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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2271. GetReal


Nice in flow at the low levels, and ventilating in all quads in the UL.
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you know if this recurves it will make it to TX/LA ahead of Aug 16-19.
I think it is safe to say they have blown that forecast :)
Member Since: February 11, 2012 Posts: 0 Comments: 9469
It's already been mentioned, but SAB is high enough for classification. TAFB reached T1.5 last night.

01/1145 UTC 9.3N 45.1W T1.5/1.5 99L -- Atlantic
Member Since: July 6, 2010 Posts: 109 Comments: 30291
2268. CJ5
Shear continues to be low in the southern Caribbean which works well for 99L. Based on the steering layers, it should cross Barbados/St. Lucia before any significant turn begins. I can still see a EC possibility but time is running out quickly.
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Cyber....do you have the link for the 06z GFS?
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Keep Your Cool because Nature Wont



The good news or silver lining in the dark cloud of unrelenting sun and heat is if you have drought you can't have tornado producing storms. In fact, as was forecast here, after the fast start to the tornado season things went quiet. But not just here in the southeast, but nationwide. In fact, it looks like July will close having produced the fewest tornadoes on record. July could even go down with the fewest tornadoes for ANY summer month on record, the old record being 20 in August of 1957.

Another long-range forecast that proved right was that the tropical storm season would quiet down after it got off to an unusually fast start, in fact July will exit without a single named tropical system for the first time since 2009. It looks like August will turn more active in the tropics.
Member Since: February 11, 2012 Posts: 0 Comments: 9469
What is going on no 8AM Model why????
Member Since: May 23, 2012 Posts: 0 Comments: 4208
2264. LargoFl
Quoting DeValk:
Any change this thing could stay south of Cuba and thread the needle into GOM?
..there is always that chance..way too early to tell just yet
Member Since: August 6, 2011 Posts: 4 Comments: 33473
Quoting CybrTeddy:
06z GFS showed 99L slowly developing until reaching the Western Caribbean where real intensification begins.


Things have changed from yesterday very significantly.

IF this can keep together until the WCARB and slow to a decent pace, then conditions could become favorable for something more than a tropical storm.

Haven't done a blog in four years. If this develops within the next 24 hours and the projected upper-level pattern continues to change, I just might.
Member Since: June 9, 2007 Posts: 4 Comments: 15718
Quoting GetReal:



99L appears to be close to becoming a TD or TS Ernesto later today. I see there is plenty of speculation as to where this system is going.

The previous runs of the M.O.D. (model of doom) had been pretty consistant on bringing an Ivan type tracking system across the southern Caribbean, before it turned WNW towards the NW Caribbean.

The latest 1300 run of the MOD has shifted slightly northward, and Ernesto tracking west to WNW as a strong Cat 1 hurricane through the central Lesser Antilles. MOD brings Erneato towards, and possibly over Jamaica as a strong Cat 2 as it tracks WNW torwards the Caymans. Ernsto bombs as a Cat 4 in NW Caribbean.

MOD turns Ernesto NW towards the Yucatan Channel, and at the end of the run has a 920 mb hurricane sitting in the central GOM.

MOD is nearly always correct.
I hope it is wrong we do not need a strong Hurricane in the C/Gulf with water temp like bath water!!!
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Quoting DeValk:
Any change this thing could stay south of Cuba and thread the needle into GOM?

Very possible.
Member Since: July 6, 2010 Posts: 109 Comments: 30291
2260. LargoFl
Quoting Hurricane1956:
Hello!!,sorry I'm not a expert what this graphic represent?,you said Miami coast what is that?,it looks to me like a low pressure (the way the arrows are pointing) off the South East coast is this correct?,thank you!.
..that was a futurecast of what the model see's friday.. for florida.....that swirl just might be what was over PR yesterday maybe
Member Since: August 6, 2011 Posts: 4 Comments: 33473
2259. DeValk
Any change this thing could stay south of Cuba and thread the needle into GOM?
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Quoting ILwthrfan:


I think the NHC is just waiting for this current blow up to persist through a little longer. It was starting to develop an anti-cyclone yesterday and judging by satellite representation it looks as if it is ventilating very well in 3 of its 4 quadrants. 99L has been steadily organizing the last 48 hours. So, at the least I'd say we will see the percentages go up by tonight, if not by tonight, then by tomorrow morning we should be looking at a Tropical Depression.

Being at 10N leaves it a place to where it is very difficult to develop westerly winds. It needs to gain a bit more in latitude, but it should do that in time. Being at 10N does make this system very difficult to turn out to sea. I wonder what the percentages of storms that form in the area of 99L are at making landfall. I bet it is high, not just for the islands, but all those beyond as well.



