Invest 91L Bringing Heavy Rains to Florida, Cuba, and Mexico

By: Dr. Jeff Masters , 3:44 PM GMT on June 03, 2013

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The Atlantic hurricane season began on June 1, and we already have a threat to discuss. A trough of low pressure has developed over the Western Caribbean, Mexico's Yucatan Peninsula, and Southeast Gulf of Mexico, and is dumping heavy rains over the area. Hurricane Barbara, which died on Thursday as it attempted to cross Mexico's Isthmus of Tehuantepec into the southernmost Gulf of Mexico, has contributed moisture to this disturbance, which has been designated 91L by NHC. Satellite loops show a large area of heavy thunderstorms with poor organization, and there is no evidence of an organized surface circulation trying to form. Wind shear is a high 30 knots, and is forecast to remain high, 20 - 30 knots, over the next five days, so any development should be slow to occur. NHC is giving the disturbance a 20% chance of developing into a tropical cyclone by Wednesday. The Hurricane Hunters are on call to fly into 91L on Tuesday afternoon, if necessary. Regardless of whether or not 91L develops into a tropical depression, heavy rains will be the storm's main threat. Mexico's Yucatan Peninsula, Western Cuba, and South Florida can expect 5 - 8" of rain from the disturbance over the next four days. Heavy rains from 91L may spread up the U.S. East Cost late this week. The computer models predict that 91L should stay large and poorly organized, and if it does develop, it will be difficult for it to get any stronger than a 45 mph tropical storm in the Gulf of Mexico.


Figure 1. Latest satellite image of Invest 91L.

Jeff Masters

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Welcome back, Largo. We got close to 4" of rain Saturday evening in S. Tampa. But, as it goes around here, I guess you got little in Largo.
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1095. pcola57
Quoting mikatnight: Post# 1073



The Saffir-Simpson Hurricane Wind Scale is a 1 to 5 categorization based on the hurricane's intensity at the indicated time. The maximum sustained surface wind speed (peak 1-minute wind at 33 feet) is the determining factor in the scale. This scale provides examples of the type of damages and impacts in the United States associated with winds of the indicated intensity. In general, it shows damages rise by about a factor of four for every category increase. However, this does not address the potential for such other hurricane-related impacts, such as storm surge, rainfall-induced floods, and tornadoes. When these additional factors are considered the rate of increase in damage is much higher. When asked to rate potential damage from a category one hurricane to a category two or three storm most people's results are often linear in increasing damage. However, since the potential damage increase from category to category is logarithmic then small increases in wind strength can dramatically increase damage.

When the cost from hurricane related damages are normalized (normalization takes into account inflation, changes in population, and changes in wealth to arrive at a common level for comparison) the result shows an eighth-power increase in damages from category to category. What this means is the potential damage from a hurricane is 28 power. For example, a doubling of the wind speed from 75 mph to 150 mph is not a doubling or quadrupling of potential damage but a 256 times increase (2 x 2 x 2 x 2 x 2 x 2 x 2 x 2=256). This is evident in that over 85% of all damages from hurricanes come from category three, four, and five storms, yet these storms make up only 24% of all landfalling storms. The following table shows the rate of increase for various wind speeds in a hurricane as compared to a minimal 75 mph category one hurricane.

These values indicate increases in damage potential ABOVE damage that occurs with a 75 mph hurricane.

Remember, damage WILL occur with a 75 mph hurricane. The multiplier values are the potential damage increases above what could occur with a 75 mph storm. Note the rapid increase in potential damage just within each category. A 95 mph hurricane can produce nearly seven times the damage as a 75 mph hurricane with just a 20 mph increase in wind strength. A 10 mph increase in wind speed, from 100 mph to 110 mph, results in over doubling potential damage from 10-times that of a 75 mph hurricane to 21-times.

Source: NWS


Good Morning All..
On the link you posted mikatight, the is a printable PDF of a "Hurricaine Wheel"..
For those whose printer works (mine is shot) that wheel looks very interesting..

