TD 8 forms; 97L a potential threat to the Caribbean and U.S.

By: Dr. Jeff Masters , 3:30 PM GMT on August 19, 2011

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Tropical Depression Eight formed last night near the coast of Honduras, and is headed westwards towards a landfall in Belize on Saturday. TD 8 is a small storm, so will impact a relatively small area of northern Honduras, northern Guatemala, all of Belize, and southern portions of Mexico's Yucatan Peninsula. TD 8 has just enough room between its center and the coast of Honduras to intensify into a moderate strength tropical storm with 50 - 60 mph winds before landfall. It is very unlikely TD8 has the time or room to intensify into a hurricane; NHC gave the storm just a 7% chance of making it to hurricane strength in their 11am EDT wind probability forecast. Should TD8 make it to tropical storm strength, it would be called Harvey.


Figure 1. Morning satellite image of TD 8.

Invest 97L likely to become a tropical storm next week, could threaten the U.S.
A tropical wave near 14°N 48°W, about 800 miles east of the Lesser Antilles Islands, is moving westward near 20 mph. This wave, designated Invest 97L by NHC yesterday, has seen a marked increase in its heavy thunderstorm activity this morning, but dry air to the north and west is slowing development. An impressive amount of large-scale spin is obvious in visible satellite loops, but the storm is at least a day away from forming a well-defined surface circulation. Ocean temperatures are about 28.5°C, about 2°C above the threshold needed to support a tropical storm, and wind shear is low, 5 - 10 knots.


Figure 2. Morning satellite image of the tropical wave 97L.

The computer models have shown an unusual amount of agreement in developing 97L over the past few days, and all the ingredients seem to be in place for a tropical storm to form by Monday or Tuesday as 97L crosses the Northeast Caribbean. The atmosphere is expected to be moister over the Caribbean, wind shear will remain a low 5 - 10 knots, and sea surface temperatures will increase to near 29°C. The main impediment for development will likely be two-fold: too much dry, stable air, and proximity to land.

As seen in Figure 3, there has been an unusual amount of dry, stable air in the Atlantic this year, due to a combination of dry air from Africa, and upper-atmosphere dynamics creating large areas of sinking air that dry as they warm and approach the surface. This stable air has been largely responsible for the fact that none of our seven tropical storms so far this year has made it to hurricane strength, despite the presence of sea surface temperatures that are the 3rd warmest on record across the tropical Atlantic. Tropical Storm Emily in early August encountered problems with dry air when it crossed the Northeast Caribbean, and 97L may have similar difficulties.


Figure 3. Vertical instability of the atmosphere during 2011 in the Caribbean (left) and tropical Atlantic between the Lesser Antilles Islands and coast of Africa (right.) The instability is plotted in °C, as a difference in temperature from near the surface to the upper atmosphere. Thunderstorms grow much more readily when vertical instability is high. Observed vertical instability (blue line) has been much lower than the climatological average from previous years (black line), due to an unusual amount of dry air in the atmosphere, inhibiting tropical storm development this year. Image credit: NOAA/CIRA.

Encounters with land will be another potential major problem for 97L. Most of the computer models take 97L near or over Puerto Rico Sunday night, then very close to or over mountainous Hispaniola Monday night through Tuesday. It is unlikely that 97L will be stronger than a 55 mph tropical storm when it encounters these islands, and passage over the islands could severely disrupt the storm. However, if 97L takes a path just south or north of Hispaniola, the potential exists for the storm to intensify into a hurricane.

There will be moderate wind shear of 10 - 20 knots to the north of the islands early next week, so a path just to the south of the Dominican Republic and Haiti would be more likely to let 97L intensify into a hurricane. A west-northwest motion is likely for 97L through Wednesday, which would bring the storm to the vicinity of Jamaica-Central Cuba-the Central Bahamas on Wednesday. On Wednesday and Thursday, the models agree that a trough of low pressure will dip down over the Eastern U.S., which is likely to turn 97L to the north. The exact timing and strength of this trough varies considerably from model to model, and will be critical in determining where and when 97L will turn to the north. The best model for predicting the timing and strength of such troughs over the past two years has been the ECMWF (European Center model), and this model currently brings 97L into the Florida Keys on Thursday night next week. You can view ECMWF forecasts on our wundermap with the model layer turned on. The European Center does not permit public display of tropical storm positions from their hurricane tracking module of their model, so we are unable to put ECMWF forecasts on our computer model forecast page that plots positions from the other major models.

Remember that a 7-day forecast by even our best model will be off by an average of over 700 miles, so it is too early to tell what part of the U.S. might be most at risk from a strike by 97L. This weekend would be a good time to go over your hurricane preparedness.


