Tropical wave bringing heavy rain to northern Lesser Antilles

By: Dr. Jeff Masters , 1:57 PM GMT on July 18, 2010

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A tropical wave near 18N, 60W is entering the northernmost Lesser Antilles Islands and is generating some disorganized heavy thunderstorm activity. This wave is under about 20 knots of wind shear, due to strong upper-level westerly winds. The strong upper-level winds are associated with the counter-clockwise flow of air around an upper-level cold-cored low pressure system a few hundred miles north of Puerto Rico. As the wave progresses west to west-northwest through Tuesday, thunderstorm activity will increase, due to interaction with the upper low. The rains from these thunderstorms will bring the threat of flooding to Puerto Rico on Monday, the Dominican Republic on Tuesday, and Haiti on Wednesday. The upper low will also bring high wind shear of 20 - 30 knots over the the wave on Monday and Tuesday. No development of the wave is likely until at least Thursday, when it will be over the eastern Bahamas and eastern Cuba. At that time, shear is expected to drop below 20 knots, and the wave has the potential to develop. However, none of the reliable computer models is calling for tropical cyclone development over the next seven days. I expect that this wave will eventually enter the Gulf of Mexico early next week. NHC is giving the wave a 10% chance of developing into a tropical depression by Tuesday.


Figure 1. Morning satellite image of tropical wave entering the Lesser Antilles Islands.

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I'll have a new post on Monday.

Jeff Masters

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2438. hydrus
7:59 PM GMT on July 19, 2010
.
Member Since: September 27, 2007 Posts: 1 Comments: 19558
2437. sailingallover
3:28 PM GMT on July 19, 2010
Quoting HurricaneGeek:
Hello,
I have seen people referring to a good looking tropical wave off Africa. I look at satellite images from the EATL, and I really don't see much. Am I missing something? Can someone explain?
Thanks.

The wave came off yesterday with impressive circulation and convection. The Dust from the SAL has stopped the convection of the northern section over the Cape Verdes where the circulation is. There is still convection to the south at about 8N 25W the. These two features bear watching. 97L the current invest was the same situation. It came all the way across the atlantic as a naked circulation and is now firing convection since it is out of the dust.

The convection to the south is interesting because it is interacting with a trough in the South Atlantic. There has been some shearing to the south as well as convergence from the south.
Member Since: September 1, 2009 Posts: 23 Comments: 1005
2435. BahaHurican
2:47 PM GMT on July 19, 2010
Quoting RitaEvac:
97L is in vicinity of where Rita started her trek westward and scared the BeJesus outta everybody
Looks like (at least for now) a similiar kind of tracking. Haven't looked at WV yet to see how things are progressing along the upside of 30N, though....

Quoting Hardcoreweather2010:
12Z Model runs from the NHC

Geez. I hate the model runs that bring the core of the storm up over New Providence from the South.... about the worst possible approach direction for us...

Quoting Jeff9641:


Shears not that bad and is expected to weaken come Wednesday. I do think Bonnie maybe in the making in the next few days. I did call this one last week when this was a naked swirl at 17N and 33W.
LOL... some of us have been looking at this since when it came off W Africa w/ a low analysed at 20N and vigorous shower activity at 10N... have to admit it was the first one that looked like it had a chance against all the conditions. OTOH, I'm not surprised the one in front of it is kicking up some water, since it was the one that cleared out a lot of the SAL and moisturized a lot of the CATL....

Quoting TampaSpin:
I really don't think both can exist together as they are really to close. One will have to win out. Best guess is usually the system to the farthest West which would be in the Caribbean as Shear from the outflow from the Caribbean will hurt 97L as the TUTT moves out if it does.
I've been thinking about this too. I've also been wondering if a serious strengthening between 75 adn 80 west might not result in a more northerly movement, thereby separating the two systems more.

