Disturbance 98L probably no threat to land

By: Dr. Jeff Masters , 1:46 PM GMT on September 18, 2009

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A tropical disturbance (98L), is located midway between Africa and the Lesser Antilles Islands. This disturbance has a well-defined surface circulation, and has developed a modest amount of heavy thunderstorm activity overnight. This morning's QuikSCAT pass (Figure 1) shows a complete, circular wind pattern around the low pressure center of 98L, but top winds were only 25 mph. Wind shear is moderate, about 15 knots, and Sea Surface Temperatures are 28°C, which is about 2°C above the 26°C threshold needed to support a tropical cyclone. There is a large amount of dry air to the north and west of 98L, and this dry air is interfering with development.

The global computer models predict differing amounts of wind shear in the path of 98L as it moves west-northwest at 10 mph over the next three days. The ECMWF, GFS, and UKMET models do not develop 98L, while the NOGAPS, GFDL, and HWRF do. The models that do develop 98L predict that a strong trough of low pressure will turn 98L to the northwest and then north beginning on Monday, with the result that 98L misses the Lesser Antilles Islands by at least 500 miles. Given the moderate or higher wind shear in 98L's path, and dry air to the northwest, the system should develop only slowly. NHC is giving 98L a medium (30 - 50%) chance of developing into a tropical depression by Sunday. At this time, it does not appear that 98L will ever threaten any land areas.

The remains of Hurricane Fred are still spinning away, near 25N 66W, about 900 miles east of Florida. Wind shear is 20 knots, which is marginal for development, and there is very dry air surrounding ex-Fred on all sides. None of the computer models develop ex-Fred, and it will have a tough time regenerating with so much dry air and wind shear. The remains of Fred should move over Florida Monday night or Tuesday morning.


Figure 1. Morning QuickSCAT image of the Atlantic, showing the well-defined surface circulation of disturbance 98L. Image credit: NOAA/NESDIS.

One year anniversary of Hurricane Ike
I've been focusing this week on the 20th anniversary of Hurricane Hugo, but we also passed the one year anniversary of Hurricane Ike. Many areas along the Texas and Louisiana coast affected by Ike have fully recovered, but recovery efforts will still take many more years in other areas. In Galveston, which suffered $3.2 billion in damage, 75% of the businesses have reopened, and 95% of the population has returned. Boston.com has posted a very nice series of clickable images that show before and after scenes of some of the areas that have recovered from Hurricane Ike.

Ike washed away huge sections of beach and dunes that helped protect the Texas coast from more serious damage, and this week the state legislature approved $135 million in funds to help replace these critical natural protection systems. The restored beaches will probably last ten years, barring another strike by a hurricane of Ike's stature. Texas considers two-thirds of its 367-mile shoreline to be critically eroding, which it defines as a historical rate of more than 2 feet a year. Much of this erosion can be blamed on sea level rise. Global sea level rose seven inches over the past century, and is expected to rise at least that much over the coming century.


Figure 2. Villagers in Haiti plant one of their "Million Tree Campaign" trees. Image credit: Lambi Fund of Haiti.

Hurricane relief donations
There hasn't been a need for new hurricane-related disaster relief efforts this year, in stark contrast to 2008. However, the charities we rely on to provide disaster relief still require funds to operate in quiet years, and I encourage you to consider a donation at this time to one of my two favorite disaster relief charities. Portlight.org, which was very effective at helping out isolated, under-served communities in the wake of Hurricane Ike, is committed to raising $12,000 to purchase and outfit a mobile kitchen. This kitchen will be capable of feeding up to 2,000 people two hot meals per day in post-disaster situations. The Lambi Fund of Haiti has launched its "Million Tree Campaign", which aims to use local labor to plant a million trees over the next three years along severely deforested slopes in Haiti. Both of these charities wrote to me several times last year about the stunning generosity readers of this blog showed with their donations. Thanks!

