Lesser Antilles Disturbance 97L Still Disorganized

By: Dr. Jeff Masters , 2:34 PM GMT on September 03, 2013

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A tropical wave over the Lesser Antilles Islands (Invest 97L) is moving west-northwest at 10 mph, and is bringing sporadic heavy rain showers to the islands. Top sustained winds observed in the islands as of 10 am AST Tuesday were mostly below 15 mph. Heavy thunderstorm activity has been low since Monday, and is spread out, as seen on satellite loops. The thunderstorms are poorly organized, and there is no sign of a well-organized surface circulation. Martinique radar shows little evidence of rotation to the echoes, and no low-level spiral bands forming. Upper level winds are favorable for development, with wind shear a low 5 - 10 knots, and an upper-level anticyclone overhead. An area of dry air from the Saharan Air Layer (SAL) surrounds 97L and is interfering with development, though the the 12Z Tuesday balloon sounding from Guadeloupe near the center of 97L showed moist air through the entire depth of the atmosphere.


Figure 1. Latest satellite image of Invest 97L.

Forecast for 97L
Wind shear is expected to be low through Friday, and ocean temperatures will be warm, 29°C. The disturbance has not been able to generate enough thunderstorms to moisten the surrounding atmosphere much, and dry air may continue to slow down development over the next few days. The models take 97L to the west-northwest, bringing it near or over Puerto Rico or Hispaniola on Wednesday night. A track over the high mountains of Hispaniola would disrupt the circulation of 97L, forcing the storm to regroup on Thursday over the Southeast Bahamas and Turks and Caicos Islands. The best chance for development of 97L would appear to be on Friday, after the storm has finished its encounter with Hispaniola. This morning's 00Z run of the experimental GFDL ensemble--which produces 10 simulations with slightly varying initial conditions to create a plume of potential storm tracks--foresees that once 97L organizes into a tropical depression, it might take only two days for it to intensify into a hurricane to the north of Hispaniola. The wave will bring heavy rain showers to the Lesser Antilles islands on Tuesday and Wednesday, and this activity will likely spread to Puerto Rico, the Virgin Islands, the Dominican Republic, and Haiti on Wednesday and Thursday. These rains will be capable of causing life-threatening flash flooding and mudslides in mountainous regions of Puerto Rico and Hispaniola. Of our three reliable models for predicting genesis, the UKMET, GFS, and European models, only the UKMET model develops the disturbance, predicting it will become a tropical depression over the Central Bahamas on Saturday. There will be a strong trough of low pressure along the U.S. East Coast this weekend, which will be capable of turning 97L to the north before the storm can hit the U.S. In their 8 am EDT Tuesday Tropical Weather Outlook, NHC left the 5-day odds of formation of 97L at 50%, and 2-day odds at 20%. The Hurricane Hunters are on call to investigate 97L Wednesday afternoon. The flight scheduled for today will likely be cancelled. The Hurricane and Severe Storm Sentinel Mission, a 5-year field project utilizing two remotely crewed Global Hawk aircraft to overfly tropical storms and hurricanes, will have one of their aircraft investigate 97L today, and again on Wednesday. You can follow the progress of the aircraft using NASA's live-plane tracker map (Global Hawk AV6 is tail number NASA872, and Global Hawk AV1 is tail number NASA871.)

98L off the coast of Africa and a Yucatan Peninsula tropical wave
A tropical wave that emerged from the coast of Africa on Monday (Invest 98L) is expected to track northwest over the Cape Verde Islands. This course will take 98L into a region of ocean where historically, very few tropical cyclones have made the long journey across the Atlantic to affect North America. In their 8 am EDT Tuesday Tropical Weather Outlook, NHC put the 5-day odds of development at 20%.

A tropical wave over Mexico's Yucatan Peninsula has a respectable area of heavy thunderstorms associated with it that is bringing heavy rains. This activity will push over the extreme Southern Gulf of Mexico's Bay of Campeche on Wednesday. The wave will have two days over water to develop before moving ashore on the Mexican coast between Veracruz and Tampico on Friday. In their 8 am EDT Tuesday Tropical Weather Outlook, NHC put the 5-day odds of development at 30%, and 2-day odds at 20%.

Jeff Masters

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12z HWRF got a thing for Bermuda?

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LAT (DEG N) 15.0 15.5 15.9 16.4 16.8 17.7 18.8 19.9 21.2 22.5 N/A N/A N/A
LONG(DEG W) 62.1 63.0 63.8 64.6 65.4 67.1 68.6 70.1 71.3 72.2 N/A N/A N/A

FORECAST TRACK FROM OFCI

Dissipate after 84 hours?


