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cieldumort
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Gulf Low P25L 92L Lounge
      #96667 - Sat Aug 27 2016 02:26 PM


Above: Current Surface Analysis (TPC/NWS/NOAA)

A moist Tropical Wave associated with two areas of low pressure currently over western Africa is forecast to emerge over the far eastern Atlantic early next week. Conditions appear favorable for development, and the NHC is giving this system 30% odds next week while it moves westward at 15 - 20 MPH.

This wave has a pouch we are tracking, P25L, but has not yet been assigned an Invest tag. It is likely to get one when it enters the Atlantic, and the title will be updated at that time.

Model runs are understandably bullish on this one, and it has the potential to become a long track Cape Verde tropical cyclone. Interests from the Cabo Verde islands westward may want to follow it closely if development looks increasingly likely.

This wave has been assigned an Invest number: 92L
The title has been updated.


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cieldumort
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East Atlantic P25L [Re: cieldumort]
      #96723 - Mon Aug 29 2016 06:36 PM



Another very impressive tropical wave w/ a pouch, P25L, is now exiting western Africa and entering the easternmost north Atlantic just southeast of the Cabo Verde islands.

This feature already has what appears to be a closed 1006mb surface low, and could potentially ramp up fairly quickly, but there are some definite limiting factors, including its size, moderate wind shear, and an abundance of stable, dry, dusty air out over the eastern Atlantic. These factors argue for keeping the wave in check until it gets closer to at least the central Atlantic, if not further west.

Top global models ECMWF and GFS both agree right now that it will track across the ATL and pose a direct threat to the southeastern United States within ten days. Usual "Lounge caveats" apply!


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Troy C
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Re: East Atlantic P25L [Re: cieldumort]
      #96724 - Mon Aug 29 2016 06:55 PM

I feel silly asking this as I have been on this forum, as a poster and more recently just as a reader. But what is a pouch in reference to a tropical 'system'?

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MikeCAdministrator
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Re: East Atlantic P25L [Re: Troy C]
      #96728 - Mon Aug 29 2016 08:42 PM

Pouch is from the http://www.met.nps.edu/~mtmontgo/predict.html Naval Postgraduate School, a program to help identify potential beginnings of tropical system, even before the invest phase. Invest usually indicates model suites ran on them, where the pouch does not.

We typically don't mention pouches unless they seem likely to do something. This one just became Invest 92L tonight.


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cieldumort
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Re: East Atlantic P25L [Re: Troy C]
      #96730 - Mon Aug 29 2016 08:48 PM


Quote:

What is a pouch in reference to a tropical 'system'?




That is an excellent question well suited for this tropical wave, now tagged Invest 92L.

The diagram below is a very good explanation.



Wave "pouches" tend to protect the moist air within them from potentially hostile forces. In the far eastern Atlantic these potential wave killers are often dusty, dry Saharan Air. In the western Atlantic it is more often just dry air, as the dusty Saharan Air Layer seldom propagates that far.

The term 'pouch' itself has etymological roots in marsupial parenting. Once a "joey" within the pouch has been nurtured sufficiently, it has better odds of existing on its own, if it should move beyond the parent wave.


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flranger
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Re: Invest 92L [Re: cieldumort]
      #96731 - Mon Aug 29 2016 09:03 PM

A monster perhaps late next week according to GFS:

https://www.windyty.com/?2016-09-08-03,26.214,-80.219,6

(Post moved to the appropriate Forum.)

Edited by Ed Dunham (Tue Aug 30 2016 12:02 AM)


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Troy C
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Re: East Atlantic P25L [Re: cieldumort]
      #96734 - Mon Aug 29 2016 09:23 PM

So basically an area of abundant water vapor that is very conducive for thunderstorm development that acts like a barrier keeping the dry air out. Kind of like gore-tex but reversed..?

