Western Caribbean disturbance a threat to develop

By: Dr. Jeff Masters , 2:16 PM GMT on October 08, 2007

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Heavy thunderstorm activity continues to flare up in association with a broad area of low pressure over the Western Caribbean (94L). This morning's QuikSCAT pass showed a 300 mile-long line of converging surface winds north of the Honduras coast (Figure 1), but not a closed circulation. Top winds were about 25 mph. Satellite loops show fewer heavy thunderstorms than yesterday, but it appears that this activity is starting to get organized. Some low-level banding of the thunderstorm activity is occurring over the Cayman Islands, to the northeast side of the center of low pressure. Surface pressures remain very low over the entire Western Caribbean, but have not fallen since Saturday. Wind shear is about 10 knots, and is expected to remain 10 knots or below through Wednesday. The low surface pressures, light wind shear, and warm ocean waters are all very favorable for formation of a tropical depression. The Hurricane Hunter flights scheduled for this afternoon and tonight were canceled, and have been rescheduled for Tuesday. I expect a tropical depression will form in the next 1-3 days, most likely on Tuesday.

Steering currents are weak in the Western Caribbean, and most of the computer models forecast that 94L will wander erratically for a week or longer in the region. A slow motion to the west or northwest is predicted for the next three days, which may bring the storm over the Yucatan Peninsula late this week. There is a strong trough of low pressure forecast to swing across the U.S. this week, which could pull 94L northwards across Western Cuba, the Florida Keys, or Southwest Florida, as forecast by the HWRF model. However, 94L would have to form quickly and grow large to "feel" the influence of this trough, and I estimate there is only a 30% chance that the trough will be able to pull 94L northwards over Florida.

Residents of the Cayman Islands, Cuba, Mexico's Yucatan Peninsula, Belize, northern Honduras, and Jamaica can expect occasional heavy rain squalls over the next 1-3 days from this storm. This activity could spread into the Florida Keys by Wednesday.


Figure 1. High-resolution (12.5 km) QuikSCAT pass from 7:34 am EDT Monday October 8, 2007. A 300 mile-long line of converging winds is apparent in association with disturbance 94L. Image credit: NOAA/NESDIS/ORA.

Elsewhere in the tropics
A tropical disturbance a few hundred miles north of Puerto Rico is generating a large area of thunderstorms. QuikSCAT data from this morning shows an elongated circulation near 25N 66W, and top winds of 25 mph. The region is under 20 knots of wind shear, and wind shear is expected to remain 20-30 knots over the region over the next three days. The high shear should discourage any significant development.

I'll have an update Tuesday morning.

Jeff Masters

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453. CaneAddict
12:25 AM GMT on October 09, 2007
Thanks Charloote.
Member Since: October 5, 2007 Posts: 3 Comments: 2151
452. charlottewx
12:20 AM GMT on October 09, 2007
CaneAddict that was nice...When I was your age I dreamed of getting a Meteorology degree..If that's what you like, go for it...There's a great feeling doing a job you love....I was fortunate to work in the National Weather Service for 14 years as a Met Tech but never got a degree in Meteorology. I wished I did because it kept me from progressing. However, I did enjoy my time working on radar, upper air and flight briefing....Unfortunately the national Weather Service stramlined itself and there was very little future for met Techs. I have a college degree but not in Meteorology which I earned later...
451. CaneAddict
12:09 AM GMT on October 09, 2007
What do you guys think coming from a 15 year old??

Currently there is one main area with potential to develop in the Atlantic basin. This area is labeled Invest 94L. Based on satellite presentation, Throughout the day today this system has become better organized. Deep/Intense convection has begun to consolidate around the center/low of 94L and on satellite it is also evident that some banding features are present, mainly to the north of the low pressure area. Shear over this area is no problem at all, the level of shear immediatly over the system is about 5 knots. Which is a very favorable level for tropical development. Shear is expected to remain below 10 knots through Wednesday at the least. Near by buoy readings indicate that pressure continues to decrease in the area 94L is in and the lowest pressure reading at the current time is 1004 mb. This decrease determines that this system is organizing and is on its way to becoming a depression and i expect a depression to form in this area by tommorow evening at the latest. After that it is highly uncertain as to where this system will go or how strong it will get. Several models hint at this system wandering erractically for up to 6 days in the same general area the reason this scenario could possibly materilize is due to a weak steering flow/weak steering currents. Other models hint at it running straight into the Yucatan Pennisula and dissipating. In the long term the models have no clue as to what this system will do, In other words the models are all over the place and there is really no good agreement as to where this system will go. Some models hint at this system getting caught or pulled north into the west coast of Florida by a trough expected to swing down later this week, While some models just totally dissipate this system. I suggest all residents from the Gulf coast to the Yucatan and caribbean islands to monitor this area closely in the coming days. Elsewhere development is not anticipated for at least the next 48 hours.

