95L growing more organized; Pakistan's Indus River flood peaking downstream

By: Dr. Jeff Masters , 2:23 PM GMT on August 21, 2010

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A tropical wave (Invest 95L) in the far eastern Atlantic about 350 miles southwest of the Cape Verdes Islands has become more organized this morning. Satellite loops show that the wave has some rotation, and heavy thunderstorm activity has increased in recent hours, after a period overnight with little change. Water vapor satellite loops show that there is some dry air to the north of 95L, but this dry air currently appears to be too far away to significantly interfere with development. The main impediment to development is the moderate 10 - 20 knots of wind shear over the system. The shear is forecast to remain in the moderate range through Monday, then decrease. This should allow 95L to develop into a tropical depression Monday or Tuesday. NHC is giving 95L a 30% chance of developing into a tropical depression by Monday morning. With 95L's recent increase in organization, these odds should probably be 50%.


Figure 1. Morning satellite image of 95L.

Forecast for 95L
A ridge of high pressure will force 95L to the west or west-northwest for the next five days, and the system should increase its forward speed from its current 5 - 10 mph to 15 - 20 mph by Monday. A series of two powerful troughs of low pressure are predicted to move off the U.S. East Coast next week and cross the Atlantic; these troughs should be able to pull 95L far enough to the northwest so that it will miss the Lesser Antilles Islands. If 95L stays weak or does not develop in the next five days, as predicted by the NOGAPS model, it has a chance of eventually threatening Bermuda. If 95L develops into a hurricane, as predicted by most of the computer models, it will probably recurve to the east of Bermuda and not threaten any land areas.

Elsewhere in the tropics
The ECMWF model is predicting formation of a tropical depression in the western Gulf of Mexico off the coast of Texas 6 - 7 days from now.

Pakistan's monsoon rains diminish; Indus River flood crest nears the coast
The flooding on Pakistan's largest river, the Indus, has slowly eased along the upper and middle stretches where most of the heavy monsoon rains fell in late July and early August. However, a pulse of flood waters from these heavy rains is headed southwards towards the coast, and flood heights have risen to near all-time record levels today at the Indus River gauge station nearest to the coast, Kotri (Figure 2.) The new flooding has forced the evacuation of an additional 150,000 people in Pakistan today. Flood heights at every monitoring station along the Indus have been the highest or almost the highest since records began in 1947. Fortunately, the monsoon has entered a weak to moderate phase, and heavy rain is not expected over the flood region over the next few days, according to the Pakistan Meteorological Department.


Figure 2. August flow rates along the Indus River, courtesy of the Pakistan Meteorology Department.

Some aid agencies helping with humanitarian crisis in Pakistan:

Doctors Without Borders

The International Red Cross

MERLIN medical relief charity

The mobile giving service mGive allows one to text the word "SWAT" to 50555. The text will result in a $10 donation to the UN Refugee Agency (UNHCR) Pakistan Flood Relief Effort.

Jeff Masters

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Quoting atmoaggie:
To French, Japanese, Hindu, or Portuguese?

I only have time of one of them, atm.
Arkansan (southern dialect)
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Errr...
Member Since: July 6, 2010 Posts: 113 Comments: 31571
Quoting breald:
It seems to me, so far this year the models have done a good job from the beginning. If all the models are in sync, why would we think otherwise?


I don't know about that. The models have been off quite a bit. Here is my little take on things. The two storms that have had the most personal impact on me, Andrew and Katrina, did things they weren't predicted to do by models and forecasts. So, until a storm is 100% not coming my way, I don't trust either. We have a saying down here, "Don't like the weather? Give it an hour and it will change." The weather changes, and changes frequently. So while X is "supposed" to happen, does not mean that Y won't happen instead.
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Quoting TropicalAnalystwx13:


Storm, [Insert your word here]
Scary,horrible,dangerous?
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Quoting tkeith:
Beta, a mathematical notation, denotes the latitudinal variation of the Coriolis parameter or the latitudinal gradient of earth's angular speed. The Coriolis parameter, twice the component of the earth's angular velocity about the local vertical, has zero value at the equator, and becomes extreme at the pole (i.e., |1.4584E-4| radian per second). On the other hand, the beta parameter has a maximum value at the equator (i.e., 2.289E-11 per meter per second) and becomes zero at the pole.

