Little change to 96L; El Salvador flood among its worst in history

By: Dr. Jeff Masters , 2:55 PM GMT on October 22, 2011

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A region of disturbed weather in the Western Caribbean (Invest 96L) is bringing heavy rains to coastal Nicaragua and Honduras, and has the potential to develop into a tropical depression Sunday or Monday. Visible satellite loops show that 96L has changed little in organization since yesterday. Some rotation is apparent, but the heavy thunderstorm activity is quite limited due to a large region of dry air to the east, as seen on water vapor satellite loops. There are no signs of a surface circulation. Surface pressures have been falling since Thursday at San Andres Island, near the center of 96L. Wind shear is a moderate 10 - 20 knots in the region, and is expected remain in the moderate range through Tuesday. Water temperatures are very warm, 29 - 30°C, and these warm waters extend to great depth.


Figure 1. Morning satellite image of 96L.

Forecast for 96L
The moderate wind shear and warm waters should allow for some development of 96L over the next few days, though this will be slowed by the dry air to the storm's east, and perhaps by proximity to the land areas of Nicaragua and Honduras. The models are less enthusiastic today about developing 96L into a tropical depression than they were yesterday. The ECMWF no longer predicts development, and the GFS and NOGAPS predict only weak development before 96L moves ashore over Honduras on Tuesday. On Wednesday, a strong trough of low pressure will be passing over the Eastern U.S., and this trough has the potential to turn 96L northwards into Western Cuba. This is more likely to happen if 96L is stronger and deeper, and thus able to "feel" the upper-level winds the trough will bring. The UKMET model predicts 96L will develop into a tropical storm that moves through the Yucatan Channel between Cuba and Mexico on Thursday. If 96L remains a weak and shallow system, though, it is more likely to stay trapped in the Western Caribbean and make landfall in Nicaragua or Honduras. NHC gave 96L a 60% chance of developing into a tropical depression by Monday in their 8 am Tropical Weather Outlook today. The hurricane hunter mission scheduled for today was cancelled due to the lack of development of 96L; the mission has been re-scheduled for Sunday afternoon.

97L
A broad region of low pressure near 10°N, 57°W, about 400 hundred miles east of Trinidad (Invest 97L), is moving slowly west-northwest towards the Lesser Antilles Islands. This low has very limited heavy thunderstorm activity, due to dry air to the northwest. NHC is giving 97L just a 10% chance of developing into a tropical depression by Monday. 97L is under a moderate 10 - 20 knots of wind shear, and this shear is expected to drop to the low range, less than 10 knots, by Monday, when the storm will be in the Eastern Caribbean Sea. By the time 97L approaches Jamaica in the Central Caribbean in 5 - 6 days, the storm should find a moister environment, and there is a chance for 97L to develop into a tropical depression, as predicted by the NOGAPS model.


Figure 2. Rainfall in El Salvador for the 10-day period ending on Friday, October 21, at 8 am EDT. At Huizucar, an astonishing 1.513 meters (4.96 feet) of rain fell during those ten days. Image credit: Hydrological Service of El Salvador.

Death toll from Central American rains rises to 105
“I want to tell the world that El Salvador is going through one of the most dramatic disasters in its history,” President Mauricio Funes said on national radio and television Wednesday night, as he appealed for international aid. A week of torrential rains across Central America have triggered extreme floods and landslides that have killed 105 people, according to media reports. El Salvador, Guatemala, Honduras and Nicaragua have declared states of emergency due to the disaster. El Salvador and Guatemala have seen the worst flooding, with 34 and 38 people killed, respectively. Another 18 have died in Honduras, 13 in Nicaragua, and 5 in Costa Rica. The rains were due to a large area of low pressure that was moistened by the landfall of Tropical Depression 12-E near the Mexico/Guatemala border last week. Contributing to the record-intensity rains were ocean temperatures off the coast of El Salvador that were 0.5 - 1°C above average during the first half of October, allowing more water vapor than usual to evaporate into the air. Over the past ten days, rainfall amounts of over a meter (39.4") have fallen over a large area of southwest El Salvador (Figure 2.) At Huizucar, an astonishing 1.513 meters (4.96 feet) of rain fell in the past ten days.

I'll have a new post on Sunday.

Jeff Masters

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Excerpt from Crown Weather.

The 00Z GFS model guidance forecasts this system to become a tropical storm during Sunday and Monday and a hurricane by Tuesday as it tracks slowly northwestward. This northwestward track would cause future Rina to potentially impact the eastern coast of the Yucatan Peninsula, including Cancun and Cozumel, as a hurricane by Wednesday into Thursday and the western tip of Cuba during Thursday. From there, the GFS model forecasts this potential hurricane to turn east-northeastward and affect the Florida Keys and south Florida on Friday night and potentially the northwestern Bahamas next Saturday.

