Caribbean disturbance 93L to drench Honduras; 97L disturbance worth watching

By: Dr. Jeff Masters , 3:04 PM GMT on August 18, 2011

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A westward-moving tropical wave in the Central Caribbean a few hundred miles south-southwest of Jamaica, Invest 93L, has continued to increase in organization, and is close to tropical depression status. 93L is a small system, but has built up a respectable area of heavy thunderstorms around its center. A few low-level spiral bands are apparent on satellite imagery, but there is almost no upper-level outflow apparent, and a surface circulation is not obvious. 93L has moistened its environment somewhat over the past day, but dry air is still in evidence around the storm, particularly to the southeast, as seen on water vapor satellite images. Wind shear continues to be low, 5 - 10 knots. There is a hurricane hunter mission scheduled for this afternoon at 2pm EDT to see if a tropical depression is forming.


Figure 1. Morning satellite image of 93L.

Heavy rains from 93L will begin spreading over Northern Honduras and Northeast Nicaragua tonight. The forward motion of 93L will slow to 5 - 10 mph by Friday, so the storm could be a major rain event for Northern Honduras, with rain amounts of 4 - 8 inches likely by the time the storm reaches Belize on Saturday. Heavy rains will spread to Belize and Mexico's Yucatan Peninsula by Friday night or Saturday morning. The latest SHIPS model forecast shows wind shear remaining in the low range and the atmosphere steadily moistening over the next two days, which should allow 93L to reach tropical storm strength. All of the models agree that the ridge of high pressure steering 93L to the west will remain strong, forcing the storm into a landfall Friday in Northeast Honduras, or Saturday near the Belize/Mexico border. It is possible that 93L will have time to intensify into a Category 1 hurricane before then, though landfall as a tropical storm would be more likely, given the dry air that 93L needs to overcome, and the possibility that the storm will pass too close to the northern coast of Honduras. Regardless, heavy rain will be a major threat from 93L. NHC gave 93L an 80% chance of developing into a tropical depression by Saturday morning in their 8am outlook. If 93L does cross the Yucatan Peninsula and enters the Gulf of Mexico, a strong ridge of high pressure should keep the storm moving due west to make a second landfall along the Mexican coast, well south of Texas.


Figure 2. Morning satellite image of the tropical wave 97L midway between the Lesser Antilles and the coast of Africa.

Invest 97L midway between the Lesser Antilles and the coast of Africa
A tropical wave near 14°N 40°W, midway between the Lesser Antilles Islands and the coast of Africa, is moving westward near 15 - 20 mph. This wave, designated 97L by NHC this morning, has little heavy thunderstorm activity associated with it due to dry air, but an impressive amount of large-scale spin is obvious in visible satellite loops. 97L is expected to arrive in the Lesser Antilles Islands by Saturday. Over the past day, all four of our reliable models for predicting tropical storm genesis have predicted that this wave could develop into a tropical depression sometime Saturday through Monday, so 97L needs to be watched carefully. NHC gave 97L a 10% chance of developing into a tropical depression by Saturday morning in their 8am outlook, and it is unlikely that this storm will pose much of a threat to the Lesser Antilles. It will take several days for the storm to overcome the large amount of dry air surrounding it, even though wind shear is a low 5 - 10 knots. By Saturday, the wave will find a moister atmosphere and warmer sea surface temperatures near the northern Lesser Antilles, and more rapid development may occur. However, there is expected to be high wind shear associated with an upper level low pressure system to the north of Puerto Rico at that time, and this wind shear may interfere with development. 97L is expected to take a west-northwest track through the Northeast Caribbean bringing the storm near Puerto Rico by Sunday or Monday. Long-range model runs, which are highly unreliable, foresee that 97L could be a threat to Hispaniola, Eastern Cuba, the Bahamas, and Florida by the middle to end of next week.

