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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1096. Levi32
Quoting atmoaggie:
doh.

The CH1, CH1, CH4 means it's visible, visible, and IR.
Given the sunglint, the low levels must be visible, not IR.

(Oops, my bad.)

Still don't think it truly depicts surface winds worth a [snip].


I think if you compare the vis and rgb loops side by side, you will see that there is absolutely no difference except for the colorization. It is my understanding that IR sensing is used to detect which of the clouds to color yellow, which are supposed to be low-level clouds. The RGB product is visible, but with a color enhancement designed to make it easier to pick out low-level clouds.
Member Since: November 24, 2005 Posts: 635 Comments: 26698
1095. xcool
Member Since: Posts: Comments:
Quoting Tazmanian:
if am looking at this right it looks like we have 98L


BEGIN
NHC_ATCF
invest_al982011.invest
FSTDA
R
U
040
010
0000
201108182101
NONE
NOTIFY=ATRP
END
INVEST, AL, L, , , , , 98, 2011, DB, O, 2011081818, 9999999999, , , , , , METWATCH, , AL982011
AL, 98, 2011081718, , BEST, 0, 116N, 126W, 25, 1009, DB, 0, , 0, 0, 0, 0,
AL, 98, 2011081806, , BEST, 0, 121N, 153W, 25, 1007, DB, 0, , 0, 0, 0, 0,
AL, 98, 2011081812, , BEST, 0, 123N, 164W, 25, 1007, DB, 0, , 0, 0, 0, 0,
AL, 98, 2011081818, , BEST, 0, 126N, 176W, 25, 1006, DB, 34, NEQ, 0, 0, 0, 0, 1008, 300, 60, 0, 0, L, 0, , 0, 0, INVEST, S,




invest_al982011.invest 1 KB 8/18/2011 8:57:00 PM
Yep that's right.Is it for that fat wave behing invest 97L?.
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Quoting TropicalAnalystwx13:
We have Invest 98L.


Lol...WTF!
Member Since: July 15, 2006 Posts: 17 Comments: 10284
1092. DFWjc
Quoting bohonkweatherman:
You are almost as hot as Central Texas, been 105 to 106 here, Dallas area 107 to 109.


Yep, we hit 109 here in North Richland Hills...
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1091. Dennis8
Quoting AegirsGal:
LOL yeah if he was working for a hvac firm. As it stands, we live here rent free.


That is great..I hope he is drinking lots of cold water.! What make you interested in Wx?
Member Since: August 15, 2008 Posts: 0 Comments: 446
1090. Stats56
Quoting Dennis8:
JUST HIT 104 AT MY HOUSE IN Houston!


105 in The Woodlands now
Member Since: Posts: Comments:
Quoting Tazmanian:
if am looking at this right it looks like we have 98L


BEGIN
NHC_ATCF
invest_al982011.invest
FSTDA
R
U
040
010
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201108182101
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NOTIFY=ATRP
END
INVEST, AL, L, , , , , 98, 2011, DB, O, 2011081818, 9999999999, , , , , , METWATCH, , AL982011
AL, 98, 2011081718, , BEST, 0, 116N, 126W, 25, 1009, DB, 0, , 0, 0, 0, 0,
AL, 98, 2011081806, , BEST, 0, 121N, 153W, 25, 1007, DB, 0, , 0, 0, 0, 0,
AL, 98, 2011081812, , BEST, 0, 123N, 164W, 25, 1007, DB, 0, , 0, 0, 0, 0,
AL, 98, 2011081818, , BEST, 0, 126N, 176W, 25, 1006, DB, 34, NEQ, 0, 0, 0, 0, 1008, 300, 60, 0, 0, L, 0, , 0, 0, INVEST, S,


Things are heating up
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We have Invest 98L.
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1086. xcool



12z Euro Ensemble mean
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Quoting Dennis8:


I could have used him 2 weeks ago....my home is 7 years old and the capacitor (sp) and a switch went out..9pm at night. $820.00 with freon added. You should be a RICH LADY!
LOL yeah if he was working for a hvac firm. As it stands, we live here rent free.
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I think within the next couple fo days, this wave will be our next invest. Looking at the 850mb vorticity map , it seems rather well defined.
I am a bit confused on how to read the divergence and convergence maps. From the little I do understrand, it looks pretty good to be. I see cicrles where the thunderstorms are. If someone can help me with reading those convergence and divergence maps better, that'd be great.
The windshear values appear to be low. Is that an anti cyclone I see developing there? Also, there is a fair amout of SAL dry air to it's north which could impede development.
Any comments, or tips on my convergence and divergence map reading skills would be helpful.
Thanks.
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1083. Grothar
I think it is a lot of dry air.

img src="">
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Quoting atmoaggie:
Seems I need to find and re-read the "about this product" statement...

doh.