The 06Z GFS model guidance has done a complete 180 and now forecasts Invest 96L to be shoved westward into Honduras and Nicaragua by later Monday and Tuesday as a tropical depression.

The European model forecasts no development whatsoever from Invest 96L which is also a complete 180 from yesterday’s model runs.

The UKMET model forecasts an overall northwestward path during the next several days which would take it near the northeastern coast of the Yucatan Peninsula by about Wednesday and then near the northern coast of the Yucatan Peninsula by Thursday. Given the approaching trough of low pressure forecast on the UKMET model, I would say a turn to the east-northeast towards south Florida is likely for Friday.

The Canadian model forecasts 96L to become a tropical storm by Sunday night and forecasts it to turn westward and west-southwestward at around the 17 North Latitude line. This west and west-southwest track would conceivably take this storm into Belize as a weakening tropical storm on Wednesday.

The GFDL model forecasts 96L to become a tropical storm by later today and shows it growing quickly into a hurricane just off of the coast of Nicaragua and Honduras on Sunday. From there, the GFDL model forecasts that this system will turn due west and come ashore on the north coast of Honduras as a Category 2 hurricane on Monday night.

The HWRF model forecasts 96L to spin-up into a tropical storm over the next 24 hours. From there, the HWRF model forecasts future Rina to intensify quite rapidly into a hurricane by late Sunday and then a major Category 3 hurricane by Monday. The HWRF model is on the northwest tracking bus as it takes future Rina into the northwestern Caribbean about halfway between the Cayman Islands and the Yucatan Peninsula by Tuesday night and Wednesday. At the end of the HWRF model run, which is Wednesday night, future Rina is tracking north-northeastward towards the western tip of Cuba as a major Category 4 hurricane.

The Experimental FIM model forecasts that 96L will develop into Tropical Storm Rina on Sunday. From there, the FIM model forecasts intensification as it tracks northwestward on Monday, Tuesday and Wednesday reaching the northwestern Caribbean as a moderately strong tropical storm late Wednesday. The FIM model then forecasts future-Rina to affect Cancun and Cozumel as a 55 to 70 mph tropical storm by Thursday and then it turns east-northeastward which would cause the storm to affect the northwestern coast of Cuba on Friday, the Florida Keys and south Florida on Friday night into Saturday morning and the northwestern Bahamas on Saturday afternoon.

One thing to keep in mind regarding waffling model runs is that this should be expected and further 180 turns in the model guidance are possible until we see a well defined center of circulation with this system. We should instead look at the current environment around this system and see what that tells us and go from there.
Member Since: October 9, 2008 Posts: 0 Comments: 8268
Quoting SouthDadeFish:
Comparison of yesterday morning and today:



And now:


There was definitely much more convection yesterday.



convection was farther from the center yest
Member Since: July 21, 2010 Posts: 0 Comments: 1065
I don't understand the criticism of Avila? I guess a PHD isn't good enough.
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The Navy site just put up 13.2 N and 81.4 W
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Quoting WoodyFL:


They will shift back.



true these things shift back and forth
Member Since: July 21, 2010 Posts: 0 Comments: 1065
Comparison of yesterday morning and today:



And now:


There was definitely much more convection yesterday.
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Quoting Tazmanian:
22/1745 UTC 13.0N 81.1W T1.0/1.5 96L -- Atlantic


That's what Ascat shows for coordinates. The next model runs will be interesting with the initial point now being 42 miles approx. further away from the coast.
Member Since: August 19, 2006 Posts: 0 Comments: 15725
22/1745 UTC 13.0N 81.1W T1.0/1.5 96L -- Atlantic
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Quoting stormwatcherCI:
Ocean Frontiers has better webcams than CaymanChillin.


Thanks could you post the link please, TIA.
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Quoting WoodyFL:


They will shift back.


Based on? After a slow drift northward high pressure will drive it to the west.
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Quoting stormwatcherCI:
Weren't all of the models predicting development on Sunday ? I don't think we are there yet and it seems to be even further from land than it was earlier which IMO should increase it's chances.


Yes they did. On Friday night my expectations were 24 to 36 hours ( and closer to 36 ) before classification as a TD. That still looks reasonable to me given what appears to be improvement in organization from early this morning.
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Down to orange eh?

Ouch.
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Quoting stormpetrol:


Ocean Frontiers has better webcams than CaymanChillin.
Member Since: October 9, 2008 Posts: 0 Comments: 8268
By now you should know..you are dealing with Avila...the most conservative one there..I never agree with the guy


Quoting cyclonekid:
Maybe this is why Avila lowered the percentages. It seems like the favored opinion is that it should be higher. I concur with that hypothesis. I say the percentages should have either been kept at 60% or have been increased to 70%.
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Link

Western half the circulation is getting covered up!
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Quoting kmanislander:


And very wet lol !

yep that's for sure almost starting to get too much of a good thing with alot more on the way!
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Quoting GeoffreyWPB:
Quite a shift...