Printable Hurricaine Wheel..PDF
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#1091 -

You are so far over my head...

Somebody...help!
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Guthrie, OK, has already received 1.86" of rain from storms this morning as severe weather moves through the area.
Member Since: October 27, 2012 Posts: 0 Comments: 2029
Let me correct myself.

"power" is the 3rd power of the velocity of the fluid impacting an object, multiplied by density, and divided by 2. The must multiply by surface area, but since we are assuming the same targets in all cases, varying only wind speed, none of that matters. The division by 2 cancels, the density cancels, the surface area cancels, adn we are left only with velocity cubed.

Velocity cubed gives us 3 of those 8 powers.

Distance penetrated gives us probably only half of one power, not a full power.

Area/size of a storm is not correlated to wind speed, so it is detrimental to that chart.

After some thought, "breaking strength" is not another power, it is merely the point at which the product of all other powers overcomes "new" targets.

So really I can actually only explain about 3.5 to 4 powers through dimensional analysis.

The most relevant milestones would be:

Mobile home damaged but not destroyed
Mobile home destroyed
Slab house has some superficial damage
Slab house roof failure
Total failure of a conventional "stick" slab house
Total failure of a foam or other non-conventional slab house.
Levee over tops
Levee breaches
Partial failure of commercial buildings ( roof peel, windows, etc)
Total failure of a commercial building. (never seen it).
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Quoting SFLWeatherman:


Good ball of convection near the MLC it needs to persist before we can get some organization. Shear expected to drop under 20 kts in the next 48 hours so it still has a shot of developing. The main inhibitor will be the dry air mass over the gulf that will prevent the west side to get going and thus keep it at best a minimal TS IF it develops. I would give it a 50% chance within the next 72 hours.
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s floridians are going to doing the backstroke down alligator alley, heavy rains moving in thanks to keller
Member Since: September 11, 2010 Posts: 1 Comments: 4986
Quoting RTSplayer:


Fine, but it stil has no dimensional analysis explanation.

I could only explain 5 or 6 powers through dimensional analysis. Where did the other 2 or 3 come from?


Don't be obstinate. You obviously are a smart person, go to the site, figure it out, then tell all of us. It's from the NWS, so I figure they know what they're talking about. If you don't trust the info, then 'splain it to us, Lucy!
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Quoting FOREX:


Still hoping to get a few inches of rain from this here in Panama City Beach, but doesn't look promising.


I feel you, it hasn't rained here in Fort Walton Beach in over 3 weeks. We had a wet Winter and Spring and then it just dried up in early May. We had storms to our North yesterday but none of them made it down to the coast before they fizzled. I'm hoping this system entering the GOM stays week and goes further West before moving North and we at least get some rain out of it.
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Let's hope for a cool or average June temperature wise!! :-)

SouthernIllinois
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Broken dam in Deggendorf - people in floods

The water levels in Saxony and Saxony-Anhalt constantly rising. Also in Passau is no relief in sight, the houses fill up.
13.50 Clock: Dams in Deggendorf broken


On the Danube in Bavaria, the situation escalated. In Deggendorf district near the village of winemakers several dams are broken, further also threaten the water masses no longer resist. Even when fishing village a dam is broken.

Been affected by the now seeping water masses initially only a few farms, other consequences are not yet clear, reports the " Passau Neue Presse ". During the day, probably have to leave their houses around 4000 people.

The newspaper quoted a spokesman for the Red Cross: "It is likely even worse." Some people had been rescued from the floods.
http://translate.google.de/translate?sl=de&tl=en& js=n&prev=_t&hl=de&ie=UTF-8&eotf=1&u=http://www.we lt.de/vermischtes/article116784740/Damm-in-Deggend orf-gebrochen-Menschen-in-Fluten.html
Member Since: October 27, 2012 Posts: 0 Comments: 2029
climatology says says no mdr activity in june. watching the area nevertheless
Member Since: September 11, 2010 Posts: 1 Comments: 4986
Quoting mikatnight:



