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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Quoting GoodOleBudSir:
Can somebody just post a link to the Navy site showing TD16?

Link
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Can somebody just post a link to the Navy site showing TD16?
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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?
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Quoting tacoman:
no gamma when all is said and done i truly doubt miami gets more then and inch of rain...


We already have an inch of rain today.
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WV shows the front stalling across florida.
If the front erodes or moves north the storm
may move up over the middle of the state.
moisture is building to the north of our TD
up across Florida.
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142. A4Guy
16L is up on the Navy site...has been for about 30 mins.
Quoting TOMSEFLA:
checked post navy listed as 96l. if it were a td it would be td15 correct


16L is up on the Navy site...has been for about 30 mins.
Member Since: June 23, 2006 Posts: 0 Comments: 668
Quoting lurkn4yrs:


Is this a good or a bad thing?


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.
Member Since: August 11, 2008 Posts: 0 Comments: 2315
Quoting TOMSEFLA:
checked post navy listed as 96l. if it were a td it would be td15 correct

I believe Matthew was 15.
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Mexico City, Mexico (CNN) -- Up to 1,000 people may have been trapped by a landslide in the southwestern Mexico state of Oaxaca, Gov. Ulises Ruiz said Tuesday morning.

A hill about 650 feet wide (200 meters) collapsed early Tuesday, sending tons of mud atop up to 300 houses, Ruiz told CNN affiliate Televisa.

Rescue officials, heavy machinery as well as police and military authorities were on their way to the scene, Ruiz said.
Member Since: August 18, 2008 Posts: 0 Comments: 474
Quoting lurkn4yrs:


Is this a good or a bad thing?


Its just OK.......
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Quoting HurricaneGeek:
People get caught off gaurd even when we have 5 days notice, let alone 2 days.
In PBC, school busses don't go if sustained winds are 30 or 35 I can't remember. But wether there is a Watch or Warning posted, has no effect on the closing of schools.

School has been in sesion under a TS watch before, and even a TS warning, when it was posted later in the day.
But things like sports and clubs after school get canceled.

I think this happened with FAY in 2008.
I'm just speaking for Palm Beach Co.


Fay cancelled school in PBC for a day. After the first day Monday, conditions got worse in the later evening hours, but before that arrived, Tuesday classes were cancelled. Classes resumed Wednesday.
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Quoting yacoub:

Where are you quoting that from? I want to see the pic but I cannot find any posts by a utilaeastwind.


Yes that was it. At about 4:45 am the wind switched from North to South West.

We moved our boats at 3:00am and that was too close.

The Chief was a good sport about it and now has the boat and engine on land.

www.utilaeastwind.com for pics

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Quoting seflagamma:
I remember times in the past when the glades were flooded so badly lots of deer got caught on this tiny islands that then went under water.. the deer died because they could not find dry land.. and if they do not die they get hoof infections due to the wet grounds they live on for weeks at a time.

You could drive along the interstate highways and see all the deer trying to stay on the higher grounds along the highways...and m any got killed by cars that did not see them.

Same thing for other "dry land" critters like the panthers and bears, etc.


I remember this very well. If you put this together with the next post about the flood gates not being opened yet, there could be a similar occurrence except this storm is not expected over the Lake or Glades or will it? No true path has been determined at this time.
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Quoting sammywammybamy:
Expect a Tornado Watch issued for south florida tonight as well.



Good heads up, Sammy.

Now's a great time to check your weather alert radio to ensure it works and the batteries are fresh...
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Such a broad LLC. 170-180 miles across.
Member Since: August 11, 2008 Posts: 0 Comments: 2315
expect Tropical storm Warnings to be issued from the middle florida keys northward to vero beach,fl
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Quoting StormChaser81:


I'd say stationary or maybe like 1-2 mph north.


Is this a good or a bad thing?
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Quoting BLee2333:
Hmm, I wonder if that means if all that energy were able to remain stationary instead of wandering into Cuba, it had the potential to develope into an unprecedented Atlantic storm?

A "Superhurricane", as in Pacific style?!

I didn't think the Atlantic was capable of a monsoonal depression of that magnitude, so never considered one.

I'm NOT saying that this scenario will play out, however it's one that I may not rule out down the road as a possibility if the conditions suggest a lengthy stall over favorable conditions... You have to remember, the currents in that area would replenish any lowered SSTs due to the storm. As long as you have the fuel and it stays over water long enough... Highly unlikely, but could rewrite the books for a "perfect storm".

Anyhow, I'm done rambling. Any thoughts?
Well, we had a monsoonal event in Key West. It was Veterans Day weekend and Key West had 23" in 24 hours. And I finally understood what it meant to have a monsoonal downpour. You could hardly breathe outside the rain was falling so hard. It was in 1979 or 1980 I believe because my daughter was in nursery school. When I picked her up early the waves were breaking over my Chevy Nova's hood. the only thing keeping that car from stalling was my feet on the gas and brakes at the same time.
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will likely see trop strm warning and watches for S florida, keys and SE florida at 11am.
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Quoting medic2luv:

See post #70
checked post navy listed as 96l. if it were a td it would be td15 correct
Quoting TOMSEFLA:
checked the navy site and it is still listed as 96l.

