Tropical wave 92L weakens but could bring heavy rains to Haiti

By: Dr. Jeff Masters , 2:23 PM GMT on June 20, 2010

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The tropical wave (92L) that brought heavy rains of 2 - 5 inches to Puerto Rico on Saturday is continuing westward at 10 - 15 mph, but has grown very disorganized. The National Hurricane Center is no longer interested enough in this wave to classify it as an "invest" worthy of generating computer forecasts for. Today through Monday, 92L will encounter 20 - 40 knots of wind shear as it plows though a region of strong upper-level winds associated with the subtropical jet stream. The disturbance will also encounter the mountainous terrain of Hispaniola and Cuba. If there is anything left of 92L after crossing these mountains, it may have the opportunity to develop beginning on Tuesday, when it will enter a region of wind shear less than 20 knots near central Cuba. None of our reliable computer forecast models is calling for 92L to develop once it reaches this region of lower wind shear. I give 92L a 10% chance of developing into a tropical depression by Saturday. The storm could bring heavy rains of up to four inches to Haiti today and Monday. Rain of four inches are probably the lower threshold for life-threatening floods to occur in the Haiti earthquake zone, and this disturbance poses the most serious flooding threat Haiti has seen since the earthquake.


Figure 1. Radar estimated rainfall over Puerto Rico from Invest 92L.

Elsewhere in the tropics
The NOGAPS and ECMWF models call for a possible tropical depression to form in the central or western Caribbean next weekend, 6 - 8 days from now.

Wind and ocean current forecast for the BP oil disaster
Southeast to east winds less than 10 knots will blow in the northern Gulf of Mexico Monday through Thursday, according to the latest marine forecast from NOAA. The resulting weak ocean currents should cause little motion of the oil slick, according to the latest trajectory forecasts from NOAA and the State of Louisiana. The long range outlook calls for a continued summertime weather pattern of weak winds over the Gulf of Mexico during the coming two weeks.


Figure 2. Visible satellite image from NASA's MODIS instrument of the Deepwater Horizon oil slick from Saturday, June 19, 2010.

Resources for the BP oil disaster
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool allows one to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Happy Father's Day, all you fathers out there, and I'll have an update on Monday.

Jeff Masters

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Quoting IKE:


Wooh...that looks like business. Shuts down the oil-rigs...goes by the oil volcano on it's way to SE Texas.


Ugh! And good morning to you too. Lol. Be curious to see where the CMC puts it this time. I need my pepcid ac.
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man thigs are this about too go pop
Member Since: May 21, 2006 Posts: 5091 Comments: 115384
Quoting Levi32:


This really is a conducive pattern for mischief. Things may not be perfect for a potential system like the ECMWF shows, but there certainly won't be the kind of shear around that tore apart 92L.
If the pattern the GFS shows comes true, there is a very high ceiling for a developing system. It will be interesting to watch. It is also of note that the GFS shows the Carib to open for business for the rest of the season with that subtropical jet lifting north finally.
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It'll be interesting to see if this actually happens.

Very low shear across most of the basin from 72 hours through the rest of the run:

Member Since: June 9, 2007 Posts: 4 Comments: 15946
The EURO shows a Hurricane in the GOM, the worst case scenario for the oil crisis. Notice it also shows something brewing east of Florida. It's time for the quietness to go, welcome the *real* 2010 Hurricane Season next week!
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Quoting SouthDadeFish:
GFS showing very favorable low wind shear for a potential system.


This really is a conducive pattern for mischief. Things may not be perfect for a potential system like the ECMWF shows, but there certainly won't be the kind of shear around that tore apart 92L.
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Quoting Levi32:
The low the ECMWF shows would be a combination of the energy from ex-92L, the monsoon trough coming north of Panama, and the wave passing the windwards piling up air in the western Caribbean. It's not going to be any one system doing all the work. There will be several things contributing energy to the situation. It's likely to be a complex event.

That good ole energy from "ex-92L". Yes, oh my. A complex system, indeed.
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GFS showing very favorable low wind shear for a potential system.
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502. IKE
6-10 day outlook/temps and precip


8-14 day outlook/temps and precip
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting Baltimorebirds:
I saw that the european model had 2 systems.I was asking do you think the wave near south america or the other one the model is latching on will develope first.


The one in the western Caribbean has for more potential for development than the wave in the Bahamas.
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Quoting MississippiWx:
This certainly won't hurt the possible tropical cyclone:



Geez...that looks like August.
Member Since: June 9, 2007 Posts: 4 Comments: 15946
The low the ECMWF shows would be a combination of the energy from ex-92L, the monsoon trough coming north of Panama, and the wave passing the windwards piling up air in the western Caribbean. It's not going to be any one system doing all the work. There will be several things contributing energy to the situation. It's likely to be a complex event.
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This certainly won't hurt the possible tropical cyclone:

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Another overall clear day for the GOM, Western Caribbean and Western Atlantic. Up, up, up go the SSTs.

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Well, all the models at diffrent points of time showed something popping in the s gom or so. the tutt split...which i think split the energy from 92l.and that energy is hanging around in various locations. then we have the wave entering the islands. then the low pressure in the sw caribbean. plus the upswing in the mjo. so something shoud pop. the models have been all over the map about the strength of the bermuda high nosing into the gulf. it looks like it will be strong for 3-4 days and maybe weaken...alowing what the euro has planned. remember--in the last 3 days the gfs , cmc and now the euro and nogaps all had a system coming onto the n, nw gulf or boc.
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Quoting Drakoen:


Yes it would likely be stronger which is what just one of the points. The other point is that we should not really rely on the global model to tell us if this is TD, TS, or Hurr. The models are used for genesis and the stronger the system is on the model the more likely it is to actually exist and potentially be something significant.


