Caribbean disurbance 96L nearly a depression; hottest day ever in Los Angeles

By: Dr. Jeff Masters , 1:54 PM GMT on September 28, 2010

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Pressures continue to fall over the Western Caribbean this morning as a strong tropical disturbance (96L) organizes. Surface observations suggest that 96L has a large circulation covering most of the Western Caribbean, as evidenced by winds out of the southwest sustained at 29 - 34 mph observed at Buoy 42057 to the southeast of 96L's center this morning. Rotation of 96L can be seen on radar loops out of Pico San Juan, Cuba, and well as satellite imagery. The heavy thunderstorms are currently quite disorganized, but are bringing torrential rains to the Cayman Islands, Jamaica, Cuba, and Honduras. A Personal Weather Station in George Town on Grand Cayman Island has picked up 3.64" of rain in the twelve hours ending at 8am this morning. 96L is not the typical sort of disturbance one sees in the Atlantic, since it is much larger than normal. What has happened is that the atmospheric flow pattern of the Eastern Pacific has shifted eastwards into the Western Caribbean, bringing in the Eastern Pacific ITCZ (Intertropical Convergence Zone, a region of converging surface winds that creates a band of strong thunderstorms). 96L resembles the "monsoon depressions" common in India's Bay of Bengal or the Western Pacific. A monsoon depression is similar to a regular tropical depression in the winds that it generates--about 30 - 35 mph near the outer edges (and usually stronger on the eastern side of the circulation.) Monsoon depressions have large, calm centers, and can evolve into a regular tropical storms, if given enough time over water to develop a tight, closed circulation. The Hurricane Hunters are scheduled to fly into 96L this afternoon near 2pm EDT to see if it has become a tropical depression.


Figure 1. Morning radar image of 96L. Image credit: Cuban Institute of Meteorology.

Forecast for 96L
Because 96L is so large and lacks a well-defined surface circulation, it will take more time than a typical disturbance for it to spin up into a strong tropical storm. Given that the steering currents are expected to pull 96L north-northeastwards over Cuba and into South Florida and the western Bahamas on Wednesday, the storm lacks sufficient time over water to be any stronger than a 55 mph tropical storm for Florida. I think the top winds in Southeast Florida are likely to be in the 30 - 45 mph range on Wednesday. By the time 96L makes landfall in North Carolina or South Carolina on Thursday morning or afternoon, it could be as strong as a 55 - 65 mph tropical storm, but I think it is only 20% likely that 96L will make it to hurricane strength on Thursday. The primary danger from the storm is heavy rainfall. A potent upper-level low and stationary front over the U.S. East Coast have been bringing moist, tropical air from the Caribbean northwards over the past few days, bringing heavy rains that have saturated the soils. Wilmington, NC received 10.33 inches of rain yesterday, its second greatest one-day rainfall since record keeping began in 1871. Only the 13.38" that fell during Hurricane Floyd on September 15, 1999 beat yesterday's rainfall total. With 96L expected to bring another 6 - 8 inches of rain to the region later this week, serious flooding is likely, and flash flood watches are posted for the North Carolina/ South Carolina border region. South Florida is also under a flood watch, for 3 - 5 inches of rain. Flooding rains of similar magnitude can also be expected in Cuba, the Cayman Islands, and the Western Bahamas through Wednesday night.


Figure 2. Radar-estimated precipitation since Saturday for the North Carolina/South Carolina border region. Widespread rain amounts of 5 - 10 inches have occurred.


Figure 3. Forecast precipitation for the 5-day period from 8am today through 8am EDT Sunday, October 3, 2010. Image credit: NOAA Hydrometeorological Prediction Center.

Elsewhere in the tropics
Once 96L moves out of the Caribbean, the GFS model predicts that the Western Caribbean will "reload" and produce another tropical disturbance capable of developing into a tropical depression late this week or early next week. The other models are not showing this, but do predict a continuation of the disturbed weather pattern over the Western Caribbean. A second disturbance, if it develops, would be subject to similar steering currents, and may also move northwards across Cuba, Florida, and the Bahamas, then up the U.S. East Coast. This second disturbance might be more dangerous, since it would be dumping heavy rains on regions already drenched by 96L.