Jeff Masters

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Member Since: Posts: Comments:
Quoting RitaEvac:
Port of Houston, Houston, Texas (PWS)
Partly Cloudy
103.3 °F
Partly Cloudy
Humidity: 41%
Dew Point: 75 °F
Wind: 6.0 mph from the WNW
Wind Gust: 6.0 mph
Pressure: 29.86 in (Falling)
Heat Index: 118 °F


Houston Heights 103 degrees HOT !
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104 here in West Fort Worth. 19% humidity. Drier than a popcorn fart!
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Quoting AegirsGal:
welcome.


I have been in over 10 storms and after Ike the 'EXCITEMENT' of wanting to be in a landfall has ebbed. I appreciated you thinking of all the folks on those beautiful islands. Sometimes we get selfish and think ONLY USA , USA!
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Quoting ecflweatherfan:


Oh sure, absolutely... especially, in the higher terrain I can only imagine, where winds are typically higher and orographic lifting increases the amount of rainfall. PR does have its fair share of problems when a TS hits, indeed.


For me, the main problem in PR if a storm hit us is the actual conditions of the power grid. Brother, if something happems this year, I'll be without power for about 2 1/2 months...and that's granted.
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High-res visible loop of 93L

Let's not forget that our friends in Central America are watching this one. Convection looks a bit lackluster at the moment. The environment around it is still a bit dry, but a whole lot less so than it was a couple of days ago. It's a small system, and could easily close off a surface circulation at any time. Based on where I am seeing the greatest turning at the surface, it looks to be headed for a scrape on top of the northern Honduras coastline. A difference in track of even 30 miles here could determine whether this dissipates quickly just inland over Honduras, or slips just north of the coastline and continues to strengthen until a landfall in Belize. Both countries should be monitoring the system.
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Maybe the models are wrong on 97L
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Port of Houston, Houston, Texas (PWS)
Partly Cloudy
103.3 °F
Partly Cloudy
Humidity: 41%
Dew Point: 75 °F
Wind: 6.0 mph from the WNW
Wind Gust: 6.0 mph
Pressure: 29.86 in (Falling)
Heat Index: 118 °F
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Quoting Dennis8:


AMEN..Thanks for saying that!
welcome.
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Quoting JLPR2:


PR and Haiti aren't compatible comparisons, we may not be in our best shape ever but we aren't that bad.
If I'm not mistaken there are areas that don't even have a power grid in Haiti.
What I meant to say is that PR would take awhile to go back to normal even after a TS.


Oh sure, absolutely... especially, in the higher terrain I can only imagine, where winds are typically higher and orographic lifting increases the amount of rainfall. PR does have its fair share of problems when a TS hits, indeed.
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Quoting kshipre1:
not sure but somehow that upper level pattern which is supposed to take place may not be as strong as once thought

never even thought for a second that the gfs ensembles would have shown recurving

Someone downblog mentioned they worked for the NHC and the GFS and GFDL were the most trusted models.

On another note, this is probably the most inclusive run of TC AOIs I've seen:

http://www.ssd.noaa.gov/PS/TROP/TCFP/data/current /mainrfps.png
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Quoting USAFwxguy:
That trough over the Northern Rockies would/should encourage movement more to the Northern GoM than Western, just to be clear.


Yep, could be knocking on our doorstep early next week! So are you on the Ride Out Crew as a WX guy or are you required to evacuate like everyone else?
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Quoting AegirsGal:
Unless you happen to be a resident of one of those islands. I can't imagine it would be best for them.


AMEN..Thanks for saying that!
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Quoting NavarreMark:


He needs to let that one go and not eat it. I've heard the big ones are toxic.


Ciguatera
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Quoting kshipre1:
not sure but somehow that upper level pattern which is supposed to take place may not be as strong as once thought

never even thought for a second that the gfs ensembles would have shown recurving
I heard the guys on TWC said the trough is supposed to lift out, by early next week, and that it wouldn't affect our system.
Member Since: August 31, 2009 Posts: 0 Comments: 5628
Quoting Stormchaser2007:
18z Suite

LGEM/SHIP have this heading WSW at the end of the period.

FULL


THANKS for posting this..TEXAS be on alert as the High breaks down next week..FINALLY. 103 degrees in the Houston Heights RIGHT NOW.