Quoting CaribbeanIslandStorm:
Storms can form very suddenly, look at the image of hurricane Katrina, in just a few hundred miles it went from a tropical disturbance to a cat 1 hurricane when it struck Florida. invest 97 in worth keeping a close eye on,especially if you live the SE USA.
Yeah, we were talking about that aspect of Katrina's cyclogenesis yesterday or Saturday. Rita is another storm from that year that organized relatively quickly (though not as fast as Katrina IIRC) in a similar location.

Member Since: October 25, 2005 Posts: 19 Comments: 20734
2434. MiamiHurricanes09
2:44 PM GMT on July 19, 2010
NEW BLOG
Member Since: September 2, 2009 Posts: 130 Comments: 21032
2433. Twinkster
2:44 PM GMT on July 19, 2010
new blog
Member Since: June 7, 2007 Posts: 4 Comments: 937
2432. Hurricanes101
2:43 PM GMT on July 19, 2010
Quoting IKE:
SUCCEEDING DAY OUTLOOK: POSSIBLE LOW LEVEL
INVEST NEAR 21.0N 73.5W AT 21/1800Z. BEGIN


Looks like they canceled the one for Tuesday and have one set Wednesday in the SE Bahamas.


the one for tomorrow is not cancelled, or else it would have said so in that same text
Member Since: March 10, 2010 Posts: 1 Comments: 7233
2431. MiamiHurricanes09
2:43 PM GMT on July 19, 2010
Quoting ElConando:
Producing some strong storms.
The actual invest isn't producing the convection, it's a TUTT low that's doing all the work.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
2430. CybrTeddy
2:43 PM GMT on July 19, 2010
Quoting Drakoen:




So much for downward MJO.. wow.
Member Since: July 8, 2005 Posts: 259 Comments: 23013
2429. Hurricanes101
2:43 PM GMT on July 19, 2010
Quoting Crawls:


LOL I wasn't looking for a specific #. I was looking for opinions and possibly historical data.


based on current forecast tracks the chances of 97L affecting TX/MX is possible

but this is so far out, a lot can change; just keep an eye on it for now
Member Since: March 10, 2010 Posts: 1 Comments: 7233
2428. IKE
2:42 PM GMT on July 19, 2010
SUCCEEDING DAY OUTLOOK: POSSIBLE LOW LEVEL
INVEST NEAR 21.0N 73.5W AT 21/1800Z. BEGIN


Looks like they canceled the one for Tuesday and have one set Wednesday in the SE Bahamas.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
2427. nrtiwlnvragn
2:42 PM GMT on July 19, 2010
NEW BLOG
Member Since: September 23, 2005 Posts: 13 Comments: 10466
2426. Crawls
2:41 PM GMT on July 19, 2010
Quoting Hurricanes101:


23.47353236275745%

lol, come on do you really think any of us can answer that question?


LOL I wasn't looking for a specific #. I was looking for opinions and possibly historical data.
Member Since: August 17, 2007 Posts: 0 Comments: 272
2425. ElConando
2:41 PM GMT on July 19, 2010
Producing some strong storms.
Member Since: September 6, 2009 Posts: 2 Comments: 3709
2424. GeoffreyWPB
2:40 PM GMT on July 19, 2010
000
NOUS42 KNHC 191300
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
0900 AM EDT MON 19 JULY 2010
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 20/1100Z TO 21/1100Z JULY 2010
TCPOD NUMBER.....10-049

I. ATLANTIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. SUCCEEDING DAY OUTLOOK: POSSIBLE LOW LEVEL
INVEST NEAR 21.0N 73.5W AT 21/1800Z. BEGIN
6-HRLY FIXES AT 22/0600Z IF SYSTEM DEVELOPS.
Member Since: September 10, 2007 Posts: 0 Comments: 10578
2422. all4hurricanes
2:40 PM GMT on July 19, 2010
Quoting Crawls:
What are the odds of another hit in the TX/MX area?

by the looks of the models pretty good
Member Since: March 29, 2008 Posts: 0 Comments: 2338
2421. CybrTeddy
2:40 PM GMT on July 19, 2010
Special Update Watching 97L and the Caribbean 7/19/10
Member Since: July 8, 2005 Posts: 259 Comments: 23013
2420. MiamiHurricanes09
2:40 PM GMT on July 19, 2010
Member Since: September 2, 2009 Posts: 130 Comments: 21032
2419. Hurricanes101
2:39 PM GMT on July 19, 2010
Quoting Crawls:
What are the odds of another hit in the TX/MX area?