Link
Member Since: September 23, 2005 Posts: 14 Comments: 11179
largo must be cuddled up in his hammock siesta right now. talking about a character that knows 97 very well.
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464. JRRP
Guys sorry i just show the buoy in that location
and looks like had problem to show it
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.
A little east of where most of us have been focusing.

Oops - cut and pasted the wrong one.
Member Since: June 25, 2011 Posts: 2 Comments: 3732
If 97L can convert all that girth into a Caribbean Hurricane downstream..






Member Since: July 3, 2005 Posts: 424 Comments: 128347
Quoting 415. weathermanwannabe:
Just to supplement the current NHC thinking on 97L; here is the early am discussion from the NCEP Caribbean Desk on conditions as to where 97L is headed:

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
656 AM EDT TUE SEP 03 2013

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI. RETROGRESSING TUTT LOW TO THE NORTH-NORTHEAST OF THE LEEWARD ISLANDS...AND AN EASTERLY WAVE...SUSTAIN MOISTURE CONVERGENCE ACROSS THE EASTERN CARIBBEAN ISLANDS. PUERTO RICO AND THE USVI ARE ON THE CONVERGENT SIDE OF THE UPPER LEVEL SYSTEM. THIS IS CAPPING CONVECTIVE DEVELOPMENT ACROSS THE FORECAST AREA...WITH TRADE WIND SHOWERS PESTERING THE USVI-EASTERN/NORTHERN PUERTO RICO.

UPPER TROUGH IS TO GENERALLY REMAIN TO THE NORTH OF THE FORECAST AREA AS A CELL OF THE SUBEQUATORIAL RIDGE ESTABLISHES A FOOTHOLD OVER THE EASTERN CARIBBEAN. THIS IS TO GENERALLY FAVOR AN UPPER DIVERGENT PATTERN ACROSS THE NORTHEAST CARIBBEAN ISLANDS THAT IS TO INTENSIFY THROUGH WEDNESDAY MORNING. PERTURBATION IN THE TRADES CROSSES THE VIRGIN ISLES INTO EASTERN PUERTO RICO DURING THE
MORNING HOURS ON WEDNESDAY...AND THROUGH THE DAY IT IS TO CONTINUE ACROSS PUERTO RICO TO THE MONA PASSAGE. ON ITS WAKE...A MOIST SOUTHEASTERLY FLOW IS TO ESTABLISH. THE GLOBAL MODELS AGREE ON DEEP ITCZ RELATED MOISTURE TO POOL ACROSS THE FORECAST AREA...WITH HIGH PWAT VALUES EXPECTED TO THEN PERSIST THROUGH THE REST OF THE WEEK INTO THE WEEKEND.





I just wish the NHC would quit SHOUTING so much! Dang! ;P
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120 hours-12z Euro
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Quoting 441. nrtiwlnvragn:
AL, 97, 2013090318, , BEST, 0, 150N, 621W, 30, 1007, LO


WHOAAA MEGA RI

Seriously... 97L is doing well this afternoon folks.
Member Since: Posts: Comments:
AL, 98, 2013090318, , BEST, 0, 107N, 172W, 20, 1009, DB
Member Since: Posts: Comments:
TXNT28 KNES 031804
TCSNTL

A. TROPICAL DISTURBANCE (97L)

B. 03/1745Z

C. 14.4N

D. 63.2W

E. FIVE/GOES-E

F. T1.0/1.0/D1.0/24HRS

G. IR/EIR/VIS

H. REMARKS...LOW LEVEL CIRCULATION IS BECOMING BETTER DEFINED ACCORDING
TO ANIMATED VISIBLE IMAGERY. IN ADDITION CONVECTION HAS INCREASED NEAR
THE CENTER OF CIRCULATION OVER THE LAST 6 HOURS...MEASURING SLIGHTLY MORE
THAN 2/10 FOR A DT OF 1.0. MET AND PT ARE ALSO 1.0. FT IS BASED ON DT.

I. ADDL POSITIONS

NIL


...TURK


Link
Member Since: September 23, 2005 Posts: 14 Comments: 11179

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Member Since: July 3, 2005 Posts: 424 Comments: 128347
EP, 99, 2013090318, , BEST, 0, 170N, 1041W, 25, 1008, DB
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Quoting 441. nrtiwlnvragn:
AL, 97, 2013090318, , BEST, 0, 150N, 621W, 30, 1007, LO


15N 62.1W right at the center of the S curvature where the north and south bands converge. Nice

dropped to 1007 too.
Member Since: August 28, 2008 Posts: 0 Comments: 367
It was the wpc filling in for the nhc
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451. weathermanwannabe
6:26 PM GMT on September 03, 2013
Per the 200mb CIMMS chart (below), there are no tutts or other upper level features at the moment in close proximity to 97L that would either retard or aid development. It's basically on it's own for the next two days, to further organize or not, if it can fight off the dry air and consolidate and generate some persistent convection before it reaches the next tutt cell due SE of Jamaica (unless it misses it to the North).