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Quoting KanKunKid:


Puerto Ricans are tough. A Puerto Rican girl can beat up a man! I see it next door all of the time! Don't count out the PR folks, they are not like the Haitians!
And the food is much better they make...;) Si no mentira?


Don't forget about rum Bacardi.
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Quoting Stormchaser2007:


Pretty much everywhere lol
Member Since: September 17, 2010 Posts: 0 Comments: 216
thanks Levi
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Quoting Stormchaser2007:


that pretty much covers every solution..
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not sure but somehow that upper level pattern which is supposed to take place may not be as strong as once thought

never even thought for a second that the gfs ensembles would have shown recurving
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871. JLPR2
Quoting ecflweatherfan:


PR isn't??? What about Haiti? IMO, PR is in FAR better shape to deal with a storm than Haiti. They have bad enough times dealing with their general everyday thunderstorms, much less a hurricane/tropical storm. Not saying the PR can deal with it, but they are far less at risk than Haiti is at this point.


PR and Haiti aren't compatible comparisons, we may not be in our best shape ever but we aren't that bad.
If I'm not mistaken there are areas that don't even have a power grid in Haiti.
What I meant to say is that PR would take awhile to go back to normal even after a TS.
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NAM shows a small system S Florida, before 97L hits PR...

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97L Pressure down 1MB:

AL, 97, 2011081818, , BEST, 0, 136N, 394W, 25, 1008, DB, 34, NEQ, 0, 0, 0, 0, 1010, 175, 90, 0, 0, L, 0, , 0, 0, INVEST, S,
Member Since: August 14, 2008 Posts: 4 Comments: 4972
Member Since: June 9, 2007 Posts: 4 Comments: 15889
866. JLPR2
Quoting MississippiWx:


Lol...I didn't even mean that at all in that post. I was mainly talking about the United States, but it doesn't look like Puerto Rico is going to receive a hit from anything terribly strong. The rain might be an issue, though. I wouldn't expect it to be strong while hitting Puerto Rico...if it hit Puerto Rico, then went west and hit Haiti it wouldn't be strong then either. That's all I meant by that statement.

Didn't take long for everyone to jump on me...sheesh. Lol.


I know you didn't mean it like that. :)
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Quoting JLPR2:


Thank you. :)
It would suck, big time, PR isn't in conditions to deal with a Tropical system.


PR isn't??? What about Haiti? IMO, PR is in FAR better shape to deal with a storm than Haiti. They have bad enough times dealing with their general everyday thunderstorms, much less a hurricane/tropical storm. Not saying the PR can deal with it, but they are far less at risk than Haiti is at this point.
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Quoting Matt1989:
Could someone post a link on where to find the ecmwf? Thanks alot.


Link
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Quoting OneDrop:
I'm not heckling and I'm mostly a lurker but this blog is going to heat up over the next few days and I just want everyone to relax and get along. Most importantly, don't feed into the trolls!!!! They will be out in full force and the only way to get rid of them is to not acknowledge them. Don't quote them to let everyone know they are trolls, we know who they are and they will go away if they don't get the reaction they expect.


Nice 'cuda!
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862. HCW
Latest 97L model runs from the NHC


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Quoting JLPR2:


Thank you. :)
It would suck, big time, PR isn't in conditions to deal with a Tropical system.


Lol...I didn't even mean that at all in that post. I was mainly talking about the United States, but it doesn't look like Puerto Rico is going to receive a hit from anything terribly strong. The rain might be an issue, though. I wouldn't expect it to be strong while hitting Puerto Rico...if it hit Puerto Rico, then went west and hit Haiti it wouldn't be strong then either. That's all I meant by that statement.

Didn't take long for everyone to jump on me...sheesh. Lol.
Member Since: July 15, 2006 Posts: 17 Comments: 10244
Quoting KanKunKid:


Puerto Ricans are tough. A Puerto Rican girl can beat up a man! I see it next door all of the time! Don't count out the PR folks, they are not like the Haitians!
And the food is much better they make...;) Si no mentira?
And here I thought it was because of the rum... silly me, carry on.
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Might see a Renumber of 93L soon, if you looks at just the Low level clouds very evident closed circulaiton... as seen Post 816, by P451...

