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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Quoting bayoubug:
Lets play fantasy hurracane pick your name and place of land fall..




thats even better



i pick LA on the gfs
Member Since: May 21, 2006 Posts: 5089 Comments: 114054
Quoting GoWVU:
Question for everyone, who is Taz? He mispells all the time but time and time again I see him saying poof... Does he run the blog? Maybe someone should say poof to him, I am a newbie but he talks down to lots of folks... Just my thoughts...


yes...Taz runs the blog....don't mess with him....he has powers to make people...well....evaporate...
Member Since: August 13, 2007 Posts: 0 Comments: 10458
2690. j2008
Quoting GoWVU:


Just asking, thanks for the answer I am trying to figure out the bloggers... Thanks for the reply

No problem, I'm happy to help out a fellow blogger anytime.
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Interesting view of 97L

Link

Hope this link/graphic works... have not tried to post one before :o)
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2687. GoWVU
Quoting FrankZapper:
Taz is DrM's bro or something.


Ok, well that explains it...
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Quoting P451:



Ugh. The msfc enhanced IR would make a fart look like a Cat 5.


However, when the rammb product looks good, you know you've got deep convection.



-80c and dropping.


All the highest cloud tops in W CONUS look like 93s, especially that one in KS.
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Quoting Tazmanian:
place your bets evere one new mode runs come out



best starting at TX is 5 points LA 30 points MS and AL 50 points


and FL 100 points so whats see where the mode runs end up this sould be fun



whats the gussing game start

Lets play fantasy hurracane pick your name and place of land fall..
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Quoting P451:
Taz, are you drinking tonight?



would you like me too ander that for you lol
Member Since: May 21, 2006 Posts: 5089 Comments: 114054
Quoting Neapolitan:

http://www.met.nps.edu/~mtmontgo/storms2011.html


Thank you. That is exactly what I was looking for. And it is good to see no ominous comments about was coming from the east. Again thanks.
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Quoting gugi182:
i got 2 question can someone answer me I'm just curious

1. What is a troll, i see everybody writing Trolls?
2. What is DMAX?


A troll is a person who makes inflammatory comments just to get a reaction, in this blog there are a few chronic trolls who come back again and again making remarks designed to get the people here all riled up.

DMAX is diurnal maximum, it's the period of time when the atmosphere has cooled enough to provide maximum growth for thunderstorms. There is also a DMin when the opposite happens, i.e. the atmosphere is more stable and thunderstorms are a minimum. Mature storms are not affected much, but invests and depressions and even weak tropical storms can have dramatic changes due to this cycle.
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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 : 014500 UTC
Lat : 16:36:36 N Lon : 85:25:24 W


CI# /Pressure/ Vmax
3.5 / 993.0mb/ 55.0kt


Final T# Adj T# Raw T#
3.1 3.5 3.7
Member Since: July 31, 2011 Posts: 4 Comments: 753
Quoting pottery:

Ditto That!
Brilliant.
Got to LOVE it.


I just spilled/spit beer all over my keyboard.
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Quoting gugi182:
i got 2 question can someone answer me I'm just curious

1. What is a troll, i see everybody writing Trolls?
2. What is DMAX?



Troll car like the ISUZU D-MAX will allow you to drive through the tough roads of the highlands of Iceland with a variety of cargo.

http://www.elvesandtrolls.com/CARRENTAL/troll-car s/Booking/3/isuzu-d-max
Member Since: July 12, 2007 Posts: 0 Comments: 5984
2676. GoWVU
Quoting j2008:

Hes a pretty cool blogger, but he can sometimes get a little troll obsessed, He doesnt give trolls any chance, I cant blame him. Shall we get back to Harvey and 97,98,99,Fernanda, Greg.


Just asking, thanks for the answer I am trying to figure out the bloggers... Thanks for the reply
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Evening All.

Harvey skirting the coast tonight.

Member Since: August 19, 2005 Posts: 5 Comments: 4863
Quoting YouCaneDoIt:
Anxiously awaiting the 11am TWO


Next two is at 2AM
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2672. KEEPEROFTHEGATE (Mod)
Quoting sunlinepr:
Vanishing... for the moment...

no i don't think so just stripping itself of the daytime convectionand heat once its all gone cycle will commence again i figure not long maybe once at the triple nickel 15/55
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2671. gugi182
thanks a lot so that's what DMAX meant ok!!! i got you thanks

Quoting HimacaneBrees:


The flare up of convection seen during the early morning hours is known as diurnal maximum.

And I think I may be a troll. Not sure yet.
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Quoting GoWVU:
Question for everyone, who is Taz? He mispells all the time but time and time again I see him saying poof... Does he run the blog? Maybe someone should say poof to him, I am a newbie but he talks down to lots of folks... Just my thoughts...
Taz is DrM's bro or something.
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Quoting HimacaneBrees:


The flare up of convection seen during the early morning hours is known as diurnal maximum.

And I think I may be a troll. Not sure yet.

Don't worry, someone will let you know.
Member Since: August 22, 2008 Posts: 12 Comments: 6010
Quoting YouCaneDoIt:
Anxiously awaiting the 11am TWO



2am 8am 2pm 8pm is the two
Member Since: May 21, 2006 Posts: 5089 Comments: 114054
Quoting bigeasystormcaster:
Did everyone notice on the GFS 18Z run (the latest) that this model now has 97L moving across the GOM and making landfall in SWLA/UTX coast!!!!!! This is an absolute worse case scenario with this system forecast to possible take a more southern track largely missing the large islands of the Carribean. If this track were to hold it would be crossing waters that are 90 degrees and would likely have good upper air support in this location causing potentially EXPLOSIVE intensification in this location (Katrina-like.)

Hopefully this will change. That would be a badddd track for everyone in it's path.