Link

Interesting to see if it can beat the clock over the next few days and consolidate that rather large circulation enough to reach TD status before significant interaction with Hispanola at around 72 hours.

Just my personal observation.
Member Since: August 8, 2006 Posts: 0 Comments: 9134
450. Tropicsweatherpr
6:26 PM GMT on September 03, 2013
Quoting 440. MississippiWx:


It's definitely below 15N.


If is at 15N or below at this point,it may avoid PR but not Hispanola.
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449. JRRP
6:26 PM GMT on September 03, 2013
Member Since: August 16, 2007 Posts: 0 Comments: 5839
448. HurricaneHunterJoe
6:25 PM GMT on September 03, 2013
Local Soo Cal report...... Monsoon/Southeasterly flow continues into Soo Cal. Yesterday, I had a Thunderstorm of about 20 minutes with Lightning and a bit of wind 25-30mph and .28 of rainfall. Also about 5 minutes of pea sized hail. temp dropped from 91 to 65 degrees and was GREAT!

Chance forecast for today also. Current weather at my location:

Weather Conditions for:
Sunshine Summit, CA (SSSSD)
Elev: 3244 ft; Latitude: 33.344; Longitude: -116.732

Current time: Tue, 03 Sep 11:24 am (PDT)
Most Recent Observation: Tue, 03 Sep 11:10 am PDT (PDT)
Time Temp. Dew Relative Wind Wind Quality
Point Humidity Direction Speed Control
(PDT) (f) (f) (%) (mph)
03 Sep 11:10 am PDT 90 52 27 SE 6G14
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447. ProgressivePulse
6:25 PM GMT on September 03, 2013
.
Member Since: August 19, 2005 Posts: 5 Comments: 5405
446. CaicosRetiredSailor
6:25 PM GMT on September 03, 2013
Worth watching:

http://www.indiegogo.com/projects/campaign-for-lo cal-power


Campaign for Local Power

This is a grassroots David and Goliath campaign to create a landmark model for how communities can take control of their energy future.

Boulder, Colorado, United States
Member Since: July 12, 2007 Posts: 0 Comments: 6037
445. will40
6:25 PM GMT on September 03, 2013
NHC is smart to not upgrade the % just yet on something headed to the graveyard
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444. IKE
6:24 PM GMT on September 03, 2013
San Juan long-range....


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443. hurricanes2018
6:24 PM GMT on September 03, 2013
good news that invest 97L will go out to sea its not going to hit the east coast at all.
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442. Patrap
6:23 PM GMT on September 03, 2013
Storm Relative 1 km Geostationary Visible Imagery

Member Since: July 3, 2005 Posts: 424 Comments: 128347
441. nrtiwlnvragn
6:23 PM GMT on September 03, 2013
AL, 97, 2013090318, , BEST, 0, 150N, 621W, 30, 1007, LO
Member Since: September 23, 2005 Posts: 14 Comments: 11179
440. MississippiWx
6:22 PM GMT on September 03, 2013
Quoting 434. JRRP:
wow
16.332 N 63.240 W



Edit: Nvm. Your picture wasn't showing up.
Member Since: July 15, 2006 Posts: 17 Comments: 10253
439. RascalNag
6:21 PM GMT on September 03, 2013
Convection now beginning to cover the center of the storm as opposed to earlier where it was mostly the north ans south areas that were bursting.

Looking better with each frame.
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438. Patrap
6:21 PM GMT on September 03, 2013
Member Since: July 3, 2005 Posts: 424 Comments: 128347
437. WoodyFL
6:20 PM GMT on September 03, 2013
Quoting 405. IKE:
WU bloggers after the 2pm TWO.....




are we that bad lol. i do this for fun but some get pretty serious here.
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436. Patrap
6:20 PM GMT on September 03, 2013
Published on May 15, 2013
NASA's Hurricane and Severe Storm Sentinel (HS3) mission uses NASA's Global Hawk Unmanned Aerial Vehicles (UAV) to study tropical storms and hurricanes. This nine-minute video describes the mission, reveals details about the Global Hawk aircraft, and offers a glimpse inside the command centers of both the ground-based pilots and the scientists who analyze satellite images to assist in flight navigation. The video concludes with information about getting students involved directly from the classroom through computer monitoring of the Global Hawk's flight patterns and participating in live chats with the ground-based pilots.