23.47353236275745%

lol, come on do you really think any of us can answer that question?
Member Since: March 10, 2010 Posts: 1 Comments: 7233
2418. Crawls
2:38 PM GMT on July 19, 2010
What are the odds of another hit in the TX/MX area?
Member Since: August 17, 2007 Posts: 0 Comments: 272
2416. ElConando
2:37 PM GMT on July 19, 2010
Quoting CybrTeddy:
SHEAR (KT) 20 19 27 28 25 24 22 21 16 3 5 7 8

NHC thinking that 97L will run into favorable shear in 80 hours or so.



At any rate development should be slow until then.
Member Since: September 6, 2009 Posts: 2 Comments: 3709
2415. claire4385
2:37 PM GMT on July 19, 2010
Ty storm, that helped quite a bit :-)
Member Since: November 8, 2009 Posts: 0 Comments: 98
2414. HurricaneGeek
2:37 PM GMT on July 19, 2010
Quoting weathermanwannabe:


I made that point this morning; was surprised to see some apparent rotation in the convection even though it is way below the normal 10N where coreolis kicks in....Hard to tell at the moment whether this feature will break away from the ITCZ and rise in latitude over the next several days, or, fizzle out as Beel has noted as it moves west.


Ok thanks, that's interesting.
Member Since: May 10, 2007 Posts: 110 Comments: 7039
2413. IKE
2:37 PM GMT on July 19, 2010
Matter of fact that SHIPS track is right for the Keys in 4 days with 5 knots of shear.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
2411. all4hurricanes
2:36 PM GMT on July 19, 2010
The models all seem to take the same general path if this forms before Cuba Texas will be in trouble
Member Since: March 29, 2008 Posts: 0 Comments: 2338
2409. weathermanwannabe
2:34 PM GMT on July 19, 2010
Quoting HurricaneGeek:


Ok. I see something at 5N, 30W but isn't 5N too far south for getting spin? But I do see a nice circle of convection free clouds stretching from 20N-10N-20W-30W.


I made that point this morning; was surprised to see some apparent rotation in the convection even though it is way below the normal 10N where coreolis kicks in....Hard to tell at the moment whether this feature will break away from the ITCZ and rise in latitude over the next several days, or, fizzle out as Beell has noted as it moves west.
Member Since: August 8, 2006 Posts: 0 Comments: 8278
2408. BahaHurican
2:33 PM GMT on July 19, 2010
Quoting SeniorPoppy:
97L is getting sheared and probably won't get its act together until it reaches the Gulf. It might not even reach the Florida straits as a potent tropical wave. How this feature is an invest right now is beyond me. The feature in the Caribbean looks more promising.
Appearances are deceiving... lol. Both of these systems have some potential. Both are going to impact large portions of the basin right away, perhaps with greater force later. As long as 97L lasts through tomorrow, its appearance today is likely to be irrelevant in the long run....

Quoting Patrap:
000
NOUS42 KNHC 181515
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1115 AM EDT SUN 18 JULY 2010
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 19/1100Z TO 20/1100Z JULY 2010
TCPOD NUMBER.....10-048

I. ATLANTIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.

2. SUCCEEDING DAY OUTLOOK: POSSIBLE LOW LEVEL
INVEST NEAR 21.0N 71.5W AT 20/1800Z. BEGIN
6-HRLY FIXES AT 21/0600Z IF SYSTEM DEVELOPS.
Wow. That's SE Bahamas.... very near Ike's track in 08.

Quoting TampaSpin:
I am clicking a minus and Admin button everytime someone mentions [name deleted]....lay off!
+1 Me too.

