus:
393. aspectre 5:29 AM GMT on April 18, 2012 +1
313 hydrus: It is hard for me to imagine a wind gust of 253 mph.

Try roof-surfing on a BugattiVeyron running at top speed.
I'll just take the Bugatti.
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Good morning all. Back home in Arizona after a spell of work in Kentucky. Hubby and I are taking a belated 53rd anniversary transatlantic cruise leaving from Miami on Saturday. He hates heavy weather at sea(I actually love it but try not to let others know). We sailed around Cape Horn twice with seas like glass so here's hoping that 91L smooths out before we hit that area. (Called wishful thinking). I'm not telling him the forecast but will stock up on ginger - which works like magic for motion sickness. Sigh. Other wishcaster comments welcome on this one.
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Quoting Skyepony:


90s are also used for the Southern Hemisphere. The letters behind the number change per the area.


Sorry, 80's are test numbers....
Never take one source on the NET as Gospel !
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I'm thinking the GOM is gonna be trouble this year.. Cancun and Grand Cayman and Cuba could see multiple strong storms before September. Hope I'm wrong!
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Quoting TampaSpin:


This might be more SEVERE than many think in FLORDA as the SYSTEM which could become a SURFACE LOW with some TROPICAL Characters as it moves across the GULF OF MEXICO.

One of our mets did mention "possible tropical stuff heading our way".
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Quoting bohonkweatherman:
Starting to panic around South Central Texas, bone dry here since March 20th. I mow several yards and I am seeing pretty good cracks in the ground from temps around 90 with lots of Wind and Sun the past month. Our Future forecast here shows little to No rain with almost all rain being well east of us. We get past May without rain then the next chance of rains here most likely will be September. Models have amounts around here in future rains less than .25 if we are lucky.


Not looking good out there, still can get major rain events into May, It's about that time TX is gonna get a tropical storm in June, that may be the missing link needed
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Quoting help4u:
If you all want info on northeast storm and the storm hitting Florida this weekend go to weatherbell they have been talking about the incoming storm for over a week.They alaways put a forcast out way before the storms hit and do not do so much after the fact and the day of the storm.Keep you informed weeks ahead of other weather sites.


Is this Joe Bastardi trying to solicit Doc's members?
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If you all want info on northeast storm and the storm hitting Florida this weekend go to weatherbell they have been talking about the incoming storm for over a week.They alaways put a forcast out way before the storms hit and do not do so much after the fact and the day of the storm.Keep you informed weeks ahead of other weather sites.
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Quoting MAweatherboy1:

Lol, I know... Still fun to watch an invest in April though.
One day the Atlantic may have hurricane seasons like the Western Pacific. Were they can form any time of the year. I would bet it has happened in the distant past.
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Quoting hydrus:
393. aspectre 5:29 AM GMT on April 18, 2012 +1
313 hydrus: It is hard for me to imagine a wind gust of 253 mph.

Try roof-surfing on a BugattiVeyron running at top speed.

Boy do I love seeing all that green over MA... We really need it
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RAMMB Currently Active Tropical Cyclones

Atlantic

AL912012 - INVEST

Enhanced Infrared (IR) Imagery (4 km Mercator)

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Quoting TampaSpin:



WATERS are too COLD for much to develop in that location!

Lol, I know... Still fun to watch an invest in April though.
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393. aspectre 5:29 AM GMT on April 18, 2012 +1
313 hydrus: It is hard for me to imagine a wind gust of 253 mph.

Try roof-surfing on a BugattiVeyron running at top speed.
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Quoting MAweatherboy1:
Little bit of east side convection but still just an open swirl:




WATERS are too COLD for much to develop in that location!
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Quoting TampaSpin:


This might be more SEVERE than many think in FLORDA as the SYSTEM which could become a SURFACE LOW with some TROPICAL Characters as it moves across the GULF OF MEXICO.


Yep, that's what the NWS offices around FL are saying. I think this is where the concern is coming from as were getting a winter type storm diving and developing over the Gulf in late April where the Gulf temps are near 80. People on the blog will take notice on Friday I can betcha if this trend continues. This Gulf system could put 91L to shame organization wise come Saturday.
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Just because it's worth reposting to correct a broken address...
33 MontanaZephyr: Gulf seafood deformities alarm scientists
Member Since: August 21, 2007 Posts: 0 Comments: 4860
Thanks for the explanations about "invests" - though I have no idea what "scare quotes" are supposed to be! Must go and Google that term! :-)

Brian
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Little bit of east side convection but still just an open swirl:

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Quoting WxGeekVA:


If I can remember correctly, 1-40 is reserved for tropical cyclones (Ex. 01L would be Alberto or TD 1 if it isn't named), 41-80 is for extratropical systems, 81-89 is for testing and experimental purposes, and 90-99 is for invests or systems with the potential to develop. Correct me if I am wrong, please.


Depending on the agency:
NHC

01 - 30
"numbered storms with forecasts issued and numbers are *not* recycled until the next season."

90 - 99 "Invest, areas of interest watched by forecasters for possible development and these numbers are re-used periodically throughout the
season"

80 - 89 "Internal training storm numbers which are to always be ignored"


Link


NAVY

01 to 49 are real storms, 80 to 89 are test storms, 90 to 99 are INVESTS

Link
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53. Skyepony (Mod)
Quoting MahFL:


It's avoid confusion with Tropical Depressions, they figure there will never be more than 79 TD's in one year.
You could have eg TD33, although I think thats never happened. 80's are used for the southern hemisphere.


90s are also used for the Southern Hemisphere. The letters behind the number change per the area.
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Quoting MontanaZephyr:
Gulf seafood deformities alarm scientists

http://www.aljazeera.com/indepth/features/2012/04 /201241682318260912.html

New Orleans, LA - "The fishermen have never seen anything like this," Dr Jim Cowan told Al Jazeera. "And in my 20 years working on red snapper, looking at somewhere between 20 and 30,000 fish, I've never seen anything like this either."

Dr Cowan, with Louisiana State University's Department of Oceanography and Coastal Sciences started hearing about fish with sores and lesions from fishermen in November 2010.


(Greatly truncated to respect copyright)


If the blindness mutations are not stopped it will permanently destroy the population.

If neither predator nor prey are being selected based on vision, perhaps due to black oil and other filth in the water, then there is reinforcement of the otherwise negative trait produced by the mutation.

This is similar to what happens to cave fish and such in genetically isolated populations in total darkness, except here it's happening at a ridiculously accelerated pace.


We will need to be breeding healthy organisms in tanks to preserve a healthy gene pool.

In the future, when the pollution goes away, we will need to hunt the mutated strains to extinction, and then re-introduce the healthy ones back to the population.

An even bigger problem is what to do about the mutated microbes?

Any mutagen powerful enough to do this to macroscopic organisms within a few generations could no doubt cause insane changes to bacteria, algae, diatoms, viruses, and other such creatures.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
Quoting StormTracker2K:
Interesting NAM run. STS?




This might be more SEVERE than many think in FLORDA as the SYSTEM which could become a SURFACE LOW with some TROPICAL Characters as it moves across the GULF OF MEXICO.
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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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