Is it completely out of the monsoon trof yet?
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I am not really liking the TVCN model for 12Z has it come stright to the Cayman Islands and recurves it in the middle of Cayman Islands

Quoting kmanislander:
I would imagine a HH will soon be positioned at St. Croix to check it out.

expected to take off on friday though I think they may bump it up to Thurs
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Quoting LargoFl:
Ew.It's like a huge Jacuzzi.
Member Since: August 14, 2010 Posts: 10 Comments: 15738
Quoting LargoFl:
..notice off miami's coast..whats that?
Hello!!,sorry I'm not a expert what this graphic represent?,you said Miami coast what is that?,it looks to me like a low pressure (the way the arrows are pointing) off the South East coast is this correct?,thank you!.
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2254. LargoFl
Member Since: August 6, 2011 Posts: 4 Comments: 33473
Quoting kmanislander:
I would imagine a HH will soon be positioned at St. Croix to check it out.
They're doing it Friday if I remembered correctly. Not 100% positive.
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Dry air and the shear from the TUTT seems to be affecting 99L as of now. Have to see how that progresses today.

Otherwise, low level banding has improved markedly form yesterday.

It's going to need more convective organization to be classified.



Member Since: June 9, 2007 Posts: 4 Comments: 15718
Quoting GetReal:


MOD has had the best handle of 99L so far.
If MOD was correct we'd have a cat 2 by now.Lol.
Member Since: August 14, 2010 Posts: 10 Comments: 15738
2250. bappit
Quoting washingtonian115:
CMC "Constantly Making Conclusions" How?.Because it has come to the conclusion that Future Ernesto will affect the east coast of Florida and has not changed it's mind other wise.

That's an old jibe at a model that has been upgraded.
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Quoting HurricaneHunterJoe:


To any of you smart gals and fellas,where is that new england trof supposed to be in 8-9 days and will it have the strength to create a weakness for Ernesto to go north if he is in the mid/eastern caribbean?
That's still a big question mark for now...
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Quoting TropicalAnalystwx13:

XTRP!


LOL!!!! Morning TA13...hahhahahah!
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Quoting wunderkidcayman:

they also changed 10.2N 47.0W to 10.7N 46.9W looking at past track still moving W-N of due W

AL, 99, 2012080100, , BEST, 0, 99N, 432W, 25, 1009, LO,

AL, 99, 2012080106, , BEST, 0, 103N, 450W, 25, 1009, LO,

AL, 99, 2012080112, , BEST, 0, 107N, 469W, 30, 1009, LO
FWIW, since the midnight GMT update, ATCF has relocated 99L 4.7 degrees to the north, and 3.7 degrees to the west.
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I strongly think that we will get renumber either at 11am or 2pm today
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I would imagine a HH will soon be positioned at St. Croix to check it out.
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Quoting GetReal:


MOD has had the best handle of 99L so far.
What is this MOD you're talking about? Just wondering...
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Quoting muddertracker:
I miss the FSU ensemble...what do yall consider the next best thing?

XTRP!
Member Since: July 6, 2010 Posts: 109 Comments: 30291
Quoting wunderkidcayman:

they also changed 10.2N 47.0W to 10.7N 46.9W looking at past track still moving W-N of due W

AL, 99, 2012080100, , BEST, 0, 99N, 432W, 25, 1009, LO,

AL, 99, 2012080106, , BEST, 0, 103N, 450W, 25, 1009, LO,

AL, 99, 2012080112, , BEST, 0, 107N, 469W, 30, 1009, LO


That new position means it will not move over our friends in Trinidad & Tobago.
Member Since: April 29, 2009 Posts: 75 Comments: 13337
Quoting HurricaneHunterJoe:

Nice banding. It looks like a TD to me. Maybe special update coming soon.
Member Since: September 30, 2007 Posts: 9 Comments: 15750
Quoting TropicalAnalystwx13:
I doubt 99L strengthens enough to come out of the Caribbean. It should pass through the Windward Islands around 14N and move west-northwest and be located just south of Jamaica in 5-6 days...probably as an intensifying hurricane.
and on to western Cuba,the Gulf and Texas(noobie wild guess)
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Quoting floridaboy14:
well i think it wont weaken in the eastern carribean. i just think it wont stregnthen. big difference. i am siding with TA13 on a track south of jamaica wnw towards the yucatan channel


To any of you smart gals and fellas,where is that new england trof supposed to be in 8-9 days and will it have the strength to create a weakness for Ernesto to go north if he is in the mid/eastern caribbean?
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I miss the FSU ensemble...what do yall consider the next best thing?
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2237. GetReal