I will have an update no later then 3 PM tomorrow.(Tuesday).
Member Since: October 5, 2007 Posts: 3 Comments: 2151
449. CaneAddict
12:03 AM GMT on October 09, 2007
I dont know...Thats a good question...Why dont you go to my website and go to "Tropical Chat" and we will talk live on there untill the blog heats up. Plus i want your opinion on my blog update considering im a 15 year old high school student.
Member Since: October 5, 2007 Posts: 3 Comments: 2151
448. charlottewx
11:55 PM GMT on October 08, 2007
CaneAddict..Where did everyone go? It's mysteriously quiet....Did everyone give up?
447. CaneAddict
11:53 PM GMT on October 08, 2007
Hello StormW! I notice the blog is quiet tonight....Well for those of you on here that want something interesting go to my website (Tropical Weather website), Where i have updated my blog and added a live tropical Chat there!!! I have a few moderators that will keep the trolls and people that act inappropiatly out of the chat!
Member Since: October 5, 2007 Posts: 3 Comments: 2151
446. charlottewx
11:51 PM GMT on October 08, 2007
Stormw...what is your latest take of 94L...The TW Outlook sounded positive for development and better organization for toda. Are you buying that?
444. charlottewx
11:10 PM GMT on October 08, 2007
Looking at the satellite imagery for 94L I can see the circulation ENE of Belize but it is just one soupy mess of clouds in the NW Carib.
443. CaneAddict
10:10 PM GMT on October 08, 2007
Good evening all, I see that 94L is starting to organize nicely as convection is starting to consolidate around the center, And some banding is evident on satellite to the north of the center. Shear immediatly over the center/low is current 5 knots which should not be a problem for 94L as thats a very favorable level. Near by buoy readings indicate a that the lowest pressure currently recorded is 1004 mb.....I expect a depression to form from this area tomorrow.
Member Since: October 5, 2007 Posts: 3 Comments: 2151
442. Ivansvrivr
9:45 PM GMT on October 08, 2007
What would a strong La Nina mean for S. FLA winter?