The Saffir-Simpson Hurricane Wind Scale is a 1 to 5 categorization based on the hurricane's intensity at the indicated time. The maximum sustained surface wind speed (peak 1-minute wind at 33 feet) is the determining factor in the scale. This scale provides examples of the type of damages and impacts in the United States associated with winds of the indicated intensity. In general, it shows damages rise by about a factor of four for every category increase. However, this does not address the potential for such other hurricane-related impacts, such as storm surge, rainfall-induced floods, and tornadoes. When these additional factors are considered the rate of increase in damage is much higher. When asked to rate potential damage from a category one hurricane to a category two or three storm most people's results are often linear in increasing damage. However, since the potential damage increase from category to category is logarithmic then small increases in wind strength can dramatically increase damage.

When the cost from hurricane related damages are normalized (normalization takes into account inflation, changes in population, and changes in wealth to arrive at a common level for comparison) the result shows an eighth-power increase in damages from category to category. What this means is the potential damage from a hurricane is 28 power. For example, a doubling of the wind speed from 75 mph to 150 mph is not a doubling or quadrupling of potential damage but a 256 times increase (2 x 2 x 2 x 2 x 2 x 2 x 2 x 2=256). This is evident in that over 85% of all damages from hurricanes come from category three, four, and five storms, yet these storms make up only 24% of all landfalling storms. The following table shows the rate of increase for various wind speeds in a hurricane as compared to a minimal 75 mph category one hurricane.

These values indicate increases in damage potential ABOVE damage that occurs with a 75 mph hurricane.

Remember, damage WILL occur with a 75 mph hurricane. The multiplier values are the potential damage increases above what could occur with a 75 mph storm. Note the rapid increase in potential damage just within each category. A 95 mph hurricane can produce nearly seven times the damage as a 75 mph hurricane with just a 20 mph increase in wind strength. A 10 mph increase in wind speed, from 100 mph to 110 mph, results in over doubling potential damage from 10-times that of a 75 mph hurricane to 21-times.

Source: NWS


Fine, but it stil has no dimensional analysis explanation.

I could only explain 5 or 6 powers through dimensional analysis. Where did the other 2 or 3 come from?
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1080. FOREX
Quoting islander101010:
getting a blow up of deep convection 91


Still hoping to get a few inches of rain from this here in Panama City Beach, but doesn't look promising.
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Out again until evening.
Member Since: August 1, 2011 Posts: 28 Comments: 8046
"...the potential damage from a hurricane is 28 power..."

can't do superscript. should be 2 to the 8th power
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72HR 1012MB Might get early cape verde development on the GFS and CMC
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1076. ncstorm
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Bad weather in Oklahoma again. Widespread hail storms.

Nothing tornadic yet. Looks more like a squall line or bow echo forming though.
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Quoting allancalderini:
Agree will be cool if we get Andrea and Barry this month.
Keep us busy for sure.\

Unkowncomic it's the best when their out to sea.
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Quoting RTSplayer:


Where did you get that and how was it calculated?

It follows the 8th power of the ratio of the wind speeds.

Here are some factors I thought of, but some of them do not follow a continuous curve.

Scientific unit "Power" is the 4th (mathematical)power impacting a stationary object, for the velocity of a fluid.

Next factor is stronger storm penetrates farther inland before dissipating. This might add another power of 1, but I doubt it would be a whole power, since weakening along the way would prevent that.

Next factor is breaking strength of objects, which is not a continuous curve. If roofs breaking strength is somewhere between 115mph and 130mph, then a category 3 would deal much, much more damage than a category 2, because there is a "step function" like behavior here. With the winds just slightly below the breaking strength, little or no damage is done. With the winds slightly above the breaking strength, wide spread damage is done. Large buildings tend to have breaking strengths somewhere around 180mph, so one could see how a 190mph storm would again do much more damage.

Anyway, I take issue with that chart, because if it were true, Camille or Labor Day 1935 would still reign as the most destructive hurricanes.


I'd like to see how it was calculated though, because a simply 8th mathematical power curve is inconsistent with the real world facts.