MOD has had the best handle of 99L so far.
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Quoting Neapolitan:
Okay, now they've bumped the winds up 5 knots:

AL, 99, 2012080112, , BEST, 0, 107N, 469W, 30, 1009, LO, 34, NEQ, 0, 0, 0, 0, 1012, 150, 50, 0, 0, L, 0, , 0, 0, INVEST, M,

TD status imminent...

they also changed 10.2N 47.0W to 10.7N 46.9W looking at past track still moving W-N of due W

AL, 99, 2012080100, , BEST, 0, 99N, 432W, 25, 1009, LO,

AL, 99, 2012080106, , BEST, 0, 103N, 450W, 25, 1009, LO,

AL, 99, 2012080112, , BEST, 0, 107N, 469W, 30, 1009, LO
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Quoting LargoFl:
..IF..its right then this will become an East coast storm,so those folks need to be paying attention as well to this system and its track huh
Yes their are so many possibilities as far as track and strength is concerned.
Member Since: August 14, 2010 Posts: 10 Comments: 15738
2234. LargoFl
..notice off miami's coast..whats that?
Member Since: August 6, 2011 Posts: 4 Comments: 33473
Quoting ackee:
When will 99L be upgraded ?


A 5pm
B 11pm
C 5Am tomorrow
D 11Am tomorrow


B
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Quoting ackee:
When will 99L be upgraded ?


A 5pm
B 11pm
C 5Am tomorrow
D 11Am tomorrow


c
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Quoting Tropicsweatherpr:


And more north in latitude than the 10.2N.


The low appears to have responded to a weakness just to its North by lifting some but the track should resume a more Westerly motion in the next 12 hours or so IMO.

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Quoting ackee:
When will 99L be upgraded ?


A 5pm
B 11pm
C 5Am tomorrow
D 11Am tomorrow

A.
Member Since: July 6, 2010 Posts: 109 Comments: 30291
2229. SLU
All that's needed to conclude the formalities now is a good ASCAT pass to confirm its structure.
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2228. LargoFl
Quoting washingtonian115:
CMC "Constantly Making Conclusions" How?.Because it has come to the conclusion that Future Ernesto will affect the east coast of Florida and has not changed it's mind other wise.
..IF..its right then this will become an East coast storm,so those folks need to be paying attention as well to this system and its track huh
Member Since: August 6, 2011 Posts: 4 Comments: 33473
Quoting StormTracker2K:
I think we will have a TD at 5pm today. 99L is really looking good right now.

or maybe straight to a storm.
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2226. ackee
When will 99L be upgraded ?


A 5pm
B 11pm
C 5Am tomorrow
D 11Am tomorrow
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Quoting GetReal:



99L appears to be close to becoming a TD or TS Ernesto later today. I see there is plenty of speculation as to where this system is going.

The previous runs of the M.O.D. (model of doom) had been pretty consistant on bringing an Ivan type tracking system across the southern Caribbean, before it turned WNW towards the NW Caribbean.

The latest 1300 run of the MOD has shifted slightly northward, and Ernesto tracking west to WNW as a strong Cat 1 hurricane through the central Lesser Antilles. MOD brings Erneato towards, and possibly over Jamaica as a strong Cat 2 as it tracks WNW torwards the Caymans. Ernsto bombs as a Cat 4 in NW Caribbean.

MOD turns Ernesto NW towards the Yucatan Channel, and at the end of the run has a 920 mb hurricane sitting in the central GOM.

MOD is nearly always correct.


Well... I've never heard of "MOD" before.
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CMC "Constantly Making Conclusions" How?.Because it has come to the conclusion that Future Ernesto will affect the east coast of Florida and has not changed it's mind other wise.
Member Since: August 14, 2010 Posts: 10 Comments: 15738
Quoting Neapolitan:
Okay, now they've bumped the winds up 5 knots:

AL, 99, 2012080112, , BEST, 0, 107N, 469W, 30, 1009, LO, 34, NEQ, 0, 0, 0, 0, 1012, 150, 50, 0, 0, L, 0, , 0, 0, INVEST, M,

TD status imminent...

And it jumped .5N...
Member Since: July 6, 2010 Posts: 109 Comments: 30291
Quoting ncstorm:


they wont admit it when it comes to the NOGAPs..just let it be..


LOL
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2221. LargoFl
Quoting gulfbreeze:
We are watching!
..yes we are watching this closely huh..water temps in the gulf..high 80's..around texas its 90 whew
Member Since: August 6, 2011 Posts: 4 Comments: 33473

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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.