African tropical wave 99L slowly organizing

By: Dr. Jeff Masters , 1:26 PM GMT on July 31, 2012

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A tropical wave (Invest 99L) near 9°N 41°W, halfway between the Lesser Antilles Islands and the coast of Africa, has the potential to develop into a tropical depression later this week as it moves westward at 10 - 15 mph. Visible satellite loops show that the disturbance now has a moderate amount of poorly-organized heavy thunderstorms that continue to slowly increase in intensity and areal coverage. There is no surface circulation, but some counter-clockwise rotation of the large-scale cloud pattern is evident. Water vapor satellite loops show that 99L has a reasonably moist environment. The latest Saharan air layer analysis shows that the dry air from the Sahara lies to the north of 99L and is currently not affecting the storm. WInd shear over the disturbance is a light 5 - 10 knots, and ocean temperatures are 28°C, (82°F) which is well above the 26.5°C (80°F) threshold typically needed to allow formation of a tropical depression.


Figure 1. Morning satellite image of Invest 99L.

Forecast for 99L
Wind shear is expected to remain light through Friday, and ocean temperatures will remain near 28°C, according to the 8 am EDT run of the SHIPS model. However, a band of high wind shear of 20 - 40 knots associated with the subtropical jet stream lies just to the north of 99L, and it would not be a surprise to see 99L experience some higher shear conditions than are currently forecast. The farther north 99L gets, the higher the shear it will experience, and the SHIPS model is predicting shear in the moderate range, 10 - 20 knots, for Saturday - Sunday, as the storm works its way to 15°N. The disturbance is at 9°N, which is close enough to the Equator that the storm will have some difficultly getting spinning. Most of the models are showing some slow development of 99L. There are some major differences in the predicted forward speed of 99L, with the ECMWF and UKMET models predicting the storm will reach the Lesser Antilles on Friday, and the GFS predicting a later arrival, on Saturday. At 8 am Tuesday, NHC gave 99L a 20% chance of developing into a tropical depression by Thursday morning. I expect the storm will begin having trouble with tendrils of dry air reaching down from the north at times this week, but give 99L a 50% chance of eventually developing into Tropical Storm Ernesto sometime in the next ten days. Residents and visitors to the Lesser Antilles Islands should anticipate heavy rains and strong winds from 99L beginning to affect the islands as early as Friday morning. The long-range fate of 99L next week is uncertain. A track west to west-northwest through the Caribbean, or to the northwest towards the U.S. East Coast are both possible. The storm is less likely to survive if it heads northwest towards the U.S.

Extreme heat in the Central U.S.
The withering heat in America's heartland continued on Monday, with high temperatures of 112° recorded in Winfield, Kansas and Searcy, Arkansas. Little Rock, Arkansas hit 111°, their 3rd hottest temperature ever record, behind the all time record of 114° set just last year on August 3, and the 112° reading of 7/31/1986. Wichita and Coffeyville in Kansas both hit 111° Monday, and in Oklahoma, Enid, Tulsa Jones Airport, and Chandler all topped out at 111°. Carr Creek, Missouri hit 110°, the hottest temperature measured in the state so far this year. Highs temperatures Tuesday and Wednesday in this region could reach 110° again, as the most extreme heat this week will stay focused over Oklahoma and surrounding states.

Jeff Masters

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Not so well, as wxchaser97 did

Note: If Ernesto can reach hurricane cat.1, the Cone will shift more to the north,since GfS are predicting weak storm,and make a disagreement with the ships, icon and others intensity models
Member Since: June 20, 2012 Posts: 0 Comments: 2157


No SAL in front
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Quoting KoritheMan:


Still no latitude though. Gonna have to lift northward if it wants to survive.


Should be at 10N by early in the morning. Expect 11 or 12N by 60W.
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Quoting kmanislander:


Could be, but shear is very near to the Northern edge of the circulation and may disrupt it for a while. Earlier today I thought that it would close off within 12 to 18 hours but it looks a little ragged tonight.It is now closing in on 45W and appears to have picked up some forward speed.


Still no latitude though. Gonna have to lift northward if it wants to survive.
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Quoting TropicalAnalystwx13:

I disagree. It should be a well-formed tropical storm by that time.


Could be, but shear is very near to the Northern edge of the circulation and may disrupt it for a while. Earlier today I thought that it would close off within 12 to 18 hours but it looks a little ragged tonight.It is now closing in on 45W and appears to have picked up some forward speed.
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1616. nigel20
99L
Member Since: November 6, 2010 Posts: 11 Comments: 7978
Quoting TropicalAnalystwx13:

Oh...yeah...that...

I kinda accidentally...closed the page about an hour ago.


Surely you can at least give me some personal thoughts, though?
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Quoting TropicalAnalystwx13:

Oh...yeah...that...