Hottest day in Los Angeles history
The mercury hit a blistering 113°F (45.0°C) at 12:15 pm PDT yesterday in downtown Los Angeles, making it the hottest day in Los Angeles history. It may have gotten hotter, but the thermometer broke shortly after the record high was set. The previous record in Los Angeles was 112°F set on June 26, 1990; records go back to 1877. Nearby Long Beach tied its hottest all-time temperature yesterday, with a scorching 111°F. And Christopher C. Burt, our new featured blogger on weather records, pointed out to me that Beverly Hills hit 119°F yesterday--the hottest temperature ever measured in the Los Angeles area, tying the 119°F reading from Woodland Hills on July 22, 2006. Yesterday's record heat was caused by an unusually large and intense upper-level high pressure system centered over Nevada that generated winds blowing from the land to the ocean, keeping the ocean from exerting its usual cooling influence. Remarkably, Los Angeles had its second coldest summer on record this year, and temperatures just five days ago were some the coldest September temperatures in the region for the past 50 years.

The remarkable summer of 2010
Wunderground is pleased to welcome a new featured blogger--weather historian Christopher C. Burt. Chris is a leading expert in the U.S. on weather records, and is author of the world's most popular weather records book published to date, Extreme Weather: A Guide and Record Book. He's spent a lifetime collaborating with like-minded individuals from around the world, and no one--including official sources such as the National Climatic Data Center and the National Extremes Committee--has done as thorough a job correlating the various weather records available and determining the most accurate extreme values of such. Each month he'll be reporting on the notable records for heat, cold, and precipitation set world-wide, and his first post takes a look at the remarkable summer of 2010. It's great to have someone like Chris who stays on top of weather extremes, and I hope you'll pay a visit to his blog and welcome him to the wunderground site!

"Hurricane Haven" airing this afternoon
My live Internet radio show, "Hurricane Haven", will be airing again today at 4pm EDT. The call in number is 415-983-2634, or you can post a question to broadcast@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line.

Today's show will be about 30 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.

I'll have updates as the situation with 96L requires.

Jeff Masters

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197. afj3
Quoting bballerf50:


Wrong. It would be warnings for everyone. It would be here tomorrow.

Is it possible that warnings and watches won't even be necessary for Florida?
Member Since: June 10, 2008 Posts: 0 Comments: 346
Quoting FSUstormnut:

warnings for cuba.. watchs for FL


Wrong. It would be warnings for everyone. It would be here tomorrow.
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Quoting CajunTexan:
The storm that could have been,
If it only had more time to form,
But continuing the trend,
It won't be more than a Tropical Storm,
Disappointment for the wishcasters,
As the U.S. escapes a hurricane yet again,
They wait for another potential disaster,
And discuss what could have been,
But the storms are getting nearer,
As the season is at its peak,
And the pattern couldn't be clearer,
Florida will get their storm next week,
And the blog will get rough,
Downcasters and Wishcasters will surely fight,
They will both huff and puff,
And argue about who was wrong and who was right,
The more things change,
The more they stay the same,
Another storm is in the short range,
And the blog is never tame,
The only thing you can count on,
Every day somehow some way,
Is Dr. Masters dialy update,
And Cajun's poem Of The Day.







Thanks Dr. Seuss!
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Quoting caneswatch:


I think that once 5 pm rolls around, expect the cancellations to come.


You hope. How you doing, Canes? Got all your supplies ready?
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193. 7544
yeap yeap could we see a center relocate when the plane goes in ?
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Quoting myway:


They will not close on a watch. They may close on a warning. Check you local school district website.


Here in Flagler County in 2005, when I was a senior in HS, we NEVER closed on Tropical Storms. Ophelia was off the coastline, had warnings, but school was still in session. Tammy as well, although Wilma caused a scare here and they closed.
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Quoting FSUstormnut:

warnings for cuba.. watchs for FL


Sound right. With warnings for FL and the Bahamas at 5 pm
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Quoting FSUstormnut:

warnings for cuba.. watchs for FL


I can agree with that.
Member Since: June 29, 2007 Posts: 0 Comments: 1136
Navy has 16 up

Link
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TS watches/warnings will more than likely go up @ 11 since they expect the worst weather to be tonight into tomorrow night for south florida
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Quoting kwgirl:
Not that I want to jinx us down south here, but I am hoping you are correct and the Lower Keys only sees light rain. I don't want to have to swim home LOL
And you would too! Seems like anytime it rains in KW the streets flood...gotta be one of the worst drainage areas of all time!
Member Since: September 10, 2010 Posts: 3 Comments: 409
185. myway
Quoting weatherman12345:

you think kids will have school tommorrow


They will not close on a watch. They may close on a warning. Check you local school district website.
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Quoting cat5hurricane:
If a Carolina track does indeed pan out, it's definitely not good news for us folks in SE SC given all the drenching rain the past 48 hours.