Atmo...could you translate that?

:)


Cool rotation verse's rotation
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Quoting tkeith:
Beta, a mathematical notation, denotes the latitudinal variation of the Coriolis parameter or the latitudinal gradient of earth's angular speed. The Coriolis parameter, twice the component of the earth's angular velocity about the local vertical, has zero value at the equator, and becomes extreme at the pole (i.e., |1.4584E-4| radian per second). On the other hand, the beta parameter has a maximum value at the equator (i.e., 2.289E-11 per meter per second) and becomes zero at the pole.

Atmo...could you translate that?

:)
To French, Japanese, Hindu, or Portuguese?

I only have time of one of them, atm.
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Quoting HurricaneGeek:
Is this debate more about IF it will recurve or WHEN?

Because to me it seems we've got 15 people with 27 different opinions.
jajaja =)


When :)
Member Since: July 6, 2010 Posts: 113 Comments: 31571
Beta, a mathematical notation, denotes the latitudinal variation of the Coriolis parameter or the latitudinal gradient of earth's angular speed. The Coriolis parameter, twice the component of the earth's angular velocity about the local vertical, has zero value at the equator, and becomes extreme at the pole (i.e., |1.4584E-4| radian per second). On the other hand, the beta parameter has a maximum value at the equator (i.e., 2.289E-11 per meter per second) and becomes zero at the pole.

Atmo...could you translate that?

:)
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Quoting KanKunKid:


Yes, I understand all that, it's in the brochure. What I want to know is what Cyberteddy said, that "Stronger systems have a more poleward bias, if its weaker it will naturally go more south."

Why is that? What forces are at work to make it migrate poleward, is it an outside force or intrinsic to the system itself?


stronger systems go poleward because they tend to (a) travel toward areas of thinner atmosphere (think of the atmosphere as a tilted surface, thicker at the equator and thinner at the poles). and (b) are deflected poleward by Coriolis forces.
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Is this debate more about IF it will recurve or WHEN?

Because to me it seems we've got 15 people with 27 different opinions.
jajaja =)
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Quoting TropicalAnalystwx13:


Storm, [Insert your word here]


could you please through some ICE in their
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when 95l reaches 40w, which i believe, will happen because i am not seeing anything that could veer it off this course at the moment,the models will be scrambling to the south and east
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Quoting KanKunKid:


Yes, I understand all that, it's in the brochure. What I want to know is what Cyberteddy said, that "Stronger systems have a more poleward bias, if its weaker it will naturally go more south."

Why is that? What forces are at work to make it migrate poleward, is it an outside force or intrinsic to the system itself?

Beta, a mathematical notation, denotes the latitudinal variation of the Coriolis parameter or the latitudinal gradient of earth's angular speed. The Coriolis parameter, twice the component of the earth's angular velocity about the local vertical, has zero value at the equator, and becomes extreme at the pole (i.e., |1.4584E-4| radian per second). On the other hand, the beta parameter has a maximum value at the equator (i.e., 2.289E-11 per meter per second) and becomes zero at the pole.
...
The beta effect on a TC can be a function of the TC size, but not necessarily the TC intensity (DeMaria, 1985). When the TC size is small and the steering flow is moderate to strong (e.g., about 15 knots or 7.7 m/s), the direction of motion reflects the direction of the steering flow. When the TC size is large, the beta effect may have a major impact on the motion.

From here: http://www.nrlmry.navy.mil/~chu/chap4/se100.htm

Part of a most excellent resource: Tropical Cyclone Forecasters' Reference Guide
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168. Relix
I am an optimist haha
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12z GFS farther east that last run so far starts making the turn around 50W
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Storm, [Insert your word here]
Member Since: July 6, 2010 Posts: 113 Comments: 31571
Quoting TropicalAnalystwx13:


Thats because I bet it is...