PLEASE REPLY AS TO THE POSSIBILITY OF THIS TRACK COMING TO FRUITION. I AM A RECENT HEART PATIENT AND DON'T NEED THIS CONCERN!!!!


You don't need to be concerned yet. It is still too early to know so relax and stay tuned. First dont rely 100 percent in those models they will shift from left to right and back before the system show a definite center which they need to be properly initialized. Yesterday runs where showing that texas LA impact you mention, Today the models are predicting an impact over the extreme east Gulfcoast. Does it mean we here in Mississippi and there where you are in Texas or Lousiana are in clear? the answer is no, but it is a waste of energy to panic about this at this point. As a matter of fact even if you were in the middle of the cone for a Katrina like event, it is pointless and a waste of energy to panic. Stay tuned to this site and enjoy the ride. A few days from now the news will start picking up on this so stay tuned to them as well when it happens but just as efore dont base your plans on their info and do not panic. Only follow NHC and your local emergency management agency advisories to make plans, but as before without panicking. Especially in your delicate condition.
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Quoting MysteryMeat:


OK, this is all a big joke, right? Right?





right right
Member Since: May 21, 2006 Posts: 5089 Comments: 114054
2663. j2008
Quoting GoWVU:
Question for everyone, who is Taz? He mispells all the time but time and time again I see him saying poof... Does he run the blog? Maybe someone should say poof to him, I am a newbie but he talks down to lots of folks... Just my thoughts...

Hes a pretty cool blogger, but he can sometimes get a little troll obsessed, He doesnt give trolls any chance, I cant blame him. Shall we get back to Harvey and 97,98,99,Fernanda, Greg.
Member Since: Posts: Comments:
Quoting gugi182:
i got 2 question can someone answer me I'm just curious

1. What is a troll, i see everybody writing Trolls?
2. What is DMAX?


The flare up of convection seen during the early morning hours is known as diurnal maximum.

And I think I may be a troll. Not sure yet.
Member Since: Posts: Comments:
Anxiously awaiting the 11am TWO
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Quoting stormwatcherCI:
That looks like after tracking the whole way through the Caribbean ,up through the eastern GOM it goes all the way up through the Eastern Seaboard.

If this scenario plays out it could definitely be a trouble maker for the northeast. They have recently received too much rain. With the ground already saturated those guys could be looking at some flooding issues depending on the speed of the system after landfall!!
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gfs comeing out place your best and the winner gets some points




starting at TX is 5 points LA 30 points MS and AL 50 points


and FL 100 points so whats see where the mode runs end up this sould be fun



whats the gussing game start

Member Since: May 21, 2006 Posts: 5089 Comments: 114054
2657. GoWVU
Quoting MysteryMeat:


OK, this is all a big joke, right? Right?


LOL, too funny
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2655. pottery
Quoting Ryuujin:


The EPICNESS of this quote can not be understated.

Just... Awesome Taz... Just... I'm in awe bro.


:D

Ditto That!
Brilliant.
Got to LOVE it.
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Quoting Tazmanian:



POOF all so larn how too spell


OK, this is all a big joke, right? Right?
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2653. Ryuujin
Quoting Levi32:
Fresh ASCAT of 97L shows nada underneath the mid-level center, which as mentioned before is obvious on satellite imagery.



So this doesn't bode well for a Hispainola strike and leads more to the agreement of a south track under Hisp & Cuba and then North into the gulf/fl?
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97L needs a big blow up like Harvey is currently having!!!! lol
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Quoting cheaterwon:
I thought the steering would change with Harvey is the pressure dropped below 1000 MB. Is this not correct, and if not at what pressure does the steering change at? TIA


If you observe the 500-850 mean wind steering flow (Steering flow for 990 to 999 MB Tropical Cyclones) you can see that the motion would still be generally westward to west-northwestward!
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Quoting xtremeweathertracker:

Check out this link!!! This IS the latest GFS at 18Z on 8/19/2011!!!
That looks like after tracking the whole way through the Caribbean ,up through the eastern GOM it goes all the way up through the Eastern Seaboard.
Member Since: October 9, 2008 Posts: 0 Comments: 8242
2648. GoWVU
Question for everyone, who is Taz? He mispells all the time but time and time again I see him saying poof... Does he run the blog? Maybe someone should say poof to him, I am a newbie but he talks down to lots of folks... Just my thoughts...
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Quoting CanesfanatUT:


LMAO! Wat does that mean, Taz?



not sure lol



am this trying too be funny
Member Since: May 21, 2006 Posts: 5089 Comments: 114054
Quoting RMM34667:
A few days ago SOMEONE on here posted a link to comments from those researching the "pouches". I think it was in reference to P18L (what I think became 98L). The continued reference to the "beast to the east" was goosebump stuff. I'd love to read their most recent comments. So if you posted that link, or smartly bookmarked that link.. I would be cool to share again.

Not that we don't have enough to watch at the moment. (yeah I'm in Florida (west coast)). But still like to be clued in on what else is coming down the pike.

http://www.met.nps.edu/~mtmontgo/storms2011.html
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60 hours out 00z nam p.r's getting swallowed up
Member Since: July 31, 2011 Posts: 4 Comments: 753
2644. JRRP
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Quoting Levi32:


The quest that is meteorology is finding ways to navigate through the darkness to find the end-destination.


Okay, now you're starting to sound like Confucius.
Member Since: August 22, 2008 Posts: 12 Comments: 6010
Quoting shadoclown45:
Taz Im sorry i have been mean to you in the past i didnt realize how much of a jerk i have been if you could forgive me i would like to forcast weather with you and the rest of this blog. Im sorry taz i have my own faults too.



thats ok whats talk weather
Member Since: May 21, 2006 Posts: 5089 Comments: 114054

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About JeffMasters

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