Ha! I like the analogy, Troy! More or less. Just a quick reply, so that we can keep the thread tighter now that we have an active Invest here. Feel free to message us directly with any more discussion related to wave pouches. Or even start a new thread over in Hurricane Ask/Tell -Ciel

Edited by cieldumort (Mon Aug 29 2016 09:53 PM)


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Lamar-Plant City
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Re: East Atlantic P25L [Re: Troy C]
      #96735 - Tue Aug 30 2016 12:14 AM

I love how, after nearly 40 years of interest in weather and meteorology (I am a biologist/biochemist by education), I still learn new things on this site all the time. GFS is turning this mere pouch (now invest) into an impressive hurricane by mid-next week. Something to watch closely as soon as we are rid of TD's 8 and 9.....

--------------------
If you don't like the weather, wait 5 minutes...
2017 Season Prediction: 16/7/3


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Ed DunhamAdministrator
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Re: Invest 92L [Re: flranger]
      #96742 - Tue Aug 30 2016 10:25 AM

At 30/12Z Invest 92L was located just off the west African coast. The system is not very impressive this morning under the influence of northeasterly wind shear. SSTs are 28.5C . The system will have a better chance for additional development later in the week as it moves into an area of lighter shear.
ED


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cieldumort
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Re: 92L [Re: cieldumort]
      #96909 - Fri Sep 02 2016 12:29 PM


Above: INVEST 92L is presently centered near 15N 46W with movement to the west at around 20 knots, and is producing a large area of disorganized showers.

Almost having been wiped out by stifling dry, stable, dusty Saharan air and shear, Invest 92L is now in a less hostile environment for some organization, and NHC has restarted Invest tracking of this wave.

As can be seen in the image above, the Saharan Air Layer is very robust throughout the central to eastern Atlantic at this time. Despite this, 92L has been able to mix out most of the dust it had been plagued by, and is actually embedded within a surge of deep atmospheric moisture. The combination of lower shear, less dust and high Total Precipitable Water should allow for some organization over the next few days, and NHC gives it a 20% chance of becoming a tropical depression within 5 days. Several days ago most models were hot on developing this wave. At present only a few are, but this looks like it could change when these models begin accounting for the far less hostile environment and improved structure.


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Owlguin
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Re: 92L [Re: cieldumort]
      #96921 - Sat Sep 03 2016 03:12 PM

Turning into a pretty vigourus wave this afternoon.

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MikeCAdministrator
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Re: 92L [Re: Owlguin]
      #96923 - Sun Sep 04 2016 01:39 PM

Added Carib radar of 92L http://flhurricane.com/imageanimator.php?224

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cieldumort
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Re: Invest 92L [Re: cieldumort]
      #96924 - Sun Sep 04 2016 03:02 PM

Invest 92L is a vigorous tropical wave with an associated broad low pressure area, producing gusts over 50MPH, and moderate to heavy showers and thunderstorms today.

However, as of 2:30PM EDT today Sunday Sept 4, the best tropical cyclone genesis models continue running cool to luke warm at best on 92L. In fact, the entire ATL basin is modeling mostly crickets at this time.

Despite regions of very supportive upper level winds, healthy precipitable water values and high to record high SSTs, the stand out among all those pluses is a robust fetch of dusty, stable Saharan Air that extends all the way from Africa now to the east coast (picture below), also noticeable in images of PTC Hermine. Until it subsides, this stable air layer will continue to make it very challenging for any spark to catch and intensify.


12z Sept 4 Models that do anything with 92L eventually:
* GFS takes 92L or its remnant energy and spins up a coastal low/possible depression off Texas coast mid-month. (Seems reasonable and maybe even conservative)

* CMC fires up a depression just south of Jamaica this coming week and runs a hurricane into Tx/La border on Monday the 12th (CMC doing what CMC does best)

* NAVGEM runs 92L as an open wave up and over the Greater Antilles, then develops a weak depression off the Florida east coast next weekend (seems possible)

* ECMWF - The Euro model now takes 92L into Tx/La border on Wed the 14th as a low-end Trop Storm

Below: Region of convection-killing SAL at 9/4/16 1045z



Edited to include final 12Z ECMWF run

Edited by cieldumort (Sun Sep 04 2016 03:19 PM)


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cieldumort
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Re: Invest 92L [Re: cieldumort]
      #96941 - Fri Sep 09 2016 05:59 AM



A highly sheared low level swirl entering the Florida Straits from the east is associated with the wave formerly being tracked as Invest 92L, and its pouch, P25L.