No need to bet. The L on your graphic is misplaced. Been SW since this morning:

Time Lat Lon Wind(mph) Pressure Storm type
-------------------------------------------------------------
06 GMT 08/20/10 11.0N 25.3W 25 1008 Invest
12 GMT 08/20/10 11.0N 26.0W 25 1008 Invest
18 GMT 08/20/10 11.0N 27.0W 25 1009 Invest
00 GMT 08/21/10 11.1N 27.1W 25 1009 Invest
06 GMT 08/21/10 11.2N 27.6W 25 1009 Invest
12 GMT 08/21/10 10.6N 31.0W 25 1009 Invest
12 GMT 08/21/10 10.6N 31.0W 25 1009 Invest
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Quoting PanhandleChuck:
Please read the following statement through before reading the entire post:

Disclaimer: I am not an ant caster or a shroom caster, The following is just an observation on my part!


As I was mowing and sweating my hind end off, I noticed that I have the most and highest ant mounds in my yard since about a week and a half before Gustav in 08.

At the same time, I had an explosion of Mushrooms in the yard as well. I have just had another explosion of mushrooms this week.

I am not saying mushrooms have anything to do with weather, except for some of those on here that found their stash from the 70's and 80's and eat them on a regular basis before commenting on this blog.

Once again, just an observation do with it what you will.

Chuck
There's no such thing as an ant-caster. The whole ant thing is just meant to draw anecdotal reports like yours, and for reporting, I thank you.
.
.
I've been keeping track of these anecdotal reports since LaDobeLady reported her ants in Houma, La., 10 days prior to Katrina's landfall...before Katrina even hit Florida. So far, I've found no to slim definite correlation...but we keep trying.
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Quoting KanKunKid:


Yes, I understand all that, it's in the brochure. What I want to know is what Cyberteddy said, that "Stronger systems have a more poleward bias, if its weaker it will naturally go more south."

Why is that? What forces are at work to make it migrate poleward, is it an outside force or intrinsic to the system itself?


I'm going to go with some Outside Force?
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72 hours out on the 12z GFS.

---

Hung parliaments are the vogue this year. First us, now the Aussies. Always taking our ideas, I tell you...
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Quoting TropicalAnalystwx13:
Consolidating to the southwest:



Also getting banding features


Good Morning.

That's very different if thats the case, as it puts the center about 4° farther WEST and about 3° farther SOUTH.
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Quoting WeatherNerdPR:

That center position seems way off.


Thats because I bet it is...
Member Since: July 6, 2010 Posts: 113 Comments: 31571
It seems to me, so far this year the models have done a good job from the beginning. If all the models are in sync, why would we think otherwise?
Member Since: May 28, 2008 Posts: 38 Comments: 5303
A Category 5 Hurricane hasn't hit the USA since Hurricane Andrew of 1992...

Its gonna happen soon...
Member Since: July 6, 2010 Posts: 113 Comments: 31571
something for you gulf residents like me to pucker up a little about ..bastardi latest

GLOBALLY, SOME INTERESTING THINGS STARTING TO HAPPEN.


Moscow has had their hottest summer on record but much cooler has finally ended their summer and in fact the next 10 days look quite cool there. The invasion of cool into the US and then the subsequent building of the ridge over the lakes and northeast, should raise pressures sufficiently in the means over the atlantic north of 35 north to finally start the still dormant hurricane season. While the system in the southeast atlantic is the storm du jur of most modeling the overall pattern is one that says that within the next 10 days, a threat to the US coastline, most likely in the gulf, is the best bet. This accentuated on the Canadian ensembles, and on the European operational, as forecasted pressures lower in the gulf while rising over much of the eastern US in the wake of the strong trough that is moving through.
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154. Relix
Guys there's a powerful trough coming. There is NO way this will not recurve or at least, minimum, misses the antilles. After that it's a whole new ballpark.
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Quoting StormW:


??????