Member Since: October 25, 2005 Posts: 19 Comments: 20734
2407. MiamiHurricanes09
2:33 PM GMT on July 19, 2010
Warm waters await...

Member Since: September 2, 2009 Posts: 130 Comments: 21032
2406. indianrivguy
2:33 PM GMT on July 19, 2010
I was going through the hurricane archives last weekend and was surprised to see something I had totally missed before.. a hurricane forming over land in Canada... it amazed me.. I'm wondering what the record is for northernmost formation. Here is the track from Doc Masters archive;


Check out the track of this killer after it crosses the Great Lakes...
Member Since: September 23, 2006 Posts: 1 Comments: 2428
2404. aquak9
2:31 PM GMT on July 19, 2010
Quoting msgambler:
Are you trying to say the invest could gain more curvature than you....LOL


most pine tree trunks have more curvature than me, hahahaha

97L to the gulf in some sorta sheared ripped-up form. More problems for development around western cuba. After that, all bets are off on development...and ending up somewhere between the LA, TX/MX border.

ya'll have a good one.
Member Since: August 13, 2005 Posts: 163 Comments: 25507
2403. msgambler
2:31 PM GMT on July 19, 2010
Good evening Aussie.
Member Since: February 27, 2010 Posts: 0 Comments: 1125
2401. MiamiHurricanes09
2:30 PM GMT on July 19, 2010
Quoting nrtiwlnvragn:


No, this

LAT (DEG N) 19.2 19.5 19.7 20.0 20.2 20.8 21.4 22.1 22.8 23.6 24.5 25.5 26.7
LONG(DEG W) 65.0 66.0 67.0 68.1 69.1 71.2 73.3 75.4 77.3 79.1 80.8 82.6 84.3


FORECAST TRACK FROM OFCI
That's an interesting track.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
2400. AussieStorm
2:30 PM GMT on July 19, 2010
Quoting msgambler:
Morning water puppy
granny you have mail.

Good Morning all.
Member Since: September 30, 2007 Posts: 9 Comments: 15749
2398. HurricaneGeek
2:29 PM GMT on July 19, 2010
Quoting weathermanwannabe:


Just keeping an eye on that convective area around 5N-10W.


Ok. I see something at 5N, 30W but isn't 5N too far south for getting spin? But I do see a nice circle of convection free clouds stretching from 20N-10N-20W-30W.
Member Since: May 10, 2007 Posts: 110 Comments: 7039
2397. msgambler
2:29 PM GMT on July 19, 2010
Quoting aquak9:


sheri, I ain't payin' nuthin no attention, till wed afternoon. honestly kinda surprised they tasked recon.

more interested in a week, ten days far east.
Are you trying to say the invest could gain more curvature than you....LOL
Member Since: February 27, 2010 Posts: 0 Comments: 1125
2396. weathermanwannabe
2:29 PM GMT on July 19, 2010
Quoting btwntx08:

agreed


TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
637 AM EDT MON JUL 19 2010

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI. THE MODELS SHOW AN UPPER LEVEL RIDGE SLOWLY BUILDING ACROSS THE NORTHEAST
CARIBBEAN ISLANDS...IN THIS PROCESS GRADUALLY DISPLACING A TUTT LOW THAT MEANDERS TO THE NORTH. THE TROUGH IS FAIRLY DEEP...REFLECTING AT MID LEVELS OF THE ATMOSPHERE. THIS
FEATURE...IN INTERACTION WITH THE ITCZ AND PERTURBATIONS IN THE LOW LEVEL EASTERLIES...FAVORS/SUSTAINS A WET/MOIST PATTERN ACROSS THE NORTHEAST CARIBBEAN ISLANDS...WITH PWS OF 50-70MM DOMINATING
THE AREA. ALTHOUGH THE PATTERN ALOFT IS TO CHANGE...THE MOISTURE IS TO PERSIST UNTIL THURSDAY/EARLY FRIDAY AS ANOTHER TUTT...IN THE
FORM OF AN INVERTED TROUGH...IS TO ENTER THE EASTERN CARIBBEAN LATER THIS WEEK. CONVERGENCE TO THE WEST OF THE INBOUND TUTT IS TO PROVIDE MUCH NEEDED RELIEF FROM THE PERSISTENT HEAVY RAINS. MODELS SEEM TO COINCIDE THAT MOST ACTIVE/INTENSE CONVECTION IS TO CONTINUE BUILDING THROUGH TUESDAY...WITH SLIGHTLY LESS
INTENSE/ACTIVE PATTERN DURING THE TRANSITION PERIOD ON WEDNESDAY TO THURSDAY.