Flash flood watches already posted:

Link


Just got home and noticed the sump pumps along the street are still busy. Fingers crossed for a track more to the east!
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Quoting HurricaneGeek:


There are going to be watches/warning posted for Cuba 100%, wether there will be for FL, remains to be seen. Especailly with it's slow speed.
We shall see.

warnings for cuba.. watchs for FL
Member Since: June 10, 2005 Posts: 0 Comments: 323
Quoting weatherman12345:

you think kids will have school tommorrow

Not in south Florida, but it ususally takes them quite a while to actually announce it.
Member Since: June 29, 2007 Posts: 0 Comments: 1136
Quoting 7544:
15 mins peeps td16 will be posted by the nhc not sure on watches tho they might wait till 5 pm


There are going to be watches/warning posted for Cuba 100%, wether there will be for FL, remains to be seen. Especailly with it's slow speed.
We shall see.
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I expect to see TS warnings for Cuba and Watches for Florida (Keys to Daytona Beach) Based on the model cluster, you really can't leave Central Florida out of it.
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175. myway
Quoting weatherman12345:
if south flordia has a tropical storm warning or watc at 11:00am then will schools be closed?


No
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174. 7544
15 mins peeps td16 will be posted by the nhc not sure on watches tho they might wait till 5 pm
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I'm still seeing a circulation near Yucatan with some banding, possible it's own separate entity, maybe Otto in the future? Possible.
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Quoting Seflhurricane:
expect Tropical storm Warnings to be issued from the middle florida keys northward to vero beach,fl
Not that I want to jinx us down south here, but I am hoping you are correct and the Lower Keys only sees light rain. I don't want to have to swim home LOL
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Quoting TOMSEFLA:
when the nhc write the first advisory a tropical storm warning will have to go up for sfla correct?


If they expect it to reach that intensity, yes, we're within 48hrs.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
170. JRRP
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Quoting weatherman12345:
if south flordia has a tropical storm warning or watc at 11:00am then will schools be closed?


I think that once 5 pm rolls around, expect the cancellations to come.
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Thanks for the link to the Navy site all.
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LMAO
Member Since: June 10, 2005 Posts: 0 Comments: 323
128 kwgirl:

It would be interesting to see the extent of that low.

That's also an area that could sustain that scenario. Problem is having a disturbance remain stationary for the length of time it would need to develope.
Member Since: January 6, 2009 Posts: 0 Comments: 217
Quoting barotropic:


I dont believe that. I dont think its the remains of matthew at all. JMO.


Ex-Matthew is still over Mexico.
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when the nhc write the first advisory a tropical storm warning will have to go up for sfla correct?
Quoting weatherman12345:
if south flordia has a tropical storm warning or watc at 11:00am then will schools be closed?


Shouldnt you be in school now? lol
Member Since: June 29, 2007 Posts: 0 Comments: 1136
Quoting divdog:
td 16 is listed on the navy site.

Yes it is. We will see it at 11 am
Member Since: June 29, 2007 Posts: 0 Comments: 1136
159. 7544
its drifing north center just south of western cuba so if it goes over there it may not weaken that fast so fla can get more than what peeps are posting here lol

waiting on the first cone that should settle it all down
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Quoting houston144:
for me this is the perfect example of whats wrong with the way systems are tracked, 96L is the remains of Matthew we all watched him pull a 180 and head back out south of cuba...so why the 96L?

Any one notice anything weird the last two days around Dallas Texas?


I dont believe that. I dont think its the remains of matthew at all. JMO.
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Quoting GoodOleBudSir:


Yes, the Cowboys won. LOL


lol
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Quoting CajunTexan:
And Cajun's poem Of The Day.









Awesome CT, always! LOL
Member Since: September 10, 2010 Posts: 3 Comments: 409
Is the HH in the system yet?
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Everyone needs to be patient for anther 5 or 6 hours, until the models can initialize a true track-able center. The exact location of landfall could be off 150+ miles from what models show now. Additionally, the front could retro-grade further impacting the situation. I expect a few more surprises....to me this part (storm forming to TD and Name) is the most exciting part to watch.
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Convection is gettig stronger over the Center.
It kind of looks likes its bridging the 2 blobs.
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Quoting TOMSEFLA:
checked the navy site and it is still listed as 96l.
td 16 is listed on the navy site.
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Regardless this system moving Northeast will be going through 30 knots of shear.
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Quoting StormChaser81:


Stationary will allow it to get it's act together.

Probably a Bad thing. Faster it gets moving the more likely less rain and wind.


Ty.. I thought so, but I just wanted to make sure.
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http://www.nrlmry.navy.mil/tc_pages/tc_home.html
navy site
Member Since: June 10, 2005 Posts: 0 Comments: 323
Quoting GoodOleBudSir:
Can somebody just post a link to the Navy site showing TD16?

Link
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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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