Figure 4. Morning satellite image of Invest 98L off the coast of Africa.

Invest 98L near the coast of Africa
A tropical wave near the coast of Africa, a few hundred miles southeast of the Cape Verde Islands, is moving west to west-northwestward at 10 - 15 mph. This wave, designated Invest 98L by NHC yesterday, is large and well-organized, with a modest amount of spin and heavy thunderstorm activity. 98L will bring strong, gusty winds and heavy rains to the Cape Verde Islands today and Saturday as the storm skirts to the south. So far this morning, top sustained winds measured in the islands were 24 mph at Mindelo. Water temperatures are warm, near 27 - 28°C, and wind shear is low, 5 - 10 knots, so 98L should continue to organize today. NHC gave the storm a 50% chance of developing into a tropical depression in their 8am advisory. Once 98L passes to the west of the Cape Verde Islands, it has a long stretch of ocean to cross before it could affect any other land areas. Approximately 70 - 80% of all tropical cyclones that pass this close to the Cape Verde Islands end up curving out to sea and not affecting any other land areas, according to Dr. Bob Hart's excellent historical probability of landfall charts. The latest set of long-range model runs go along with this idea, but it is too early to be confident of this.

Jeff Masters

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Prime set up for Dmax

Member Since: Posts: Comments:
Quoting atmoaggie:
*Some* mountains, but not a great deal:


Ah, so maybe that's why Richard was so slow to weaken?
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Quoting nigel20:

In terms surge, wouldn't it be limited due to the barrier reef?
Yes, some.
But the angle of approach combined with the shape of the coastline probably makes it an even wash.

Still should slow the water some...even if the heights attained are about the same.
(good thought, though)
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2839. pottery
Quoting presslord:


What time do you break the seal on the rum?

The minute you get here.
Hurry.....
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Quoting pottery:

Check Patrap's blog.
Bottom of this page, click 'blog directory'.

Thanks, forgot that Patrap keeps a nice preparation list.

Also thanks KEEPER for posting the list (did not want to quote since it's pretty long). I may create my own list and post it, but there is nothing like the practical experience of having gone through a major tropical event to really show what works and what does not (I sincerely hope I don't get to use the list with 97L).
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Quoting KEEPEROFTHEGATE:



Weather Safety Emergency Checklist
Be ready for a weather emergency in advance and put together a basic survival kit.

Food Items:
Bottled drinking water
Bread
Crackers
Cookies, snacks
Canned fruit
Canned meat, fish
Apples, bananas
Dried fruit
Canned/boxed beverages
Fruit drinks
Peanut butter

Non-Food Items:
Ice
Coolers
Plastic forks and cups
Napkins
Can opener (non-electric)
Batteries for flashlights and radio
Plastic trash bags
Charcoal
Water purifying tablets
Flashlights
Candles and matches
Clothing and bedding
Extra socks and underwear
Pillows
Sleeping bag and blankets
Washcloth and towel for each person
Soap, toothbrushes, toothpaste
Deodorant
Shaving kit
Contact lens solution
Hair care items and mirror
Dentures
Sanitary napkins and tampons
Paper towels, toilet paper
Hearing aid batteries
Watch or clock
Portable radio with fresh batteries
Chlorine tablets
Spare pair of eyeglasses
Cash
Prescription medicines
Important papers (drivers licenses, insurance policies, social security cards)
Toolbox with hammer, nails, screws, screwdrivers and wrenches (to use after the storm to make your home livable again)
Cell phone (take an extra battery or a means to power or charge it)
list of people to contact for emergencies

First Aid Kit:
Keep contents of first aid kit in a waterproof metal or plastic box.

Prescription medicines (four-week supply)
Bandages and Band-Aids
Antiseptic
Adhesive tape rolls
Aspirin
Insect repellent
First aid handbook
Scissors
Antibacterial soap
Safety pins
Thermometer
Needle (for splinters)
Items for Infants:

Small toys include favorite stuffed animals
Clothes
Diapers and baby wipes
Milk or formula
Powders, creams or ointments
Bottles and nipples
Baby food
Sheets, blankets, rubber pads
Portable crib
Plastic bags
Pacifiers


No Kit complete without one of these: Link
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2836. rv1pop
Quoting bayoubug:
Lets play fantasy hurracane pick your name and place of land fall..