THE CLIMATOLOGICAL MODELS SHOW FAVORABLE MJO CONDITIONS FOR THE REST OF THE WEEK. THE MORE RELIABLE CLIMATE FORECAST SYSTEM INDICATES THAT BY THE BEGINNING OF NEXT WEEK WE ARE TO TRANSITION TO A WEAK CONVERGENT/NEUTRAL PATTERN...WHICH IS TO LAST FOR TEN DAYS...AND TRANSITIONING AGAIN TO A DIVERGENT PATTERN ALOFT BY THE FIRST WEEK IN AUGUST.


Member Since: August 8, 2006 Posts: 0 Comments: 8278
2394. nrtiwlnvragn
2:28 PM GMT on July 19, 2010
Quoting CybrTeddy:


Is this what your talking about?
TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120
V (KT) NO LAND 25 28 30 33 36 39 42 44 45 49 56 63 66
V (KT) LAND 25 28 30 33 36 39 42 44 45 49 56 63 66
V (KT) LGE mod 25 27 28 29 29 29 29 30 32 35 40 49 59


No, this

LAT (DEG N) 19.2 19.5 19.7 20.0 20.2 20.8 21.4 22.1 22.8 23.6 24.5 25.5 26.7
LONG(DEG W) 65.0 66.0 67.0 68.1 69.1 71.2 73.3 75.4 77.3 79.1 80.8 82.6 84.3


FORECAST TRACK FROM OFCI
Member Since: September 23, 2005 Posts: 13 Comments: 10466
2393. aquak9
2:28 PM GMT on July 19, 2010
Quoting beell:


Possibly some dry air. But I have been a bit of a downcaster of late-so a grain of salt!


SALT-CASTER!!!! :)
Member Since: August 13, 2005 Posts: 163 Comments: 25507
2392. aquak9
2:27 PM GMT on July 19, 2010
Quoting catastropheadjuster:


You to funny Aquak9, morning, don't want to be flagged or banned.
so what do ya think about the wave out there?
sheri


sheri, I ain't payin' nuthin no attention, till wed afternoon. honestly kinda surprised they tasked recon.

more interested in a week, ten days far east.
Member Since: August 13, 2005 Posts: 163 Comments: 25507
2391. IKE
2:27 PM GMT on July 19, 2010
Quoting IKE:
That model has shifted north more on the end of the run....

LAT (DEG N) 24.5 25.5 26.7
LONG(DEG W) 80.8 82.6 84.3



That's south of Apalachicola by about 200 miles.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
2390. GeoffreyWPB
2:27 PM GMT on July 19, 2010
Just updated:

Member Since: September 10, 2007 Posts: 0 Comments: 10578
2389. beell
2:26 PM GMT on July 19, 2010
Quoting weathermanwannabe:


Good insight there........Guess we'll have to wait a few days and see what happens with it...There has been talk about how the tropics seemed a few weeks ahead of schedule (in terms of general set-up and the June/July doldrums notwithstanding).....Now that sheer levels have dropped so low between the Antilles and Africa south of 20N, I see no reason (other than possible SAL issues) why we could could not see a late July/early August long-track CV storm as opposed to the normal mid to late-August time frame.


Possibly some dry air. But I have been a bit of a downcaster of late-so a grain of salt!
Member Since: September 11, 2007 Posts: 137 Comments: 15339

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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.