The Saffir-Simpson Hurricane Wind Scale is a 1 to 5 categorization based on the hurricane's intensity at the indicated time. The maximum sustained surface wind speed (peak 1-minute wind at 33 feet) is the determining factor in the scale. This scale provides examples of the type of damages and impacts in the United States associated with winds of the indicated intensity. In general, it shows damages rise by about a factor of four for every category increase. However, this does not address the potential for such other hurricane-related impacts, such as storm surge, rainfall-induced floods, and tornadoes. When these additional factors are considered the rate of increase in damage is much higher. When asked to rate potential damage from a category one hurricane to a category two or three storm most people's results are often linear in increasing damage. However, since the potential damage increase from category to category is logarithmic then small increases in wind strength can dramatically increase damage.

When the cost from hurricane related damages are normalized (normalization takes into account inflation, changes in population, and changes in wealth to arrive at a common level for comparison) the result shows an eighth-power increase in damages from category to category. What this means is the potential damage from a hurricane is 28 power. For example, a doubling of the wind speed from 75 mph to 150 mph is not a doubling or quadrupling of potential damage but a 256 times increase (2 x 2 x 2 x 2 x 2 x 2 x 2 x 2=256). This is evident in that over 85% of all damages from hurricanes come from category three, four, and five storms, yet these storms make up only 24% of all landfalling storms. The following table shows the rate of increase for various wind speeds in a hurricane as compared to a minimal 75 mph category one hurricane.

These values indicate increases in damage potential ABOVE damage that occurs with a 75 mph hurricane.

Remember, damage WILL occur with a 75 mph hurricane. The multiplier values are the potential damage increases above what could occur with a 75 mph storm. Note the rapid increase in potential damage just within each category. A 95 mph hurricane can produce nearly seven times the damage as a 75 mph hurricane with just a 20 mph increase in wind strength. A 10 mph increase in wind speed, from 100 mph to 110 mph, results in over doubling potential damage from 10-times that of a 75 mph hurricane to 21-times.

Source: NWS
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getting a blow up of deep convection 91
Member Since: September 11, 2010 Posts: 1 Comments: 4986
1071. ncstorm
East Atlantic


Central Atlantic
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Quoting LargoFl:
hI GUYS,IM HOPING WE do GET SOME RAIN OUT OF THIS SYSTEM,WE CAN USE IT AROUND TAMPA BAY AREA..WE'LL SEE WHAT HAPPENS AS THIS WEEK GOES ON..
Nice to see you again! Hopefully you stick around for the season!
Member Since: August 1, 2011 Posts: 28 Comments: 8046
Quoting washingtonian115:
Might get early cape verde development..
It will be out to sea no doubt.
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1068. ncstorm


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Quoting ncstorm:
00Z CMC..might have another potential to watch..Central Atlantic Storm

54 hours

60 hours






I don't get what that's picking up on.

The wave at 40W is too far south, too disorganized, and moving too quickly to be the progenitor of that system. Further, there is no other obvious wave in the vicinity.
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Quoting washingtonian115:
Might get early cape verde development..
Agree will be cool if we get Andrea and Barry this month.
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Might get early cape verde development..
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1064. ncstorm
06z GFS..Central Atlantic-not as strong as the CMC but the potential is there on the GFS
60 hours


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1063. ncstorm
6z Navgem-also the Central Atlantic potential


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Quoting LargoFl:
hI GUYS,IM HOPING WE do GET SOME RAIN OUT OF THIS SYSTEM,WE CAN USE IT AROUND TAMPA BAY AREA..WE'LL SEE WHAT HAPPENS AS THIS WEEK GOES ON..

Hi Largo! Welcome back!
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1061. ncstorm
00Z CMC..might have another potential to watch..Central Atlantic Storm

54 hours

60 hours




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1060. VR46L
Hmm Not the scariest looking image of water Vapour In the Gulf I have ever seen


NorthAmerica-CONUS-East/vap_images/goes


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Invest 91L:

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1058. ncstorm
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1057. VR46L
Morning Folks!!!

