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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Pressure is really dropping at Buoy 42057.



The winds are pretty decent as well, even on the NW side of the system.

Wind Direction (WDIR): ENE ( 70 deg true )
5-day plot - Wind Speed Wind Speed (WSPD): 23.3 kts
5-day plot - Wind Gust Wind Gust (GST): 29.1 kts
5-day plot - Wave Height Wave Height (WVHT): 4.9 ft
5-day plot - Dominant Wave Period Dominant Wave Period (DPD): 6 sec
5-day plot - Average Period Average Period (APD): 4.7 sec
5-day plot - Mean Wave Direction Mean Wave Direction (MWD): ESE ( 102 deg true )
5-day plot - Atmospheric Pressure Atmospheric Pressure (PRES): 29.80 in
5-day plot - Pressure Tendency Pressure Tendency (PTDY): -0.07 in ( Falling )
5-day plot - Air Temperature Air Temperature (ATMP): 80.2 °F
5-day plot - Water Temperature Water Temperature (WTMP): 85.1 °F
5-day plot - Dew Point Dew Point (DEWP): 76.5 °F
5-day plot - Heat Index Heat Index (HEAT): 86.0 °F
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Hi all. Sideglance to Europe: Western parts today are hit by devastating thunderstorms. Report BBC with video, but not of the accident itself:

Deadly storm strikes Belgium's Pukkelpop festival

At least two people have been killed at the Pukkelpop music festival in Belgium after a sudden storm caused two stages to collapse, reports say.

Television pictures from the scene, about 65km (40 miles) east of Brussels, showed fallen stage rigging and people scrambling for cover.

Initial reports in the Belgian media said four people had been killed.

About 60,000 people were believed to be at the event, one of Europe's largest outdoor festivals.

The mayor of the town of Hasselt, where Pukkelpop is held, said 40 people were injured, AP news agency reported.

The TV images showed rain-soaked festival-goers bracing against strong winds. Fallen gantries and rigging could be seen on the ground.

Belgian media reported that trees were uprooted by the violent storm and smashed into the stage, bringing it down.

Some festival-goers said on the Twitter website that a tornado had struck.

The BBC's Matthew Cole, in Brussels, said the storms swept across Belgium in the early evening, turning the sky dark.

Five people were killed last week at a festival in the US state of Indiana when a stage collapsed in high winds.



Source: http://www.bbc.co.uk/news/world-europe-14582448
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994. xcool

Invest97----Allan Huffman, Raleigh Weather Examiner

The wave we have been watching all week because of the global models insistence that it could be a US threat is still out there but as of now not rapidly getting better organized. There is a circulation apparent on visible satellite imagery but there is a lack of deep convection and the convection that is there is not concentrated in the center. A point to keep in mind here is that no model is really showing any immediate development. In fact at 00z Sunday (8pm Saturday night), the storm is still an open wave on the Euro and is only a 1008mb low on the 12z GFS as it approaches the northern and central Islands.

The 12z data is in and is all over the place with the eventual landfall risks with this system. Each model has taken turns threatening the Gulf coast, the west coast of Florida, the Keys, the east coast of Florida, and the southeast coast. The 12z GFS showed the storm running right over Hispaniola, Cuba, into the Gulf and then striking the west coast of Florida and into the southeast US. The 12z ECMWF has shifted way west too after the 00z run showed an impending strike on the southeast coast, the 12z now shows the storm tracking much further west and moving through the Yucatan Channel into the Gulf as a powerful hurricane. The 12z Canadian looks like last night’s Euro through 180 hours with a close pass to Florida and an impending strike on the southeast US coast. The various 12z GFS ensemble members showed a similar spread with more members in the Gulf as opposed to off the southeast US coast.
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Quoting Ameister12:
Good afternoon!

Somebody probably already posted this, but the ECMWF has a sick sense of humor.