I have experienced 2 La nina winters in Fl. Both had a late season system coming out of the W.Carrib. then warm, dry on average. Jet stream stayed way north for most of winter. Late season Killing freeze/ frost caused by Jet stream damming cold polar air eventually breaking through. ('85 citrus killer). No rain to speak of in spring(1999 fire season) then average summer rainy season, Eastern seaboard hurricane Gloria in 85, Floyd in 1999. Other La Ninas were weaker,less dramatic.
With La Nina, whatever you get is usually amplified. Drought, flood heat, cold. There are other players in the atmospheric picture besides La Nina so nothing is set in stone, but so far every cold front this year has been much weaker than expected. That is the usual la nina pattern.
441. charlottewx
9:44 PM GMT on October 08, 2007
CosmicEvents..that was good..."I did stay at a Holiday Inn Express last night"!
440. charlottewx
9:43 PM GMT on October 08, 2007
The Tropical Weather Outlook is on the positive for development.....check it out....
439. Needice
9:07 PM GMT on October 08, 2007
I was asking earlier if anyone knew a link for the jet stream images. Does the la Nina event keep the jet stream further north?
438. weatherboyfsu
8:59 PM GMT on October 08, 2007
Very bright for 16!!!
Member Since: July 17, 2005 Posts: 0 Comments: 1025
437. WPBWeatherBoy
8:58 PM GMT on October 08, 2007
lol newxguy i dont think the cold would matter at that temperature u wouldnt be able to feel anything
Member Since: August 27, 2007 Posts: 4 Comments: 104
436. weatherboyfsu
8:58 PM GMT on October 08, 2007
I wish i was married...........lol
Member Since: July 17, 2005 Posts: 0 Comments: 1025
435. weatherboyfsu
8:58 PM GMT on October 08, 2007
You must be talking about the other weatherboy...lol
Member Since: July 17, 2005 Posts: 0 Comments: 1025
434. WPBWeatherBoy
8:57 PM GMT on October 08, 2007
lol no im 16
Member Since: August 27, 2007 Posts: 4 Comments: 104
433. TropicalStalker
8:55 PM GMT on October 08, 2007
looks like you are married weatherboy...LOL
432. NEwxguy
8:55 PM GMT on October 08, 2007
try getting locked out of your house in -20 deg wind chill.Can you say extra set of keys??
Member Since: September 6, 2007 Posts: 863 Comments: 15114
431. beell
8:54 PM GMT on October 08, 2007
thanks mlc-likewise Few more of us out there to.
Member Since: September 11, 2007 Posts: 137 Comments: 15353
430. IKE
8:54 PM GMT on October 08, 2007
NEW BLOG!
Member Since: June 9, 2005 Posts: 23 Comments: 37858
429. WPBWeatherBoy
8:53 PM GMT on October 08, 2007
The cold is great unless u get locked out of ur house in the middle of the night and its about 40 degrees lol
Member Since: August 27, 2007 Posts: 4 Comments: 104
428. moonlightcowboy
8:52 PM GMT on October 08, 2007
beell, I like your assessment and thinking!
Member Since: July 9, 2006 Posts: 184 Comments: 29594
427. TropicalStalker
8:51 PM GMT on October 08, 2007
It's really funny, because if it rained as much as it has thus far in fla, back in Maryland, we would still be under water, yet here in Fla, we are at -7 inches (I think).
426. moonlightcowboy
8:50 PM GMT on October 08, 2007
We may have La Nina; but old-weather wise tales have it, that if there is an abundance of acorns, it usually means that there'll be a cold winter. We've had TONS this year. More than ever since before Katrina. Of course, Katrina probably blew most of them away that year!!!
Member Since: July 9, 2006 Posts: 184 Comments: 29594
425. CosmicEvents
8:50 PM GMT on October 08, 2007
First....I believe that I finally see a LLC. Just needs to close off on the south side. This could allow 94L to get somewhat stronger quicker than the models are allowing for. This in turn could cause the models to shift from what we see now. One thing that we haven't sen this year that we normally do see is a drastic model shift. Just my gut feeling. I'm not a Met, but I did stay at a Holiday Inn Express last night.
Member Since: August 3, 2005 Posts: 10 Comments: 5462
424. beell
8:49 PM GMT on October 08, 2007
Modified longitude in bold
Maybe one factor inhibiting development is the lack of a good exhaust system in the upper levels. Check the upper cloud on vis right over a suspect area (17N 86.5). Looks calm up there. If you're pro development, a bit of shear induced upper outflow might help. Lack of inflow does not appear to be a big problem. A more robust outflow would overcome capping/inversion stuff. We really should be seeing some good solid-not wispy outflow by now. cimss seems to show a bit of a "pink arrow antic kink", but maybe not as good as analyzed -as always imho.
Member Since: September 11, 2007 Posts: 137 Comments: 15353
423. IKE
8:49 PM GMT on October 08, 2007
From everything I've seen, it looks like Florida is gonna miss out on most or all of the rain from 94L...the state could use it.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
422. FLWeatherFreak91
8:48 PM GMT on October 08, 2007
419. TheCaneWhisperer 4:45 PM EDT on October 08, 2007 Hide this comment.
403. WPBWeatherBoy 4:31 PM EDT on October 08, 2007 Hide this comment.
would a strong la niña make south florida colder than average or higher than average?

I'm trying to find a link or something, but I believe it makes it WARMER than average. Not sure though

I will also have to dig up the article but, a La Nina usually means a cooler than normal winter for South Florida. Low Pressure systems typically ride higher up in the CONUS due to high pressure on the east coast during a La Nina, allowing cooler Arctic air to penetrate further south. Give me some time but, I will find that article.