You should also see 16L Sixteen, that's TD16.
Link
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123. 7544
drifting north ?
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Quoting TOMSEFLA:
checked the navy site and it is still listed as 96l.
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121. cre13
Thanks for the info! It's been pouring here in NE NC for 2 days now, even had some pretty good winds yesterday associated with a line of t-storms that were worse than what we had with Earl. More wind and rain is not a good thing for the region.
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Quoting HurricaneGeek:
How fast does TD16 appear to be moving? I does not seem very fast by looking at Loop


I'd say stationary or maybe like 1-2 mph northeastern.
Member Since: August 11, 2008 Posts: 0 Comments: 2315
Quoting 7544:
hate to say this but the blob south of cuba looks like a strong ts right now could this be a sep system . as it drits north looks like some nasty stuff going on in there tia


Bouys under that blob suggest sustained winds of appx 27knts and gusts to 33knts. Pressure under that convection is about 2 mbs higher that the surrounding areas to north and west where winds are much lighter.
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checked the navy site and it is still listed as 96l.
How fast does TD16 appear to be moving? I does not seem very fast by looking at Loop
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114. srada
Now it looks like we may have rain up until friday..system may linger over our area..great!!

FORECAST SOUNDINGS KEEP PRECIPITABLE WATER VALUES OVER 2
INCHES WED AND WED NIGHT TOPPING OUT AT 2.74 INCHES THU MORNING.
FOUS PRECIP TOTALS FOR WED AND WED NIGHT APPROACH 4 INCHES AT ILM.

HAVE LESS CONFIDENCE CONCERNING FORECAST FOR THU. ECMWF IS SLOWER TO
MOVE THE SYSTEM OUT OF SOUTHERN FL WHICH RESULTS IN PRECIP LINGERING
INTO THU AFTERNOON/EVENING. THE 00Z NAM/GFS/CANADIAN HAVE SIMILAR
TIMING CONCERNING THE LOW...BUT THE GFS/CANADIAN KEEP THE FARTHER
EAST AND ARE MORE PROGRESSIVE WITH THE UPPER TROF...KICKING THE
FRONT OFFSHORE AND BRINGING DRIER AIR INTO THE REGION ON THU. LATEST
FORECAST FAVORS A BLEND OF THE NAM/GFS/CANADIAN SOLUTIONS...HOLDING
ONTO CLOUDS AND PRECIP INTO THU BUT KEEPING HIGHEST POPS CONFINED TO
THE IMMEDIATE NC COAST. THIS IS LINE WITH PREVIOUS FORECAST.

ABUNDANT CLOUDS AND PRECIP WILL KEEP HIGH TEMPERATURES NEAR TO
SLIGHTLY ABOVE CLIMO AND HELP KEEP LOWS ABOVE TO WELL ABOVE CLIMO.

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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



That is going to be 16's calling card, the rain. There's going to be a lot of flooding up the coast, especially if they keep coming like the GFS forecasts.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Complete Update


AOI
AOI AOI AOI

AOI AOI AOI

TS BUSTED FORECAST ALIBI
Member Since: October 1, 2007 Posts: 81 Comments: 26516
Quoting seflagamma:
I am still not fully convenced this system will form a TS before it comes to South Florida, possibly before going to the Carolina's it may have time ..but it is really big and wide to "tighten up" before our area.

I agree with Dr Jeff, a lot of rain and some wind but nothing serious....and most of the models keep it off shore so we may not even get that much rain.


but I am talking about this system, and I could be wrong b ut nothing is really panning out as predicted last weekend for mid week.
It looks like most of the rain will be east of florida with this system being right side loaded.
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Quoting tacoman:
gamma it will have tropical storm force winds in heavier squalls but miami will get the least of the weather due to the tropical depression passing to the south of miami....


we can get wind gusts like that in any afternoon thunderstorm.. that knock down weak tree branches or cleans up our palm trees from the dead fronds that are hanging on...

but that is nothing they will close schools or business for at all...

I hope we do not get the flooding; that is a mess.
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Quoting HurricaneGeek:


The HH don't fly over foregin country's land as far as I know.
For years the HH have not flown over Cuba. Maybe with things loosening up and it would be to their benefit, maybe they will. But I think they don't fly into a storm over land, just in case.....I don't want to put my mouth on it:|
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Quoting 7544:
hate to say this but the blob south of cuba looks like a strong ts right now could this be a sep system . as it drits north looks like some nasty stuff going on in there tia


Rotation is northwest of that area. That's on the southeast side of the Low.
Member Since: August 11, 2008 Posts: 0 Comments: 2315
Quoting Seflhurricane:
we have Tropical Depression 16
Where is this posted? tia
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Quoting TOMSEFLA:
has anyone checked the navy site?
they will post a td before nhc advisory

See post #70
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Ok thanks.
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af recon can fly over cuba with there
permission.
we have Tropical Depression 16
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101. 7544
hate to say this but the blob south of cuba looks like a strong ts right now could this be a sep system . as it drits north looks like some nasty stuff going on in there tia
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Quoting RobbWilder:


You are absolutely right. Business will be open and school in session. The only ones that will make benefit from this will be body shops and repair shops.
The NHC having to be conservative is not good. But you mean the weather mets on TV and radio have been making no mention of this?
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Hmm, I wonder if that means if all that energy were able to remain stationary instead of wandering into Cuba, it had the potential to develope into an unprecedented Atlantic storm?

A "Superhurricane", as in Pacific style?!

I didn't think the Atlantic was capable of a monsoonal depression of that magnitude, so never considered one.

I'm NOT saying that this scenario will play out, however it's one that I may not rule out down the road as a possibility if the conditions suggest a lengthy stall over favorable conditions... You have to remember, the currents in that area would replenish any lowered SSTs due to the storm. As long as you have the fuel and it stays over water long enough... Highly unlikely, but could rewrite the books for a "perfect storm".

Anyhow, I'm done rambling. Any thoughts?
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#71, thanks for posting that.. that is so sad.
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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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