Twenty years ago today
As Hurricane Hugo approached the U.S. Virgin Islands in the early morning hours of September 18, 1989, the storm slowed down to 10 mph. The slower speed allowed Hugo to punish the island of St. Croix with the worst beating of any location along the hurricane's destructive path. At 2am local time on September 18, 1989, Hurricane Hugo's eyewall struck St. Croix, bringing incredibly ferocious Category 4 winds, sustained at 140 mph. The hurricane's gusts were remarkably violent, and many residents witnessed tornado-like vorticies barreling across the island as the hurricane raged about them. A storm surge of 2 - 3 feet, topped by battering waves 20 - 23 feet high, assaulted the coast, adding to the destruction. Wunderground member Mike Steers wrote me to describe his experience on St. Croix: "Hugo was incredible. Many vortexes came in that night. The roar and intensity of the winds that night were incredible. When the eyewall came over, we were forced to take refuge in the bathroom as the rest of the house came apart. The pressure was so low outside the house that all of the water was sucked out of the toilet and an air draft was created through the toilet. Just when I thought it was as bad as it would get, the intensity of it all dialed up even higher. Dozens and dozens of times, my ears would violently pop due to rapid pressure changes. The next morning, of course, the devastation was unbelievable. In my front yard was a 18-foot boat with an outboard on it, that had been picked up from a marina two miles away. I had lost my house, and job, the Seaplane company I was a pilot for. After a couple months, I had to leave everything behind. In some respects, after 20 years, there an many aspects of the society that have yet to recover". Two people were killed on St. Croix, 80 injured, and 90% of the buildings were damaged or destroyed. Damage estimates for St. Croix were astronomical, over $1 billion, and the island's entire infrastructure was virtually wiped out. Six weeks after the hurricane, only 25% of the public roads had been cleared, and only 25% of the island had power.


Figure 3. GOES visible satellite image of Hurricane Hugo taken on September 18, 1989. Note the lack of cloud cover on the hurricane's southwest side, indicating that strong upper-level winds from the southwest were likely creating wind shear, weakening the storm. Image credit: Google Earth rendition of the NOAA HURSAT data base.

As Hugo departed St. Croix, strong upper-level winds from the southwest created wind shear that weakened the storm to a Category 3 hurricane with 130 mph winds. The upper level winds also caused Hugo to accelerate to 15 mph and turn more northwest. The eye passed over Puerto Rico's Vieques Island at 8am and over Fajardo on the extreme northeastern tip of Puerto Rico at 9am. On Culebra Island, an island twelve miles east of Fajardo, a gust to 170 mph was recorded by the ship Night Cap in the main harbor. The south-facing harbor received sustained southerly winds in excess of 120 mph for several hours as Hugo roared by to the south. The resulting wave "set-up" created a storm surge in excess of 13 feet in the supposedly hurricane-proof harbor. A large portion of the Caribbean's charter boat fleet, some 200 boats, was sheltering in Culebra's harbor, and 136 of these boats were badly damaged or sunk. Over 80% of the wooden structures on both Culebra and Vieques were destroyed.


Figure 4. Damage on St. Croix (two top photos), Culebra Island (bottom right), and Puerto Rico's Roosevelt Roads Navy Base (bottom left), after Hurricane Hugo. Image credit: NOAA Photo Library.

Along the northeastern coast of Puerto Rico, waves up to ten feet high riding on top of a 3 - 4 foot storm surge caused severe coastal flooding of low-lying areas. Hugo's winds tore into Puerto Rico's El Yunque rainforest, downing thousands of trees. The agricultural sector was devastated, with nearly all of the island's banana and coffee crops wiped out. Twelve deaths in Puerto Rico were attributed to Hugo, six of which occurred in the southern city of Guayama where some residents were electrocuted by downed power lines. Nearly 28,000 people were left homeless by the storm, and damage to the island exceeded $1 billion.

Storm chaser Michael Laca was at Luquillo Beach on the northeast shore of Puerto Rico, and has posted a remarkable 28-minute video on YouTube of Hurricane Hugo footage.

Jeff Masters

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Quoting centex:
98L looks like TD. Models pull NW, I don't see that in short term. What am I missing?


I think the models are underestimating the strength of the subtropical ridge to the north.
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Link

See the red blob on the TEX/MEX coast? that's what I meant Ice. Wouldn't let me post a pic. A lot of the models show that to some extent.
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1388. JLPR
well thank God the power came back xD
I was going nuts lol

im on my way to replace all the double posts with a lot of . xD
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Quoting KoritheMan:


38L?