Educational resources about the HS3 mission can be found at the NASA Wavelength Digital Library nasawavelength.org/resource/nw-000-000-03-539/

For more information about HS3 and the NASA Airborne Science Program visit airbornescience.nasa.gov, and nasa.gov/hs3


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435. IKE
6:19 PM GMT on September 03, 2013

Quoting JRRP:
wow
16.332 N 63.240 W

Looks about right to me.
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434. JRRP
6:18 PM GMT on September 03, 2013
wow
16.332 N 63.240 W


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433. air360
6:18 PM GMT on September 03, 2013
you know what would be cool - a live video feed from the Global Hawk drone along with live data. I'm picture like a video screen showing what the pilot sees and then all the gauges below. That would be so awesome. We could "fly" with them.
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432. HurricaneHunterJoe
6:18 PM GMT on September 03, 2013
Quoting 423. clwstmchasr:


Totally agree. These systems continuously show promise then revert. It's already happened with 97L.


Like I said yesterday.....I am not looking at any models til a Closed LLC has been established and for a period of not less than 24 hours.
Member Since: September 18, 2010 Posts: 0 Comments: 5223
431. hurricanes2018
6:17 PM GMT on September 03, 2013
Quoting 426. ProgressivePulse:
S shape slowly coming together with 97L. A little skewed with the arc clouds pushing out in the NW quadrant however. Surely battling dry air. I see a couple LLV's rotating around a common center around 14.5N 63.1W or so, in my opinion.

good opinion.
I like it
Member Since: March 12, 2013 Posts: 18 Comments: 35539
430. IKE
6:16 PM GMT on September 03, 2013

Quoting clwstmchasr:


Oh yes.
And....going into the afternoon......

(1)Cloud tops are warming.
(2)DMIN.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
429. nrtiwlnvragn
6:15 PM GMT on September 03, 2013
Quoting 419. daddyjames:


Are you sure? NHC has been having issues lately.


It is a test that WPC can backup NHC. They do it once a month during hurricane season, normally in the first week of the month.
Member Since: September 23, 2005 Posts: 14 Comments: 11179
428. Abacosurf
6:15 PM GMT on September 03, 2013
Quoting 413. Drakoen:


So it's up for debate then...till the next TWO ? ;)
Of course!! Isn't everything!! LMAO
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427. RGVtropicalWx13
6:14 PM GMT on September 03, 2013
I disagree on the Yucatan percentage for 5 days. Should've been the same imo
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426. ProgressivePulse
6:14 PM GMT on September 03, 2013
S shape slowly coming together with 97L. A little skewed with the arc clouds pushing out in the NW quadrant however. Surely battling dry air. I see a couple LLV's rotating around a common center around 14.5N 63.1W or so, in my opinion.

Member Since: August 19, 2005 Posts: 5 Comments: 5405
425. Drakoen
6:14 PM GMT on September 03, 2013
Quoting 412. WoodyFL:


hey were you the guy in met school a few years ago?

if you are, do you know why the models are mving so much to the north but yet we don't see what theyre thiniking is? I would think more wnw


If the answer to this is no do I still need to respond lol?
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424. MississippiWx
6:14 PM GMT on September 03, 2013
Quoting 406. KEEPEROFTHEGATE:
THIS IS A TEST


OKAY.
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422. Patrap
6:14 PM GMT on September 03, 2013
Member Since: July 3, 2005 Posts: 424 Comments: 128347
421. Patrap
6:13 PM GMT on September 03, 2013

NASA-871 Global Hawk still orbiting around AL97
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420. HurricaneHunterJoe
6:12 PM GMT on September 03, 2013
Anyone been assigned to count how many times the 2 gets posted?....LOLOLOL
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419. daddyjames
6:12 PM GMT on September 03, 2013
Quoting 406. KEEPEROFTHEGATE:
THIS IS A TEST


Are you sure? NHC has been having issues lately.
Member Since: June 25, 2011 Posts: 2 Comments: 3732
417. MississippiWx
6:12 PM GMT on September 03, 2013
Quoting 401. MiamiHurricanes09:
WU evidently heartbroken by Sullivan's percentages. lol


Percentages are good. Even though it is getting better organized this afternoon, it's heading into a climatologically unfavorable area for TC development. Still has a little more time today into early tomorrow at its current speed to establish a well organized low level structure. Also, track is a bit uncertain and, as always, the big islands throw a curveball into development chances.
Member Since: July 15, 2006 Posts: 17 Comments: 10253

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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.