I Lost my link for ATCF site on the page where you can find the Renumberings and Initiations of invests, anyone have it? TIA
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For the time being GFS/ECMWF have basically the same track after it leave Hispanola.

GFS is not as aggressive as ECMWF on a WNW track and stalls it more (waiting for the steering to become more conductive for a displacement to happen).

Forecast sure is getting interesting specially if it interacts directly with DR.
Member Since: August 14, 2008 Posts: 4 Comments: 4972
Quoting CarolinaHurricanes87:


Do you believe I am safe in SE NC and likely to be outside the "cone" if 97 develops as expected?


No, not yet...Way too early to know that answer. However the pattern favors a more direct hit farther to your south. Things change, though and change fast.
Member Since: July 15, 2006 Posts: 17 Comments: 10244
Could someone post a link on where to find the ecmwf? Thanks alot.
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853. JLPR2
Quoting sporteguy03:

Unless your on the Islands of course ;)


Thank you. :)
It would suck, big time, PR isn't in conditions to deal with a Tropical system.
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Quoting nrtiwlnvragn:
TROPICAL DISCUSSION - INTERNATIONAL DESKS

Excerpt:

TROPICAL WAVE ALONG 39W AND SOUTH OF 19N IS A SYSTEM OF CONCERN.
THE NHC IS MONITORING THIS PERTURBATION FOR POSSIBILITY OF
TROPICAL CYCLOGENESIS AND WILL ISSUE THE OFFICIAL FORECAST. THE
WAVE IS TO ENTER THE ISLAND CHAIN ON DAY 03. AS RIDGE PATTERN
ESTABLISHES ALOFT...AND MJO CONDITIONS BECOME MORE
FAVORABLE...THIS IS LIKELY TO FAVOR RAIN SQUALLS AND HEAVY
CONVECTION. IN THIS AREA WE EXPECT RAINFALL AMOUNTS OF 15-20MM/DAY
AND MAXIMA OF 40-80MM/DAY. AS IT ENTERS THE GUIANAS...THE WAVE
WILL FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM/DAY.

The mjo is something Don nor Emily had going for it when they were traversing the Caribbean, because the phase was in downward motion, now for 97L its in upward motion.
Member Since: August 31, 2009 Posts: 0 Comments: 5628
Quoting cloudburst2011:



im not just giving the cold hard facts...
I'm not heckling and I'm mostly a lurker but this blog is going to heat up over the next few days and I just want everyone to relax and get along. Most importantly, don't feed into the trolls!!!! They will be out in full force and the only way to get rid of them is to not acknowledge them. Don't quote them to let everyone know they are trolls, we know who they are and they will go away if they don't get the reaction they expect.
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Quoting MississippiWx:


Yeah, it's going to change several more times. However, any chance of an out-to-sea solution seems low.

If it can skirt just south of the big islands, that would be the worst case scenario for the Gulf states. A track skirting just north would be worse for Florida/GA/SC.

A track directly over the islands would be best for everyone...lol.


Do you believe I am safe in SE NC and likely to be outside the "cone" if 97 develops as expected?
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Quoting P451:


Everyone should pay attention to it.

No one should expect any of the current model runs to be successful.

As I always say "expect the unexpected"
Member Since: August 31, 2009 Posts: 0 Comments: 5628
Have to run again. Back later
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Quoting Tropicsweatherpr:


But not for those like me that live in one of the islands.
Quoting AegirsGal:
Unless you happen to be a resident of one of those islands. I can't imagine it would be best for them.


Well, yeah, obviously it would be bad for them if it were anything strong. However, models have been showing a fairly weak solution over the islands because of too much land interaction.

Rain would be the worst issue, which could be bad in mountainous areas.
Member Since: July 15, 2006 Posts: 17 Comments: 10244

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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.