Welcome back Largo
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I guess that chart could be true in "material damage," rather than our fake paper money damage.

It predicts that Andrew's Landfall in Florida should have produced $880 Billion dollars damage, using last year's Issac as a baseline...

Obviously, that didn't happen, and part of the reason may well be that there weren't $880 billion dollars worth of "stuff" in it's path.


The 6th power produces a (wrong), but much more reasonable monetary relationship, and I can explain at least "inputs" for all 6 of those powers. I can't figure out where the other two would come from in that chart.
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1055. LargoFl
hI GUYS,IM HOPING WE do GET SOME RAIN OUT OF THIS SYSTEM,WE CAN USE IT AROUND TAMPA BAY AREA..WE'LL SEE WHAT HAPPENS AS THIS WEEK GOES ON..
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Beautiful morning here in Southern Illnois. Nice temperatures today, light wind, and low humidity.
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1052. ncstorm
Quoting SFLWeatherman:
Wow it was not like that yesterday they now go up to TS


CMC dont seem so crazy now..
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1051. Mikla
This blob is still pretty much a mess. It looks like the "center" is over land and 20-30 knots of shear blowing the convection WAY off to the east leaving a bunch of dry air in the circulation.
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Quoting barbamz:


Good morning everybody from Germany. As I've promised yesterday I've made a morning walk to the banks of Rhine River when high waters reached their crest (7 meters = 23 feet above normal). Amazing to be suddenly at eye level with the swans. Mind, Mainz City isn't in danger of beeing flooded since it was fortified against the river in the 19th century. So we are very lucky compared to those poor people in the southeastern parts of our country and the adjacent countries.

The photo above is the first one of a series of photos (10). You can see, at some parts we are trying to catch up to the swamps of Florida, lol.

13.34 Clock:
In the district of Deggendorf in Bavaria, a dam has the waters of the Danube can not withstand. Near the village of winemakers, a dam was broken, said a spokesman of the district administration. The water is then spread out behind it. Initially affected were only a few farms, other consequences are not yet clear.

13.21 Clock:
Again, Merkel said "bureaucratic relief" in order to cope with the consequences of the disaster. For every euro to give the land, and the federal government would give one euro.
Member Since: October 27, 2012 Posts: 0 Comments: 2029
Anyway, I'm out until later.

Quoting Andrebrooks:
I am so mad,bye.
??? Why? If you're mad, better stay away for awhile. It'll calm you and keep yourself from ban.
Member Since: August 1, 2011 Posts: 28 Comments: 8046
Quoting Andrebrooks:
I say a 40-60% chance.Recon is still going out there.


But the recon won't make the 0800 hr update right? It will be more the 1400hr update unless they make a special update and classify it as our first depression.
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Quoting mikatnight:
Hurricane Damage Potential

These values indicate increases in damage potential ABOVE damage that occurs with a 75 mph hurricane.


Where did you get that and how was it calculated?

It follows the 8th power of the ratio of the wind speeds.

Here are some factors I thought of, but some of them do not follow a continuous curve.

Scientific unit "Power" is the 4th (mathematical)power impacting a stationary object, for the velocity of a fluid.

Next factor is stronger storm penetrates farther inland before dissipating. This might add another power of 1, but I doubt it would be a whole power, since weakening along the way would prevent that.

Next factor is breaking strength of objects, which is not a continuous curve. If roofs breaking strength is somewhere between 115mph and 130mph, then a category 3 would deal much, much more damage than a category 2, because there is a "step function" like behavior here. With the winds just slightly below the breaking strength, little or no damage is done. With the winds slightly above the breaking strength, wide spread damage is done. Large buildings tend to have breaking strengths somewhere around 180mph, so one could see how a 190mph storm would again do much more damage.

Anyway, I take issue with that chart, because if it were true, Camille or Labor Day 1935 would still reign as the most destructive hurricanes.


I'd like to see how it was calculated though, because a simply 8th mathematical power curve is inconsistent with the real world facts.
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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.