Lol. See i push wrong buttons everywhere. :) 98 L
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1386. centex
98L looks like TD. Models pull NW, I don't see that in short term. What am I missing?
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Quoting homelesswanderer:


NP. I'm always hitting the wrong buttons on my IPOD touch. Lol. I don't have a pic of 38l but it seemed to be getting a lot better organized before blackout.


38L?
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Quoting JLPR2:
sorry for the parade of posts :p stupid phone lol but even with all the posts no one replied :(


NP. I'm always hitting the wrong buttons on my IPOD touch. Lol. I don't have a pic of 38l but it seemed to be getting a lot better organized before blackout.
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1382. JLPR2
sorry for the parade of posts :p stupid phone lol but even with all the posts no one replied :(
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Quoting iceman55:
Link


new models runs


Hey Ice. Have you seen BT? Looks like almost all the models to some degree have another stretched out low pressure/850vort thing along the Tex/Mex border coast. Almost like what we watched all week last time. Lol.
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1380. centex
We all know the models have limited use before TD forms. Why do we expect them to be correct for invest? I just get impression model consensus means something at this point when it does not.
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Quoting centex:
No, the dup post.


O ok. :)
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1377. centex
Quoting homelesswanderer:


Me?
No, the dup post.
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Quoting centex:
explain


Me?
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1374. centex
explain
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Whoops. Thats a lot a posts. lol
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1372. JLPR2
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1371. JLPR2
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1361. JLPR2
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1360. JLPR2
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1359. centex
5 degree blow up, not your normal wax and wane.
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1358. JLPR2
hello all :) Secondary acount xp anything new with 98l im on amobile phone also a picture of 98l would be nice :)
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Quoting reedzone:


2 hours old, guess we wont get any updated images till 2:30 a.m.


That's about right!!
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Quoting Bordonaro:
Link

Link above is to the Navy Microwave Satellites for AL07 FredEx and 98L! Last update was at 0400 UTC, 11 AM CDT


2 hours old, guess we wont get any updated images till 2:30 a.m.
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Link

Link above is to the Navy Microwave Satellites for AL07 FredEx and 98L! Last update was at 0400 UTC, 11 AM CDT
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1354. centex
I see Grace and W for next couple of days.
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Quoting centex:
looks like invest or more to me.



Yep. Its certainly ballooning up. The last visible to the last frame big difference.
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1352. centex
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1351. centex
looks like invest or more to me.

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Quoting reedzone:
Umm is it just my computer or is every satellite not updating.. even ramsdis wont update.. Somethings not right.

Satellite eclipse every night from about 11:30PM through 2-2:30AM CDT
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Umm is it just my computer or is every satellite not updating.. even ramsdis wont update.. Somethings not right.
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1348. centex
I'm not seeing temp blow up. They saw this 4 hours ago. I'm a believer, and Beatles fan.
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Now that 07L is out of the 20 knot shear zone, it could manage to blow some convection in a few hours or so during DMAX.
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Quoting centex:
The Texas ULL has finally moved out. We had beneficial rain but east of lakes in central texas.So expect restrictions until water supply satisfied.


I know!! The main ULL is over AR/LA border area and pieces of energy keep ripping through the Mid TN valley!! LOL!!

I lived in DFW Metroplex for 28YRS!! Here in Nashville, TN with my daughter, helping her out for awhile!! We've had from 5.5 to 11 IN of rain over the last 3 days!! Plus rain is in the forecast through next Thursday!!

No Mexican Plume here!! VERY little cap at ALL on the atmosphere!! MAN the clouds here need lil excuse to rain!! Nashville AP is at about 8 IN in 9-09 and 10 days to go!!

This is an El Nino year, the rains will come ALL winter long, ENJOY!!
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1345. IKE
Good night/morning, folks.....

Day 111 of the season starts.
72 to go after today.
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1344. IKE
Unless FRED-EX puts on a magical display of convection in a negative MJO, I'd look for recon to be canceled tomorrow.

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Quoting IKE:
What happened to FRED-EX? He go bye-bye again?



He does not want to let Wilma see what has become of him.
Member Since: September 6, 2009 Posts: 2 Comments: 3720
1342. centex
I see bright red. Not just last hour.
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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.