Presently shear is very high over this wave, but 92L could be entering a window, however brief, for some development south or west of Florida. Shear looks like it could drop to under 15 knots from the present 30-40 knots over 92L later today and, depending on the wave's location, possibly collapse to near zero by Saturday afternoon. This would be a long shot for this one, and as of this entry, Invest tracking has not yet been restarted, but there is a possibility that it will be.

Given 92L's resilience, the chance of greatly reduced shear ahead for a period of roughly 12-48 hours, and its proximity to land (it may soon be entirely landlocked in the Gulf on its current heading), this wave now bears closer watching.



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cieldumort
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Re: Invest 92L [Re: cieldumort]
      #96942 - Fri Sep 09 2016 01:02 PM


Above: 1615z Sep 9 Visible image of this well organized, but highly sheared Low

This feature is becoming much more interesting today, and the Invest tag "92L" has formally been green balled (restarted).


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Owlguin
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Re: Invest 92L [Re: cieldumort]
      #96945 - Fri Sep 09 2016 02:26 PM

They've upgraded the outlook, appears to me about the same time as the LLC has become totally exposed.

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doug
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Re: Invest 92L [Re: Owlguin]
      #96946 - Fri Sep 09 2016 02:59 PM

My My! how fast things can change....from "dead in the water" to a reasonable possibility of becoming a classified system in a matter of hours...the early discussions suggested that the shear would largely relax into tomorrow....not so much now...steering currents ahead of it resemble those that influenced Hermine over the next couple of days...slow westward motion...

Edited by doug (Fri Sep 09 2016 03:08 PM)


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cieldumort
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Re: Gulf Low P25L - 92L [Re: cieldumort]
      #96967 - Wed Sep 14 2016 05:01 PM


Above: P25L Gulf Low and UW CIMSS Shear Product

The pouch of this particular tropical wave we have been following for what seems like forever (the theme for 2016), has persisted in the Gulf of Mexico this week and is now melding with a preexisting trof, with a broad surface low starting to form. This feature may or may not retain the Invest tag 92L if model runs are restarted on it, but the title will be adjusted accordingly if appropriate.

Shear over P25L is low today, with UW CIMSS analyzing less than 10 knots. Additionally, sea surface temps are quite high in the Gulf, and the humidity is also very supportive. With a drift to the west expected, P25L may run out of real estate necessary to really spin up again, but given its tenacity and the much improved environment, still bears watching, and NHC's 10% development odds could be conservative. A rain and wind maker, either way. Gusts to tropical storm force have already been noted only 100' or so above the surface.


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cieldumort
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Re: Gulf Low P25L 92L Lounge [Re: cieldumort]
      #96974 - Fri Sep 16 2016 10:49 AM



This gulf low, former Invest 92L, is right along the coast of SE Tx this morning, with a trof that extends to the southwest and east-northeast to east, with a min pressure of about 1010mb in the low center.

This feature should set up a convergence zone along the upper Tx coast today, and provide a focus for numerous showers and thunderstorms, some of which could be heavy and slow moving, with possible local flood risks. Development into a tropical cyclone is less likely now that the primary center is just about onshore, but it is possible that it drifts back out a little, or reforms under the deepest convection offshore, and is still being watched. NHC 10% odds and falling this morning.


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cieldumort
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Re: Gulf Low P25L 92L Lounge [Re: cieldumort]
      #96975 - Fri Sep 16 2016 01:41 PM

This system is still worth watching today. Convection has been improving throughout the region, with weather station and ship reports suggesting the possibility of a surface center reformation trying to fire within the deepest convection well offshore.



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