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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I suspect 99L goes straight to Ernesto over the next 24 hours.

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I respect the response for sure.

Thank you
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Quoting hydrus:
99L looks good for being that far south, but there is not much deep convection with it yet.


The convection has dried up over the past 6 hours but the organization has improved at the same time. That's the problem We/I have looking at Satt loops all day and noticing tiny changes in a short time frame.

I have to learn to leave the loops for while at 6-10 hour intervals like NHC does to really gauge improvement or degeneration but it is so hard to do............ :)
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Pat,I apologize as I didn't know the games are on tape tonight not live in US.
Member Since: April 29, 2009 Posts: 75 Comments: 14315
Quoting CybrTeddy:


Brings it up to 58kts before it hits that barrier of sheer. Maybe what kman said would prove correct if it managed to get a CDO by then.


Not even a hurricane would be able to withstand that. Not sure what he was trying to imply.

CDO + 25kt shear =

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Quoting ncstorm:
continued..and the GFS has it warm core now

yes!!! we may have Florence out of that. that would be two for August if it occur and and the month is just starting.
Member Since: October 15, 2011 Posts: 0 Comments: 4401
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Quoting RitaEvac:
Houston area, one year difference in weather pattern

All,



I have compared the rainfall cross Harris County for July 2011 and July 2012 and the results are very impressive (showing how dry 2011 was and how wet 2012 has been).



Over the northwest part of the county, where rainfall was least last July it has been the greatest this July. Most locations across Harris County are running over 5 times the amount of rainfall this July compared to last July and across the NW part of the county the rainfall this July is 10-15 times more. For a dramatic comparison site 1190 (Little Mound Creek at Mathis Road: July 2011: .04 in compared to July 2012: 17.52 in)



I have also attached all the Flood Warning gage stations for July 2012 and July 2011 rainfall at each site and the differences along with a graph showing the difference. I also attached the January to July rainfall and those differences.



July 2012 Rainfall:


July 2011 Rainfall:
The weather pattern has certainly changed, not just in Texas, but across the US and the Atlantic. I'm happy for you guys this year getting the rains you need to help alleviate the drought conditions you were faced with last year. Still bad in some spots, but not like last year where everywhere was in the red.

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Quoting MAweatherboy1:
Good afternoon. 99L looks good, I say 50% at 8PM, though the odds may be even higher than that:



Still doesn't look like it will be too strong though.


mother nature, please pull that thing north
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Quoting hydrus:
99L looks good for being that far south, but there is not much deep convection with it yet.


A good DMAX tonight will do it.
Member Since: April 29, 2009 Posts: 75 Comments: 14315
Quoting Tropicsweatherpr:
Phelps came second.


Dude... seriously?
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continued..and the GFS has it warm core now

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see post 749
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Quoting weathermanwannabe:
99L is starting to get that blossoming "look" and overall rotation but still below 10N.....Looking real good at the moment in a Tutt free environment until it gets to around 55W (see below). It's going to be a real interesting watch over the next 48 hours; "if" it is able a organize and break out from the ITCZ within the next 48, the models might shift to the North where the CMC has been for the past two days. Then we have to look at how sheer impacts the system.

Link
99L looks good for being that far south, but there is not much deep convection with it yet.
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Quoting Patrap:
There are 3 BAMM Models.

Deep, Medium, and shallow


It's actually just the "BAM" suite. Believe its the Beta Advection Model. Haven't read the paper in years.

Then there's the BAM(Shallow),BAM(Medium), and BAM(Deep).
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Quoting Pocamocca:

Allan. Really?
hahaha yes the models are trending south maybe the Gfs track is not crazy after all.
Member Since: October 15, 2011 Posts: 0 Comments: 4401
Houston area, one year difference in weather pattern

All,

I have compared the rainfall cross Harris County for July 2011 and July 2012 and the results are very impressive (showing how dry 2011 was and how wet 2012 has been).


Over the northwest part of the county, where rainfall was least last July it has been the greatest this July. Most locations across Harris County are running over 5 times the amount of rainfall this July compared to last July and across the NW part of the county the rainfall this July is 10-15 times more. For a dramatic comparison site 1190 (Little Mound Creek at Mathis Road: July 2011: .04 in compared to July 2012: 17.52 in)



I have also attached all the Flood Warning gage stations for July 2012 and July 2011 rainfall at each site and the differences along with a graph showing the difference. I also attached the January to July rainfall and those differences.