They will shift back.
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Quoting kmanislander:


Agree with all of that. I was about to run a few errands and the skies opened up here. Over hlaf an inch this morning and bucketing down.
Weren't all of the models predicting development on Sunday ? I don't think we are there yet and it seems to be even further from land than it was earlier which IMO should increase it's chances.
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I composed a blog entry focused mainly on 96L if anyone cares to read:

Link

If we see convection build eastward over the developing circulation center, the %'s should go back up....
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Quoting stormpetrol:
Dark and gloomy here!


And very wet lol !
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Dark and gloomy here!
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Quoting Levi32:


Notice the nearly complete absence of trade winds through the Caribbean. Disturbances like 96L need trade winds to help pile up air in their vicinity from the east in order to force air to rise. That's one of the only major negative factors that it is struggling with right now. However, the environment remains more conducive than not.

Also, the pressures and heights over central America and the eastern Pacific seem too high to allow westward movement into Nicaragua and Honduras right now. Any left turn seems more likely to be after a couple days of northward drift, when the ridge builds in over the southern U.S. for a couple days. At that point a move towards the Yucatan is possible, but whether it gets there will be another question. Right now the path of least resistance is either no path at all or a very slow northward drift.


Agree with all of that. I was about to run a few errands and the skies opened up here. Over half an inch this morning and bucketing down.
Member Since: August 19, 2006 Posts: 0 Comments: 15725
NHC says slow northward drift. Xtrap showing current westward movement. Nothing saying NNE or NE movement.
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Quoting GeoffreyWPB:
Quite a shift...



The model shifts make sense. The steering flow will eventually turn whatever this is westward.
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151. Skyepony (Mod)
ASCAT caught 97L when it flared up a ball of convection earlier. Almost got there.



Quoting Jedkins01:
Well its safe to say that 4.96 feet of rain is not your typical every day thundershower.


Even over 10days that is insane.

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Quite a shift...

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Quoting kmanislander:
Based upon this Ascat pass 96L now has a well defined surface low center and it is also further East near 81W than the 81.7 given earlier.If the convection gets a little better organized it would not take much for this to be classified IMO.

50% seems too low me.



Notice the nearly complete absence of trade winds through the Caribbean. Disturbances like 96L need trade winds to help pile up air in their vicinity from the east in order to force air to rise. That's one of the only major negative factors that it is struggling with right now. However, the environment remains more conducive than not.

Also, the pressures and heights over central America and the eastern Pacific seem too high to allow westward movement into Nicaragua and Honduras right now. Any left turn seems more likely to be after a couple days of northward drift, when the ridge builds in over the southern U.S. for a couple days. At that point a move towards the Yucatan is possible, but whether it gets there will be another question. Right now the path of least resistance is either no path at all or a very slow northward drift.
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Quoting Tazmanian:
other one bit the dust this like 95L


It may not quite bite the dust but according to the NHC it has very limited time before it moves into Central America. Their lowering the % is reflective of that.
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Maybe this is why Avila lowered the percentages. It seems like the favored opinion is that it should be higher. I concur with that hypothesis. I say the percentages should have either been kept at 60% or have been increased to 70%.
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other one bit the dust this like 95L
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145. Skyepony (Mod)
Quoting stormpetrol:


Posted the same thing awhile back and suggested the same, I don't see this one going into CA anytime soon!


You posted a different satellite that passed 3hrs & 15mins before.

I posted the same one before Kman but zoomed in. I wouldn't call that a nice tight closed low yet.

Maybe Oceansat will get a good pass on a few hours.
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Well its safe to say that 4.96 feet of rain is not your typical every day thundershower.
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12Z, HWRF at 126 hours
One of the few models still showing a developed system.
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I'm out again
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Quoting stormpetrol:


Posted the same thing awhile back and suggested the same, I don't see this one going into CA anytime soon!


Well I guess we just have to wait and see. By tonight the models and the NHC could be back to where they were before lol
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96L is much more organized than earlier!
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Quoting kmanislander:
Based upon this Ascat pass 96L now has a well defined surface low center and it is also further East near 81W than the 81.7 given earlier.If the convection gets a little better organized it would not take much for this to be classified IMO.

50% seems too low me.



Posted the same thing awhile back and suggested the same, I don't see this one going into CA anytime soon!
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I'm surprised to see it at 50%, I thought it would stay the same.
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A weaker system will drift westward with the lower level flow. That's what the models are picking up on today.