OK in the name of fun, and almost as accurate as many other predictions, I guess Fairbanks AK in 9 hours and Nome in 22 hours.
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The poll:
CACA.
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2834. nigel20
Quoting atmoaggie:
*Some* mountains, but not a great deal:

In terms of storm surge, wouldn't it be limited due to the barrier reef?
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Quoting spiceymonster:
See Thunderpig's quote reminds me of question.

how do you get down off an elephant?

Lee
*groan*

(sorry)
;-)
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Quoting pottery:

It's DARK here, dont you know?
Everything is done, except all the stuff that still needs doing.
I am Totally in control of the situation.
(he said nervously...)

What time do you get here?


What time do you break the seal on the rum?
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2829. j2008
Quoting WeatherNerdPR:

Central America and Mexico got pounded last year.

Yea its really amazing how such a small coast line can get hit so much in a year, but with how many storms there were affecting the CA area its no surprise.
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Quoting hahaguy:


Probably in the morning.


Ok, thanks
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2827. pottery
Quoting presslord:


Aren't you supposed to be preparing a party?

It's DARK here, dont you know?
Everything is done, except all the stuff that still needs doing.
I am Totally in control of the situation.
(he said nervously...)

What time do you get here?
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I pick the Apalachicola, Fl, as the landfall target per the next GFS model run. Can't have a hurricane season without warnings going up Apalachicola, Fl
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Quoting KoritheMan:


I'm unsure just how mountainous Belize really is, but hurricanes typically weaken very quickly after making landfall in Central America. While a Category 2 is nothing to sneeze at, when it is crossing over dangerously rugged terrain, the winds will quickly subside, confining those effects to areas along the coast and just inland from it.

Of course, this does not downplay the significance of Harvey, or any hurricane, at all. I am just saying; freshwater flooding is what kills in Central America, not wind.

Hopefully a situation like that won't happen this year.
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2824. KEEPEROFTHEGATE (Mod)
T.C.F.A.
INV/XX/97L
MARK
14.69N/53.15W
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The poll:
CAA
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UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 20 AUG 2011 Time : 021500 UTC
Lat : 16:10:41 N Lon : 85:04:38 W


CI# /Pressure/ Vmax
3.5 / 993.2mb/ 55.0kt


Final T# Adj T# Raw T#
3.1 3.5 4.2

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2821. hahaguy
Quoting HoustonTxGal:
Question......

When can we expect a new update from Dr. Masters?


Probably in the morning.
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See Thunderpig's quote reminds me of question.

how do you get down off an elephant?

Lee
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Quoting HoustonTxGal:
Question......

When can we expect a new update from Dr. Masters?


Tomorrow morning.
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...oh, man...
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Quoting KoritheMan:


I'm unsure just how mountainous Belize really is, but hurricanes typically weaken very quickly after making landfall in Central America. While a Category 2 is nothing to sneeze at, when it is crossing over dangerously rugged terrain, the winds will quickly subside, confining those effects to areas along the coast and just inland from it.

Of course, this does not downplay the significance of Harvey, or any hurricane, at all. I am just saying; freshwater flooding is what kills in Central America, not wind.
*Some* mountains, but not a great deal:
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Question......

When can we expect a new update from Dr. Masters?
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Quoting KEHCharleston:
RE: 2730

Regarding safe-guarding important papers, items etc. I have heard a couple of interesting solutions.
One is to use your dishwasher - Makes sense to me.
Another is to mail important papers (insurance etc) to yourself.


I always kept my important papers in an old ammo box in my freezer. When my house burned down last November the firemen helped pry open the melted lump of freezer, there was the ammo box and all my papers were perfectly fine. Note: keep the box on the side where the door opens, rescuing the box is easier when they don't have to open it all the way in order to get to the other side.
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2814. 3211976
Wave height is increasing quit a bit in Bouy Station 41040 - West Atlantic
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2812. KEEPEROFTHEGATE (Mod)
T.C.F.W.
08L/TS/H/CX
NEARING LANDFALL


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Quoting dfwstormwatch:
Poll Time!!!!!!!!!!!!!!!


1. how strong will harvey become?
A 65 MPH
B 70 MPH
C 75 MPH
D Higher/Lower


2. what percentage will invest 97 be at 2 am
A 60%
B 70%
C 80%
D Higher/Lower


3. what percentage will invest 98/99 be at 2 am
A 30%
B 40%
C 50%
D Higher/Lower


daa
Member Since: June 17, 2011 Posts: 11 Comments: 6493
2810. Grothar
Member Since: Posts: Comments:
Quoting j2008:

Yea last year was bad for Belize, they seemed like they couldnt get a break. I think three to four storms made landfall there last year. Hope the luck changes, thy could use a break.