If you look at the ECMWF loop it gives a different picture. It shows a strong system in the Gulf of Mexico at that time.
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Quoting GetReal:


That animation is really nice where do you get it?
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The 1999 version of Irene caused lots of flooding here in S FL.
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Quoting Levi32:
12z ECMWF ensembles show track possibilities anywhere from the Gulf of Mexico to east of Virginia in 9-10 days. It is weighted more towards the gulf like the operational run.

Don't do this to me Levi!!.I just said that it'll probally never go into the Gulf.(Hopefully with those sst and TCHP nothing goes into there).
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Quoting MississippiWx:
Convection is building persistently around the apparent center, which is something 93L hasn't done until now. The convection would develop then die, only to reform several hours later. Convection is now constantly re-firing each frame, which tells me we have more activity at the surface causing the air to rise more.

Been watching the sat loop, and I agree.
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12z ECMWF ensembles show track possibilities anywhere from the Gulf of Mexico to east of Virginia in 9-10 days. It is weighted more towards the gulf like the operational run.

Member Since: November 24, 2005 Posts: 635 Comments: 26746
Quoting tatoprweather:


I live in a rural area about 500 feet high. And again...if something hit us this year that's 2 1/2 months without power in my area...granted. Preventive Maintenance here is mainly non existent and during the last few years all the discussion regarding our power company goes around switching from oil to natural gas + the daily politics of course (which by the way it's our national sport).
I keep thinking Bahamians and Puerto Ricans are related... think arroz con gandules.... but the politics comment is clear proof.
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Convection is building persistently around the apparent center, which is something 93L hasn't done until now. The convection would develop then die, only to reform several hours later. Convection is now constantly re-firing each frame, which tells me we have more activity at the surface causing the air to rise more.

Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting Ameister12:
Good afternoon!

Somebody probably already posted this, but the ECMWF has a sick sense of humor.
That probally (and hopefully) willnever materialize.By the way I see the model is developing that wave behind it.
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I am observing a much defined circulation for 97L around 13.5N40.5W. I'm watching tropical floater #2 19:45 UTC. Could somebody confirm this?
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Quoting lottotexas:

yesterday accuweather's forecast was "anywhere from Brownsville to Hatteras"
Didn't there used to be something on here call the "stoopid circle"? One of the better forecast tools for CV originating Twaves we've had on here....

Quoting Stats56:


Glock and lots of ammo was in my Ike kit since we were getting a direct hit.
I would certainly think about gators and snakes in the bayou country.... if nothing else...

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This year my duaghter had a science project.She told me to help her out with what theme to come up with.So I said hurricanes.At first she didn't agree but she did it.And the best part is she didn't even need a computer to do research.I told her everything she needed to know.And thanks to my artistic skills I help create her board.She won 3rdlace in the science fair!!!.I was very proud of her.
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just ran the loop on the central atlantic wave very impressive sorry jenkins disagree with you its large and situated just in the right spot to move into the carib. i guess the donut will shrink or will convection break out inside the wave as it gets stronger? not sure if this is the wave jb was talking about or is it the one behind? good luck to everyone
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Quoting USAFwxguy:
Check out the pressure drop:


Station 42057 - Western Caribbean
Today, August 18, 2011, 4 minutes ago
August 18, 2011 2:50 pm EDT
Location: 17.003N 81.501W
Wind Direction: ENE (70°)
Wind Speed: 17.5 knots
Wind Gust: 19.4 knots
Significant Wave Height: 4.3 ft
Dominant Wave Period: 6 sec
Average Period: 4.4 sec
Mean Wave Direction: E (92°)
Atmospheric Pressure: 29.83 in (1010.1 mb)
Pressure Tendency: -0.05 in (-1.6 mb)
Air Temperature: 83.5°F (28.6°C)
Dew Point: 75.6°F (24.2°C)
Water Temperature: 85.1°F (29.5°C)