July 2012 Rainfall:


July 2011 Rainfall:


Edit: not gonna show up looks like
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99L is looking better and better as time goes by. Also it is gaining latitude and attitude. I would give 99L 50% chance of development and then wait until it detaches from the ITCZ to give it TD status unless this system gets any funny ideas.
Member Since: March 16, 2012 Posts: 127 Comments: 7948
Quoting MAweatherboy1:
Good afternoon. 99L looks good, I say 50% at 8PM, though the odds may be even higher than that:



Still doesn't look like it will be too strong though.


NHC has been very conservative with their %'s ... soo I'm going only 40% at 8pm.

IMO
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Quoting Stormchaser2007:
SHIPS brings shear up to 28 knots with the BAMM track.

Ooof...



Brings it up to 58kts before it hits that barrier of sheer. Maybe what kman said would prove correct if it managed to get a CDO by then.
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AN OVERVIEW OF NHC PREDICTION MODELS

Bernard N. Meisner
Scientific Services Division
National Weather Service Southern Region


BAM - The Beta and Advection Model

The Beta and Advection Model is a baroclinic-dynamical track prediction model. It produces a forecast track by following a trajectory in the vertically averaged horizontal wind starting at the current storm location out to 120 hours. The trajectory is corrected to account for the variation of the Coriolis force with latitude, the so-called Beta effect. (Beta is the Greek letter frequently used in meteorological equations to represent the change in the Coriolis parameter with latitude.)

The figure shows how the conservation of absolute vorticity results in the formation of anticyclonic relative vorticity in the northeast quadrant of the storm, and the formation of cyclonic relative vorticity in the southwest quadrant of the storm: . The result adds a component of motion to the northwest to the storm's trajectory.



Three versions of the BAM model are run with shallow (850-700 mb), medium (850-400 mb), and deep (850-200 mb) layers. All three versions of the model are run operationally four times per day.

Reference: Marks, D. G., 1992: The beta and advection model for hurricane track forecasting. NOAA Tech. Memo. NWS NMC- 70, 89 pp.
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Good afternoon. 99L looks good, I say 50% at 8PM, though the odds may be even higher than that:



Still doesn't look like it will be too strong though.
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Quoting hydrus:
This is the second time the CMC has brought a storm near East Central Florida.


Is that the 12Z run?
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There are 3 BAMM Models.

Deep, Medium, and shallow
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Gonna be real interesting to see how GFS performs with this system as compared to the other models. The GFS folks scored a major victory with the track forecast on Debby (as against all of the other models) but the CMC has been the outlier so far with this wave. Big difference between forecasting development of a wave and forecasting track with a more developed system however.
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Quoting hydrus:
This is the second time the CMC has brought a storm near East Central Florida.
This is a new run or old run, because I have now seen like 3 different runs of the CMC today, and I'm confused :(
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SHIPS brings shear up to 28 knots with the BAM(Medium) track.

Ooof...

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as I posted this morning but watch the east coast for a runner from the Alabama system when it exits off into the atlantic-the Euro is much weaker than the GFS, NOGAPS and CMC







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Quoting Patrap:
Can you folks not discuss the Olympic results here as a lot of us wont see the games today, till tonight.

Thanks.

Pfffth


Semper Fi.
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Quoting Pocamocca:

Allan. Really?


LMAO!
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Quoting Methurricanes:
was it a qualifier? or a Sliver?
Quoting Tropicsweatherpr:
Phelps came second.

Little tips for the future... don't post results of Olympics. Most of the events is tape delayed for later tonight.
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Can you folks not discuss the Olympic results here as a lot of us wont see the games today, till tonight.

Thanks.

Pfffth
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Quoting Tropicsweatherpr:
Phelps came second.
was it a qualifier? or a Sliver?
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storms.can.intensify.in.the.e.carib/...http://www.h istory.com/this-day-in-history/hurricane-gilbert-s lams-jamaica
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99L is approaching TD status...
Should see it upped to 50% or greater, at the 8pm TWO.
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This is the second time the CMC has brought a storm near East Central Florida.
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860

WHXX01 KWBC 311836

CHGHUR

TROPICAL CYCLONE GUIDANCE MESSAGE

NWS NATIONAL HURRICANE CENTER MIAMI FL

1836 UTC TUE JUL 31 2012



DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.

PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE

AND SUBTROPICAL CYCLONE INFORMATION.



ATLANTIC OBJECTIVE AIDS FOR



DISTURBANCE INVEST (AL992012) 20120731 1800 UTC



...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...

120731 1800 120801 0600 120801 1800 120802 0600



LAT LON LAT LON LAT LON LAT LON

BAMS 9.6N 41.3W 10.3N 44.8W 10.7N 48.2W 10.6N 51.8W

BAMD 9.6N 41.3W 10.1N 43.5W 10.6N 45.4W 10.9N 47.3W

BAMM 9.6N 41.3W 10.1N 43.8W 10.6N 46.0W 11.0N 48.2W

LBAR 9.6N 41.3W 10.1N 44.1W 10.6N 47.1W 11.0N 50.1W

SHIP 25KTS 32KTS 41KTS 47KTS

DSHP 25KTS 32KTS 41KTS 47KTS



...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...

120802 1800 120803 1800 120804 1800 120805 1800



LAT LON LAT LON LAT LON LAT LON

BAMS 10.6N 55.1W 10.0N 61.4W 10.8N 66.8W 12.9N 71.8W

BAMD 11.1N 49.1W 11.7N 52.7W 12.9N 57.0W 14.2N 61.2W

BAMM 11.4N 50.3W 12.4N 55.1W 14.0N 60.8W 16.2N 67.1W

LBAR 11.4N 53.2W 11.8N 59.1W 12.6N 64.2W .0N .0W

SHIP 52KTS 57KTS 58KTS 58KTS

DSHP 52KTS 57KTS 58KTS 58KTS



...INITIAL CONDITIONS...

LATCUR = 9.6N LONCUR = 41.3W DIRCUR = 280DEG SPDCUR = 16KT

LATM12 = 9.1N LONM12 = 38.1W DIRM12 = 278DEG SPDM12 = 15KT

LATM24 = 8.7N LONM24 = 35.8W

WNDCUR = 25KT RMAXWD = 80NM WNDM12 = 20KT

CENPRS = 1010MB OUTPRS = 1011MB OUTRAD = 150NM SDEPTH = S

RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM



$$

NNNN
Member Since: July 15, 2006 Posts: 174 Comments: 54353
Now an Earl 2004 track is seemingly more realistic to me.
Member Since: October 15, 2011 Posts: 0 Comments: 4401
Quoting kwgirl:

Well I would like to watch it tonight so please do not discuss the outcome on here. Thanks


I asked yesterday as well PLEASE no results on here.
And it is a weather blog :)
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721. etxwx
Quoting LargoFl:
.......in his radio show..he said the power failure was because india stopped using COAL to generate electricity...i have NO idea what he is thinking because last i heard it was a monsoon that hit the power plants..again I..could be wrong also

BBC and NYT both report that about 200 coal miners were temporarily trapped underground when the power for the lifts failed, so I'd take Limbaugh's pontificating about coal with a grain of salt..it's about as helpful as coal in your Christmas stocking. ;-)

The NYT story also mentions this, for what it's worth:
But despite the scale of the power failure, many Indians responded with shrugs. In the first place, India’s grid is still being developed and does not reach into many homes. An estimated 300 million Indians have no routine access to electricity.

Second, localized failures are routine. Diners do not even pause in conversation when the lights blink out in a restaurant. At Delhi’s enormous Safdarjung Hospital, doctors continued to rush around as hundreds of patients lay in darkened hallways.

Third, so many businesses employ backup generators that, for many, life continued without much of a hiccup. Dr. Sachendra Raj, the manager of a private Lucknow hospital, rented two new generators two months ago, and they were keeping the hospital’s dialysis machines running and the wards air-conditioned. “It’s a very common problem,” Mr. Raj said. “It’s part and parcel of our daily life.”


The cause of the failure seems to be a number of factors. It sounds like folks there are pretty resourceful...but it's still, as the BBC says: A "Complete mess" .
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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.