Yesterday, the models were expecting a developing system that would favor a northword pull.
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96L will move inland and 97L is unlikely to develop according to the NHC.
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Based upon this Ascat pass 96L now has a well defined surface low center and it is also further East near 81W than the 81.7 given earlier.If the convection gets a little better organized it would not take much for this to be classified IMO.

50% seems too low me.

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I'm confused by Avila's actions sometimes....
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133. Skyepony (Mod)
Fresh ASCAT
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Quoting TropicalAnalystwx13:
Down to 50%. They're thinking it will go into Central America.

1. THE AREA OF LOW PRESSURE IN THE SOUTHWESTERN CARIBBEAN SEA IS NOW
LOCATED A LITTLE BIT LESS THAN 100 MILES NORTHEAST OF SAN ANDRES
ISLAND. THE LOW IS CURRENTLY DRIFTING NORTHWARD...BUT STRONG HIGH
PRESSURE TO THE NORTH SHOULD FORCE THE LOW TO MOVE TOWARD CENTRAL
AMERICA ON SUNDAY. CLOUDINESS AND SHOWERS REMAIN DISORGANIZED...AND
ALTHOUGH THE POTENTIAL FOR DEVELOPMENT IS DIMINISHING...THIS SYSTEM
COULD STILL BECOME A TROPICAL DEPRESSION BEFORE IT INTERACTS WITH
CENTRAL AMERICA DURING THE NEXT FEW DAYS. THIS SYSTEM NOW HAS A
MEDIUM CHANCE...50 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING
THE NEXT 48 HOURS. REGARDLESS OF DEVELOPMENT HEAVY RAINS SHOULD
CONTINUE PRIMARILY OVER HONDURAS AND NICARAGUA.


They didn't mentioned before the strong high pressure.
Member Since: April 29, 2009 Posts: 75 Comments: 14012
This is becoming more and more of a Hurricane Paula (2010) type deal.

The NHC had it at Code Red in the same location as 96L, but then as it started moving, they dropped it down to 50%. It barely scooted offshore, and then became a Category 2 hurricane in the western Caribbean.

Avila is taking 96L's percentages down too fast.
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Avila is very conservative, I'll say that!
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One more NHC-2pm-50%
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THE AREA OF LOW PRESSURE IN THE SOUTHWESTERN CARIBBEAN SEA IS NOW
LOCATED A LITTLE BIT LESS THAN 100 MILES NORTHEAST OF SAN ANDRES
ISLAND. THE LOW IS CURRENTLY DRIFTING NORTHWARD...BUT STRONG HIGH
PRESSURE TO THE NORTH SHOULD FORCE THE LOW TO MOVE TOWARD CENTRAL
AMERICA ON SUNDAY. CLOUDINESS AND SHOWERS REMAIN DISORGANIZED...AND
ALTHOUGH THE POTENTIAL FOR DEVELOPMENT IS DIMINISHING...THIS SYSTEM
COULD STILL BECOME A TROPICAL DEPRESSION BEFORE IT INTERACTS WITH
CENTRAL AMERICA DURING THE NEXT FEW DAYS. THIS SYSTEM NOW HAS A
MEDIUM CHANCE...50 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING
THE NEXT 48 HOURS. REGARDLESS OF DEVELOPMENT HEAVY RAINS SHOULD
CONTINUE PRIMARILY OVER HONDURAS AND NICARAGUA.
Member Since: July 7, 2010 Posts: 0 Comments: 5627
Down to 50%. They're thinking it will go into Central America.

1. THE AREA OF LOW PRESSURE IN THE SOUTHWESTERN CARIBBEAN SEA IS NOW
LOCATED A LITTLE BIT LESS THAN 100 MILES NORTHEAST OF SAN ANDRES
ISLAND. THE LOW IS CURRENTLY DRIFTING NORTHWARD...BUT STRONG HIGH
PRESSURE TO THE NORTH SHOULD FORCE THE LOW TO MOVE TOWARD CENTRAL
AMERICA ON SUNDAY. CLOUDINESS AND SHOWERS REMAIN DISORGANIZED...AND
ALTHOUGH THE POTENTIAL FOR DEVELOPMENT IS DIMINISHING...THIS SYSTEM
COULD STILL BECOME A TROPICAL DEPRESSION BEFORE IT INTERACTS WITH
CENTRAL AMERICA DURING THE NEXT FEW DAYS. THIS SYSTEM NOW HAS A
MEDIUM CHANCE...50 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING
THE NEXT 48 HOURS. REGARDLESS OF DEVELOPMENT HEAVY RAINS SHOULD
CONTINUE PRIMARILY OVER HONDURAS AND NICARAGUA.
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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.