The CH1, CH1, CH4 means it's visible, visible, and IR.
Given the sunglint, the low levels must be visible, not IR.

(Oops, my bad.)

Still don't think it truly depicts surface winds worth a [snip].
Member Since: Posts: Comments:
1081. hahaguy
Melbourne,FL discussion

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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1080. Dennis8
Quoting AegirsGal:
LOL! Hubby is A/C tech. We keep ours 80-83 during the day and then cooler at night. Now if the rest of the residents in our complex would do the same thing (hubby is lead maintenance)he would not have to constantly be up on roofs all day.


I could have used him 2 weeks ago....my home is 7 years old and the capacitor (sp) and a switch went out..9pm at night. $820.00 with freon added. You should be a RICH LADY!
Member Since: August 15, 2008 Posts: 0 Comments: 446
Quoting TropicalAnalystwx13:
It's hard to ignore the models when they have had a significant hurricane making landfall somewhere on the USA for several days now.

You can't deny that. While a specific landfall point cannot be made for a long time, and things may change, the threat of a USA landfall at this time is medium/high.
I'm not discounting anything at this moment It's just that it's to far out.
Member Since: Posts: Comments:
if am looking at this right it looks like we have 98L


BEGIN
NHC_ATCF
invest_al982011.invest
FSTDA
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040
010
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201108182101
NONE
NOTIFY=ATRP
END
INVEST, AL, L, , , , , 98, 2011, DB, O, 2011081818, 9999999999, , , , , , METWATCH, , AL982011
AL, 98, 2011081718, , BEST, 0, 116N, 126W, 25, 1009, DB, 0, , 0, 0, 0, 0,
AL, 98, 2011081806, , BEST, 0, 121N, 153W, 25, 1007, DB, 0, , 0, 0, 0, 0,
AL, 98, 2011081812, , BEST, 0, 123N, 164W, 25, 1007, DB, 0, , 0, 0, 0, 0,
AL, 98, 2011081818, , BEST, 0, 126N, 176W, 25, 1006, DB, 34, NEQ, 0, 0, 0, 0, 1008, 300, 60, 0, 0, L, 0, , 0, 0, INVEST, S,




invest_al982011.invest 1 KB 8/18/2011 8:57:00 PM
Member Since: May 21, 2006 Posts: 5091 Comments: 115437
Birmingham Discussion:

WILL BE INTERESTING TO SEE WHAT ACTUALLY BECOMES OF THAT TROPICAL
WAVE MIDWAY BETWEEN AFRICA AND THE AMERICAS...GIVEN THE
INTERESTING SOLUTIONS OF THE GFS AND ECMWF.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting stormhank:
Going to get busier in the tropics next few weeks it seems....Link
There still may be some storms in the Gulf of Mexico this year? I just hope it does not get too bad for anyone but 2011 seems to be a year of Extreme Weather so I think the tropics could be pretty tough also before it is over.
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1075. Dennis8
93 L Looking better by the frame on the IR satellite..banding, convection..headed west toward a landfall in Belize Friday.
Member Since: August 15, 2008 Posts: 0 Comments: 446
1074. barbamz
Another video of the violent and deadly storm that hit a big pop festival in Belgium today, but a quite cheerful sight:
http://www.youtube.com/watch?v=t-lgzwggWfk
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1073. WxLogic
18Z NAM 84HR:



500MB:

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Question: Will the NHC give 93L TS status if it forms an eye without any recon data ;).
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Quoting Dennis8:


Girl...I bet that A/C NEVER shuts OFF
LOL! Hubby is A/C tech. We keep ours 80-83 during the day and then cooler at night. Now if the rest of the residents in our complex would do the same thing (hubby is lead maintenance)he would not have to constantly be up on roofs all day.
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Lol...The NWS offices all across the South are jumping on the potential hurricane for next week...