I kinda accidentally...closed the page about an hour ago.


I like to use Notepad to copy/paste my blog, just in case.
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Quoting KoritheMan:
Come on Cody, how long does it take to churn out a blog? It's not like you even draw forecasts cones like I do!

Oh...yeah...that...

I kinda accidentally...closed the page about an hour ago.
Member Since: July 6, 2010 Posts: 113 Comments: 31884
1612. nigel20
Good evening everyone!

One of my earlier posts

Hopefully if 99L will stay away from Jamaica if it develops into a strong TS or hurricane. Work is now in progress on the Palisadoes shoreline protection to reduce the beach erosion and damage from storms and hurricanes...the project is slated for completion in December of this year.

Palisadoes is the thin strip of land connecting one of our airports to the mainland.

Palisadoes after hurricane Ivan

on going work


The road will be raised from its existing levels of 0.6 %u2013 1.0 metre, to 2.4 - 3.2 metres above sea level.
Rehabilitative and protective works along the Peninsula have been designed for a 100-Year Return Period (i.e. the shoreline will be expected to withstand storm surges only anticipated to re-occur every 100 years). A design rainfall intensity of 178mm per 24 hours was utilized in this design.
Member Since: November 6, 2010 Posts: 11 Comments: 7978
Come on Cody, how long does it take to churn out a blog? It's not like you even draw forecasts cones like I do!
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.
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Quoting kmanislander:


LOL. The thing is that 99L is in a steady state at the moment. Still too early for whatever Dmax may bring and the system needs to pull up to at least 11 N to avoid running into SA. I do believe that it will enter the Caribbean near 11/12 N and just skirt along the N coast of SA.

The main thing I am watching for now is a bit of a blow up overnight followed by a solid CDO developing near 55W. My best guess is classification as a TD close to 60W


I disagree. It should be a well-formed tropical storm by that time.
Member Since: July 6, 2010 Posts: 113 Comments: 31884
1608. Grothar
Quoting wunderkidcayman:

THANK YOU!!!!!!!!

PLEASE SAY THAT AGAIN


Stop yelling, my kids are sleeping.
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Good convergence
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Quoting KoritheMan:


Evening kman. Looking forward to some possible analysis from you this evening.


LOL. The thing is that 99L is in a steady state at the moment. Still too early for whatever Dmax may bring and the system needs to pull up to at least 11 N to avoid running into SA. I do believe that it will enter the Caribbean near 11/12 N and just skirt along the N coast of SA.

The main thing I am watching for now is a bit of a blow up overnight followed by a solid CDO developing near 55W. My best guess is classification as a TD close to 60W

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1605. JLPR2
Seems to be farther north than I thought.



Barely in the picture.
Member Since: September 4, 2007 Posts: 7 Comments: 8656
If they don't declare this a depression by the time
it gets away from ITCZ I will blow a fuse..

Literally.
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1603. etxwx
Typhoons trigger flood alerts
China Daily, August 1, 2012 Excerpt: Two typhoons will challenge the country's flood control capabilities in coming days, as many regions are now suffering from torrential rains and floods, authorities said. Heavy rains brought by Saola, the ninth typhoon of the year, are expected to hit coastal areas in Fujian and Zhejiang provinces on Thursday or Friday accompanied by strong winds. The 10th typhoon, named Damrey, may affect Jiangsu and Shandong provinces on Friday, Chen Zhenlin, spokesman for the China Meteorological Administration, said on Tuesday. The winds could reach 51 kilometers per second when the center of Saola passes the coastal areas, he added. The two typhoons may cover more than 10 provinces in the country, according to the State Flood Control and Drought Relief Headquarters on Tuesday.
Report continues here.
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1602. KEEPEROFTHEGATE (Mod)



convective areas are diminshing at the moment
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1601. Grothar
Dry air to the North, but not affecting it that much. Nice moisture field ahead of it upon which it can feed.

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Pacific water currents hidden agenda?

I’m sure authorities in US are detecting contamination from Fukushima Daiichi in fish on West Coast and not telling people

Arnold Gundersen, Nuclear Engineer: I’ve been encouraging people on the West Coast to demand of their state government to take some samples because the US government is not taking samples. And of course what samples are being taken, if it’s below an arbitrary number, the authorities are not announcing what that number is.

I’m sure the authorities have caught fish and they’re contaminated and to avoid a public health scare, or more likely to avoid a business collapse in the fisheries, they’re not telling people what the number is.

Is the radiation high or low? I don’t know, but I’m sure they’re detecting it in fish even on the West Coast of the United States.
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Quoting TropicalAnalystwx13:

Wind shear is not increasing and it didn't take dry air didn't bite it. 99L is separating from the ITCZ during DMIN...do you really expect it to look perfect?