Central America and Mexico got pounded last year.
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Poll Time!!!!!!!!!!!!!!!


1. how strong will harvey become?
A 65 MPH
B 70 MPH
C 75 MPH
D Higher/Lower


2. what percentage will invest 97 be at 2 am?
A 60%
B 70%
C 80%
D Higher/Lower


3. what percentage will invest 98/99 be at 2 am?
A 30%
B 40%
C 50%
D Higher/Lower
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Quoting pottery:

Check Patrap's blog.
Bottom of this page, click 'blog directory'.


Aren't you supposed to be preparing a party?
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Quoting AtHomeInTX:


Lol. My exact thoughts when I read that. Good evening everyone. :)

Athome, you remember that best-case scenario about Harvey RIing and coughing up a bunch of moisture to the
WV wagon around TX? It's going to happen and you may get rain tomorrow from that big blob circling down from KS.
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Quoting WeatherNerdPR:

Last year, Richard hit Belize as a Cat 2. From Wiki:
"Throughout Belize, Hurricane Richard caused an estimated US$80 million in damage. Two fatalities took place in the country, one direct and the other indirect. One person drowned after his ship capsized during the storm and another was mauled to death by a jaguar that escaped its cage after a tree fell and broke the cage."


I'm unsure just how mountainous Belize really is, but hurricanes typically weaken very quickly after making landfall in Central America. While a Category 2 is nothing to sneeze at, when it is crossing over dangerously rugged terrain, the winds will quickly subside, confining those effects to areas along the coast and just inland from it.

Of course, this does not downplay the significance of Harvey, or any hurricane, at all. I am just saying; freshwater flooding is what kills in Central America, not wind.
Member Since: Posts: Comments:
Quoting CaicosRetiredSailor:
Circulation is well south of the convective activity.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
Thanks Keeper, thought it had been Patrap
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RE: 2730

Regarding safe-guarding important papers, items etc. I have heard a couple of interesting solutions.
One is to use your dishwasher - Makes sense to me.
Another is to mail important papers (insurance etc) to yourself.
Member Since: Posts: Comments:
2801. j2008
Quoting WeatherNerdPR:

Last year, Richard hit Belize as a Cat 2. From Wiki:
"Throughout Belize, Hurricane Richard caused an estimated US$80 million in damage. Two fatalities took place in the country, one direct and the other indirect. One person drowned after his ship capsized during the storm and another was mauled to death by a jaguar that escaped its cage after a tree fell and broke the cage."

Yea last year was bad for Belize, they seemed like they couldnt get a break. I think three to four storms made landfall there last year. Hope the luck changes, thy could use a break.
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2800. Skyepony (Mod)
Diurnal Dancing Abstract..
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Quoting avthunder:
Don't get too nervous - just be prepared. This would be the weekend to check all your supplies. Non obvious? Hmm - books, dog food, medications, pay your bills before your internet goes down. Propane or charcoal for the grill - we used ours for 2 weeks after Wilma. Things to alleviate boredom with no power. Birth Control? :)
Saw Norcross on TWC - seems to think there is no way 97L will miss CONUS.

That "pay you bill" idea is golden, will add it to my hurricane preparation permanent list. Thanks.
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2798. pottery
Quoting Huracaneer:

Thanks. That's the kind of idea I was looking for, always like to collect these hints. You know about what post number that was, too lazy to go through all 2700 posts.

Check Patrap's blog.
Bottom of this page, click 'blog INDEX'.

edited
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Quoting KoritheMan:


In Belize's case, the winds won't be a problem even if Harvey does ramp up to a hurricane. Their primary source of damage from tropical cyclones, barring extreme examples like Iris in 2001, is freshwater flooding.

Last year, Richard hit Belize as a Cat 2. From Wiki:
"Throughout Belize, Hurricane Richard caused an estimated US$80 million in damage. Two fatalities took place in the country, one direct and the other indirect. One person drowned after his ship capsized during the storm and another was mauled to death by a jaguar that escaped its cage after a tree fell and broke the cage."
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Member Since: July 12, 2007 Posts: 0 Comments: 6037
Harvey-fuel is quite good. Might be what he was waiting for, honestly.

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2794. pottery
Quoting KEEPEROFTHEGATE:
yes it is imagine what it could be if there was none

Would be a VERY different story for sure!
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Quoting aislinnpaps:


Charge your cell phone.
Patrap gave a good list earlier tonight.

Thanks. That's the kind of idea I was looking for, always like to collect these hints. You know about what post number that was, too lazy to go through all 2700+ posts.
Member Since: Posts: Comments:

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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.