Shreveport, LA Forecast Discussion:

THE BLOCKING RIDGE LOOKS TO REMAIN IN CONTROL THROUGH AT LEAST
MIDWEEK...BEFORE TROUGHING ACROSS THE MID-MS/TN VALLIES WILL
PROVIDE ADDITIONAL WEAKNESSES WHICH MAY YIELD ISOLATED CONVECTION
MAINLY OVER SW AR/N LA. WILL MAINTAIN PERSISTENCE WITH TRIPLE
DIGIT HEAT CONTINUING ACROSS MUCH OF THE REGION THROUGH THE
EXTENDED...BEFORE THE RIDGE IS NUDGED FAR ENOUGH W BY LATE NEXT
WEEK. THE LATTER PORTIONS OF THE EXTENDED /10+ DAYS OUT/ WILL BE
DEPENDENT ON A POTENTIAL TROPICAL SYSTEM THAT MAY WANDER WNW INTO
THE WRN CARRIBEAN/GULF OF MX.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting Levi32:


That is a visible product, with color enhancements for aiding in low-cloud detection.
Seems I need to find and re-read the "about this product" statement...

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1067. Dennis8
Quoting stormhank:
Going to get busier in the tropics next few weeks it seems....Link


Lots to watch...! thanks for posting!
Member Since: August 15, 2008 Posts: 0 Comments: 446
Quoting SouthDadeFish:
What do you mean? The RGB is made to see the low-level clouds in the milky colors....
Those "low-level clouds" are not necessarily indicate of surface winds. (And very rarely of any utility.)

Just what I've seen in comparing that product against SFMR wind directions, scatterometer, etc.
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1065. Grothar
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1064. Dennis8
REA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
349 PM CDT THU AUG 18 2011

.DISCUSSION...
YET ANOTHER 100 DEGREE DAY FOR HOUSTON TODAY...NUMBER 18...WITH
VERY WARM TEMPERATURES ACROSS SOUTHEAST TEXAS THIS AFTERNOON. THE
HIGH TEMPERATURE AT OUR OFFICE HAS REACHED 103 DEGREES THIS
AFTERNOON...THE HOTTEST TEMPERATURE WE HAVE SEEN YET THIS YEAR AND
THE THIRD HIGHEST TEMPERATURE RECORDED AT OUR CURRENT OFFICE. A
SLIGHT INCREASE IN MOISTURE TODAY HAS LED TO GREATER CLOUD
COVERAGE AND EVEN A FEW ISOLATED SHOWERS AND THUNDERSTORMS ACROSS
THE REGION. THIS ACTIVITY SHOULD COME TO AN END LATE THIS EVENING
WHEN AFTERNOON HEATING IS LOST.

THE FORECAST REMAINS RELATIVELY UNCHANGED THIS AFTERNOON. THE
RIDGE IS EXPECTED TO FLATTEN OUT OVER THE WEEKEND AND ALLOW FOR
SLIGHTLY COOLER TEMPERATURES ACROSS OUR REGION. RAIN CHANCES
CONTINUE TO LOOK BLEAK AS THE RIDGE BUILDS BACK IN THROUGH EARLY NEXT
WEEK.
Member Since: August 15, 2008 Posts: 0 Comments: 446
Going to get busier in the tropics next few weeks it seems....Link
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It's hard to ignore the models when they have had a significant hurricane making landfall somewhere on the USA for several days now.

You can't deny that. While a specific landfall point cannot be made for a long time, and things may change, the threat of a USA landfall at this time is medium/high.
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Quoting oakland:


I'm sorry! That's brutal!
You are almost as hot as Central Texas, been 105 to 106 here, Dallas area 107 to 109.
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1060. Dennis8
Quoting AegirsGal:
We just bumped up to 106, but humidity is 15%.


Girl...I bet that A/C NEVER shuts OFF
Member Since: August 15, 2008 Posts: 0 Comments: 446
Quoting atmoaggie:
? An IR satellite product cannot show you surface winds.