OOoh. I'm glad I was wrong because I like the cold. YES! I hope you're right about it being colder
Member Since: December 1, 2006 Posts: 2 Comments: 3616
421. moonlightcowboy
8:47 PM GMT on October 08, 2007
407. jphurricane2006 8:35 PM GMT on October 08, 2007 Hide this comment.
afternoon all

Im in for a quick second

ULLs dont always inhibit development, just depends on where it is in relation


...thanks, for adding that JP. I know I've read that somewhere!
Member Since: July 9, 2006 Posts: 184 Comments: 29594
420. IKE
8:46 PM GMT on October 08, 2007
StSimonsIslandGAGuy 3:44 PM CDT on October 08, 2007
I am here from time to time fsu--although I post more in weatherguy03's blog. The new format reminds me of a cheesy online dating site, lol.


LOL. You do have a point.

MEMO to WU: I like your new sight...not so sure about avatars on a weather blog....MLB baseball forums have em too though...so whatever.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
419. TheCaneWhisperer
8:45 PM GMT on October 08, 2007
403. WPBWeatherBoy 4:31 PM EDT on October 08, 2007 Hide this comment.
would a strong la niña make south florida colder than average or higher than average?

I'm trying to find a link or something, but I believe it makes it WARMER than average. Not sure though


I will also have to dig up the article but, a La Nina usually means a cooler than normal winter for South Florida. Low Pressure systems typically ride higher up in the CONUS due to high pressure on the east coast during a La Nina, allowing cooler Arctic air to penetrate further south. Give me some time but, I will find that article.
417. IKE
8:42 PM GMT on October 08, 2007
Panhandle of Florida.......no rain for at least a week...cooler this weekend....

"Friday through Monday
Mostly clear. Highs 81 to 84. Lows 53 to 58 inland...59 to 63 at the coast.".........


That'll cool the GOM water temps down...
Member Since: June 9, 2005 Posts: 23 Comments: 37858
416. TropicalStalker
8:42 PM GMT on October 08, 2007
I am with you charlotte, while we don't need 100+ mile an hour winds, we do need the moisture. I am hoping that we get something out of this one! We are about to enter into the dry season...dry!
415. WPBWeatherBoy
8:41 PM GMT on October 08, 2007
Well that ruins my year, la niña probably wont let the temperature dip as low as last year during winter in S.Florida
Member Since: August 27, 2007 Posts: 4 Comments: 104
414. weatherboyfsu
8:40 PM GMT on October 08, 2007
Whats up St Simons?? Havent seen you in a while...
Member Since: July 17, 2005 Posts: 0 Comments: 1025
413. charlottewx
8:40 PM GMT on October 08, 2007
Any other season I would be pleased to not see a storm but this year with the drought on the Florida West Coast up to the panhandle we really need the rain! Hopefully some of the low pressure can remain once the front passes by and it might pull up to the north. I've never seen so many invests fail so far....
412. weatherboyfsu
8:40 PM GMT on October 08, 2007
Lastest sat over 94L looking like NOEL is forming.......Thunderstorms are forming on the southern half of the circulation.........
Member Since: July 17, 2005 Posts: 0 Comments: 1025
410. NEwxguy
8:38 PM GMT on October 08, 2007
La Niña often features drier than normal conditions in the Southwest in late summer through the subsequent winter. Drier than normal conditions also typically occur in the Central Plains in the fall and in the Southeast in the winter. In contrast, the Pacific Northwest is more likely to be wetter than normal in the late fall and early winter with the presence of a well-established La Niña. Additionally, on average La Niña winters are warmer than normal in the Southeast and colder than normal in the Northwest.
Member Since: September 6, 2007 Posts: 863 Comments: 15114
406. FLWeatherFreak91
8:34 PM GMT on October 08, 2007
403. WPBWeatherBoy 4:31 PM EDT on October 08, 2007 Hide this comment.
would a strong la niña make south florida colder than average or higher than average?


I'm trying to find a link or something, but I believe it makes it WARMER than average. Not sure though
Member Since: December 1, 2006 Posts: 2 Comments: 3616
404. moonlightcowboy
8:32 PM GMT on October 08, 2007
UYA, you may be onto something there! Kind of like the way we saw multiple vortices associated with 93L and that broad area of low pressure, too.

It's still a bit early, but for development to proceed, 94L has to procure an llc from somewhere!
Member Since: July 9, 2006 Posts: 184 Comments: 29594
403. WPBWeatherBoy
8:31 PM GMT on October 08, 2007
would a strong la niña make south florida colder than average or higher than average?
Member Since: August 27, 2007 Posts: 4 Comments: 104

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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.