Give it 'till morning.


lol!
Member Since: August 16, 2007 Posts: 1 Comments: 2338

Very strong vorticity
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Quoting Grothar:


Never mind!

XD!
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1596. Grothar
Quoting TropicalAnalystwx13:

You, you twit.


Never mind!
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I went back through the Storm Prediction Center's Storm Reports and counted 15/16 confirmed tornadoes in July 2012. The record low is 23.

I think we've set a new record.
Member Since: July 6, 2010 Posts: 113 Comments: 31884
Quoting kmanislander:
Good evening

99L is slowly getting its act together. Down to 1009 mbs, winds up a bit to 30 mph and convection consolidating over the center. Still lots of sea room before it reaches the Eastern Caribbean


Evening kman. Looking forward to some possible analysis from you this evening.
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Good evening

99L is slowly getting its act together. Down to 1009 mbs, winds up a bit to 30 mph and convection consolidating over the center. Still lots of sea room before it reaches the Eastern Caribbean
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Quoting Grothar:
Who was the idiot who said 99L would be a depression by late Tuesday or Wednesday?

You, you twit.
Member Since: July 6, 2010 Posts: 113 Comments: 31884
I am confused.. What happened to my other posts.
O.o
:\
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Quoting wunderkidcayman:

THANK YOU!!!!!!!!

PLEASE SAY THAT AGAIN

Wind shear is not increasing and dry air didn't bite it. 99L is separating from the ITCZ during DMIN...do you really expect it to look perfect?

Give it 'till morning.
Member Since: July 6, 2010 Posts: 113 Comments: 31884
Quoting Grothar:
Who was the idiot who said 99L would be a depression by late Tuesday or Wednesday?


You forgot to say "twit".
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Quoting KoritheMan:
99L is not being sheared. It has actually changed little during the last couple hours.
Quoting TropicalAnalystwx13:
Wind shear is not increasing and it didn't take dry air didn't bite it. 99L is separating from the ITCZ during DMIN...do you really expect it to look perfect?

Give it 'till morning.

THANK YOU!!!!!!!!

PLEASE SAY THAT AGAIN
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1587. Grothar
Who was the idiot who said 99L would be a depression by late Tuesday or Wednesday?
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Member Since: March 16, 2012 Posts: 127 Comments: 7940
Quoting wunderkidcayman:

there is no dry air


Actually there is, it's just that 99L is not ingesting it at the moment.
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Let me try posting something ...
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Quoting CybrTeddy:


I wouldn't say that, you'd be able to tell if it was being sheared. I'd say it just took a bite of dry air.I think that if 99L does form, it will happen on Thursday evening.

there is no dry air
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Wind shear is not increasing and dry air didn't bite it. 99L is separating from the ITCZ during DMIN...do you really expect it to look perfect?

Give it 'till morning.
Member Since: July 6, 2010 Posts: 113 Comments: 31884
99L is not being sheared. It has actually changed little during the last couple hours.
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There is actually a TUTT feature developing out ahead of 99L and why the increase in shear.

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Quoting KoritheMan:


Still not much definition to the circulation.

Perhaps 99L needs a dictionary.
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Quoting Gearsts:
Doesnt look that great actually, shear is increasing over it.

That's a negative.

Member Since: July 6, 2010 Posts: 113 Comments: 31884
Quoting Gearsts:
Doesnt look that great actually, shear is increasing over it.


I wouldn't say that, you'd be able to tell if it was being sheared. I'd say it just took a bite of dry air.I think that if 99L does form, it will happen on Thursday evening.
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Quoting Gearsts:
Doesnt look that great actually, shear is increasing over it.

It is detaching from the ITCZ, this is expected for a little bit and then convection should increase. 99L actually has an anticyclone over it. Anyway it is still looking good.
Member Since: March 16, 2012 Posts: 127 Comments: 7940
Quoting ilovehurricanes13:
wow!! look at the next tropical wave ready to come in the water its big!!


WOW !!!!!!
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Quoting ncstorm:


The GFS and CMC are showing a storm off the SC coast starting tomorrow and riding up both coasts..Im not going back and posting model runs but the CMC had a 1004mb and the 12z GFS had it clearly at warm core..the 18z I dont count as far as reliable when it comes to the GFS..

Good Night Everyone!
Yeah I saw the same thing that is why I was asking.it show it warm core last run.
Member Since: October 15, 2011 Posts: 0 Comments: 4231
1572. Gearsts
Quoting wxchaser97:
Doesnt look that great actually, shear is increasing over it.
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Quoting ilovehurricanes13:
wow!! look at the next tropical wave ready to come in the water its big!!

yeah I'm more looking at that low south of CV islands
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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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