Station 42057 - Western Caribbean
Today, August 18, 2011, 1 hour ago
August 18, 2011 1:50 pm EDT
Location: 17.003N 81.501W
Wind Direction: E (80°)
Wind Speed: 17.5 knots
Wind Gust: 21.4 knots
Significant Wave Height: 3.9 ft
Dominant Wave Period: 5 sec
Average Period: 4.1 sec
Mean Wave Direction: ENE (75°)
Atmospheric Pressure: 29.86 in (1011.1 mb)
Pressure Tendency: -0.01 in (-0.4 mb)
Air Temperature: 82.4°F (28.0°C)
Dew Point: 75.6°F (24.2°C)
Water Temperature: 85.1°F (29.5°C)



HH found 1009.9 about 3 hours ago at 15.0N 78.5W
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I realize the consistency of model forecasts as far as the track of 97L goes, but 97L is a very unimpressive with lots of dry embedded around it. Tropical systems need MASSIVE amounts of moisture to function properly and grow. 97L is far from that.

Could that change? Of course, but until then, don't worry about a system that doesn't even match half the intensity of sea breeze storms in Florida.

The one thing 97L does have going for it so far is that it has a well defined circulation, if it can get into a much more favorable environment for convection and break away from the dry air, then we will likely see a completely different system.
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Good afternoon!

Somebody probably already posted this, but the ECMWF has a sick sense of humor.
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Quoting KanKunKid:


I don't know I watched a whole Jimmy Stewart movie and never saw Harvey, although every one was talking about him.
I expect the same. But if he does show, he won't be no 6' tall rabbit. Maybe a depression headed for Honduras or Belize maybe.
Have fun looking for Huh Huh Harvey!
93L will be Harvey.jmo...Irene will be a big storm...We seem to get hit with the "I" storms quite a bit...Went thru Irene in 99. It was rather nasty.
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Pretty soon the entire east coast will have a discusion out on this system.
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Quoting tatoprweather:


I live in a rural area about 500 feet high. And again...if something hit us this year that's 2 1/2 months without power in my area...granted. Preventive Maintenance here is mainly non existent and during the last few years all the discussion regarding our power company goes around switching from oil to natural gas + the daily politics of course (which by the way it's our national sport).


Dont forget the fact that we dont get hit that much by these storms our last hurricane was george. This is very important when thinking about possible damage senarios because of vegetation growth, the rainforest grows fast and over the last 13 years the trees have had time to grow and so has the jungle so when the next storm does come it will have alot to throw around so to speak. This will complicate clean up to say the least.
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Quoting wxhatt:
I think if 97L develops faster and moves north of the islands, it will be in a better position to ride up the eastern seaboard.



I think you're right about that. (And cheering for it to do so; at least there is some chance it will not severely impact anyone if it does that.)

Reflected by difference between BAMS, BAMM, BAMD:

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NWS in Melbourne is indeed keeping a close eye on this one!
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10,990.58
-419.63
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When the get a recon into 93L we will have more information...and a TD is likely
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Quoting extreme236:
18Z DSHIPS and LGEM still bring 93L up to low-end Cat 1 strength before landfall in 48 hours.
Well the very warm sst are there along with TCHP.That's if the envierement allows so.
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Issued: Aug 18, 2011 8:00 am HST

For the central north Pacific, between 140°W and 180.

1. The Central Pacific Hurricane Center in Honolulu Hawaii is issuing advisories on tropical storm Fernanda, located about 1000 miles east-southeast of Hilo Hawaii. Additional informations can be found under AWIPS header hnltcpcp1 and WMO header WTPA31 PHFO.

Elsewhere, no tropical cyclones are expected through Saturday morning.
Member Since: July 31, 2011 Posts: 5 Comments: 891
Would love to have recon in 93L...

Member Since: July 15, 2006 Posts: 17 Comments: 10284
A big hurricane anywhere will not benefit that area.
1rst of all - human lives are lost....
Then; lost of property, jobs and many other factors induce more criminality and emigration...

And that's only a little consideration of all the negative effects a hurricane has...

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Quoting FLdewey:


Read their first discussion of the day... pretty much gives the why.


Just posted this afternoon's discussion... so even more reason why. :-)
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Quoting atmoaggie:
Island influence in the intensity forecast for 97L, I think, at 96 hours out.