Mid-level winds? Yeah, sure.
What do you mean? The RGB is made to see the low-level clouds in the milky colors....
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Quoting Dennis8:


39% humidity....feels like 109-110
We just bumped up to 106, but humidity is 15%.
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1057. Dennis8
Quoting AegirsGal:
Uh, Happy Birthday? seems lacking somehow...

WELL..I am a meteorologist by degree so extreme wx is always a nice bday gift! :>) Thank you. I had a nice lunch at The Palm and it was air conditioned. My family was originally from Dallas.
Member Since: August 15, 2008 Posts: 0 Comments: 446
Rapid Scan is on for the NASA satellite:

Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting Levi32:


It's weak northerly switching to weak southerly. Remembering that there can be an illusion due to a system's forward motion, making a circulation look closed relative to itself, if you look closer it seems that the winds are still a switch from north to south, nearly stationary directly south of the center, but not yet moving out of the west relative to the Earth's surface. It's very close to happening though. We may see a closing off within the next 6 hours.


I call 11 PM!
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Quoting Levi32:


It's weak northerly switching to weak southerly. Remembering that there can be an illusion due to a system's forward motion, making a circulation look closed relative to itself, if you look closer it seems that the winds are still a switch from north to south, nearly stationary directly south of the center, but not yet moving out of the west relative to the Earth's surface. It's very close to happening though. We may see a closing off within the next 6 hours.
I respect your analysis, but my eyes see weak west winds. I didn't see them six hours ago, but I see them now. Not like it makes a huge difference between now and six hours though.
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1053. Dennis8
Quoting AegirsGal:
105.8 Fort Worth. I would imagine there is a higher humidity there.


39% humidity....feels like 109-110
Member Since: August 15, 2008 Posts: 0 Comments: 446
Quoting Dennis8:


Same as yesterday! 19 days above 100 degrees. I turned 49 today and lived on the Texas coast my whole life..never seen this before and I have written daily obs down since I was a teenage boy! Less than 11 inches of rain and we average almost 50" a year. Ike brought 11" in one night to my house in 2008 to give you an idea of the drought!
Uh, Happy Birthday? seems lacking somehow...
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1051. Levi32
Quoting atmoaggie:
? An IR satellite product cannot show you surface winds.

Mid-level winds? Yeah, sure.


That is a visible product, with color enhancements for aiding in low-cloud detection.
Member Since: November 24, 2005 Posts: 635 Comments: 26698
1050. Dennis8
Quoting oakland:


I'm sorry! That's brutal!


Same as yesterday! 19 days above 100 degrees. I turned 49 today and lived on the Texas coast my whole life..never seen this before and I have written daily obs down since I was a teenage boy! Less than 11 inches of rain and we average almost 50" a year. Ike brought 11" in one night to my house in 2008 to give you an idea of the drought!
Member Since: August 15, 2008 Posts: 0 Comments: 446
Quoting nativhoustonian:


My farm pic shows rows of fruit trees. They have all survived due to drip irrigation. Still have to check for leaks, and had to switch from well water to county water last week (well going dry).
My mom is having the do to the same thing to try and keep her fruit trees. She is in Granbury, just off the dwindling lake.
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1048. Levi32
Quoting SouthDadeFish:


Levi you don't see west winds on this? I do.


It's weak northerly switching to weak southerly. Remembering that there can be an illusion due to a system's forward motion, making a circulation look closed relative to itself, if you look closer it seems that the winds are still a switch from north to south, nearly stationary directly south of the center, but not yet moving out of the west relative to the Earth's surface. It's very close to happening though. We may see a closing off within the next 6 hours.
Member Since: November 24, 2005 Posts: 635 Comments: 26698
Quoting AegirsGal:
This is especially tricky if you have water lines on the property. There have been several reports of waterlines rupturing because the dirt surrounding the pipes is so dry its not providing the needed stability, making a bad situation even worse.


My farm pic shows rows of fruit trees. They have all survived due to drip irrigation. Still have to check for leaks, and had to switch from well water to county water last week (well going dry).
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Quoting Dennis8:
JUST HIT 104 AT MY HOUSE IN Houston!
105.8 Fort Worth. I would imagine there is a higher humidity there.
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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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