I didn't say anything like that. Just said the movement of the invest continues to defy the forecast of the models.
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Quoting TropicalAnalystwx13:
Consolidating to the southwest:



Also getting banding features

That center position seems way off.
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151. SLU
Quoting MrNatural:
Will the slower development of 95L tend to give it a more southerly and westerly route?


That's right!
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Quoting StormW:


??????


Sounds like they skipped class this morning Storm
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Quoting KanKunKid:


I understand what they are saying, I just don't know why. If it develops slow, it isn't as affected by steering? keeps a low profile and sneaks by? Or, by developing, it is more affected by the steering, or does the steering push it to make it grow?


Ensemble models provide more of an indication of probabilities than specific track or intensity guidance for individual systems. The theory is you run 20 or 40 or more versions of a model with either slight differences in each weather analysis that starts each model run, or you tinker slightly with each model runs internal processes (there are other ways, but it gets long...). What this takes into account is the basic error weather models start with. There's no such thing as a perfect analysis, and according to theory, small errors can sometimes amplify into much bigger ones over time in the model.When you look at all the model runs in an ensemble, you can see the variance between each model run (this tells you how much initial condition (analysis) errors affect predictability. If variance is low, the model is suggesting the future is pretty predictable. And the opposite is true.

What the GFS 06Z ensemble is suggesting is that on Friday the 27th, the Verde system, by this time a TS or weak hurricane, will make its closest point of approach to North America at or near 55W 30N with around a 10 degree longitudinal spread. So according to the ensemble, it could be out around 65W or as far east as 45W. The model's uncertainly envelope precludes a N. American landfall.
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WeathernerdPR,must have.Since all the media had the attention focused only on Haiti for the most part.
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Quoting MrNatural:
Will the slower development of 95L tend to give it a more southerly and westerly route?


Yes
Member Since: July 6, 2010 Posts: 113 Comments: 31571
Will the slower development of 95L tend to give it a more southerly and westerly route?
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Quoting atmoaggie:
OT, but I just want to say:

I [bleeping] [blank][blankity] hate summer [bleep][bleep] hot [bleep][bleep] sweaty [bleep][bleep] mowing [bleep][bleep] mosquitos [bleep] poison ivy [bleep][bleep] air conditioning [bleep][bleep][bleep].

LOL!!!!!!!! =D
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Just saw this on the update.....hmmmmmm

Elsewhere in the tropics
The ECMWF model is predicting formation of a tropical depression in the western Gulf of Mexico off the coast of Texas 6 - 7 days from now.

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Please read the following statement through before reading the entire post:

Disclaimer: I am not an ant caster or a shroom caster, The following is just an observation on my part!


As I was mowing and sweating my hind end off, I noticed that I have the most and highest ant mounds in my yard since about a week and a half before Gustav in 08.

At the same time, I had an explosion of Mushrooms in the yard as well. I have just had another explosion of mushrooms this week.

I am not saying mushrooms have anything to do with weather, except for some of those on here that found their stash from the 70's and 80's and eat them on a regular basis before commenting on this blog.

Once again, just an observation do with it what you will.

Chuck
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Quoting atmoaggie:
OT, but I just want to say:

I [bleeping] [blank][blankity] hate summer [bleep][bleep] hot [bleep][bleep] sweaty [bleep][bleep] mowing [bleep][bleep] mosquitos [bleep] poison ivy [bleep][bleep] air conditioning [bleep][bleep][bleep].
I take it you live down in the south?.I love summer!.And it is always a welcomed season to us here in the northeast.Especially after the winter we've just been through.However I hate spring with a passion.......
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138. JRRP
mmm ¬¬

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Quoting sporteguy03:


Ike so you are rooting for it to get strong too?


This should make Ike very conflicted.
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Consolidating to the southwest:



Also getting banding features
Member Since: July 6, 2010 Posts: 113 Comments: 31571

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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.