It will be interesting to see how much land interaction it will really have.
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Quoting extreme236:
18Z DSHIPS and LGEM still bring 93L up to low-end Cat 1 strength before landfall in 48 hours.


No renumber yet, so we'll likely have to wait another forecast package...maybe the 8pm one. It's simply running out of time and I'd be surprised if it took another 48 hours to make landfall.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
200 PM EDT THU AUG 18 2011
EXTENDED PERIOD...SUNDAY THROUGH THURSDAY...SLIGHTLY DRIER AIR WILL
MOVE OVER S FLA THROUGH MIDWEEK WITH CLIMO POPS. NOCTURNAL E COAST
AND DIURNAL INTERIOR AND W CONVECTION EXPECTED. THE LONG RANGE MODELS
LINING UP AND AGREEING THAT A DEVELOPING TROPICAL WAVE APPROACHES
THE AREA LATE NEXT WEEK. AT THIS TIME...LOADING ECMWF WINDS AND
LEAVING WEATHER AS IS PENDING ADDITIONAL GUIDANCE/DEVELOPMENT.
Member Since: July 31, 2011 Posts: 5 Comments: 891
AFD NWS Melbourne, FL says this about 97L:

LOOKING OUT TO THURSDAY AND THURSDAY NIGHT NEXT WEEK...GFS/ECMWF AND
CANADIAN MODELS ARE COMING INTO BETTER AGREEMENT WITH A POTENTIAL
TROPICAL SYSTEM NEAR HISPANIOLA VICINITY TUE...THE SRN BAHAMAS ON
WED AND HAVING A CHANCE TO POSSIBLY AFFECT FL JUST BEYOND THE 7 DAY
FORECAST PERIOD...ASSUMING THIS SYSTEM DOES INDEED DEVELOP AS THE
MODELS ARE INDICATING. WOULD NOT NORMALLY MENTION THE POTENTIAL FOR
A TROPICAL SYSTEM AT THIS LONG TIME RANGE BUT THE MODELS ARE COMING
INTO SOMEWHAT BETTER AGREEMENT AND HAVE BEEN SHOWING THE POTENTIAL
OF A SYSTEM FOR MULTIPLE DAYS. AT THIS POINT...IT IS BEST TO
CONTINUE TO MAKE PREPARATIONS AS YOU NORMALLY WOULD AS WE ENTER THE
PEAK OF THE HURRICANE SEASON FROM MID AUG TO EARLY OCT AND KEEP UP
WITH LATEST TROPICAL WEATHER OUTLOOKS AND FORECASTS OVER THE NEXT
WEEK.
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I think if 97L develops faster and moves north of the islands, it will be in a better position to ride up the eastern seaboard.



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18Z DSHIPS and LGEM still bring 93L up to low-end Cat 1 strength before landfall in 48 hours.
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Animated water vapor imagery shows that the environment around 93L is still somewhat dry, but a lot more moist than it was a couple of days ago, and thus more conducive for development. The increase in random popup showers throughout the western Caribbean supports this.

Member Since: November 24, 2005 Posts: 635 Comments: 26746
Quoting atmoaggie:
Well, 93L is running out of real estate. I think his chance to be someone's nightmare (read: 'cane) has already passed. JMO.
I think it might be minimal tropical storm.
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Afternoon all!

93l looking good this afternoon, but IMO doesn't look like it has enough time to develop into something significant. And the consistency of all the models on 97l is concerning, but IMO if this thing gets into the gulf, then the gulf coast needs to watch out.
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Quoting mrpuertorico:
Still alot of dry air for 97l to contend with




SAL is playing a very important role inhibiting TS formation.... A real saviour for us all...
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Island influence in the intensity forecast for 97L, I think, at 96 hours out.

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Quoting ecflweatherfan:
Here is the Melbourne, FL forecast for next Thursday from the NWS office in Melbourne...

Thursday...Partly sunny with a chance of showers and thunderstorms. Windy. Highs in the upper 80s. Chance of rain 40 percent.


So far out and using that terminology is NOT a good sign.


True that
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DFWjc you have mail.
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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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