Which is why, again, all that really matters to me is the fact that it shows a deepening system of this low of a pressure. It is showing positive feedback. To speculate on the intensity of a system even before it forms is ridiculous anyway.
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Quoting IKE:
I bet Bastardi is salivating over that 12Z ECMWF run. He loves that model.


Probably lol. He's probably jumping around and doing back flips in the office.
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Quoting nrtiwlnvragn:
Compare how the ECMWF presents hurricane Celia.


Tells us that it's forecasting the western Caribbean storm to be a larger feature, and also of course weaker than major hurricane Celia.
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EP, 03, 2010062018, , BEST, 0, 178N, 1143W, 30, 1006, TD

Blas weakens to a TD


such is the life of tropical systems, Blas was the deal a few days ago, but his time has passed and Celia is now in the limelight
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EP, 04, 2010062018, , BEST, 0, 116N, 1000W, 65, 990, HU

Celia the 1st Hurricane of the EPAC season
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Quoting IKE:


ECMWF would be an unusual track for late June. I'm not saying it won't happen.


Courtesy of the massive SE US ridge we've had since May. It won't be letting up through July either.
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Quoting Levi32:


What I don't understand is why you guys point out the tendency for global models to underestimate the intensity of tropical cyclones, when we're not even looking at a situation of underestimation. We're looking at a strong system on the ECMWF that in reality would be stronger because of the resolution issues you guys keep bringing up.


Yes it would likely be stronger which is what just one of the points. The other point is that we should not really rely on the global model to tell us if this is TD, TS, or Hurr. The models are used for genesis and the stronger the system is on the model the more likely it is to actually exist and potentially be something significant.
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Compare how the ECMWF presents hurricane Celia.
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482. IKE
Quoting WinterAnalystwx13:




ECMWF would be an unusual track for late June. I'm not saying it won't happen.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Also look at what's going on in the Bahamas by Day 10 with that wave currently off French Guiana that will be moving up into that area.

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Quoting Levi32:


That's a hurricane....closed 995mb isobar and the central pressure will be lower than what the model shows.


Ouch 216 hours if i'm correct thats 9 days out June 29th! My Birthday!oh yeah perfect
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Quoting Levi32:


What I don't understand is why you guys point out the tendency for global models to underestimate the intensity of tropical cyclones, when we're not even looking at a situation of underestimation. We're looking at a strong system on the ECMWF that in reality would be stronger because of the resolution issues you guys keep bringing up.


Oh I'm not trying to judge anything it's doing now, I'm just saying that I don't trust the intensity that the models show because a lot of times they are wrong.
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Quoting Drakoen:


Global models are of very little use when it comes to strength. Ballparking is of little use as well. We can estimate cautiously based on what we see but ultimately the model will not be able to resolve the winds in the eye wall of this system.


I think the point is that the ECMWF is showing feedback and a deepening tropical low. I really don't care exactly how strong it is on the model, but rather the fact that it is showing a deepening system with this low of a pressure, is what matters to me.
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Normally, the GOM wouldn't have the heat content conducive for rapid intensification, but this year:

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990mb at 216 hours.

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Quoting Levi32:


Exact strength yes, but ballpark if you see a sub-1000mb isobar enclosed around a tropical system on a global model then you have a strong storm.


Global models are of very little use when it comes to strength. Ballparking is of little use as well. We can estimate cautiously based on what we see but ultimately the model will not be able to resolve the winds in the eye wall of this system.
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472. IKE
Quoting Levi32:


Are you asking if I think this will be Alex or if another system will be?

I'm not ready to commit to this yet. If things start to come together in the central Caribbean in 48-72 hours like the models show then I'll be able to see what's going on and make a forecast. For now it is just concerning to see the ECMWF being this consistent, and it is definitely something to watch closely.


Somebody please post the maps of normal tracks in June or late June/early July.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting extreme236:
Global models showed Felix as just a weak TS when it all reality it would become a very powerful major hurricane. So, I don't really trust model intensities.


What I don't understand is why you guys point out the tendency for global models to underestimate the intensity of tropical cyclones, when we're not even looking at a situation of underestimation. We're looking at a strong system on the ECMWF that in reality would be stronger because of the resolution issues you guys keep bringing up.
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996mb in the central gulf at 192 hours.

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469. IKE
I bet Bastardi is salivating over that 12Z ECMWF run. He loves that model.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
I remember the ECMWF developing an incredibly powerful system back in October. The system never actually developed, however.

Nevertheless, something will form next week through July.
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Quoting Baltimorebirds:
Levie will that be alex in the gulf or another storm that the models are also picking up on??


Are you asking if I think this will be Alex or if another system will be?

I'm not ready to commit to this yet. If things start to come together in the central Caribbean in 48-72 hours like the models show then I'll be able to see what's going on and make a forecast. For now it is just concerning to see the ECMWF being this consistent, and it is definitely something to watch closely.
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Good afternoon!

Kind of interesting what the EURO is showing and it doesn't hurt that it has support from a few other models.

Just an idea to ponder...Even 2005 only had 1 named storm at this point in the season and didn't have its second named storm until June 27th. I have seen a lot of posts on here calling 2010 a bust and other things because we haven't had a named system yet. Some of you seem to forget that even 2005 didn't heat up until July. With that said, I don't think anyone should expect 2010 to be like 2005 number-wise. The Atlantic may never see a season like that again. What we do know is that the setup this year is dangerous and to not forget we are still on pace for an extremely active and destructive season.
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464. IKE
That's the strongest system the ECMWF has shown since the season started...by far.

12Z ECMWF.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Global models showed Felix as just a weak TS when it all reality it would become a very powerful major hurricane. So, I don't really trust model intensities.
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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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